Studies of multiple stellar systems - IV. The triple-lined spectroscopic system Gliese 644

Tsevi Mazeh*, David W. Latham, Elad Goldberg, Guillermo Torres, Robert P. Stefanik, Todd J. Henry, Shay Zucker, Orly Gnat, Eran O. Ofek

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

19 Scopus citations

Abstract

We present a radial velocity study of the triple-lined system Gliese 644 and derive spectroscopic elements for the inner and outer orbits with periods of 2.965 5 and 627 d. We also utilize old visual data, as well as modern speckle and adaptive optics observations, to derive a new astrometric solution for the outer orbit. These two orbits together allow us to derive masses for each of the three components in the system: MA = 0.410 ± 0.028 (6.9 per cent), MBa = 0.336 ± 0.016 (4.7 per cent), and MBb = 0.304 ± 0.014 (4.7 per cent) M. We suggest that the relative inclination of the two orbits is very small. Our individual masses and spectroscopic light ratios for the three M stars in the Gliese 644 system provide three points for the mass-luminosity relation near the bottom of the main sequence, where the relation is poorly determined. These three points agree well with theoretical models for solar metallicity and an age of 5 Gyr. Our radial velocities for Gliese 643 and vB 8, two common proper motion companions of Gliese 644, support the interpretation that all five M stars are moving together in a physically bound group. We discuss possible scenarios for the formation and evolution of this configuration, such as the formation of all five stars in a sequence of fragmentation events leading directly to the hierarchical configuration now observed, versus formation in a small N cluster with subsequent dynamical evolution into the present hierarchical configuration.

Original languageAmerican English
Pages (from-to)343-357
Number of pages15
JournalMonthly Notices of the Royal Astronomical Society
Volume325
Issue number1
DOIs
StatePublished - 21 Jul 2001
Externally publishedYes

Keywords

  • Binaries: spectroscopic
  • Binaries: visual
  • Stars: individual: Gliese 644
  • Techniques: radial velocities

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