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We present the discovery of a unique object, a chemically peculiar Ap-type star showing $\delta$ Scuti pulsations which is bound in an eclipsing binary system with an orbital period shorter than 3 days. HD 99458 is, therefore, a complex astrophysical laboratory opening doors for studying various, often contradictory, physical phenomena at the same time. It is the first Ap star ever discovered in an eclipsing binary. The orbital period of 2.722 days is the second shortest among all known chemically peculiar (CP2) binary stars. Pulsations of $\delta$ Scuti type are also extremely rare among CP2 stars and no unambiguously proven candidate has been reported. HD 99458 was formerly thought to be a star hosting an exoplanet, but we definitely reject this hypothesis by using photometric observations from the K2 mission and new radial velocity measurements. The companion is a low-mass red dwarf star ($M_{2}=0.45(2)$ M$_{\odot}$) on an inclined orbit ($i=73.2(6)$ degrees) that shows only grazing eclipses. The rotation and orbital periods are synchronized, while the rotation and orbital axes are misaligned. HD 99458 is an interesting system deserving of more intense investigations., Comment: 8 pages, 4 figures, 4 tables, accepted in MNRAS

Context. EE Cep is one of few eclipsing binary systems with a dark, dusty disk around an invisible object similar to {\epsilon} Aur. The system is characterized by grey and asymmetric eclipses every 5.6 yr, with a significant variation in their photometric depth, ranging from ~ 0 m .5 to ~ 2 m .0. Aims. The main aim of the observational campaign of the EE Cep eclipse in 2014 was to test the model of disk precession (Galan et al. 2012). We expected that this eclipse would be one of the deepest with a depth of ~ 2 m .0. Methods. We collected multicolor observations from almost 30 instruments located in Europe and North America. This photometric data covers 243 nights during and around the eclipse. We also analyse the low- and high-resolution spectra from several instruments. Results. The eclipse was shallow with a depth of 0 m .71 in V-band. The multicolor photometry illustrates small color changes during the eclipse with a total amplitude of order ~ +0 m . 15 in B-I color index. The linear ephemeris for this system is updated by including new times of minima, measured from the three most recent eclipses at epochs E = 9, 10 and 11. New spectroscopic observations were acquired, covering orbital phases around the eclipse, which were not observed in the past and increased the data sample, filling some gaps and giving a better insight into the evolution of the H {\alpha} and NaI spectral line profiles during the primary eclipse. Conclusions. The eclipse of EE Cep in 2014 was shallower than expected 0 m .71 instead of ~ 2 m . 0. This means that our model of disk precession needs revision., Comment: 10 pages, 13 figures, 29 tables in appendix, submited to Astronomy & Astrophysics

Only a few exoplanets are known to orbit around fast rotating stars. One of them is XO-6b, which orbits an F5V-type star. Shortly after the discovery, we started multicolor photometric and radial-velocity follow-up observations of XO-6b, using the telescopes of Astronomical Institute of the Slovak Academy of Sciences. Our main scientific goals were to better characterize the planetary system and to search for transit timing variations. We refined several planetary and orbital parameters. Based on our measurements, the planet XO-6b seems to be about 10% larger, which is, however, only about $2\sigma$ difference, but its orbit inclination angle, with respect to the plane of the sky, seems to be significantly smaller, than it was determined originally by the discoverers. In this case we found about $9.5\sigma$ difference. Moreover, we observed periodic transit timing variations of XO-6b with a semi-amplitude of about 14 min and with a period of about 450 days. There are two plausible explanations of such transit timing variations: (1) a third object in the system XO-6 causing light-time effect, or (2) resonant perturbations between the transiting planet XO-6b and another unknown low-mass planet in this system. From the O-C diagram we derived that the assumed third object in the system should have a stellar mass, therefore significant variations are expected in the radial-velocity measurements of XO-6. Since this is not the case, and since all attempts to fit radial velocities and O-C data simultaneously failed to provide a consistent solution, more realistic is the second explanation., Comment: Accepted for publication in MNRAS

Context. The structure of the wind from the cool giants in symbiotic binaries carries important information for understanding the wind mass transfer to their white dwarf companions and its fuelling. Aims. In this paper, we indicate a non-spherical distribution of the neutral wind zone around the red giant (RG) in the symbiotic binary star, EG And. Methods. We achieved this aim by analysing the periodic orbital variations of fluxes and radial velocities of individual components of the H$\alpha$ and [OIII]$\lambda$5007 lines observed on our high-cadence medium (R $\sim$ 11 000) and high-resolution (R $\sim$ 38 000) spectra. Results. The asymmetric shaping of the neutral wind zone at the near-orbital-plane region is indicated by: (i) the asymmetric course of the H$\alpha$ core emission fluxes along the orbit; (ii) the presence of their secondary maximum around the orbital phase $\varphi = 0.1$, which is possibly caused by the refraction effect; and (iii) the properties of the H$\alpha$ broad wing emission originating by Raman scattering on H$^0$ atoms. The wind is substantially compressed from polar directions to the orbital plane as constrained by the location of the [OIII]$\lambda$5007 line emission zones in the vicinity of the RG at/around its poles. The corresponding mass-loss rate from the polar regions of $\lesssim 10 ^{-8}$ Msun/yr is a factor of $\gtrsim 10$ lower than the average rate of $\approx 10^{-7}$Msun/yr derived from nebular emission of the ionised wind from the RG. Furthermore, it is two orders of magnitude lower than that measured in the near-orbital-plane region from Rayleigh scattering. Conclusions. The startling properties of the nebular [OIII]$\lambda$5007 line in EG And provides an independent indication of the wind focusing towards the orbital plane., Comment: 10 pages, 8 figures

