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We present a comprehensive analysis of a planetary microlensing event OGLE-2015-BLG-1609. The planetary anomaly was detected by two survey telescopes, OGLE and MOA. Each of these surveys collected enough data over the planetary anomaly to allow for an unambiguous planet detection. Such survey detections of planetary anomalies are needed to build a robust sample of planets that could improve studies on the microlensing planetary occurrence rate by reducing biases and statistical uncertainties. In this work, we examined different methods for modeling microlensing events using individual datasets, particularly we incorporated a Galactic model prior to better constrain poorly defined microlensing parallax. Ultimately, we fitted a comprehensive model to all available data, identifying three potential typologies, with two showing comparably high Bayesian evidence. Our analysis indicates that the host of the planet is a brown dwarf with a probability of 34%, or a low-mass stellar object (M-dwarf) with the probability of 66%., Comment: 12 pages, 7 figures

Stellar theory enables us to understand the properties of stars at different stages of their evolution, and contributes to other fields of astrophysics such as galactic and exoplanet studies. Assessing the accuracy of stellar theories necessitates high precision, model-independent measurements of the properties of real stars, such as those obtainable for the components of double lined eclipsing binaries (DLEBs), while asteroseismology offers probing power of the stellar interior if one or both components pulsate. KIC 4851217 is a DLEB containing two late A-type stars and exhibits pulsations of the $\delta$ Scuti type. By analysing high resolution HERMES and moderate resolution ISIS spectra, jointly with Kepler and TESS light curves, we measured the masses, radii and effective temperatures of the components to precisions of ~0.5, ~1.1 and ~1 per cent, respectively. We additionally report the discovery and characterisation of a tertiary M-dwarf companion. Models of the system's spectral energy distribution agree with an age of 0.82 Gyr, with the more massive and larger secondary component near the end of the main sequence lifetime. An examination of the pulsating component's pulsation frequencies reveals 39 pulsation multiplets that are split by the orbital frequency. For most of these, it is evident that the pulsation axes have been tilted into the orbital plane. This makes KIC 4851217 a tidally tilted pulsator (TTP). This precisely characterized $\delta$ Scuti DLEB is an ideal candidate for advancing intermediate-mass stellar theory, contributing to our understanding of hierarchichal systems as well as to the topic of TTPs., Comment: 23 pages

Context. High frame-rate imaging was employed to mitigate the effects of atmospheric turbulence (seeing) in observations of globular cluster Terzan 5. Aims. High-precision time-series photometry has been obtained with the highest angular resolution so far taken in the crowded central region of Terzan 5, with ground-based telescopes, and ways to avoid saturation of the brightest stars in the field observed. Methods. The Electron-Multiplying Charge Coupled Device (EMCCD) camera installed at the Danish 1.54-m telescope at the ESO La Silla Observatory was employed to produce thousands of short-exposure time images (ten images per second) that were stacked to produce the normal-exposure-time images (minutes). We employed difference image analysis in the stacked images to produce high-precision photometry using the DanDIA pipeline. Results. Light curves of 1670 stars with 242 epochs were analyzed in the crowded central region of Terzan 5 to statistically detect variable stars in the field observed. We present a possible visual counterpart outburst at the position of the pulsar J1748-2446N, and the visual counterpart light curve of the low-mass X-ray binary CX 3. Additionally, we present the discovery of 4 semiregular variables. We also present updated ephemerides and properties of the only RR Lyrae star previously known in the field covered by our observations in Terzan 5. Finally, we report a significant displacement of two sources by ~0.62 and 0.59 arcseconds with respect to their positions in previous images available in the literature., Comment: 22 pages, 18 figures, 7 tables. Accepted for publication in A&A

The binary star NY Hya is a bright, detached, double-lined eclipsing system with an orbital period of just under five days with two components each nearly identical to the Sun and located in the solar neighbourhood. The objective of this study is to test and confront various stellar evolution models for solar-type stars based on accurate measurements of stellar mass and radius. We present new ground-based spectroscopic and photometric as well as high-precision space-based photometric and astrometric data from which we derive orbital as well as physical properties of the components via the method of least-squares minimisation based on a standard binary model valid for two detached components. Classic statistical techniques were invoked to test the significance of model parameters. Additional empirical evidence was compiled from the public domain; the derived system properties were compared with archival broad-band photometry data enabling a measurement of the system's spectral energy distribution that allowed an independent estimate of stellar properties. We also utilised semi-empirical calibration methods to derive atmospheric properties from Str\"{o}mgren photometry and related colour indices. Data was used to confront the observed physical properties with classic and magnetic stellar evolution models., Comment: 34 pages, 19 figures, 13 tables, (accepted for publication in A&A)

We update the ephemerides of 16 transiting exoplanets using our ground-based observations, new TESS data, and previously published observations including those of amateur astronomers. All these light curves were modeled by making use of a set of quantitative criteria with the EXOFAST code to obtain mid-transit times. We searched for statistically significant secular and/or periodic trends in the mid-transit times. We found that the timing data are well modeled by a linear ephemeris for all systems except for XO-2 b, for which we detect an orbital decay with the rate of -12.95 $\pm$ 1.85 ms/yr that can be confirmed with future observations. We also detect a hint of potential periodic variations in the TTV data of HAT-P-13 b which also requires confirmation with further precise observations., Comment: 23 pages, 17 figures

Our aim in this paper is to refine the orbital and physical parameters of the HATS-2 planetary system and study transit timing variations and atmospheric composition thanks to transit observations that span more than ten years and that were collected using different instruments and pass-band filters. We also investigate the orbital alignment of the system by studying the anomalies in the transit light curves induced by starspots on the photosphere of the parent star. We analysed new transit events from both ground-based telescopes and NASA's TESS mission. Anomalies were detected in most of the light curves and modelled as starspots occulted by the planet during transit events. We fitted the clean and symmetric light curves with the JKTEBOP code and those affected by anomalies with the PRISM+GEMC codes to simultaneously model the photometric parameters of the transits and the position, size, and contrast of each starspot. We found consistency between the values we found for the physical and orbital parameters and those from the discovery paper and ATLAS9 stellar atmospherical models. We identified different sets of consecutive starspot-crossing events that temporally occurred in less than five days. Under the hypothesis that we are dealing with the same starspots, occulted twice by the planet during two consecutive transits, we estimated the rotational period of the parent star and, in turn the projected and the true orbital obliquity of the planet. We find that the system is well aligned. We identified the possible presence of transit timing variations in the system, which can be caused by tidal orbital decay, and we derived a low-resolution transmission spectrum., Comment: 23 pages, 21 figures, Accepted for publication in Astronomy & Astrophysics

The atmospheric characterisation of hot and warm Neptune-size exoplanets is challenging due to their small radius and atmospheric scale height. The warm-Neptune HAT-P-11b is a remarkable target for such characterisation due to the large brightness of its host star (V=9.46 mag; H=7.13 mag). The aims of this work are to review the main physical and architectural properties of the HAT-P-11 planetary system, and to probe the presence of 8 molecular species in the atmosphere of HAT-P-11b at high spectral resolution in the near-infrared. The planetary system was reviewed by analysing transits and occultations of HAT-P-11b from the Kepler data set as well as HIRES at Keck archival radial-velocity (RV) data. We modelled the latter with Gaussian-process regression and a combined quasi-periodic and squared-exponential kernel to account for stellar variations on both (short-term) rotation and (long-term) activity-cycle timescales. In order to probe the atmospheric composition of HAT-P-11b, we observed 4 transits of this target with GIANO-B at TNG. We find that the long-period ($P\sim9.3$ years) RV signal previously attributed to planet HAT-P-11c is more likely due to the stellar magnetic activity cycle. Nonetheless, the Hipparcos-Gaia difference in the proper-motion anomaly suggests that an outer-bound companion might still exist. For HAT-P-11b, we measure a radius $R_{\rm p}=0.4466\pm0.0059\,R_{\rm J}$, a mass $M_{\rm p}=0.0787\pm0.0048\,M_{\rm J}$, and an eccentricity $e=0.2577^{+0.0033}_{-0.0025}$, in accordance with values in the literature. Probing its atmosphere, we detect $NH_3$ (S/N$=5.3$, significance$=5.0\sigma$) and confirm the presence of $H_2O$ (S/N$=5.1$, significance$=3.4\sigma$). We also tentatively detect the signal of $CO_2$ (S/N$=3.0$, significance$=3.2\sigma$) and $CH_4$ (S/N$=4.8$, significance$=2.6\sigma$), whose presence need to be confirmed by further observations., Comment: 25 pages, 19 figures, accepted for publication in Astronomy & Astrophysics (A&A) journal. Version corrected by the language editor, title edited

