1997/11/03 by Ivan R. King, Jay Anderson, Adrienne M. Cool +1 · 4 citations
Physics and Astronomy · #Astronomy and Astrophysical Research #Astrophysics and Star Formation Studies #Cluster (spacecraft) #Globular cluster #Hydrogen #Initial mass function #Luminosity #Luminosity function #Metallicity #Solar mass #Stars #Stellar, planetary, and galactic studies #astro-ph
paper · pdf · doi:10.1086/311082
Tex, 4 pages, 4 figures, 2 style files (apjlet.tex, twocolumns.tex); Astrophysical Journal Letters, accepted
arxiv created 1997/11/03 · openalex publication_date 1998/01/01 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
Second-epoch Hubble Space Telescope observations of NGC 6397 have led to the measurement of proper motions accurate enough to separate the faintest cluster stars from the field, thus extending the luminosity function of this globular cluster far enough to approach the limit of hydrogen burning on the main sequence. We isolate a sample of 1385 main-sequence stars, from just below the turnoff down to I = 24.5 ( M I ≃ 12.5), which corresponds to a mass of less than 0.1 m ☉ for the metallicity of this cluster. Below I = 22 ( M I ≃ 10), the main-sequence luminosity function drops rapidly, in a manner similar to that predicted by theoretical models of low-mass stars near the hydrogen-burning limit.