M dwarfs in the Galactic halo

  • I. Neill Reid
  • Suzanne L. Hawley
Part of the Astronomy and Planetary Sciences book series (PRAXIS)

Abstract

Approximately 99.7% of the stars in the immediate vicinity of the Sun are members of the Galactic disk. The remaining stars belong to the Galactic halo — the fossil remnants of the first extensive burst of star formation in the history of the Galaxy (see Chapter 6). A clear distinction should be drawn between the stellar halo population — made of baryonic material and having a total mass of only ~109 M — and the dark-matter halo, which is believed to be the dominant contributor to the Galactic potential. The dark-matter halo is held responsible for the relatively flat Galactic rotation curve, but its constituents have not yet been identified; those are the targets of gravitational lensing surveys. The present chapter concentrates on the stellar halo, and illustrates how observations of the lower-mass halo subdwarfs provide insight into the structure of the oldest stellar population so far identified in the Galaxy. The nature of the dark-matter halo is a subject in itself, and recent investigations are summarised elsewhere [T1].

Keywords

Magnesium Hydride Spectrophotometry Poss 

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Copyright information

© Springer-Verlag Berlin Heidelberg 2000

Authors and Affiliations

  • I. Neill Reid
    • 1
  • Suzanne L. Hawley
    • 2
  1. 1.Formerly of Edinburgh UniversityEdinburghScotland
  2. 2.Department of Physics and AstronomyMichigan State UniversityEast LansingUSA

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