Abridged. Eclipsing spectroscopic double-lined binaries are the prime source of precise and accurate measurements of masses and radii of stars. These measurements provide a stringent test of models of stellar evolution that are persistently reported to contain major shortcomings. The mass discrepancy observed for the eclipsing spectroscopic double-lined binaries is one of the manifestations of shortcomings in stellar evolution models. Our ultimate goal is to provide an observational mapping of the mass discrepancy and propose a recipe for its solution. We initiate a spectroscopic monitoring campaign of 573 candidate eclipsing binaries of which 83 are analysed in this work with the methods of least-squares deconvolution and spectral disentangling. TESS light curves are used to provide photometric classification of the systems according to the type of their intrinsic variability. We confirm 69 systems as either spectroscopic binaries or higher-order multiple systems. Twelve stars are classified as single and two more objects are found at the interface of their line profile variability being interpreted as due to binarity and intrinsic variability of the star. Moreover, 20 eclipsing binaries are found to contain at least one component that exhibits stellar oscillations. The sample presented in this work contains both detached and semi-detached systems and covers a range in the effective temperature and mass of the star of Teff = [7000,30000] K and M = [1.5,15] M_Sun, respectively. We conclude an appreciable capability of the spectral disentangling method to deliver precise and accurate spectroscopic orbital elements from as few as 6-8 orbital phase-resolved spectroscopic observations. Orbital solutions obtained this way are accurate enough to deliver age estimates with accuracy of 10% or better, an important resource for calibration of stellar evolution models., Comment: 18 pages with appendices, 5 figures. Accepted for publication in A&A

We present the discovery and validation of two TESS exoplanets orbiting nearby M dwarfs: TOI-2084b, and TOI-4184b. We characterized the host stars by combining spectra from Shane/Kast and Magellan/FIRE, SED (Spectral Energy Distribution) analysis, and stellar evolutionary models. In addition, we used Gemini-South/Zorro & -North/Alopeke high-resolution imaging, archival science images, and statistical validation packages to support the planetary interpretation. We performed a global analysis of multi-colour photometric data from TESS and ground-based facilities in order to derive the stellar and planetary physical parameters for each system. We find that TOI-2084b and TOI-4184b are sub-Neptune-sized planets with radii of Rp = 2.47 +/- 0.13R_Earth and Rp = 2.43 +/- 0.21R_Earth, respectively. TOI-2084b completes an orbit around its host star every 6.08 days, has an equilibrium temperature of T_eq = 527 +/- 8K and an irradiation of S_p = 12.8 +/- 0.8 S_Earth. Its host star is a dwarf of spectral M2.0 +/- 0.5 at a distance of 114pc with an effective temperature of T_eff = 3550 +/- 50 K, and has a wide, co-moving M8 companion at a projected separation of 1400 au. TOI-4184b orbits around an M5.0 +/- 0.5 type dwarf star (Kmag = 11.87) each 4.9 days, and has an equilibrium temperature of T_eq = 412 +/- 8 K and an irradiation of S_p = 4.8 +/- 0.4 S_Earth. TOI-4184 is a metal poor star ([Fe/H] = -0.27 +/- 0.09 dex) at a distance of 69 pc with an effective temperature of T_eff = 3225 +/- 75 K. Both planets are located at the edge of the sub-Jovian desert in the radius-period plane. The combination of the small size and the large infrared brightness of their host stars make these new planets promising targets for future atmospheric exploration with JWST., Comment: Accepted for publication in A&A

Multiple parametric limb-darkening laws have been presented, and there are many available sources of theoretical limb-darkening coefficients (LDCs) calculated using stellar model atmospheres. The power-2 limb-darkening law allows a very good representation of theoretically predicted intensity profiles, but few LDCs are available for this law from spherically symmetric model atmospheres. We therefore present such coefficients in this work. We computed LDCs for the space missions \textit{Gaia}, \textit{Kepler}, TESS, and CHEOPS and for the passbands $uvby$, $UBVRIJHK$, and SDSS $ugriz$, using the \textsc{phoenix-cond} spherical models. We adopted two methods to characterise the truncation point, which sets the limb of the star: the first (M1) uses the point where the derivative d$I(r)$/d$r$ is at its maximum where I(r) is the specific intensity as a function of the normalised radius r corresponding to $\mu_{\rm cri}$, and the second (M2) uses the midpoint between the point $\mu_{\rm cri}$ and the point located at $\mu_{\rm cri-1}$. The LDCs were computed adopting the Levenberg-Marquardt least-squares minimisation method, with a resolution of 900 equally spaced $\mu$ points, and covering 823 model atmospheres for a solar metallicity, effective temperatures of 2300 to 12000\,K, $\log g$ values from 0.0 to 6.0, and microturbulent velocities of 2\,km\,s$^{-1}$. As our previous calculations of LDCs using spherical models included only 100 $\mu$ points, we also updated the calculations for the four-parameter law for the passbands listed above, and compared them with those from the power-2 law. Comparisons between the quality of the fits provided by the power-2 and four-parameter laws show that the latter presents a lower merit function, $\chi^2$, than the former for both cases (M1 and M2). This is important when choosing the best approach for a particular science goal.

Precise measurements of stellar parameters are required in order to develop our theoretical understanding of stellar structure. These measurements enable errors and uncertainties to be quantified in theoretical models and constrain the physical interpretation of observed phenomena, such as the inflated radii of low-mass stars. We use newly-available TESS light curves combined with published radial velocity measurements to improve the characterization of 12 low mass eclipsing binaries composed of an M~dwarf accompanied by a brighter F/G star. We present and analyse ground-based simultaneous four-colour photometry for two targets. Our results include the first measurements of the fundamental properties of two of the systems. Light curve and radial velocity information were converted into the physical parameters of each component of the systems using an isochrone fitting method. We also derive the effective temperatures of the M~dwarfs, almost tripling the number of such measurements. The results are discussed in the context of radius inflation. We find that exquisite precision in the age estimation of young objects is required to determine their inflation status. However, all but three of the objects are securely located among the main sequence, demonstrating radius inflation and the necessity to develop our understanding of the complex physical processes governing the evolution of low-mass stars. We investigated the hypothesis that luminosity is unaffected by the inflation problem but the findings were not conclusive., Comment: 16 pages, 7 figures

Context. Thanks to the high-precision photometry from space missions such as Kepler and TESS, tidal perturbations and tilting of pulsations have been detected in more than a dozen binary systems. However, only two of these were g-mode pulsators. Aims. We aim to detect tidally perturbed g modes in additional binary systems and characterise them observationally. Methods. We perform a custom data reduction of the available Kepler and TESS photometry of a well-studied sample of 35 binary systems with gamma Doradus pulsators. For each target, we model the binary signal using a sum of 100 sine waves, with frequencies at orbital harmonics, and measure significant pulsation frequencies by iteratively prewhitening the residual light curve. Pulsations are labelled as tidally perturbed g modes if they are part of both period-spacing patterns and orbital-frequency-spaced multiplets. After visual inspection and confirmation, the properties of these targets and g modes are characterised. Results. We detect tidally perturbed g-mode pulsations for five short-period binaries that are circularised and (almost) synchronously rotating: KIC3228863, KIC3341457, KIC4947528, KIC9108579, and KIC12785282. Tidally perturbed g modes that occur within the same star and have the same mode identification (k,m), are found to have near-identical relative amplitude and phase modulations, which are within their respective 1-sigma uncertainties also identical for the Kepler and TESS photometric passbands. By contrast, pulsations with different mode identification (k,m) are found to exhibit different modulations. Moreover, the observed amplitude and phase modulations are correlated, indicating that the binary tides primarily distort g-mode amplitudes on the stellar surface. The phase modulations are then primarily a geometric effect of the integration of the stellar flux over the visible stellar surface. (abbreviated), Comment: 21 pages, 33 figures, 2 tables. Accepted for publication in Astronomy and Astrophysics on 17 January 2023

