Search

Both the 1866 and 1946 outbursts of the recurrent symbiotic nova T CrB have displayed a mysterious secondary maximum peaking in brightness ~5 months past the primary one. Common to all previous modeling attempts was the rejection of plain irradiation of the red giant (RG), on the basis that the secondary maximum of T CrB would have been out of phase with the transit at superior conjunction of the RG. Implicit to this line of reasoning is the assumption of a constant temperature for the white dwarf (WD) irradiating the red giant. I show by radiative modeling that irradiation of the RG by a cooling WD nicely reproduces the photometric evolution of the secondary maximum, both in terms of brightness and color, removes the phasing offset, and provides a straightforward explanation that will be easy to test at the next and imminent outburst., Comment: correcting a label in Figure 1

Lightcurves of many classical novae deviate from the canonical "fast rise - smooth decline" pattern and display complex variability behavior. We present the first TESS-space-photometry-based investigation of this phenomenon. We use TESS Sector 41 full-frame images to extract a lightcurve of the slow Galactic nova V606 Vul that erupted nine days prior to the start of the TESS observations. The lightcurve covers the first of two major peaks of V606 Vul that was reached 19 days after the start of the eruption. The nova reached its brightest visual magnitude V=9.9 in its second peak 64 days after the eruption onset, following the completion of Sector 41 observations. To increase the confidence level of the extracted lightcurve, we performed the analysis using four different codes implementing the aperture photometry (Lightkurve, VaST) and image subtraction (TESSreduce, tequila_shots) and find good agreement between them. We performed ground-based photometric and spectroscopic monitoring to complement the TESS data. The TESS lightcurve reveals two features: periodic variations (0.12771d, 0.01mag average peak-to-peak amplitude) that disappeared when the source was within 1mag of peak optical brightness and a series of isolated mini-flares (with peak-to-peak amplitudes of up to 0.5mag) appearing at seemingly random times. We interpret the periodic variations as the result of azimuthal asymmetry of the photosphere engulfing the nova-hosting binary that was distorted by and rotating with the binary. Whereas we use spectra to associate the two major peaks in the nova lightcurve with distinct episodes of mass ejection, the origin of mini-flares remains elusive., Comment: 31 pages, 10 figures, submitted to ApJ; comments welcome

We use more than 872,000 mid-to-high resolution (R $\sim$ 20,000) spectra of stars from the GALAH survey to discern the spectra of diffuse interstellar bands (DIBs). We use four windows with the wavelength range from 4718 to 4903, 5649 to 5873, 6481 to 6739, and 7590 to 7890 \AA, giving a total coverage of 967 \AA. We produce $\sim$400,000 spectra of interstellar medium (ISM) absorption features and correct them for radial velocities of the DIB clouds. Ultimately, we combine the 33,115 best ISM spectra into six reddening bins with a range of $0.1 \,\mathrm{mag} < E\mathrm{(B-V)} < 0.7\, \mathrm{mag}$. A total of 183 absorption features in these spectra qualify as DIBs, their fitted model parameters are summarized in a detailed catalogue. From these, 64 are not reported in the literature, among these 17 are certain, 14 are probable and 33 are possible. We find that the broad DIBs can be fitted with a multitude of narrower DIBs. Finally, we create a synthetic DIB spectrum at unit reddening which should allow us to narrow down the possible carriers of DIBs and explore the composition of the ISM and ultimately better model dust and star formation as well as to correct Galactic and extragalactic observations. The majority of certain DIBs show a significant excess of equivalent width when compared to reddening. We explain this with observed lines of sight penetrating more uniform DIB clouds compared to clumpy dust clouds., Comment: 28 pages, 15 figures, 11 tables, accepted for publication in MNRAS

Nova V5856 Sagittarii is unique for having remained more than nine magnitudes above its pre-outburst brightness for more than six years. Extensive visible and IR spectra from the time of outburst to the present epoch reveal separate emitting regions with distinct spectral characteristics. Permitted emission lines have both broad and narrow components, whereas the forbidden line profiles are almost entirely broad. The permitted line components frequently display P Cygni profiles indicating high optical depth, whereas the broad components do not show detectable absorption. The densities and velocities deduced from the spectra, including differences in the O I 7773 and 8446 lines, are not consistent with an on-going wind. Instead, the prolonged high luminosity and spectral characteristics are indicative of a post-outburst common envelope that enshrouds the binary, and is likely the primary source of the visible and IR emission., Comment: 27 pages; 13 figures. Accepted for publication in the ApJ

RS Oph has persistently displayed flickering at optical wavelengths when observed away from its repeating nova outbursts. During the 2006 eruption the flickering disappeared, and this repeated during the recent 2021 event. We have been monitoring RS Oph looking for the reappearance of flickering at B-band following the 2021 outburst. The flickering was still absent (sigma(B)<0.002 mag) on day +210 (counted from nova optical maximum), appeared at sigma(B)=0.008 mag on day +224, and raised to sigma(B)=0.029 mag on day +250. On following dates the amplitude remained large, although fluctuating. The recovery of B-band quiescence brightness by RS Oph begun around day +225 and was completed by day +260. The parallel patterns followed by the rise in system brightness and the reappearance of flickering confirm the central role played in RS Oph by the return to pre-outburst conditions of the accretion disk and the refilling by the RG wind of the immediate circumstellar space.

We present the second part (days 19 to 102) of our high-resolution Echelle atlas of the spectral evolution of RS Oph during the 2021 nova outburst. Some quick conclusions that can be drawn are: (1) the spectra evolution has progressed smoothly, suggesting that both the expansion of the ejecta through the pre-existing RG wind and the photo-ionization from the central source did not encountered sudden discontinuities prior to switch-off of the nuclear burning; (2) the 2021 spectral evolution is similar to that of the 2006 eruption, with a mirror-appearance of the triple-peaked line profiles (blue peak brighter than red in 2006, the opposite in 2021); (3) the evolution of the triple-peaked profiles progressed similarly through different excitation and ionization degrees, suggesting an origin in a bipolar outflow nested to an equatorial torus; (4) the time-behavior of coronal emission lines appears quite smooth, both in terms of radiated flux as well as evolution of the triple-peaked profiles, with a plateau at maximum lasting up to about day 87; (5) there seems to exist within RS Oph two distinct types of ejecta: one fast moving and producing Gaussian-like line profiles (primarely [NII] and [OIII]), that keep expanding at FWHM=1000 km/s with no sign of ongoing deceleration during the two months leading up to Solar conjunction, and slower moving ejecta giving rise to the triple-peaked line profiles (HeI, HeII, coronal lines, and also Balmer lines at later times), for which the separation in velocity of blue and red peaks is still shrinking at the time of Solar conjunction when it reaches an average of 330 km/s; (6) the "symbiotic band" at 6825 Ang, due to Raman scattering of OVI 1032 by neutral hydrogen, appears simultaneously with the coronal lines: its very presence indicates that a sizeable part of the wind of the red giant has remained neutral during the development of coronal lines., Comment: 16 pages, 11 figures

