We discuss the properties of Hα emission stars across the sample of 22035 spectra from the Gaia-ESO Survey internal data release, observed with the GIRAFFE instrument and largely belonging to stars in young open clusters. Automated fits using two independent Gaussian profiles and a third component that accounts for the nebular emission allow us to discern distinct morphological types of Hα line profiles with the introduction of a simplified classification scheme. All in all, we find 3765 stars with intrinsic emission and sort their spectra into eight distinct morphological categories: single-component emission, emission blend, sharp emission peaks, double emission, P-Cygni, inverted P-Cygni, self- absorption, and emission in absorption. We have more than one observation for 1430 stars in our sample, thus allowing a quantitative discussion of the degree of variability of Hα emission profiles, which is expected for young, active objects. We present a catalogue of stars with properties of their Hα emission line profiles, morphological classification, analysis of variability with time and the supplementary information from the SIMBAD, VizieR, and ADS databases. The records in SIMBAD indicate the presence of Hα emission for roughly 25% of all stars in our catalogue, while at least 305 of them have already been more thoroughly investigated according to the references in ADS. The most frequently identified morphological categories in our sample of spectra are emission blend (23%), emission in absorption (22%), and self-absorption (16%). Objects with repeated observations demonstrate that our classification into discrete categories is generally stable through time, but categories P- Cygni and self-absorption seem less stable, which is the consequence of discrete classification rules, as well as of the fundamental change in profile shape. Such records of emission stars can be valuable for automatic pipelines in large surveys, where it may prove very useful for pinpointing outliers when calculating general stellar properties and elemental abundances. They can be used in studies of star formation processes, interacting binaries, and other fields of stellar physics.
F.02 Acquisition of new scientific knowledge
COBISS.SI-ID: 566913Data 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∼ 7500) covering the Ca-triplet region (8410–8795 Å) 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 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 catalog 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 subsamples 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.
F.02 Acquisition of new scientific knowledge
COBISS.SI-ID: 761729The ongoing Gaia mission of ESA will provide an accurate spatial and kinematical information for a large fraction of stars on our side of the Galactic centre. Interstellar extinction and line absorption studies toward a large number of stars at different distances and directions can give a 3- dimensional distribution map of interstellar absorbers, and thus reach a similar level or spatial and kinematic perfection. Specifically, under certain morphologies (e.g. geometrically thin absorption curtains and sheets) one can infer a complete velocity vector from its radial velocity component and so obtain a dynamical information comparable to stars. For that, observations of large number of stars at different distances are needed to determine where (along the line of sight) are the absorption pockets. Therefore, techniques to measure interstellar absorptions towards (abundant) cool stars are needed. A complex mix of colliding absorption clouds in found in the Galactic plane. Thus, one would wish to start with deep observations to detect the weak, but much more simple interstellar absorptions at high Galactic latitudes. Finally, interstellar atomic line absorption studies toward cool stars in the optical are largely limited to Sodium and Potassium doublets, not covered by many surveys, including Gaia. Diffuse interstellar bands (DIBs) can be important, as their measurement can give the same type of information as interstellar atomic absorption lines. A combination of both may also point to differences in dynamics of different components of the interstellar medium. In particular, Gaia spectra can be used to study the DIB at 8620 Å, and build 3- dimensional absorption maps, as already demonstrated by RAVE. Additionally, several the survey ground-based surveys (e.g APOGEE in the infrared, Gaia-ESO and Galah) that are pursuing this approach will be discussed in this contribution. The use of this new information can change our understanding in many areas (e.g. determination of membership of stars in clusters, studies of a few Myr old supernova remnants and investigations of Galactic fountains). The invited lecture is documented in http://eas.unige.ch/EWASS2015/session.jsp?id=Sp20 .
B.04 Guest lecture
COBISS.SI-ID: 619137