We investigate whether there is a variation in the orbital period of the short-period brown dwarf-mass KELT-1\,b, which is one of the best candidates to observe orbital decay. We obtain 19 high-precision transit light curves of the target using six different telescopes. We add all precise and complete transit light curves from open databases and the literature, as well as the available TESS observations from sectors 17 and 57, to form a transit timing variation (TTV) diagram spanning more than 10 years of observations. The analysis of the TTV diagram, however, is inconclusive in terms of a secular or periodic variation, hinting that the system might have synchronized. We update the transit ephemeris and determine an informative lower limit for the reduced tidal quality parameter of its host star of Q$_{\star}^{\prime} > (8.5 \pm 3.9) \times 10^{6}$ assuming that the stellar rotation is not yet synchronised. Using our new photometric observations, published light curves, the TESS data, archival radial velocities and broadband magnitudes, we also update the measured parameters of the system. Our results are in good agreement with those found in previous analyses., Comment: Accepted for publication by the MNRAS on 2023/01/16

The surface chemical compositions of stars are affected by physical processes which bring the products of thermonuclear burning to the surface. Despite their potential in understanding the structure and evolution of stars, elemental abundances are available for only a few high-mass binary stars. We aim to enlarge this sample by determining the physical properties and photospheric abundances for four eclipsing binary systems containing high-mass stars: V1034 Sco, GL Car, V573 Car and V346 Cen. The components have masses 8-17 Msun and effective temperatures from 22500 to 32200 K, and are all on the main sequence. We present new high-resolution and high signal-to-noise spectroscopy from HARPS, and analyse them using spectral disentangling and NLTE spectral synthesis. We model existing light curves and new photometry from the TESS satellite, We measure the stellar masses to 0.6-2.0 percent precision, radii to 0.8-1.7 percent precision, effective temperatures to 1.1-1.6 percent precision, and abundances of C, N, O, Mg and Si. The abundances are similar to those found in our previous studies of high-mass eclipsing binaries; our sample now comprises 25 high-mass stars in 13 binary systems. We also find tidally-excited pulsations in V346 Cen. We reinforce our previous conclusions: interior chemical element transport is not as efficient in binary star components as in their single-star counterparts in the same mass regime and evolutionary stage, possibly due to the effects of tidal forces. Our ultimate goal is to provide a larger sample of OB-type stars in binaries which would enable a thorough comparison to stellar evolutionary models, as well as to single high-mass stars., Comment: Accepted for publication in Astronomy & Astrophysics

Transmission spectroscopy of exoplanets has revealed signatures of water vapor, aerosols, and alkali metals in a few dozen exoplanet atmospheres. However, these previous inferences with the Hubble and Spitzer Space Telescopes were hindered by the observations' relatively narrow wavelength range and spectral resolving power, which precluded the unambiguous identification of other chemical species$-$in particular the primary carbon-bearing molecules. Here we report a broad-wavelength 0.5-5.5 $\mu$m atmospheric transmission spectrum of WASP-39 b, a 1200 K, roughly Saturn-mass, Jupiter-radius exoplanet, measured with JWST NIRSpec's PRISM mode as part of the JWST Transiting Exoplanet Community Early Release Science Team program. We robustly detect multiple chemical species at high significance, including Na (19$\sigma$), H$_2$O (33$\sigma$), CO$_2$ (28$\sigma$), and CO (7$\sigma$). The non-detection of CH$_4$, combined with a strong CO$_2$ feature, favours atmospheric models with a super-solar atmospheric metallicity. An unanticipated absorption feature at 4$\mu$m is best explained by SO$_2$ (2.7$\sigma$), which could be a tracer of atmospheric photochemistry. These observations demonstrate JWST's sensitivity to a rich diversity of exoplanet compositions and chemical processes., Comment: 41 pages, 4 main figures, 10 extended data figures, 4 tables. Under review in Nature

CPD-54 810 is a double-lined detached eclipsing binary containing two mid-F type dwarfs on an eccentric 26-day orbit. We perform a combined analysis of the extensive photometry obtained by the TESS space mission along with previously published observations to obtain a full orbital and physical solution for the system. We measure the following model-independent masses and radii: M1 = 1.3094+/-0.0051 Msun, M2 = 1.0896+/-0.0034 Msun, R1 = 1.9288+/-0.0030 Rsun, and R2 = 1.1815+/-0.0037 Rsun. We employ a Bayesian approach to obtain the bolometric flux for both stars from observed magnitudes, colours, and flux ratios. These bolometric fluxes combined with the stars' angular diameters (from R1, R2 and the parallax from Gaia EDR3) lead directly to the stars' effective temperatures: Teff,1 = 6462+/-43 K, and Teff,2 = 6331+/-43 K, with an additional systematic error of 0.8% (13 K) from the uncertainty in the zero-point of the flux scale. Our results are robust against the choice of model spectra and other details of the analysis. CPD-54 810 is an ideal benchmark system that can be used to test stellar parameters measured by large spectroscopic surveys or derived from asteroseismology, and calibrate stellar models by providing robust constraints on the measured parameters. The methods presented here can be applied to many other detached eclipsing binary systems to build a catalogue of well-measured benchmark stars., Comment: Accepted for publication in MNRAS. 16 pages, 9 figures, 10 tables

Surface brightness -- colour relations (SBCRs) are very useful tools for predicting the angular diameters of stars. They offer the possibility to calculate very precise spectrophotometric distances by the eclipsing binary method or the Baade-Wesselink method. Double-lined Detached Eclipsing Binary stars (SB2 DEBs) with precisely known trigonometric parallaxes allow for a calibration of SBCRs with unprecedented precision. In order to improve such calibrations, it is important to enlarge the calibration sample of suitable eclipsing binaries with very precisely determined physical parameters. We carefully chose a sample of ten SB2 DEBs in the solar neighbourhood which contain inactive main-sequence components. The components have spectral types from early A to early K. All systems have high-precision parallaxes from the Gaia mission. We analysed high precision ground- and space-based photometry simultaneously with the radial velocity curves derived from HARPS spectra. We used spectral disentangling to obtain the individual spectra of the components and used these to derive precise atmospheric parameters and chemical abundances. For almost all components, we derived precise surface temperatures and metallicities. We derived absolute dimensions for 20 stars with an average precision of 0.2% and 0.5% for masses and radii, respectively. Three systems show slow apsidal motion. One system, HD 32129, is most likely a triple system with a much fainter K6V companion. Also three systems contain metallic-line components and show strong enhancements of barium and ittrium. The components of all systems compare well to the SBCR derived before from the detached eclipsing binary stars. With a possible exception of HD 32129, they can be used to calibrate SBCRs with a precision better than 1% with available Gaia DR3 parallaxes., Comment: Accepted in Astronomy & Astrophysics, 18 pages

Near-Earth asteroid population models predict the existence of bodies located inside the orbit of Venus. Despite searches up to the end of 2019, none had been found. We report discovery and follow-up observations of (594913) 'Ayl\'o'chaxnim, an asteroid with an orbit entirely interior to Venus. (594913) 'Ayl\'o'chaxnim has an aphelion distance of ~0.65 au, is ~2 km in diameter and is red in colour. The detection of such a large asteroid inside the orbit of Venus is surprising given their rarity according to near-Earth asteroid population models. As the first officially numbered and named asteroid located entirely within the orbit of Venus, we propose that the class of interior to Venus asteroids be referred to as 'Ayl\'o'chaxnim asteroids., Comment: 7 pages, 8 figures, 1 table. Published in Monthly Notices of the Royal Astronomical Society: Letters (2022). arXiv admin note: text overlap with arXiv:2009.04125

Limb darkening is an important stellar phenomenon and must be accounted for in the study of stellar spectra, eclipsing binaries, transiting planetary systems, and microlensing events. The power-2 limb-darkening law provides a good match to the specific intensities predicted by stellar atmosphere models: it is better than other two-parameter laws and is only surpassed by the four-parameter law. Predictions of the limb-darkening coefficients for the power-2 law are not widely available. We therefore compute them, using stellar atmosphere models generated by the ATLAS (plane-parallel) code. Limb-darkening coefficients were computed for the space missions Gaia, Kepler, and TESS as well as for the photometric systems uvby, UBVRIJHK, and SDSS ugriz.The calculations were performed by adopting the Levenberg-Marquardt least-squares minimisation method and were computed with a resolution of 100 equally spaced viewing angles. We used 9586 model atmospheres covering 19 metallicities, effective temperatures of 3500 to 50000 K, log g values from 0.0 to 5.0, and microturbulent velocities of 0, 1, 2, 4, and 8 km. We confirm the superiority of the power-2 law, in terms of the quality of the fits, over other two-parameter laws. This is particularly relevant for the quadratic law, which is widely used. We recommend the use of the power-2 law in cases where a two-parameter law is needed.