We present multi-epoch optical and near-infrared observations of the highly reddened, \pion{Fe}{ii} class slow nova V2891 Cygni. The observations span 15 months since its discovery. The initial rapid brightening from quiescence, and the presence of a $\sim$35 day long pre-maximum halt, is well documented. The evidence that the current outburst of V2891 Cyg has undergone several distinct episodes of mass ejection is seen through time-varying P Cygni profiles of the O\,{\sc i} 7773\,$\AA$ line. A highlight is the occurrence of a dust formation event centred around $\sim$+273d, which coincides with a phase of coronal line emission. The dust mass is found to be $\sim0.83-1.25 \times 10^{-10} M_{\odot}$. There is strong evidence to suggest that the coronal lines are created by shock heating rather than by photoionization. The simultaneous occurrence of the dust and coronal lines (with varying velocity shifts) supports the possibility that dust formation is shock-induced. Such a route for dust formation has not previously been seen in a nova, although the mechanism has been proposed for dust formation in some core-collapse supernovae. Analysis of the coronal lines indicates a gas mass and temperature of 8.35--8.42$\times10^{-7}$ M$_\odot$ and $\sim(4.8-9.1)\times10^{5}$~K respectively, and an overabundance of aluminium and silicon. A Case B analysis of the hydrogen lines yields a mass of the ionized gas of ($8.60\pm1.73)\times10^{-5}$ M$_{\odot}$. The reddening and distance to the nova are estimated to be $E(B-V)$ = 2.21$\pm$0.15 and $d$ = 5.50 kpc respectively., Comment: Accepted for Publication in MNRAS

Pioneering photometric, astrometric, and spectroscopic surveys are helping exoplanetary scientists better constrain the fundamental properties of stars within our galaxy, and the planets these stars host. In this study, we use the third data release from the stellar spectroscopic GALAH Survey, coupled with astrometric data of eDR3 from the \textit{Gaia} satellite, and other data from NASA's Exoplanet Archive, to refine our understanding of 279 confirmed and candidate exoplanet host stars and their exoplanets. This homogenously analysed data set comprises 105 confirmed exoplanets, along with 146 K2 candidates, 95 TESS Objects of Interest (TOIs) and 52 Community TOIs (CTOIs). Our analysis significantly shifts several previously (unknown) planet parameters while decreasing the uncertainties for others; Our radius estimates suggest that 35 planet candidates are more likely brown dwarfs or stellar companions due to their new radius values. We are able to refine the radii and masses of WASP-47 e, K2-106 b, and CoRoT-7 b to their most precise values yet, to less than 2.3\% and 8.5\% respectively. We also use stellar rotational values from GALAH to show that most planet candidates will have mass measurements that will be tough to obtain with current ground-based spectrographs. With GALAH's chemical abundances, we show through chemo-kinematics that there are five planet-hosts that are associated with the galaxy's thick disc, including NGTS-4, K2-183 and K2-337. Finally, we show there is no statistical difference between the chemical properties of hot Neptune and hot rocky exoplanet hosts, with the possibility that short-period rocky worlds might be the remnant cores of hotter, gaseous worlds., Comment: 21 pages with 11 figures and 5 tables. Accepted into MNRAS with appendix tables available within this arXiv submission

Hot, compact, hydrogen-deficient pre-white dwarfs (pre-WDs) with effective temperatures of Teff > 70,000 K and a surface gravity of 5.0 < log g < 7.0 are rather rare objects despite recent and ongoing surveys. It is believed that they are the outcome of either single star evolution (late helium-shell flash or late helium-core flash) or binary star evolution (double WD merger). Their study is interesting because the surface elemental abundances reflect the physics of thermonuclear flashes and merger events. Spectroscopically they are divided in three different classes, namely PG1159, O(He), or He-sdO. We present a spectroscopic analysis of five such stars that turned out to have atmospheric parameters in the range Teff = 70,000-80,000 K and log g = 5.2-6.3. The three investigated He-sdOs have a relatively high hydrogen mass fraction (10%) that is unexplained by both single (He core flash) and binary evolution (He-WD merger) scenarios. The O(He) star JL9 is probably a binary helium-WD merger, but its hydrogen content (6%) is also at odds with merger models. We found that RL 104 is the 'coolest' (Teff = 80,000 K) member of the PG1159 class in a pre-WD stage. Its optical spectrum is remarkable because it exhibits C IV lines involving Rydberg states with principal quantum numbers up to n = 22. Its rather low mass (0.48 +0.03/-0.02 Msun) is difficult to reconcile with the common evolutionary scenario for PG1159 stars due to it being the outcome of a (very) late He-shell flash. The same mass-problem faces a merger model of a close He-sdO plus CO WD binary that predicts PG1159-like abundances. Perhaps RL 104 originates from a very late He-shell flash in a CO/He WD formed by a merger of two low-mass He-WDs., Comment: Accepted for publication in A&A

We report on the Fermi-LAT detection (with ~5.7 sigma significance) as well as the multi-wavelength analysis of the 2017 nova eruption V549 Vel. Unlike the recent shock-powered novae ASASSN-16ma and V906 Car, the optical and gamma-ray light curves of V549 Vel show no correlation, likely implying relatively weak shocks in the eruption. Gaia detected a candidate progenitor of V549 Vel and found a parallax measurement of 1.91+/-0.39 mas, equivalent to a mode distance of d=560 pc (90% credible interval of 380-1050 pc). The progenitor was also observed by the 2MASS and WISE surveys. When adopting the Gaia distance, the spectral energy distribution of the progenitor is close to that of a G-type star. Swift/XRT detected the supersoft X-ray emission of the nova (kT=30-40 keV) since day 236, and the inferred blackbody size is comparable to that of other novae assuming d=560 pc (i.e., R_bb~5*10^8 cm). However, there is also an unknown astrometric excess noise of 3.2 mas found in the Gaia data, and the inferred distance becomes controversial. If the Gaia distance is accurate, the gamma-ray luminosity of V549 Vel will be as low as L_gamma~4*10^33 erg/s, making it the least luminous gamma-ray nova known so far. This may imply that the shock properties responsible for the gamma-ray emission in V549 Vel are different from those of the more luminous events. If the nova is located farther away, it is likely a symbiotic system with a giant companion as the observed progenitor., Comment: 10 pages, including 5 figures and 1 tables. Accepted for publication in ApJ

