Gould Belt Members in X-ray RAVE: Cross-Matching RAVE Stars with 3XMM Point Sources

In this paper the results of matching the RAdial Velocity Experiment (RAVE), a spectroscopic Southern hemisphere survey (9 $< I_{DENIS} <$ 12), and XMM-Newton Serendipitous Source Catalogue (3XMM) are presented. The latest data releases of RAVE and XMM were matched and a X-ray RAVE catalogue of 1071 stars was obtained. Then the catalogue was checked for possible Gould Belt (GB) members. We obtained a subsample of 10 stars that meet the GB membership criteria. This subsample and GB member candidates were tested photometrically and kinematically. Among the members there are two BY Dra type variables, an NGC2451 open cluster member, a high proper motion star. The rest are regular main sequence stars. The members have very low velocity dispersions which lead us to think that the members belong in a single structure. We also found out that a kinematical GB membership test might be possible to derive given a large enough GB member sample as they fit in a narrow interval in space velocity diagrams.Comment: Accepted by Astrophysics and Space Scienc

Photometric calibration of the [alpha/Fe] element: II. Calibration with SDSS photometry

We present the calibration of the [alpha/Fe] element in terms of ultra-violet excess for 465 dwarf stars with spectral type F0-K2. We used a single calibration, fitted to a third degree polynomial with a square of the correlation coefficient 0.74 and standard deviation 0.05 mag, for all stars due to their small colour range, 0.1 < (g - r)(0) <= 0.6 mag, and high frequency in the blueward of the spectrum which minimize the guillotine effect. Our calibration provides [alpha/Fe] elements in the range (-0.05, 0.35] dex. We applied the procedure to a high-latitude field, 85 degrees <= b <= 90 degrees with size 78 deg(2) and we could estimate the [alpha/Fe] elements of 23,414 dwarf stars which occupy a Galactic region up to a vertical distance of z = 9 kpc. We could detect a small positive gradient, d[alpha/Fe]/dz = +0.032 +/- 0.002 dex kpc(-1), for the range 0 < z < 5 kpc, while the distribution of the [alpha/Fe] element is flat for further z distances

Multiwavelength Absolute Magnitudes and Colors of Red Clump Stars in the Gaia Era

This study presents the multiwavelength investigation of the absolute magnitudes and colors of the red clump (RC) stars selected from APOGEE and GALAH DR2 combined catalog which is complemented with Gaia DR2 astrometric data and multiwavelength photometric data of GALEX GR6/7, SDSS DR7, Gaia DR2, 2MASS, and WISE sky surveys. The analyses are centered on the different distance estimation methods using Gaia trigonometric parallaxes, (1/piv) and Bayes statistics, and chemically defined Galactic disk populations on [α/Fe] × [Fe/H] plane. This investigation questions the long-studied problem of the population effects on RC luminosity. Using two different distance estimation approaches, (i) chemical thin and chemical thick disk RC stars are shown to have different absolute magnitudes, while colors remain the same in all photometric bands. Absolute magnitudes vary between −0.12 and +0.13 mag for the 1/piv with the change of the Galactic population. This variation in absolute magnitudes is found to be larger for the other method, (ii) the Besançon population synthesis model of Galaxy for 2MASS photometry, in which the absolute magnitude difference between chemical populations were found between −0.35 and −0.40 mag from thin disk to thick disk. When results compared with each other, differences of absolute magnitudes are about three times larger in the model than in the observations. We confirm that the RC absolute magnitudes depend on α-element abundances of Galactic populations

Local Stellar Kinematics from RAVE Data - VI. Metallicity Gradients Based on the F-G Main-Sequence Stars

We estimated iron and metallicity gradients in the radial and vertical directions with the F and G type dwarfs taken from the Radial Velocity Experiment Data Release 4 database. The sample defined by the constraints Z(max) 8 kpc. The range of the iron and metallicity abundance for the F and G type dwarfs on elongated orbits, [-0.13, -0.01), is similar to the thin-disc stars, while at least half of their space velocity components agree better with those of the thick-disc stars. The vertical iron gradients estimated for the F and G type dwarfs on circular orbits are d[Fe/H]/dZ(max) = -0.176 +/- 0.039 dex kpc(-1) and d[Fe/H]/dZ(max) = -0.119 +/- 0.036 dex kpc(-1) for the intervals Z(max) <= 825 and Z(max) <= 1500 pc, respectively

Metallicity calibration and photometric parallax estimation: II. SDSS photometry

We used the updated [Fe/H] abundances of 168 F-G type dwarfs and calibrated them to a third order polynomial in terms of reduced ultraviolet excess, delta(0.41) defined with ugr data in the SDSS. We estimated the M-g absolute magnitudes for the same stars via the re-reduced Hipparcos parallaxes and calibrated the absolute magnitude offsets, Delta M-g, relative to the intrinsic sequence of Hyades to a third order polynomial in terms of delta(0.41). The ranges of the calibrations are -2 18 mag)