Aim: We aim to refine the orbital and physical parameters and determine the sky-projected planet orbital obliquity of five eccentric transiting planetary systems: HAT-P-15, HAT-P-17, HAT-P-21, HAT-P-26, and HAT-P-29. Each of the systems hosts a hot Jupiter, except for HAT-P-26 which hosts a Neptune-mass planet. Methods: We observed transit events of these planets with the HARPS-N spectrograph, obtaining high-precision radial velocity measurements that allow us to measure the Rossiter-McLaughlin effect for each of the target systems. We used these new HARPS-N spectra and archival data, including those from Gaia, to better characterise the stellar atmospheric parameters. The photometric parameters for four of the hot Jupiters were recalculated using 17 new transit light curves, obtained with an array of medium-class telescopes, and data from the TESS space telescope. HATNet time-series photometric data were checked for the signatures of rotation periods of the target stars and their spin axis inclination. Results: From the analysis of the Rossiter-McLaughlin effect, we derived a sky-projected obliquity of 13, -26.3, -0.7, -26 degree for HAT-P-15b, HAT-P-17b, HAT-P-21b and HAT-P-29b, respectively. Due to the quality of the data, we were not able to well constrain the sky-projected obliquity for HAT-P-26b, although a prograde orbit is favoured. The stellar activity of HAT-P-21 indicates a rotation period of 15.88 days, which allowed us to determine its true misalignment angle (25 degree). Our new analysis of the physical parameters of the five exoplanetary systems returned values compatible with those existing in the literature. Using TESS and the available transit light curves, we reviewed the orbital ephemeris for the five systems and confirmed that the HAT-P-26 system shows transit timing variations, which may tentatively be attributed to the presence of a third body., Comment: 31 pages, 16 figures, Accepted for publication in Astronomy & Astrophysics

EBLM J0113+31 is moderately bright (V=10.1), metal-poor ([Fe/H]$\approx-0.3$) G0V star with a much fainter M dwarf companion on a wide, eccentric orbit (=14.3 d). We have used near-infrared spectroscopy obtained with the SPIRou spectrograph to measure the semi-amplitude of the M dwarf's spectroscopic orbit, and high-precision photometry of the eclipse and transit from the CHEOPS and TESS space missions to measure the geometry of this binary system. From the combined analysis of these data together with previously published observations we obtain the following model-independent masses and radii: $M_1 = 1.029 \pm 0.025 M_{\odot}$, $M_2 = 0.197 \pm 0.003 M_{\odot}$, $R_1 = 1.417 \pm 0.014 R_{\odot}$, $R_2 = 0.215 \pm 0.002 R_{\odot}$. Using $R_1$ and the parallax from Gaia EDR3 we find that this star's angular diameter is $\theta = 0.0745 \pm 0.0007$ mas. The apparent bolometric flux of the G0V star corrected for both extinction and the contribution from the M dwarf ($<0.2$ per cent) is ${\mathcal F}_{\oplus,0} = (2.62\pm 0.05)\times10^{-9}$ erg.cm$^{-2}$.s$^{-1}$. Hence, this G0V star has an effective temperature $T_{\rm eff,1} = 6124{\rm\,K} \pm 40{\rm \,K\,(rnd.)} \pm 10 {\rm \,K\,(sys.)}$. EBLM J0113+31 is an ideal benchmark star that can be used for "end-to-end" tests of the stellar parameters measured by large-scale spectroscopic surveys, or stellar parameters derived from asteroseismology with PLATO. The techniques developed here can be applied to many other eclipsing binaries in order to create a network of such benchmark stars., Comment: Accepted for publication in MNRAS. 15 pages, 9 figures

Context. Brown dwarfs are poorly understood transition objects between stars and planets, with several competing mechanisms having been proposed for their formation. Mass measurements are generally difficult for isolated objects but also for brown dwarfs orbiting low-mass stars, which are often too faint for spectroscopic follow-up. Aims. Microlensing provides an alternative tool for the discovery and investigation of such faint systems. Here we present the analysis of the microlensing event OGLE-2019-BLG-0033/MOA-2019-BLG-035, which is due to a binary system composed of a brown dwarf orbiting a red dwarf. Methods. Thanks to extensive ground observations and the availability of space observations from Spitzer, it has been possible to obtain accurate estimates of all microlensing parameters, including parallax, source radius and orbital motion of the binary lens. Results. After accurate modeling, we find that the lens is composed of a red dwarf with mass $M_1 = 0.149 \pm 0.010M_\odot$ and a brown dwarf with mass $M_2 = 0.0463 \pm 0.0031M_\odot$, at a projected separation of $a_\perp = 0.585$ au. The system has a peculiar velocity that is typical of old metal-poor populations in the thick disk. Percent precision in the mass measurement of brown dwarfs has been achieved only in a few microlensing events up to now, but will likely become common with the Roman space telescope., Comment: 13 pages, 6 figures

We study the transit timings of 10 exoplanets in order to investigate potential Transit Timing Variations (TTVs) in them. We model their available ground-based light curves, some presented here and others taken from the literature, and homogeneously measure the mid-transit times. We statistically compare our results with published values and find that the measurement errors agree. However, in terms of recovering the possible frequencies, homogeneous sets can be found to be more useful, of which no statistically relevant example has been found for the planets in our study. We corrected the ephemeris information of all ten planets we studied and provide these most precise light elements as references for future transit observations with space-borne and ground-based instruments. We found no evidence for secular or periodic changes in the orbital periods of the planets in our sample, including the ultra-short period WASP-103 b, whose orbit is expected to decay on an observable timescale. Therefore, we derive the lower limits for the reduced tidal quality factors (Q$^{\prime}_{\star}$) for the host stars based on best fitting quadratic functions to their timing data. We also present a global model of all available data for WASP-74 b, which has a Gaia parallax-based distance value ~25% larger than the published value., Comment: 16 pages, 5 figures, accepted for publication by the MNRAS

Context. Many well-known bright stars have been observed by the ongoing Transiting Exoplanet Survey Satellite (TESS) space mission. For several of them, these new data reveal previously unobserved variability, such as tidally perturbed pulsations in close binary stars. Aims. Using newly detected gravity-mode (g-mode) pulsations in V456 Cyg, we aim to determine the global stellar properties of this short-period eclipsing binary and evaluate the interaction between these pulsations and the tides. Methods. We model the binary orbit and determine the physical properties of the component stars using the TESS photometry and published spectroscopy. We then measure the pulsation frequencies from the residuals of the light curve fit using iterative prewhitening, and analyse them to determine the global asteroseismic stellar parameters. We evaluate the pulsation parameters as a function of the orbital phase. Results. We find that the pulsations belong to the secondary component of V456 Cyg and that this star likely has a uniform radial rotation profile, synchronous ($\nu_{\rm rot} = 1.113(14) \rm d^{-1}$) with the binary orbit ($\nu_{\rm orb} = 1.122091(8) \rm d^{-1}$). The observed g modes are amplified by almost a factor three in the stellar hemisphere facing the primary. We present evidence that this is caused by tidal perturbation of the pulsations, with the mode coupling being strongly affected. Conclusions. V456 Cyg is only the second object for which tidally perturbed high-order g-mode pulsations are identified, after $\pi^5$ Ori. This opens up new opportunities for tidal g-mode asteroseismology, as it demonstrates another avenue in which g modes and tides can interact with each other., Comment: 8 pages, 6 figures, 3 tables. Accepted for publication in Astronomy & Astrophysics on 12 January 2022

Cometary activity is a manifestation of sublimation-driven processes at the surface of nuclei. However, cometary outbursts may arise from other processes that are not necessarily driven by volatiles. In order to fully understand nuclear surfaces and their evolution, we must identify the causes of cometary outbursts. In that context, we present a study of mini-outbursts of comet 46P/Wirtanen. Six events are found in our long-term lightcurve of the comet around its perihelion passage in 2018. The apparent strengths range from $-0.2$ to $-1.6$ mag in a 5" radius aperture, and correspond to dust masses between $\sim10^4$ to $10^6$ kg, but with large uncertainties due to the unknown grain size distributions. However, the nominal mass estimates are the same order of magnitude as the mini-outbursts at comet 9P/Tempel 1 and 67P/Churyumov-Gerasimenko, events which were notably lacking at comet 103P/Hartley 2. We compare the frequency of outbursts at the four comets, and suggest that the surface of 46P has large-scale ($\sim$10-100 m) roughness that is intermediate to that of 67P and 103P, if not similar to the latter. The strength of the outbursts appear to be correlated with time since the last event, but a physical interpretation with respect to solar insolation is lacking. We also examine Hubble Space Telescope images taken about 2 days following a near-perihelion outburst. No evidence for macroscopic ejecta was found in the image, with a limiting radius of about 2-m., Comment: Accepted for publication in The Planetary Science Journal. 33 pages, 11 figures, 3 tables