Lithium depletion and enrichment in the cosmos is not yet well understood. To help tighten constraints on stellar and Galactic evolution models, we present the largest high-resolution analysis of Li abundances A(Li) to date, with results for over 100 000 GALAH field stars spanning effective temperatures $5900\,\mathrm{K} \lesssim \rm{T_{eff}} \lesssim7000\,\mathrm{K}$ and metallicities $-3 \lesssim \rm[Fe/H] \lesssim +0.5$. We separated these stars into two groups, on the warm and cool side of the so-called Li-dip, a localised region of the Kiel diagram wherein lithium is severely depleted. We discovered that stars in these two groups show similar trends in the A(Li)-[Fe/H] plane, but with a roughly constant offset in A(Li) of 0.4 dex, the warm group having higher Li abundances. At $\rm[Fe/H]\gtrsim-0.5$, a significant increasing in Li abundance with increasing metallicity is evident in both groups, signalling the onset of significant Galactic production. At lower metallicity, stars in the cool group sit on the Spite plateau, showing a reduced lithium of around 0.4 dex relative to the primordial value predicted from Big Bang nucleosynthesis (BBN). However, stars in the warm group between [Fe/H] = -1.0 and -0.5, form an elevated plateau that is largely consistent with the BBN prediction. This may indicate that these stars in fact preserve the primordial Li produced in the early Universe., Comment: 5 pages, 2 figures, Accepted for publication by MNRAS

We present part 2 of the 6th and final Data Release (DR6 or FDR) of the Radial Velocity Experiment (RAVE), a magnitude-limited (9

The Radial Velocity Experiment (RAVE) is a magnitude-limited (9

Any white dwarf or neutron star that accretes enough material from a red giant companion, such that this interaction can be detected at some wavelength, is currently termed Symbiotic Star (typical P(orb)=2-3 years). In the majority of ~400 known systems, the WD burns nuclearly at its surface the accreted material, and the resulting high temperature (T(eff)=10(^5)~K) and luminosity (L(hot)=10(^3)-10(^4) Lsun) allow ionization of a large fraction of the cool giant's wind, making such symbiotic stars easily recognizable through the whole Galaxy and across the Local Group. X-ray observations are now revealing the existence of a parallel (and larger ?) population of optically-quiet, accreting-only symbiotic stars. Accretion flows and disks, ionization fronts and shock, complex 3D geometries and new evolution channels are gaining relevance and are reshaping our understanding of symbiotic stars. We review the different types of symbiotic stars currently in the family and their variegated outburst behaviors through an unified evolution scheme connecting them all., Comment: Invited Review, published in "The Impact of Binary Stars on Stellar Evolution", G. Beccari and M.J. Boffin eds., Cambridge Univ. Press., Cambridge Astrophysical Series vol. 54, pag. 77 (2019). Proceedings of a Conference held on 3-7 July 2017, at ESO Headquarters, Garching, Germany

This research note presents a comparison of radial velocities between the RAVE DR5 data release with Gaia DR2. RAVE DR5 and Gaia DR2 have 450587 stars in common. In particular we would like to shed light on a small subset of joint targets (707 stars) that exhibit a constant velocity offset of +105 km/s or -76 km/s, respectively. Overall this comparison confirms the excellent agreement between those two data sets. The velocity differences can well be matched with two Gaussians with FWHM of 1.2 km/s and 3.6 km/s, respectively. There is a systematic offset of about -0.32 km/s, consistent with the findings in Gaia DR2, who find an offset of -0.29 km/s. The offset is also comparable to the offset found between Gaia DR2 and other ground-based spectroscopic surveys in a similar magnitude range, indicative that the source for this offset may at least partially be related to the radial velocity zeropoint of Gaia DR2. We identified 707 stars that exhibit large constant velocity offsets. These cases can be traced to a problem of the reduction pipeline in propagating the wavelength calibration between neighboring fibres near the edges of the field plate, in particular for observations done just before fibre repairs, i.e. when live fibres were separated by large gaps of broken ones. In 82\%\ of these cases the offset between RAVE DR5 and Gaia DR2 radial velocity is in the $+105 \pm 15$~\kms range. These spectra belong to the first 10 fibres of the field plate. Another 3\%\ of the spectra have velocity offset in the $-76 \pm 4$~\kms range and were observed with the fibres 148-150. Even though the majority of these 707 stars do not exhibit any particularity in the radial velocity, we recommend excluding them from future studies., Comment: 3 pages, 1 figure, Research Notes of the American Astronomical Society, accepted

Swan bands - characteristic molecular absorption features of the C$_2$ molecule - are a spectroscopic signature of carbon-enhanced stars. They can also be used to identify carbon-enhanced metal-poor (CEMP) stars. The GALAH (GALactic Archaeology with Hermes) is a magnitude-limited survey of stars producing high-resolution, high signal-to-noise spectra. We used 627,708 GALAH spectra to search for carbon-enhanced stars with a supervised and unsupervised classification algorithm, relying on the imprint of the Swan bands. We identified 918 carbon-enhanced stars, including 12 already described in the literature. An unbiased selection function of the GALAH survey allows us to perform a population study of carbon-enhanced stars. Most of them are giants, out of which we find 28 CEMP candidates. A large fraction of our carbon-enhanced stars with repeated observations show variation in radial velocity, hinting that there is a large fraction of variables among them. 32 of the detected stars also show strong Lithium enhancement in their spectra., Comment: 13+5 pages, 13 figures, 1 catalog, accepted to MNRAS

We explore the connections between stellar age, chemistry, and kinematics across a Galactocentric distance of $7.5 < R\,(\mathrm{kpc}) < 9.0$, using a sample of $\sim 12\,000$ intermediate-mass (FGK) turnoff stars observed with the RAdial Velocity Experiment (RAVE) survey. The kinematics of this sample are determined using radial velocity measurements from RAVE, and parallax and proper motion measurements from the Tycho-Gaia Astrometric Solution (TGAS). In addition, ages for RAVE stars are determined using a Bayesian method, taking TGAS parallaxes as a prior. We divide our sample into young ($0 < \tau < 3$ Gyr) and old ($8 < \tau < 13$ Gyr) populations, and then consider different metallicity bins for each of these age groups. We find significant differences in kinematic trends of young and old, metal-poor and metal-rich, stellar populations. In particular, we find a strong metallicity dependence in the mean Galactocentric radial velocity as a function of radius ($\partial {V_{\rm R}}/\partial R$) for young stars, with metal-rich stars having a much steeper gradient than metal-poor stars. For $\partial {V_{\phi}}/\partial R$, young, metal-rich stars significantly lag the LSR with a slightly positive gradient, while metal-poor stars show a negative gradient above the LSR. We interpret these findings as correlations between metallicity and the relative contributions of the non-axisymmetries in the Galactic gravitational potential (the spiral arms and the bar) to perturb stellar orbits., Comment: 14 pages, 13 figures, accepted for publication in MNRAS

