Early-type stars in orthogonal halo fields. 2: Identification of metal-rich A stars in the halo

Abstract

view Abstract Citations (22) References (48) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Early-Type Stars in Orthogonal Halo Fields. II. Identification of Metal-Rich A Stars in the Halo Rodgers, A. W. ; Roberts, W. H. Abstract The results of spectrophotometry of the Ca II K and Balmer lines and radial velocity measurements for stars earlier than type FO, with 10 less than V less than 15.5 in fields at (l;b) = 90 deg, 270 deg; -45 deg) are reported. Slit spectroscopy of 320 stars shows that in this magnitude range there are approximately 80 stars with (Fe/H) greater than -0.5. The metal-rich population has a vertical scale height of approximately 600 pc and a space density at the Sun equal to 1/225 of the young thin disk A star population. The metal-rich A stars have Vrot = 210 +/- 60 km/s with decreasing angular momentum as a function of distance from the Galactic plane. The line-of-sight velocity dispersion is 40 +/- 3 km/s indicating an anomalous relation between structure and kinematics. There is strong evidence that these stars are identical in properties to the metal-rich extended populations found by Perry (1969) at the NGP and Rodgers (1971) at the SGP. Publication: The Astronomical Journal Pub Date: November 1993 DOI: 10.1086/116769 Bibcode: 1993AJ....106.1839R Keywords: A Stars; Balmer Series; Calcium; Early Stars; Galactic Halos; Metallicity; Potassium; Radial Velocity; Abundance; Interstellar Extinction; Kinematics; Stellar Spectrophotometry; Telescopes; Astronomy; GALAXY: HALO; GALAXY: STELLAR CONTENT full text sources ADS | data products SIMBAD (331) CDS (1) Related Materials (2) Part 1: 1993AJ....106..591R Part 3: 1993AJ....106.2294R