We present broad-band photometry of 30 planetary transits of the ultra-hot Jupiter KELT-16b, using five medium-class telescopes. The transits were monitored through standard B, V, R, I filters and four were simultaneously observed from different places, for a total of 36 new light curves. We used these new photometric data and those from the TESS space telescope to review the main physical properties of the KELT-16 planetary system. Our results agree with previous measurements but are more precise. We estimated the mid-transit times for each of these transits and combined them with others from the literature to obtain 69 epochs, with a time baseline extending over more than four years, and searched for transit time variations. We found no evidence for a period change, suggesting a lower limit for orbital decay at 8 Myr, with a lower limit on the reduced tidal quality factor of $Q^{\prime}_{\star}>(1.9 \pm 0.8) \times 10^5$ with $95\%$ confidence. We built up an observational, low-resolution transmission spectrum of the planet, finding evidence of the presence of optical absorbers, although with a low significance. Using TESS data, we reconstructed the phase curve finding that KELT-16b has a phase offset of $25.25 \pm 14.03$ $^{\circ}$E, a day- and night-side brightness temperature of $3190 \pm 61$ K and $2668 \pm 56$ K, respectively. Finally, we compared the flux ratio of the planet over its star at the TESS and Spitzer wavelengths with theoretical emission spectra, finding evidence of a temperature inversion in the planet's atmosphere, the chemical composition of which is preferably oxygen-rich rather than carbon-rich., Comment: 17 pages, 16 figures, Accepted for publication in Monthly Notices of the Royal Astronomical Society

We report the analysis of planetary microlensing event OGLE-2018-BLG-1185, which was observed by a large number of ground-based telescopes and by the $Spitzer$ Space Telescope. The ground-based light curve indicates a low planet-host star mass ratio of $q = (6.9 \pm 0.2) \times 10^{-5}$, which is near the peak of the wide-orbit exoplanet mass-ratio distribution. We estimate the host star and planet masses with a Bayesian analysis using the measured angular Einstein radius under the assumption that stars of all masses have an equal probability to host this planet. The flux variation observed by $Spitzer$ was marginal, but still places a constraint on the microlens parallax. Imposing a conservative constraint that this flux variation should be $\Delta f_{\rm Spz} < 4$ instrumental flux units indicates a host mass of $M_{\rm host} = 0.37^{+0.35}_{-0.21}\ M_\odot$ and a planet mass of $m_{\rm p} = 8.4^{+7.9}_{-4.7}\ M_\oplus$. A Bayesian analysis including the full parallax constraint from $Spitzer$ suggests smaller host star and planet masses of $M_{\rm host} = 0.091^{+0.064}_{-0.018}\ M_\odot$ and $m_{\rm p} = 2.1^{+1.5}_{-0.4}\ M_\oplus$, respectively. Future high-resolution imaging observations with $HST$ or ELTs could distinguish between these two scenarios and help to reveal the planetary system properties in more detail., Comment: 30 pages, 11 figures, 5 tables, Accepted for publication in Astronomical Journal (AJ)

The surface brightness -- colour relation (SBCR) is a basic tool in establishing precise and accurate distances within the Local Group. Detached eclipsing binary stars with accurately determined radii and trigonometric parallaxes allow for a calibration of the SBCRs with unprecedented accuracy. We analysed four nearby eclipsing binary stars containing late F-type main sequence components: AL Ari, AL Dor, FM Leo and BN Scl. We determined very precise spectroscopic orbits and combined them with high precision ground- and space-based photometry. We derived the astrophysical parameters of their components with mean errors of 0.1% for mass and 0.4% for radius. We combined those four systems with another 24 nearby eclipsing binaries with accurately known radii from the literature for which $Gaia$ EDR3 parallaxes are available, in order to derive the SBCRs. The resulting SBCRs cover stellar spectral types from B9 V to G7 V. For calibrations we used Johnson optical $B$ and $V$, $Gaia$ $G_{\rm BP}$ and $G$ and 2MASS $JHK$ bands. The most precise relations are calibrated using the infrared $K$ band and allow to predict angular diameters of A-, F-, and G-type dwarf and subgiant stars with a precision of 1%., Comment: Accepted for publication in Astronomy & Astrophysics, 17 pages

We present a detailed study of KIC 2306740, an eccentric double-lined eclipsing binary system. Kepler satellite data were combined with spectroscopic data obtained with the 4.2 m William Herschel Telescope (WHT). This allowed us to determine precise orbital and physical parameters of this relatively long period (P=10.3 d) and slightly eccentric, ($e=0.3$) binary system. The physical parameters have been determined as $M_1 = 1.194\pm0.008$ M$_{\odot}$, $M_2 = 1.078\pm0.007$ M$_{\odot}$, $R_1 = 1.682\pm0.004$ R$_{\odot}$, $R_2 = 1.226\pm0.005$ R$_{\odot}$, $L_1 = 2.8\pm0.4$ L$_{\odot}$, $L_2 = 1.8\pm0.2$ L$_{\odot}$ and orbital seperation $a = 26.20\pm0.04$ R$_{\odot}$ through simultaneous solutions of Kepler light curves and of the WHT radial velocity data. Binarity effects were extracted from the light curve in order to study intrinsic variations in the residuals. Five significant and more than 100~combination frequencies were detected. We modeled the binary system assuming non-conservative evolution models with the Cambridge STARS (TWIN) code and we show evolutionary tracks of the components in the $\log L - \log T$ plane, the $\log R - \log M$ plane and the $\log P - \rm age$ plane for both spin and orbital periods together with eccentricity $e$ and $\log R_1$. The model of the non-conservative processes in the code led the system to evolve to the observed system parameters in roughly $5.1 $ Gyr., Comment: 9 pages, 6 figures, 7 tables. Accepted for publication in ApJ

Near-Earth asteroids (NEAs) are organized into five main classes: Amor, Apollo, Aten, Atira and 'Ayl\'{o}'chaxnim. Asteroids belonging to the 'Ayl\'{o}'chaxnim class are located entirely within the orbit of Venus making them difficult to detect by ground-based observatories. The first-known asteroid of this class, (594913) 'Ayl\'{o}'chaxnim, was discovered by the Zwicky Transient Facility (ZTF) in 2020 January during a twilight search for asteroids at small solar elongations that ran between September 2019 and January 2020. Due to its large diameter of $\sim$2 km, the discovery of (594913) 'Ayl\'{o}'chaxnim is surprising because contemporary NEA population models predict a scarcity of asteroids of this size located inside the orbit of Venus. To compare the discovery of (594913) 'Ayl\'{o}'chaxnim by ZTF with the predictions of NEA population models, we estimated the ZTF survey completeness at detecting 'Ayl\'{o}'chaxnim asteroids and the number of 'Ayl\'{o}'chaxnim asteroids expected to have been discovered by simulating observations of synthetic 'Ayl\'{o}'chaxnim asteroids. We find that the 'Ayl\'{o}'chaxnim population completeness of the survey is $\sim$18$\%$ and there is only a 5$\%$ probability that a single 'Ayl\'{o}'chaxnim asteroid would have been discovered. Given the small chance for (594913) 'Ayl\'{o}'chaxnim to have been discovered, its presence is either a statistical fluke or it implies that asteroid population models may need to be revised., Comment: 9 pages, 2 figures. Accepted for publication in Icarus

V453 Cyg is an eclipsing binary containing 14 Msun and 11 Msun stars in an eccentric short-period orbit. We have discovered $\beta$ Cep-type pulsations in this system using TESS data. We identify seven significant pulsation frequencies, between 2.37 and 10.51 d$^{-1}$, in the primary star. These include six frequencies which are separated by yet significantly offset from harmonics of the orbital frequency, indicating they are tidally-perturbed modes. We have determined the physical properties of the system to high precision: V453 Cyg A is the first $\beta$ Cep pulsator with a precise mass measurement. The system is a vital tracer of the physical processes that govern the evolution of massive single and binary stars., Comment: Accepted for publication as a Letter by MNRAS. 5 pages, 3 figures, 2 tables