GALAH is a large-scale magnitude-limited southern stellar spectroscopic survey. Its second data release (GALAH DR2) provides values of stellar parameters and abundances of 23 elements for 342,682 stars (Buder et al.). Here we add a description of the public release of radial velocities with a typical accuracy of 0.1 km/s for 336,215 of these stars, achievable due to the large wavelength coverage, high resolving power and good signal to noise ratio of the observed spectra, but also because convective motions in stellar atmosphere and gravitational redshift from the star to the observer are taken into account. In the process we derive medians of observed spectra which are nearly noiseless, as they are obtained from between 100 and 1116 observed spectra belonging to the same bin with a width of 50 K in temperature, 0.2 dex in gravity, and 0.1 dex in metallicity. Publicly released 1181 median spectra have a resolving power of 28,000 and trace the well-populated stellar types with metallicities between -0.6 and +0.3. Note that radial velocities from GALAH are an excellent match to the accuracy of velocity components along the sky plane derived by Gaia for the same stars. The level of accuracy achieved here is adequate for studies of dynamics within stellar clusters, associations and streams in the Galaxy. So it may be relevant for studies of the distribution of dark matter., Comment: Accepted to MNRAS, compared to the initial submission it now reports radial velocities for more stars (336,215 instead of 199,628) and all radial velocities have been recalculated

The technique of chemical tagging uses the elemental abundances of stellar atmospheres to `reconstruct' chemically homogeneous star clusters that have long since dispersed. The GALAH spectroscopic survey --which aims to observe one million stars using the Anglo-Australian Telescope -- allows us to measure up to 30 elements or dimensions in the stellar chemical abundance space, many of which are not independent. How to find clustering reliably in a noisy high-dimensional space is a difficult problem that remains largely unsolved. Here we explore t-distributed stochastic neighbour embedding (t-SNE) -- which identifies an optimal mapping of a high-dimensional space into fewer dimensions -- whilst conserving the original clustering information. Typically, the projection is made to a 2D space to aid recognition of clusters by eye. We show that this method is a reliable tool for chemical tagging because it can: (i) resolve clustering in chemical space alone, (ii) recover known open and globular clusters with high efficiency and low contamination, and (iii) relate field stars to known clusters. t-SNE also provides a useful visualization of a high-dimensional space. We demonstrate the method on a dataset of 13 abundances measured in the spectra of 187,000 stars by the GALAH survey. We recover 7 of the 9 observed clusters (6 globular and 3 open clusters) in chemical space with minimal contamination from field stars and low numbers of outliers. With chemical tagging, we also identify two Pleiades supercluster members (which we confirm kinematically), one as far as 6$^\circ$ -- one tidal radius away from the cluster centre.

We combine parallaxes from the first Gaia data release with the spectrophotometric distance estimation framework for stars in the fifth RAVE survey data release. The combined distance estimates are more accurate than either determination in isolation - uncertainties are on average two times smaller than for RAVE-only distances (three times smaller for dwarfs), and 1.4 times smaller than TGAS parallax uncertainties (two times smaller for giants). We are also able to compare the estimates from spectrophotometry to those from Gaia, and use this to assess the reliability of both catalogues and improve our distance estimates. We find that the distances to the lowest log g stars are, on average, overestimated and caution that they may not be reliable. We also find that it is likely that the Gaia random uncertainties are smaller than the reported values. As a byproduct we derive ages for the RAVE stars, many with relative uncertainties less than 20 percent. These results for 219566 RAVE sources have been made publicly available, and we encourage their use for studies that combine the radial velocities provided by RAVE with the proper motions provided by Gaia. A sample that we believe to be reliable can be found by taking only the stars with the flag notification flag_any=0, Comment: MNRAS accepted. Updated to final version, reflecting referee reports. Title changed to better reflect scientific content. Data available through RAVE website: https://www.rave-survey.org/project/

The orbit and physical parameters of the previously unsolved double-lined eclipsing binary Tyc 5227-1023-1, discovered during the search for RR Lyr variables candidate members of the Aquarius stream, are derived using high resolution \'echelle spectroscopy and $V$, $i^\prime$ photometry. Synthetic spectral analysis of both components has been performed, yielding metallicity [M/H] = $-0.63 \pm 0.11$ for both stars and the temperature of the secondary which is in close agreement with the one from the orbital solution, while the temperature of the primary is determined from photometry (T$_1 = 6350$ K). The masses and radii ($M_1 = 0.96 \pm 0.02, M_2 = 0.84 \pm 0.01$ M$_{\odot}$, $R_1 = 1.39 \pm 0.01, R_2 = 0.98 \pm 0.01$ R$_{\odot}$) reveal that both stars have already slightly evolved away from the Main Sequence band having an age of about $7$ Gyr, and the results of synthetic spectral analysis support the claim of co-rotation with the orbital motion. The radial velocity of the system is $-60 \pm 2$ km sec$^{-1}$ while its distance, computed from orbital parameters and the derived reddening $E_{B-V}$ = 0.053, is $496 \pm 35$ pc. Even though Tyc 5227-1023-1 was initially treated as a possible member of the Aquarius stream, the results presented here disagree with reported values for this ancient structure, and suggest a likely membership of the thick disk.

We characterize the selection function of RAVE using 2MASS as our underlying population, which we assume represents all stars which could have potentially been observed. We evaluate the completeness fraction as a function of position, magnitude, and color in two ways: first, on a field-by-field basis, and second, in equal-size areas on the sky. Then, we consider the effect of the RAVE stellar parameter pipeline on the final resulting catalogue, which in principle limits the parameter space over which our selection function is valid. Our final selection function is the product of the completeness fraction and the selection function of the pipeline. We then test if the application of the selection function introduces biases in the derived parameters. To do this, we compare a parent mock catalogue generated using Galaxia with a mock-RAVE catalogue where the selection function of RAVE has been applied. We conclude that for stars brighter than I = 12, between $4000 \rm K < T_{\rm eff} < 8000 \rm K$ and $0.5 < \rm{log}\,g < 5.0$, RAVE is kinematically and chemically unbiased with respect to expectations from Galaxia., Comment: 14 pages, 12 figures, accepted for publication in MNRAS