We present long-term photometric observations of the young open cluster IC 348 with a baseline time-scale of 2.4 yr. Our study was conducted with several telescopes from the Young Exoplanet Transit Initiative (YETI) network in the Bessel R band to find periodic variability of young stars. We identified 87 stars in IC 348 to be periodically variable; 33 of them were unreported before. Additionally, we detected 61 periodic non-members of which 41 are new discoveries. Our wide field of view was the key to those numerous newly found variable stars. The distribution of rotation periods in IC 348 has always been of special interest. We investigate it further with our newly detected periods but we cannot find a statistically significant bimodality. We also report the detection of a close eclipsing binary in IC 348 composed of a low-mass stellar component (M ≳ 0.09 M⊙) and a K0 pre-main-sequence star (M ≈ 2.7 M⊙). Furthermore, we discovered three detached binaries among the background stars in our field of view and confirmed the period of a fourth one.

We report results of the first five observing campaigns for the open stellar cluster NGC 7243 in the frame of project Young Exoplanet Transit Initiative (YETI). The project focuses on the monitoring of young and nearby stellar clusters, with the aim to detect young transiting exoplanets and to study other variability phenomena on time-scales from minutes to years. After five observing campaigns and additional observations during 2013 and 2014, a clear and repeating transit-like signal was detected in the light curve of J221550.6+495611. Furthermore, we detected and analysed 37 new eclipsing binary stars in the studied region. The best fit parameters and light curves of all systems are given. Finally, we detected and analysed 26 new, presumably pulsating variable stars in the studied region. The follow-up investigation of these objects, including spectroscopic measurements of the exoplanet candidate, is currently planned. (© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

The star V426 Sge (HBHA~1704-05), originally classified as an emission-line object and a semi-regular variable, brightened at the beginning of August 2018, showing signatures of a symbiotic star outburst. We aim to confirm the nature of V426 Sge as a classical symbiotic star, determine the photometric ephemeris of the light minima, and suggest the path from its 1968 symbiotic nova outburst to the following 2018 Z And-type outburst. We re-constructed an historical light curve (LC) of V426 Sge from approximately the year 1900, and used original low- and high-resolution spectroscopy complemented with Swift-XRT and UVOT, optical UBVRcIc and near-infrared JHKL photometry obtained during the 2018 outburst and the following quiescence. The historical LC reveals no symbiotic-like activity from 1900 to 1967. In 1968, V426 Sge experienced a symbiotic nova outburst that ceased around 1990. From approximately 1972, a wave-like orbitally related variation with a period of $493.4\pm 0.7$ days developed in the LC. This was interrupted by a Z And-type outburst from the beginning of August 2018 to the middle of February 2019. At the maximum of the 2018 outburst, the burning white dwarf (WD) increased its temperature to $>2\times 10^5$ K, generated a luminosity of $\sim 7\times 10^{37}(d/3.3kpc)^2$ erg/s, and blew a wind at the rate of $\sim 3\times 10^{-6}$ M$_{\odot}$/yr. The donor is a normal M4-5 III giant and the accretor is a low-mass $\sim$0.5 M$_{\odot}$ WD. During the transition from the symbiotic nova outburst to the quiescent phase, a pronounced sinusoidal variation along the orbit develops in the LC of most symbiotic novae. The following eventual outburst is of Z And-type, when the accretion by the WD temporarily exceeds the upper limit of the stable burning. At this point the system becomes a classical symbiotic star., 19 pages, 12 figures, 9 tables, 2 appendices, accepted for A&A, Tables A.1, A.2 and A.3 are only available at the CDS, added references for section 1

We report new multi-colour photometry and high-resolution spectroscopic observations of the long-period variable V501 Aur, previously considered to be a weak-lined T-Tauri star belonging to the Taurus-Auriga star-forming region. The spectroscopic observations reveal that V501 Aur is a single-lined spectroscopic binary system with a 68.8-day orbital period, a slightly eccentric orbit (e ~ 0.03), and a systemic velocity discrepant from the mean of Taurus-Auriga. The photometry shows quasi-periodic variations on a different, ~55-day timescale that we attribute to rotational modulation by spots. No eclipses are seen. The visible object is a rapidly rotating (vsini ~ 25 km/s) early K star, which along with the rotation period implies it must be large (R > 26.3 Rsun), as suggested also by spectroscopic estimates indicating a low surface gravity. The parallax from the Gaia mission and other independent estimates imply a distance much greater than the Taurus-Auriga region, consistent with the giant interpretation. Taken together, this evidence together with a re-evaluation of the LiI~$\lambda$6707 and H$\alpha$ lines shows that V501 Aur is not a T-Tauri star, but is instead a field binary with a giant primary far behind the Taurus-Auriga star-forming region. The large mass function from the spectroscopic orbit and a comparison with stellar evolution models suggest the secondary may be an early-type main-sequence star., Comment: 13 pages, 7 figures. Accepted to MNRAS

A new off-shelf low-cost echelle spectrograph was installed recently on the 0.6m telescope at the Star\'a Lesn\'a Observatory (Slovakia). In this paper we describe in details the radial velocity (RV) analysis of the first three transiting planetary systems, HAT-P-2, WASP-14 and XO-3, observed with this instrument. Furthermore, we compare our data with the RV data achieved with echelle spectrographs of other sub-meter-, meter- and two-meter-class telescopes in terms of their precision. Finally, we investigate the applicability of our RV data for modeling orbital parameters., Comment: AN accepted