We present the results of 14 nights of \textit{I}-band photometric monitoring of the nearby brown dwarf binary, $\epsilon$ Indi Ba,Bb. Observations were acquired over 2 months, and total close to 42 hours of coverage at a typically high cadence of 1.4 minutes. At a separation of just $0.7''$, we do not resolve the individual components, and so effectively treat the binary as if it were a single object. However, $\epsilon$ Indi Ba (spectral type T1) is the brightest known T-type brown dwarf, and is expected to dominate the photometric signal. We typically find no strong variability associated with the target during each individual night of observing, but see significant changes in mean brightness - by as much as $0.10$ magnitudes - over the 2 months of the campaign. This strong variation is apparent on a timescale of at least 2 days. We detect no clear periodic signature, which suggests we may be observing the T1 brown dwarf almost pole-on, and the days-long variability in mean brightness is caused by changes in the large-scale structure of the cloud coverage. Dynamic clouds will very likely produce lightning, and complementary high cadence \textit{V}-band and H\textit{$\alpha$} images were acquired to search for the emission signatures associated with stochastic "strikes." We report no positive detections for the target in either of these passbands.

We report the discovery and analysis of the planetary microlensing event OGLE-2017-BLG-0406, which was observed both from the ground and by the ${\it Spitzer}$ satellite in a solar orbit. At high magnification, the anomaly in the light curve was densely observed by ground-based-survey and follow-up groups, and it was found to be explained by a planetary lens with a planet/host mass ratio of $q=7.0 \times 10^{-4}$ from the light-curve modeling. The ground-only and ${\it Spitzer}$-"only" data each provide very strong one-dimensional (1-D) constraints on the 2-D microlens parallax vector $\bf{\pi_{\rm E}}$. When combined, these yield a precise measurement of $\bf{\pi_{\rm E}}$, and so of the masses of the host $M_{\rm host}=0.56\pm0.07\,M_\odot$ and planet $M_{\rm planet} = 0.41 \pm 0.05\,M_{\rm Jup}$. The system lies at a distance $D_{\rm L}=5.2 \pm 0.5 \ {\rm kpc}$ from the Sun toward the Galactic bulge, and the host is more likely to be a disk population star according to the kinematics of the lens. The projected separation of the planet from the host is $a_{\perp} = 3.5 \pm 0.3 \ {\rm au}$, i.e., just over twice the snow line. The Galactic-disk kinematics are established in part from a precise measurement of the source proper motion based on OGLE-IV data. By contrast, the ${\it Gaia}$ proper-motion measurement of the source suffers from a catastrophic $10\,\sigma$ error., Comment: 40 pages, 12 figures, 10 tables, accepted for publication in The Astronomical Journal

(Abridged) Eclipsing, spectroscopic double-lined binary star systems (SB2) are excellent laboratories for calibrating theories of stellar interior structure and evolution. We aim to investigate the mass discrepancy in binary stars. We study the effect of near-core mixing on the mass of the convective core of the stars and interpret the results in the context of the mass discrepancy. Two scenarios are considered, where individual stellar components of a binary system are treated independent of each other and where they are forced to have the same age and initial chemical composition. We find that the mass discrepancy is present in our sample and that it is anti-correlated with the surface gravity of the star. No correlations are found with other fundamental and atmospheric parameters, including the stellar mass. The mass discrepancy can be partially accounted for by increasing the amount of near-core mixing in stellar evolution models. We also find that ignoring the microturbulent velocity and turbulent pressure in stellar atmosphere models of hot evolved stars results in overestimation of their effective temperature by up to 8%. Together with enhanced near-core mixing, this can almost entirely account for the 30% mass discrepancy found for the evolved primary component of V380 Cyg. We find a strong link between the mass discrepancy and the convective core mass. The mass discrepancy can be solved by considering the combined effect of extra near-core boundary mixing and consistent treatment in the spectrum analysis of hot evolved stars. Our binary modelling results in convective core masses between 17 and 35% of the stellar mass, in excellent agreement with results from gravity-mode asteroseismology of single stars. This implies larger helium core masses near the end of the main sequence than anticipated so far., Comment: 22 pages (17 pages of main text + 5 pages of appendix), 14 figures. Accepted for publication in A&A

We perform a detailed study of six transiting planetary systems with relatively bright stars close enough to affect observations of these systems. Light curves are analysed taking into account the contaminating light and its uncertainty. We present and apply a method to correct the velocity amplitudes of the host stars for the presence of contaminating light. We determine the physical properties of six systems (WASP-20, WASP-70, WASP-8, WASP-76, WASP-2 and WASP-131) accounting for contaminating light. In the case of WASP-20 the measured physical properties are very different for the three scenarios considered (ignoring binarity, planet transits brighter star, and planet transits fainter star). In the other five cases our results are very similar to those obtained neglecting contaminating light. We use our results to determine the mean correction factors to planet radius, $\langle X_R\rangle$, mass, $\langle X_M\rangle$, and density, $\langle X_\rho\rangle$, caused by nearby objects. We find $\langle X_R\rangle=1.009\pm0.045$, which is smaller than literature values because we were able to reject the possibility that the planet orbits the fainter star in all but one case. We find $\langle X_M\rangle=1.031\pm0.019$, which is larger than $\langle X_R\rangle$ because of the strength of the effect of contaminating light on the radial velocity measurements of the host star. We find $\langle X_\rho\rangle=0.995\pm 0.046$: the small size of this correction is due to two effects: the corrections on planet radius and mass partially cancel; and some nearby stars are close enough to contaminate the light curves of the system but not radial velocities of the host star. We conclude that binarity of planet host stars is important for the small number of transiting hot Jupiters with a very bright and close nearby star, but it has only a small effect on population-level studies of these objects., Comment: Accepted for publication in A&A (12 pages, 7 figures, 7 tables). Version 2 includes language corrections and a revised orbital ephemeris for WASP-76

We study the multiplicity of host stars to known transiting extra-solar planets to test competing theories on the formation mechanisms of hot Jupiters. We observed 45 exoplanet host stars using VLT/SPHERE/IRDIS to search for potential companions. For each identified candidate companion we determined the probability that it is gravitationally bound to its host by performing common proper motion checks and modelling of synthetic stellar populations around the host. We detected new candidate companions around K2-38, WASP-72, WASP-80, WASP-87, WASP-88, WASP-108, WASP-118, WASP-120, WASP-122, WASP123, WASP-130, WASP-131 and WASP-137. The closest candidates were detected at separations of $0.124''\pm0.007''$ and $0.189''\pm0.003''$ around WASP-108 and WASP-131; the measured $K$ band contrasts indicate that these are stellar companions of $0.35\pm0.02\,M_{\odot}$ and $0.62^{+0.05}_{-0.04}\,M_{\odot}$, respectively. Including the re-detection and confirmation of previously known companions in 13 other systems we derived a multiplicity fraction of $55.4^{+5.9}_{-9.4}\,\%$. For the representative sub-sample of 40 hot Jupiter host stars among our targets, the derived multiplicity rate is $54.8^{+6.3}_{-9.9}\,\%$. Our data do not confirm any trend that systems with eccentric planetary companions are preferably part of multiple systems. On average, we reached a magnitude contrast of $8.5\pm0.9$ mag at an angular separation of 0.5''. This allows to exclude additional stellar companions with masses larger than $0.08$ M$_\odot$ for almost all observed systems; around the closest and youngest systems this sensitivity is achieved at physical separations as small as 10 au. The presented study shows that SPHERE is an ideal instrument to detect and characterize close companions to exoplanetary host stars., Comment: Accepted for publication in A&A (22 pages, 14 figures, 4 tables)