Data Release 5 (DR5) of the Radial Velocity Experiment (RAVE) is the fifth data release from a magnitude-limited (9< I < 12) survey of stars randomly selected in the southern hemisphere. The RAVE medium-resolution spectra ($R\sim7500$) covering the Ca-triplet region (8410-8795\AA) span the complete time frame from the start of RAVE observations in 2003 to their completion in 2013. Radial velocities from 520,781 spectra of 457,588 unique stars are presented, of which 255,922 stellar observations have parallaxes and proper motions from the Tycho-Gaia astrometric solution (TGAS) in Gaia DR1. For our main DR5 catalog, stellar parameters (effective temperature, surface gravity, and overall metallicity) are computed using the RAVE DR4 stellar pipeline, but calibrated using recent K2 Campaign 1 seismic gravities and Gaia benchmark stars, as well as results obtained from high-resolution studies. Also included are temperatures from the Infrared Flux Method, and we provide a catalogue of red giant stars in the dereddened color $(J-Ks)_0$ interval (0.50,0.85) for which the gravities were calibrated based only on seismology. Further data products for sub-samples of the RAVE stars include individual abundances for Mg, Al, Si, Ca, Ti, Fe, and Ni, and distances found using isochrones. Each RAVE spectrum is complemented by an error spectrum, which has been used to determine uncertainties on the parameters. The data can be accessed via the RAVE Web site or the Vizier database., Comment: accepted Astronomical Journal version, data tables on RAVE Web site: https://www.rave-survey.org/project/

The orbits, atmospheric parameters, chemical abundances, and ages of individual stars in the Milky Way provide the most comprehensive illustration of galaxy formation available. The Tycho-Gaia Astrometric Solution (TGAS) will deliver astrometric parameters for the largest ever sample of Milky Way stars, though its full potential cannot be realized without the addition of complementary spectroscopy. Among existing spectroscopic surveys, the RAdial Velocity Experiment (RAVE) has the largest overlap with TGAS ($\gtrsim$200,000 stars). We present a data-driven re-analysis of 520,781 RAVE spectra using The Cannon. For red giants, we build our model using high-fidelity APOGEE stellar parameters and abundances for stars that overlap with RAVE. For main-sequence and sub-giant stars, our model uses stellar parameters from the K2/EPIC. We derive and validate effective temperature $T_{\rm eff}$, surface gravity $\log{g}$, and chemical abundances of up to seven elements (O, Mg, Al, Si, Ca, Fe, Ni). We report a total of 1,685,851 elemental abundances with a typical precision of 0.07 dex, a substantial improvement over previous RAVE data releases. The synthesis of RAVE-on and TGAS is the most powerful data set for chemo-dynamic analyses of the Milky Way ever produced., Comment: Derived labels, associated errors, and relevant metadata are available from the RAVE database (http://www.rave-survey.org) from 19 September 2016

We present the data reduction procedures being used by the GALAH survey, carried out with the HERMES fibre-fed, multi-object spectrograph on the 3.9~m Anglo-Australian Telescope. GALAH is a unique survey, targeting 1 million stars brighter than magnitude V=14 at a resolution of 28,000 with a goal to measure the abundances of 29 elements. Such a large number of high resolution spectra necessitates the development of a reduction pipeline optimized for speed, accuracy, and consistency. We outline the design and structure of the Iraf-based reduction pipeline that we developed, specifically for GALAH, to produce fully calibrated spectra aimed for subsequent stellar atmospheric parameter estimation. The pipeline takes advantage of existing Iraf routines and other readily available software so as to be simple to maintain, testable and reliable. A radial velocity and stellar atmospheric parameter estimator code is also presented, which is used for further data analysis and yields a useful verification of the reduction quality. We have used this estimator to quantify the data quality of GALAH for fibre cross-talk level ($\lesssim0.5$%) and scattered light ($\sim5$ counts in a typical 20 minutes exposure), resolution across the field, sky spectrum properties, wavelength solution reliability (better than $1$ $\mathrm{km\ s^{-1}}$ accuracy) and radial velocity precision.

EGB 6 is a faint, large, ancient planetary nebula (PN). Its central star, a hot DAOZ white dwarf (WD), is a prototype of a rare class of PN nuclei associated with dense, compact emission-line knots. The central star also shows excess fluxes in both the near- (NIR) and mid-infrared (MIR). In a 2013 paper, we used Hubble Space Telescope (HST) images to show that the compact nebula is a point-like source, located 0".16 (~118 AU) from the WD. We attributed the NIR excess to an M dwarf companion star, which appeared to coincide with the dense emission knot. We now present new ground-based NIR spectroscopy, showing that the companion is actually a much cooler source with a continuous spectrum, apparently a dust-enshrouded low-luminosity star. New HST images confirm common proper motion of the emission knot and red source with the WD. The I-band, NIR, and MIR fluxes are variable, possibly on timescales as short as days. We can fit the spectral-energy distribution with four blackbodies (the WD, a ~1850 K NIR component, and MIR dust at 385 and 175 K). Alternatively, we show that the NIR/MIR SED is very similar to that of Class 0/I young stellar objects. We suggest a scenario in which the EGB 6 nucleus is descended from a wide binary similar to the Mira system, in which a portion of the wind from an AGB star was captured into an accretion disk around a companion star; a remnant of this disk has survived to the present time, and is surrounded by gas photoionized by UV radiation from the WD., Comment: Accepted by Astrophysical Journal

It has recently been discovered that some, if not all, classical novae emit GeV gamma-rays during outburst. Despite using an unreliable method to determine its distance, previous work showed that nova V1324 Sco was the most gamma-ray luminous of all gamma-ray-detected novae. We present here a different, more robust, method to determine the reddening and distance to V1324 Sco using high-resolution optical spectroscopy. Using two independent methods we derived a reddening of E(B-V) = 1.16 +/- 0.12 and a distance rD > 6.5 kpc. This distance is >40% greater than previously estimated, meaning that V1324 Sco has an even higher gamma-ray luminosity than previously calculated. We also use periodic modulations in the brightness, interpreted as the orbital period, in conjunction with pre-outburst photometric limits to show that a main-sequence companion is strongly favored., Comment: Submitted to ApJ. 6 pages, 5 figures

The diffuse interstellar bands (DIBs) are absorption lines observed in visual and near infrared spectra of stars. Understanding their origin in the interstellar medium (ISM) is one of the oldest problems in astronomical spectroscopy, as DIBs ahave been known since 1922. In a completely new approach to understanding DIBs, we combined information from nearly 500,000 stellar spectra obtained by the massive spectroscopic survey RAVE (Radial Velocity Experiment) to produce the first pseudo three-dimensional map of the strength of the DIB at 8620~{\AA}ngstroms covering the nearest 3 kiloparsecs from the Sun, and show that it follows our independently constructed spatial distribution of extinction by interstellar dust along the Galactic plane. Despite having a similar distribution in the Galactic plane, the DIB 8620 carrier has a significantly larger vertical scale height than the dust. Even if one DIB may not represent the general DIB population, our observations outline the future direction of DIB research., Comment: Science 15 August 2014: 791-795, 4 pages, 3 figures

