A metallicity, chemical composition, and kinematic survey has been conducted for a sample of 340 candidate field red horizontal-branch (RHB) stars. Spectra with high resolution and high signal-to-noise ratio were gathered with the McDonald Observatory 2.7 m Tull and the Hobby-Eberly Telescope echelle spectrographs, and were used to determine effective temperatures, surface gravities, microturbulent velocities, [Fe/H] metallicities, and abundance ratios [X/Fe] for seven {alpha} and Fe-group species. The derived temperatures and gravities confirm that at least half of the candidates are true RHB stars, with (average) parameters T_eff_~5000 K and log g~2.5. From the {alpha} abundances alone, the thin and thick Galactic populations are apparent in our sample. Space motions for 90% of the program stars were computed from Hipparcos and Gaia parallaxes and proper motions. Correlations between chemical compositions and Galactic kinematics clearly indicate the existence of both thin-disk and thick-disk RHB stars.
The ESA PLAnetary Transits and Oscillations of stars (PLATO) mission will search for terrestrial planets in the habitable zone of solar-like stars. Because of telemetry limitations PLATO targets need to be pre-selected. In this paper we present an all sky catalog that will be fundamental to select the best PLATO fields and the most promising target stars, derive their fundamental parameters, analyze the instrumental performances and then plan and optimize follow-up observations. This catalog also represents a valuable resource for the general definition of stellar samples optimized for the search of transiting planets. We used Gaia Data Release 2 (DR2) astrometry and photometry and 3D maps of the local interstellar medium to isolate FGK (V<=13) and M(V<=16) dwarfs and subgiant stars. We present the first public release of the all sky PLATO Input Catalog (asPIC1.1) containing a total of 2675539 stars among which 2378177 FGK dwarfs and subgiants and 297362 M dwarfs. The median distance in our sample is 428pc for FGK stars and 146 pc for M dwarfs, respectively. We derived the reddening of our targets and developed an algorithm to estimate stellar fundamental parameters (Teff, radius, mass) from astrometric and photometric measurements. We show that our overall (internal+external) uncertainties on the stellar parameters determination is ~230K (4%) for the effective temperatures, ~0.1R_{sun}_ (9%) for the stellar radii and ~0.1M_{sun}_ (11%) for the stellar mass. We release a special target list containing all known planet hosts cross-matched with our catalog.
We carried out an unbiased, spectroscopic survey using the low-resolution module of the infrared spectrograph (IRS) onboard Spitzer targeting two 2.6 square arcminute regions in the GOODS-North field. The IRS was used in a spectral mapping mode with 5hr of effective integration time per pixel. One region was covered between 14 and 21um and the other between 20 and 35um. We extracted spectra for 45 sources. About 84% of the sources have reported detections by GOODS at 24um, with a median f_{nu}_(24um)~100uJy. All but one source are detected in all four IRAC bands, 3.6 to 8um. We use a new cross-correlation technique to measure redshifts and estimate IRS spectral types; this was successful for ~60% of the spectra. Fourteen sources show significant polycyclic aromatic hydrocarbon emission, four mostly SiO absorption, eight present mixed spectral signatures (low PAH and/or SiO) and two show a single line in emission. For the remaining 17, no spectral features were detected. Redshifts range from z~0.2 to z~2.2, with a median of 1. IR luminosities are roughly estimated from 24um flux densities, and have median values of 2.2x10^11^L_{sun}_ and 7.5x10^11^L_{sun}_ at z~1 and z~2, respectively. This sample has fewer active galactic nuclei than previous faint samples observed with the IRS, which we attribute to the fainter luminosities reached here.