We present the analysis of the binary-lens microlensing event OGLE-2013-BLG-0911. The best-fit solutions indicate the binary mass ratio of q~0.03 which differs from that reported in Shvartzvald+2016. The event suffers from the well-known close/wide degeneracy, resulting in two groups of solutions for the projected separation normalized by the Einstein radius of s~0.15 or s~7. The finite source and the parallax observations allow us to measure the lens physical parameters. The lens system is an M-dwarf orbited by a massive Jupiter companion at very close (M_{host}=0.30^{+0.08}_{-0.06} M_{Sun}, M_{comp}=10.1^{+2.9}_{-2.2} M_{Jup}, a_{exp}=0.40^{+0.05}_{-0.04} au) or wide (M_{host}=0.28^{+0.10}_{-0.08} M_{Sun}, M_{comp}=9.9^{+3.8}_{-3.5}M_{Jup}, a_{exp}=18.0^{+3.2}_{-3.2} au) separation. Although the mass ratio is slightly above the planet-brown dwarf (BD) mass-ratio boundary of q=0.03 which is generally used, the median physical mass of the companion is slightly below the planet-BD mass boundary of 13M_{Jup}. It is likely that the formation mechanisms for BDs and planets are different and the objects near the boundaries could have been formed by either mechanism. It is important to probe the distribution of such companions with masses of ~13M_{Jup} in order to statistically constrain the formation theories for both BDs and massive planets. In particular, the microlensing method is able to probe the distribution around low-mass M-dwarfs and even BDs which is challenging for other exoplanet detection methods., Comment: 22 pages, 10 figures, Accepted for publication in The Astronomical Journal

The transiting exoplanetary system WASP-174 was reported to be composed by a main-sequence F star (V=11.8 mag) and a giant planet, WASP-174b (orbital period 4.23 days). However only an upper limit was placed on the planet mass (<1.3 Mj), and a highly uncertain planetary radius (0.7-1.7 Rj) was determined. We aim to better characterise both the star and the planet and precisely measure their orbital and physical parameters. In order to constrain the mass of the planet, we obtained new measurements of the radial velocity of the star and joined them with those from the discovery paper. Photometric data from the HATSouth survey and new multi-band, high-quality (precision reached up to 0.37~mmag) photometric follow-up observations of transit events were acquired and analysed for getting accurate photometric parameters. We fit the model to all the observations, including data from the TESS space telescope, in two different modes: incorporating the stellar isochrones into the fit, and using an empirical method to get the stellar parameters. The two modes resulted to be consistent with each other to within 2 sigma. We confirm the grazing nature of the WASP-174b transits with a confidence level greater than 5 sigma, which is also corroborated by simultaneously observing the transit through four optical bands and noting how the transit depth changes due to the limb-darkening effect. We estimate that ~76% of the disk of the planet actually eclipses the parent star at mid-transit of its transit events. We find that WASP-174b is a highly-inflated hot giant planet with a mass of 0.330 Mj and a radius of 1.435 Rj, and is therefore a good target for transmission-spectroscopy observations. With a density of 0.135 g/cm^3, it is amongst the lowest-density planets ever discovered with precisely measured mass and radius., Comment: 12 pages, 14 figures, Accepted for publication in Astronomy & Astrophysics

We present the analysis of stellar binary microlensing event OGLE-2015-BLG-0060 based on observations obtained from 13 different telescopes. Intensive coverage of the anomalous parts of the light curve was achieved by automated follow-up observations from the robotic telescopes of the Las Cumbres Observatory. We show that, for the first time, all main features of an anomalous microlensing event are well covered by follow-up data, allowing us to estimate the physical parameters of the lens. The strong detection of second-order effects in the event light curve necessitates the inclusion of longer-baseline survey data in order to constrain the parallax vector. We find that the event was most likely caused by a stellar binary-lens with masses $M_{\star1} = 0.87 \pm 0.12 M_{\odot}$ and $M_{\star2} = 0.77 \pm 0.11 M_{\odot}$. The distance to the lensing system is 6.41 $\pm 0.14$ kpc and the projected separation between the two components is 13.85 $\pm 0.16$ AU. Alternative interpretations are also considered., Comment: 13 pages, 5 figures, Published in MNRAS

Some M-dwarfs around F-/G-type stars have been measured to be hotter and larger than predicted by stellar evolution models. Inconsistencies between observations and models need addressing with more mass, radius and luminosity measurements of low-mass stars to test and refine evolutionary models. Our aim is to measure the masses, radii and ages of the stars in five low-mass eclipsing binary systems discovered by the WASP survey. We use WASP photometry to establish eclipse-time ephemerides and to obtain initial estimates for the transit depth and width. Radial velocity measurements were simultaneously fitted with follow-up photometry to find the best-fitting orbital solution. This solution was combined with measurements of atmospheric parameters to interpolate evolutionary models and estimate the mass of the primary star, and the mass and radius of the M-dwarf companion. We assess how the best fitting orbital solution changes if an alternative limb-darkening law is used and quantify the systematic effects of unresolved companions. We also gauge how the best-fitting evolutionary model changes if different values are used for the mixing length parameter and helium enhancement. We report the mass and radius of five M-dwarfs and find little evidence of inflation with respect to evolutionary models. The primary stars in two systems are near the ``blue hook'' stage of their post sequence evolution, resulting in two possible solutions for mass and age. We find that choices in helium enhancement and mixing-length parameter can introduce an additional 3-5\,\% uncertainty in measured M-dwarf mass. Unresolved companions can introduce an additional 3-8\% uncertainty in the radius of an M-dwarf, while the choice of limb-darkening law can introduce up to an additional 2\% uncertainty., Comment: 36 pages, 29 Figures. Accepted for publication in Section 7. Stellar structure and evolution of Astronomy & Astrophysics

We started a program to search for companions around hybrid $\delta$ Sct/$\gamma$ Dor stars with the frequency modulation method using Kepler data. Our best candidate was KIC 5709664, where we could identify Fourier peaks with sidelobes, suggesting binary orbital motion. We determined the orbital parameters with the phase modulation method and took spectroscopic measurements to confirm unambiguously the binary nature with radial velocities. The spectra show that the object is a double-lined spectroscopic binary, and we determined the orbital solutions from the radial velocity curve fit. The parameters from the phase modulation method and the radial velocity fits are in good agreement. We combined a radial velocity and phase modulation approach to determine the orbital parameters as accurately as possible. We determined that the pulsator is a hybrid $\delta$ Sct/$\gamma$ Dor star in an eccentric binary system with an orbital period of ~95 d and an eccentricity of 0.55. The measured mass ratio is 0.67. We analysed the pulsation content and extracted 38 frequencies with amplitudes greater than 20 $\mu$mag. At low frequencies, we found broad power excesses which are likely attributed to spots on the rotating surface of the lower-mass component. We inferred rotation periods of 0.56 and 2.53 d for the primary and secondary, respectively., Comment: 8 pages, 10 figures, accepted for publication in MNRAS

We report observations of the binary microlensing event OGLE-2018-BLG-0022, provided by the ROME/REA Survey, which indicate that the lens is a low-mass binary star consisting of M3 (0.375+/-0.020 Msun) and M7 (0.098+/-0.005 Msun) components. The lens is unusually close, at 0.998+/-0.047 kpc, compared with the majority of microlensing events, and despite its intrinsically low luminosity, it is likely that AO observations in the near future will be able to provide an independent confirmation of the lens masses., Comment: Accepted by AJ. 23 pages, 8 figures

We present broad-band photometry of eleven planetary transits of the hot Jupiter WASP-74b, using three medium-class telescopes and employing the telescope-defocussing technique. Most of the transits were monitored through I filters and one was simultaneously observed in five optical (U, g', r', i', z') and three near infrared (J, H, K) passbands, for a total of 18 light curves. We also obtained new high-resolution spectra of the host star. We used these new data to review the orbital and physical properties of the WASP-74 planetary system. We were able to better constrain the main system characteristics, measuring smaller radius and mass for both the hot Jupiter and its host star than previously reported in the literature. Joining our optical data with those taken with the HST in the near infrared, we built up an observational transmission spectrum of the planet, which suggests the presence of strong optical absorbers, as TiO and VO gases, in its atmosphere., Comment: 12 pages, 9 figures, accepted for publication in Monthly Notices of the Royal Astronomical Society

Two independent investigations of the atmosphere of the hot Jupiter HAT-P-12b by two different groups resulted in discrepant solutions. Using broad-band photometry from the ground, one study found a flat and featureless transmission spectrum which was interpreted as a gray absorption by dense cloud coverage. The second study made use of the Hubble Space Telescope (HST) observations and found Rayleigh scattering at optical wavelengths caused by haze. The main purpose of this work is to find the source of this inconsistency and provide feedback to prevent similar discrepancies in future analyses of other exoplanetary atmospheres. We studied the observed discrepancy via two methods. With further broad-band observations in the optical wavelength regions, we strengthened the previous measurements in precision and with a homogeneous reanalysis of the published data, we managed to assess the systematic errors and the independent analyses of the two different groups. Repeating the analysis steps of both works, we found that deviating values for the orbital parameters are the reason for the aforementioned discrepancy. Our work showed a degeneracy of the planetary spectral slope with these parameters. In a homogeneous reanalysis of all data, the two literature data sets and the new observations converge to a consistent transmission spectrum, showing a low-amplitude spectral slope and a tentative detection of potassium absorption., Comment: Accepted for publication in A&A