We present early decline spectra of the two Large Magellanic Cloud novae: LMC 2004 (YY Dor) and LMC 2009a and discuss their spectral an line profile evolution with special emphasis on the existence and appearance of a sharp component. We show that the narrow component that characterizes the emission lines in the maximum spectra of nova LMC 2004 originates in the ejecta. The HeII 4686 A, narrow emission which appears at the onset of the nebular phase in both novae is somewhat controversial. Our observations suggest that the corresponding line forming region is physically separated from the rest of the ejecta (the broad line region) and environmentally different. However, the lack of late time observations covering the super-soft source (SSS) phase, the post-SSS phase and the quiescence state does not allow to securely establish any non-ejecta origin/contribution as, instead, in the case of U Sco and KT Eri., Comment: 11 pages, 9 figures. Accepted for publication in Astronomy and Astrophysics on Aug 13 2014

The Asiago plate archive has been searched for old plates covering the region of the sky containing Nova Del 2013 (V339 Del). The brightness of the progenitor was measured against a deep BVRI photometric sequence that we calibrated on purpose. The mean brightness of the progenitor on Asiago plates is =17.27 and =17.6, for a mean color (B-V) = -0.33. The recorded total amplitude of variation in B band is 0.9 mag. Color and variability are in agreement with a progenitor dominated by the emission from an accretion disc. The progenitor was marginally detected also by the APASS all sky survey on April 2012. We have stacked the CCD images from three individual visits and measured the progenitor at B=17.33+/-0.09 and V=17.06+/-0.10 mag., Comment: IBVS 6087

We present an automated tool for measuring atmospheric parameters (T_eff, log(g), [Fe/H]) for F-G-K dwarf and giant stars. The tool, called GAUFRE, is written in C++ and composed of several routines: GAUFRE-RV measures radial velocity from spectra via cross-correlation against a synthetic template, GAUFRE-EW measures atmospheric parameters through the classic line-by-line technique and GAUFRE-CHI2 performs a chi^2 fitting to a library of synthetic spectra. A set of F-G-K stars extensively studied in the literature were used as a benchmark for the program: their high signal-to-noise and high resolution spectra were analysed by using GAUFRE and results were compared with those present in literature. The tool is also implemented in order to perform the spectral analysis after fixing the surface gravity (log(g)) to the accurate value provided by asteroseismology. A set of CoRoT stars, belonging to LRc01 and LRa01 fields was used for first testing the performances and the behaviour of the program when using the seismic log(g)., Comment: 7 pages, 3 figures, to appear in proceedings of 40th Liege International Astrophysical Colloquium 'Ageing low-mass stars: from red giants to white dwarfs'

We present multi-frequency radio observations of the 2010 nova event in the symbiotic binary V407 Cygni, obtained with the Karl G. Jansky Very Large Array and spanning 1-45 GHz and 17-770 days following discovery. This nova---the first ever detected in gamma rays---shows a radio light curve dominated by the wind of the Mira giant companion, rather than the nova ejecta themselves. The radio luminosity grew as the wind became increasingly ionized by the nova outburst, and faded as the wind was violently heated from within by the nova shock. This study marks the first time that this physical mechanism has been shown to dominate the radio light curve of an astrophysical transient. We do not observe a thermal signature from the nova ejecta or synchrotron emission from the shock, due to the fact that these components were hidden behind the absorbing screen of the Mira wind. We estimate a mass loss rate for the Mira wind of Mdot_w ~ 10^-6 M_sun/yr. We also present the only radio detection of V407 Cyg before the 2010 nova, gleaned from unpublished 1993 archival VLA data, which shows that the radio luminosity of the Mira wind varies by a factor of >~20 even in quiescence. Although V407 Cyg likely hosts a massive accreting white dwarf, making it a candidate progenitor system for a Type Ia supernova, the dense and radially continuous circumbinary material surrounding V407 Cyg is inconsistent with observational constraints on the environments of most Type Ia supernovae., Comment: Resubmitted to ApJ after incorporating referee's comments

We present an abundance analysis of six member stars of the recently discovered Aquarius stream, in an attempt to ascertain whether this halo stream is real and, if so, to understand its origin. The mean metallicities of the six stars have a dispersion of only 0.10 dex, indicating that they are part of a chemically coherent structure. We then investigate whether the stream represents the debris of a disrupted dwarf galaxy or a disrupted globular cluster. The [Ni/Fe] - [Na/Fe] plane provides a good diagnostic: globular cluster stars and dwarf spheroidal galaxy stars are well separated in this plane, and the Aquarius stream stars lie unambiguously in the globular cluster region. The Aquarius stream stars also lie on the distinct [Na/Fe] - [O/Fe] and [Mg/Fe] - [Al/Fe] relations delineated by Galactic globular cluster stars. Spectroscopic parameters for the six Aquarius stars show that they are tightly confined to a 12 Gyr, [Fe/H] = -1.0, alpha-enhanced isochrone, consistent with their identification as globular cluster debris. We present evidence that the Aquarius stream may continue through the disk and out into the northern halo. Our results indicate a globular cluster origin for the Aquarius stream, and demonstrate the potential for chemical tagging to identify the origins of Galactic substructures., Comment: As accepted to ApJ, 2012 32 pages, 5 figures, 5 tables

We report the discovery of eight lithium-rich field giants found in a high resolution spectroscopic sample of over 700 metal-poor stars ([Fe/H]<-0.5) selected from the RAVE survey. The majority of the Li-rich giants in our sample are very metal-poor ([Fe/H]<-1.9), and have a Li abundance (in the form of 7Li), A(Li)=log(n(Li)/n(H))+12, between 2.30 and 3.63, well above the typical upper red giant branch limit, A(Li)<0.5, while two stars, with A(Li)~1.7-1.8, show similar lithium abundances to normal giants at the same gravity. We further included two metal-poor, Li-rich globular cluster giants in our sample, namely the previously discovered M3-IV101 and newly discovered (in this work) M68-A96. This comprises the largest sample of metal-poor Li-rich giants to date. We performed a detailed abundance analysis of all stars, finding that the majority our sample stars have elemental abundances similar to that of Li-normal halo giants. Although the evolutionary phase of each Li-rich giant cannot be definitively determined, the Li-rich phase is likely connected to extra mixing at the red giant branch bump or early asymptotic giant branch that triggers cool bottom processing in which the bottom of the outer convective envelope is connected to the H-burning shell in the star. The surface of a star becomes Li-enhanced as 7Be (which burns to 7Li) is transported to the stellar surface via the Cameron-Fowler mechanism. We discuss and discriminate among several models for the extra mixing that can cause Li-production, given the detailed abundances of the Li-rich giants in our sample., Comment: 17 pages, 8 figures, accepted for publication in ApJ

