A spectroscopic survey of faint, high-Galactic-latitude red clump stars

I. The high resolution sample

¹ INAF-OAPD – Osservatorio Astronomico di Padova, via dell’Osservatorio 8, 36012 Asiago (VI), Italy
e-mail: marica.valentini@oapd.inaf.it, valentini@astro.ulg.ac.be
² Dipartimento di Astronomia, Universitá di Padova, vicolo dell’Osservatorio 3, 35122 Padova, Italy
e-mail: ulisse.munari@oapd.inaf.it
³ Institut d’Astrophysique et de Géophysique de l’Université de Liège, Allée du 6 Août 17, 4000 Liège, Belgium

Received: 27 April 2010
Accepted: 31 May 2010

Abstract

Context. Their high intrinsic brightness and small dispersion in absolute magnitude make red clump (RC) stars a prime tracer of Galactic structure and kinematics.

Aims. We aim to derive accurate, multi-epoch radial velocities and atmospheric parameters (T_eff, log g, [M/H], V_rotsini) of a large sample of carefully selected RC stars, fainter than those present in other spectroscopic surveys and located over a great circle at high Galactic latitudes.

Methods. We acquired data of the program stars of high signal-to-noise ratio (S/N) and high resolution with the Asiago Echelle spectrograph. Radial velocities were obtained by applying cross-correlation and atmospheric parameters via χ² fit to a synthetic spectral library. Extensive tests were carried out by re-observing with the same instrument a large number of standard stars taken from a variety of sources in the literature. During these tests, we found that the absolute Tycho V_T magnitude of local red clump stars is not dependent on metallicity

Results. A total of 277 red clump stars (101 of them with a second epoch observation) of the extended solar neighborhood and 55 calibration stars were observed and included in an output catalog that contains (in addition to relevant support astrometric and photometric data taken from literature) the main output of our survey: accurate multi-epoch radial velocities (σ(RV)_⊙ ≤ 0.4 km s^-1), accurate atmospheric parameters (σ(T_eff) = 68 K, σ(log g) = 0.11 dex, σ([M/H]) = 0.10 dex, σ(V_rotsini) = 1.1 km s^-1), distances, and space velocities (U,V,W).