Algol-type binary systems are the product of rapid mass transfer between the initially more massive component to its companion. It is still unknown whether the process is conservative, or whether substantial mass is lost from the system. The history of a system prior to mass exchange is imprinted in the photospheric chemical composition, in particular in the carbon-to-nitrogen (C/N) ratio. We use this to trace the efficiency of mass-transfer processes in the components of a classical Algol-type system, $\delta$ Librae. The present analysis is based on new spectroscopic data (ground-based high-resolution \'echelle spectra) and extracted archival photometric observations (space-based measurements from the STEREO satellites). In the orbital solution, non-Keplerian effects on the radial-velocity variations were taken into account. This reduces the primary's mass by 1.1 \Msun\ ($\sim$23\%) significantly in comparison to previous studies, and removes a long-standing discrepancy between the radius and effective temperature. A spectral disentangling technique is applied to the \'echelle observations and the spectra of the individual components are separated. Atmospheric and abundance analyses are performed for the mass-gaining component and we found C/N $= 1.55 \pm 0.40$ for this star. An extensive set of evolutionary models ($3.5\times10^6$) for both components are calculated from which the best-fitting model is derived. It is found that $\beta$, the parameter which quantifies the efficiency of mass-loss from a binary system, is close to zero. This means that the mass-transfer in $\delta$ Lib is mostly conservative with little mass loss from the system., Comment: Accepted for publication in MNRAS, 17 pages, 11 figures

A prerequisite for probing theortical evolutionary models for high-mass stars is the determination of stellar physical properties with a high accuracy. We do this for three binary systems containing components with masses above 10 Msun: V478 Cyg, AH Cep and V453 Cyg. New high-resolution and high-S/N echelle spectra were secured and analysed using spectral disentangling, yielding improved orbital elements and the individual spectra for the component stars. In conjuction with a re-analysis of archival light curves, the stellar masses and radii were measured to accuracies of 1.5-2.5% and 1.0-1.9%, respectively. Detailed spectroscopic analysis then yielded atmospheric parameters and abundances for C, N, O, Mg and Si. Abundances were also deter- mined for V578 Mon. These results allowed a detailed comparison to the predictions of stellar evolutionary models. No star in our sample fits its position on the evolutionary track for its dynamical mass, leaving mass discrepancy (or alternatively overluminosity) an open problem in theoretical modelling. Moreover, the CNO abundances cluster around the initial values with mean values log(N/C) = -0.56 +/- 0.06 and log(N/O) = -1.01 +/- 0.06. No trend in the CNO abundances for single OB stars are found for the eight high-mass stars analysed here, as well in an extended sample including literature results. This opens an important question on the role of binarity in terms of tides on damping internal mixing in stars residing in binary systems., Comment: Accepted for publication in MNRAS

(abridged) Using the particularly long gravitational microlensing event OGLE-2014-BLG-1186 with a time-scale $t_\mathrm{E}$ ~ 300 d, we present a methodology for identifying the nature of localised deviations from single-lens point-source light curves, which ensures that 1) the claimed signal is substantially above the noise floor, 2) the inferred properties are robustly determined and their estimation not subject to confusion with systematic noise in the photometry, 3) there are no alternative viable solutions within the model framework that might have been missed. Annual parallax and binarity could be separated and robustly measured from the wing and the peak data, respectively. We find matching model light curves that involve either a binary lens or a binary source. Our binary-lens models indicate a planet of mass $M_2$ = (45 $\pm$ 9) $M_\oplus$, orbiting a star of mass $M_1$ = (0.35 $\pm$ 0.06) $M_\odot$, located at a distance $D_\mathrm{L}$ = (1.7 $\pm$ 0.3) kpc from Earth, whereas our binary-source models suggest a brown-dwarf lens of $M$ = (0.046 $\pm$ 0.007) $M_\odot$, located at a distance $D_\mathrm{L}$ = (5.7 $\pm$ 0.9) kpc, with the source potentially being a (partially) eclipsing binary involving stars predicted to be of similar colour given the ratios between the luminosities and radii. The ambiguity in the interpretation would be resolved in favour of a lens binary by observing the luminous lens star separating from the source at the predicted proper motion of $\mu$ = (1.6 $\pm$ 0.3) mas yr$^{-1}$, whereas it would be resolved in favour of a source binary if the source could be shown to be a (partially) eclipsing binary matching the obtained model parameters. We experienced that close binary source stars pose a challenge for claiming the detection of planets by microlensing in events where the source passes very close to the lens star hosting the planet., Comment: 26 pages, 14 figures

We report the discovery of four transiting hot Jupiters, WASP-147, WASP-160B, WASP-164 and WASP-165 from the WASP survey. WASP-147b is a near Saturn-mass ($M_P = 0.28 M_{J}$) object with a radius of $ 1.11 \, R_{J}$ orbiting a G4 star with a period of $ 4.6 $ d. WASP-160Bb has a mass and radius ($ M_p = 0.28 \, M_J $, $ R_p = 1.09 \, R_J$) near-identical to WASP-147b, but is less irradiated, orbiting a metal-rich ([Fe/H] = 0.27) K0 star with a period of $3.8$ d. WASP-160B is part of a near equal-mass visual binary with an on-sky separation of 28.5 arcsec. WASP-164b is a more massive ($M_P = 2.13 \, M_J$, $R_p = 1.13 \, R_J$) hot Jupiter, orbiting a G2 star on a close-in ($P=1.8$ d), but tidally stable orbit. WASP-165b is a classical ($M_p = 0.66 \, M_J$, $R_P = 1.26 \, R_J$) hot Jupiter in a $3.5$~d period orbit around a metal-rich ([Fe/H] = 0.33) star. WASP-147b and WASP-160Bb are promising targets for atmospheric characterization through transmission spectroscopy, while WASP-164b presents a good target for emission spectroscopy., Comment: published in MNRAS

The internal structures and properties of oscillating red-giant stars can be accurately inferred through their global oscillation modes (asteroseismology). Based on 1460 days of Kepler observations we perform a thorough asteroseismic study to probe the stellar parameters and evolutionary stages of three red giants in eclipsing binary systems. We present the first detailed analysis of individual oscillation modes of the red-giant components of KIC 8410637, KIC5640750 and KIC9540226. We obtain estimates of their asteroseismic masses, radii, mean densities and logarithmic surface gravities by using the asteroseismic scaling relations as well as grid-based modelling. As these red giants are in double-lined eclipsing binaries, it is possible to derive their independent dynamical masses and radii from the orbital solution and compare it with the seismically inferred values. For KIC 5640750 we compute the first spectroscopic orbit based on both components of this system. We use high-resolution spectroscopic data and light curves of the three systems to determine up-to-date values of the dynamical stellar parameters. With our comprehensive set of stellar parameters we explore consistencies between binary analysis and asteroseismic methods, and test the reliability of the well-known scaling relations. For the three red giants under study, we find agreement between dynamical and asteroseismic stellar parameters in cases where the asteroseismic methods account for metallicity, temperature and mass dependence as well as surface effects. We are able to attain agreement from the scaling laws in all three systems if we use $\Delta\nu_{\rm ref,emp} = 130.8 \pm 0.9\,\mu$Hz instead of the usual solar reference value., Comment: 30 pages, 17 figures; accepted for publication in MNRAS

By analysing the K2 short-cadence data from Campaign 14 we detect phase-curve modulation in the light curve of the hot-Jupiter host star WASP-104. The ellipsoidal modulation is detected with high significance and in agreement with theoretical expectations, while Doppler beaming and reflection modulations are detected tentatively. We show that the visual geometric albedo is lower than 0.03 at 95% confidence, making it one of the least-reflective planets found to date. The light curve also exhibits a rotational modulation, implying a stellar rotational period likely to be near 23 or 46 days. In addition, we refine the system parameters and place tight upper limits for transit timing and duration variations, starspot occultation events, and additional transiting planets., Comment: 7 pages, 5 figures, 1 table. Accepted for publication in The Astronomical Journal