We have undertaken the study of the elemental abundances and kinematic properties of a metal-poor sample of candidate thick-disk stars selected from the RAVE spectroscopic survey of bright stars to differentiate among the present scenarios of the formation of the thick disk. In this paper, we report on a sample of 214 red giant branch, 31 red clump/horizontal branch, and 74 main-sequence/sub-giant branch metal-poor stars, which serves to augment our previous sample of only giant stars. We find that the thick disk [alpha/Fe] ratios are enhanced, and have little variation (<0.1 dex), in agreement with our previous study. The augmented sample further allows, for the first time, investigation of the gradients in the metal-poor thick disk. For stars with [Fe/H] < -1.2, the thick disk shows very small gradients, <0.03 +/- 0.02 dex/kpc, in alpha-enhancement, while we find a +0.01 +/- 0.04 dex/kpc radial gradient and a -0.09 +/- 0.05 dex/kpc vertical gradient in iron abundance. In addition, we show that the peak of the distribution of orbital eccentricities for our sample agrees better with models in which the stars that comprise the thick disk were formed primarily in the Galaxy, with direct accretion of stars contributing little. Our results thus disfavor direct accretion of stars from dwarf galaxies into the thick disk as a major contributor to the thick disk population, but cannot discriminate between alternative models for the thick disk, such as those that invoke high-redshift (gas-rich) mergers, heating of a pre-existing thin stellar disk by a minor merger, or efficient radial migration of stars., Comment: 21 pages, 31 figures, and 5 tables. Accepted for publication in ApJ

We identify a new, nearby (0.5 < d < 10 kpc) stream in data from the RAdial Velocity Experiment (RAVE). As the majority of stars in the stream lie in the constellation of Aquarius we name it the Aquarius Stream. We identify 15 members of the stream lying between 30 < l < 75 and -70< b <-50, with heliocentric line-of-sight velocities V_los~-200 km/s. The members are outliers in the radial velocity distribution, and the overdensity is statistically significant when compared to mock samples created with both the Besan\c{c}on Galaxy model and newly-developed code Galaxia. The metallicity distribution function and isochrone fit in the log g - T_eff plane suggest the stream consists of a 10 Gyr old population with [m/H]~-1.0. We explore relations to other streams and substructures, finding the stream cannot be identified with known structures: it is a new, nearby substructure in the Galaxy's halo. Using a simple dynamical model of a dissolving satellite galaxy we account for the localization of the stream. We find that the stream is dynamically young and therefore likely the debris of a recently disrupted dwarf galaxy or globular cluster. The Aquarius stream is thus a specimen of ongoing hierarchical Galaxy formation, rare for being right in the solar suburb., Comment: 17 pages, 10 figures, accepted for publication in ApJ

We report the discovery of the first known symbiotic star in IC10, a starburst galaxy belonging to the Local Group, at a distance of ~750kpc. The symbiotic star was identified during a survey of emission-line objects. It shines at V = 24.62+-0.04, V - R_C = 2.77+-0.05 and R_C - I_C = 2.39+-0.02 and suffers from E(B-V) = 0.85+-0.05 reddening. The spectrum of the cool component well matches that of solar neighborhood M8III giants. The observed emission lines belong to Balmer series, [SII], [NII] and [OIII]. They suggest a low electronic density, negligible optical depth effects and 35,000K < T_eff < 90,000K for the ionizing source. The spectrum of the new symbiotic star in IC10 is an almost perfect copy of that of Hen 2-147, a well known Galactic symbiotic star and Mira., Comment: 5 pages including 3 figures. MNRAS Letters accepted. Also available at http://pessoais.ov.ufrj.br/denise/

Following the outburst of the unusual variable star V838 Monocerotis in 2002, a spectacular light echo appeared. A light echo provides the possibility of direct geometric distance determination, because it should contain a ring of highly linearly polarized light at a linear radius of ct, where t is the time since the outburst. We present imaging polarimetry of the V838 Mon light echo, obtained in 2002 and 2005 with the Advanced Camera for Surveys onboard the Hubble Space Telescope, which confirms the presence of the highly polarized ring. Based on detailed modeling that takes into account the outburst light curve, the paraboloidal echo geometry, and the physics of dust scattering and polarization, we find a distance of 6.1+-0.6 kpc. The error is dominated by the systematic uncertainty in the scattering angle of maximum linear polarization, taken to be theta_{max}=90^o +- 5^o. The polarimetric distance agrees remarkably well with a distance of 6.2+-1.5 kpc obtained from the entirely independent method of main-sequence fitting to a sparse star cluster associated with V838 Mon. At this distance, V838 Mon at maximum light had M_V\simeq-9.8, making it temporarily one of the most luminous stars in the Local Group. Our validation of the polarimetric method offers promise for measurement of extragalactic distances using supernova light echoes., Comment: 43 pages, 17 figures, 3 tables; accepted for publication in the Astronomical Journal. Version with high-quality figures available at http://www.stsci.edu/~bond/v838monpolariz.pdf

New and previously published observations of the bright eclipsing binary VV Orionis are analyzed. We present new radial velocities and interstellar reddening measurements from high-resolution spectra of this detached, short-period (P=1.48 d) binary. We discuss the validity of prior claims for the existence of a third body and show that our new velocities and light curve solution cast doubt on them. The components of VV Ori are shown to be a B1 V primary with a mass $M{_1}=10.9 \pm 0.1 M_{\sun}$ and a radius $R_{1}=4.98 \pm 0.02 R_{\sun}$ and a B4.5 V secondary with a mass $M{_2}=4.09 \pm 0.05 M_{\sun}$ and a radius $R_{2}=2.41 \pm 0.01 R_{\sun}$., Comment: 6 pages, 6 figures, 3 tables; accepted for publication in MNRAS

We present photometric and spectroscopic data on the early-type binary MP Centauri. The photometric data are analyzed simultaneously with radial velocities to derive preliminary absolute dimensions for the binary components. Analysis of the spectra shows that the stars rotate synchronously and that the line of sight to the system crosses two kinematically sharp and well-separated interstellar reddening sources. It is shown that MP Cen consists of a B3 primary with M_1 = 11.4 +/- 0.4 M_sun, R_1 = 7.7 +/- 0.1 R_sun and a lobe-filling B6-B7 secondary with M_2 = 4.4 +/- 0.2 M_sun, R_2 = 6.6 +/- 0.1 R_sun, Comment: Accepted for publication in the MNRAS

