Luminosities, abundances, and motions of stars brighter than visual magnitude 15.1 and annual proper motions larger than one-half arcsecond

Abstract

view Abstract Citations (28) References (35) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Luminosities, Abundances, and Motions of Stars Brighter than Visual Magnitude 15.1 and Annual Proper Motions Larger than One-Half Arcsecond Eggen, Olin J. Abstract The stars with annual proper motion larger than 0.5 arcsec (PM I, II, III) and for which both photometry and radial-velocity determinations are available confirm the complete absence of objects with planar, galactic orbital eccentricities greater than 0.5 and [Fe/H] more than - 0.6 dex. Adopting an eccentricity of at least 0.5 as the definition of a halo star leads to a minimum density in the solar neighborhood of 41 x l0-5 pc-3 for Mv brighter than + 13 mag, with an additional 39 x l0-5 pc-3 from two white dwarfs of Mv = + 14 and + 15 mag. The luminosity function for the halo stars shows a sharp malconformation between Mv = + 5 and + 7 mag and a slope, for lower luminosities, of γ =0.047 (φ = 10γ( Mv-6)). The luminosity function of the disk (nonhalo) stars of large proper motion is very similar to the GLF (McCuskey 1966) but its slope, like that of the GLF, is considerably less than that found for the nearest stars. The relationship between the photometric abundances P[Fe/H] and the W (perpendicular) component of the space motion can be represented by a uniformly increasing upper limit ∣W + 6∣ = 70 - 50P[Fe/H] km s-1, which excludes only six stars of the sample. Space-motion vectors of all stars in PM I, II, and III for which the planar orbital eccentricity exceeds 0.5 from the photometric luminosities and proper motions alone, together with the percentage contribution from the unknown radial velocity, are tabulated, as are those of the disk (nonhalo) objects, and it is from these lists that probable and possible halo stars can be selected for confirming radial-velocity determinations. The luminosities discussed here are based on main sequences for the halo and disk populations that are confirmed by stellar models, and on calibrations of photometric indices, applied to the interme- diate band, (R,I), and/or Hβ photometry obtained for 400 stars in PM I, II, and III. The photometry is also used for abundance determinations, based on previously published calibrations. Publication: The Astronomical Journal Pub Date: February 1987 DOI: 10.1086/114324 Bibcode: 1987AJ.....93..393E Keywords: Abundance; Astronomical Catalogs; Radial Velocity; Stellar Luminosity; Stellar Motions; Visible Spectrum; Annual Variations; Solar Neighborhood; Stellar Envelopes; Stellar Orbits; Stellar Spectrophotometry; Astronomy; STARS: PROPER-MOTION; STARS: ABUNDANCES; STARS: LUMINOSITIES full text sources ADS | data products SIMBAD (408)