One may consider cross-correlation routines applied to stellar spectra as a way to determine not only the radial velocities but also to assess the properties of stellar atmospheres. We show that this is not the case. High value of the cross-correlation coefficient between the observed and a template spectrum does not mean that the template corresponds to correct values of stellar temperature, gravity or metallicity. Cross-correlation operates in normalized space, so it is not sensitive to scaling or shifting of stellar flux. It is argued that cross-correlation is useful to efficiently determine the velocity shift between the observed and the template spectrum. But minimal distance methods need to be used to determine which template gives the best match to the observed spectrum, and so derive values of physical parameters. To illustrate the point we use data from the RAVE project which are being obtained at very similar spectral resolution and wavelength domain as will be the case for GAIA's RVS., Comment: 4 pages, 3 figures, Proceedings of the Symposium "The Three-Dimensional Universe with Gaia", 4-7 October 2004, Observatoire de Paris-Meudon, France, ESA-SP 576, in print

The photometric evolution of M31-RV has been investigated on 1447 plates of the Andromeda galaxy obtained over half a century with the Asiago telescopes. M31-RV is a gigantic stellar explosion that occurred during 1988 in the Bulge of M31 and that was characterized by the appearance for a few months of an M supergiant reaching M_bol=-10. The 1988 outburst has been positively detected on Asiago plates, and it has been the only such event recorded over the period covered by the plates (1942-1993). In particular, an alleged previous outburst in 1967 (Sharov 1990, SvAL, 16, 199) is excluded by the more numerous and deeper Asiago plates, with relevant implication for the interpretative models of this unique event. We outline a close analogy in spectral and photometric evolution with those of V838 Mon which exploded in our Galaxy in 2002. The analogy is found to extend also to the closely similar absolute magnitude at the time of the sudden drop in photospheric temperature that both M31-RV and V838 Mon exhibited. These similarities, in spite of the greatly differing metallicity, age and mass of the two objects, suggest that the same, universal and not yet identified process was at work in both cases., Comment: A&A in press. Table 3 available only in electronic form from CDS or http://ulisse.pd.astro.it/M31-RV.html

A library of 183588 synthetic spectra based on Kurucz's ATLAS9 models is presented for the far red spectral interval (7653 -- 8747\AA). It is characterized by 3500 K <= T_eff <= 47500 K, 0.0 <= log g <= 5.0, -3.0 <= [M/H] <= +0.5, 0 <= V_rot <= 500 km/s, xi = 2 km/s. The whole grid of spectra is calculated for resolving powers 8500, 11500 and 20000. A section of the grid is also computed for [alpha/Fe]=+0.4 and for microturbulent velocities 0 and 4 km/s. The library covers the wavelength ranges and resolutions of the two ambitious spectroscopic surveys by the ground experiment RAVE and the space mission GAIA. Cross-sections across the multi-dimensional data-cube are used to illustrate the behaviour of the strongest spectral lines. Interpretation of real data will have to include interpolation to grid substeps. We present a simple estimate of the accuracy of such a procedure., Comment: accepted for publication in Astronomy and Astrophysics, 8 pages, 6 figures, data will be published electronically

Accurate and deep BVI CCD photometry is presented for the core regions of six southern compact open clusters (supplemented in one case by U and R bands). These clusters generally have only scanty photometric data published, in some case only photoelectric or photographic. Together with adoption of modern reference isochrones, this has allowed us to derive improved values for their distance, reddening, age and main sequence morphology., Comment: 8 pages, 4 eps figures, in press in MNRAS

We present new spectroscopic and photometric data on the early-type overcontact binary TU Muscae. The analysis of the spectroscopic data shows that the line of sight to the system crosses three kinematically sharp and well-separated interstellar reddening sources and that the stars rotate synchronously. We present new radial velocities that are in good agreement with earlier optical velocities and, thus, do not confirm the systematically smaller velocities obtained from IUE spectra. The optical velocities are analyzed simultaneously with the photometric data to derive accurate absolute dimesions for the binary components.The results show that TU Mus consists of an O7.5 primary with M_1=23.5 +/- 0.8 M_sun, R_1=7.48 +/- 0.08 R_sun and an O9.5 secondary with M_2=15.3 +/- 0.4 M_sun, R_2=6.15 +/- 0.07 R_sun in an overcontact configuration and that the orbital period has remained constant over the three decades covered by the observations. These results might imply that the mass transfer seen in late-type overcontact binaries does not occur in their early-type counterparts., Comment: 11 pages, 10 figures, accepted for Dce 2003 issue of AJ

GAIA astrometric mission of ESA will be very efficient in discovering binary and multiple stars with any orbital period, from minutes to millions of years. Main parameters of the revised mission design are presented. Next we estimate the fraction of binary stars discovered by means of astrometry, photometry and on-board spectroscopy. Finally we summarize observations that confirm the ability to measure physical parameters like masses, radii and spectroscopic distance from GAIA data alone. GAIA will fly only in 2010, but the Radial velocity experiment (RAVE) has started this year. We show that its spectroscopic observations have the capacity to discover a large fraction of so far unknown binary systems., Comment: Invited talk, IAU Coll. 191, "Environments and evolution of double and multiple stars", Merida (Mexico), Feb 2003, to be published in RevMexAA

Two sets of grids of Kurucz ATLAS~9 model spectra are presented. The first one covers the GAIA spectral interval, while the second one which is still being computed covers the whole range from 2500 -- 10500 \AA. Both grids include parameters needed for realistic spectral simulation, e.g. stellar rotation and are computed at R=20000 and lower spectral resolutions. They can be useful for preparation of the GAIA and RAVE missions and also for a general radial velocity correlation work, Comment: 6 pages, 3 figures; to be published in GAIA spectroscopy, Science and Technology, ASP Conference Series, U.Munari (ed.)

Deep, wide-range and accurate UBVRI photometric sequences have been established around more than 80 symbiotic stars, to assist current photometry as well as measurement of old photographic plates. Sequences for 40 symbiotic stars have already been published; the observations for the others have already been secured., Comment: To appear in the proceedings of "Symbiotic stars probing stellar evolution", R.L.M. Corradi, J. Mikolajewska and T.J. Mahoney eds., ASP Conference Series, 2002, in press

High resolution (R~20,000), high signal-to-noise (S/N~100) spectra were collected for ~40 symbiotic stars with the Asiago echelle spectrograph over the same 8480-8740 Ang wavelength range covered by the ESA Cornerstone mission GAIA, centered on the near-IR CaII triplet and the head of the Paschen series. A large number (~140) of cool MKK giant and supergiant templates were observed with the same instrumentation to serve as a reference and classification grid. The spectra offer bright prospects in classifying and addressing the nature of the cool component of symbiotic stars (deriving T(eff), log g, [Fe/H], [alpha/Fe], V(rot)sin i both via MDM-like methods and syntetic atmosphere modeling) and mapping the physical condition and kinematics of the gas regions responsible for the emission lines., Comment: to appear in the proceedings of "Symbiotic stars probing stellar evolution", R.L.M. Corradi, J. Mikolajewska, T.J. Mahoney eds., ASP Conference Series, 2002, in press