Two new long-period hot subdwarf binaries with dwarf companions

Brad N. Barlow, Sandra E. Liss, Richard A. Wade, Elizabeth M. Green

Research output: Contribution to journalArticlepeer-review

20 Scopus citations

Abstract

Hot subdwarf stars with F-K main sequence binary companions have been known for decades, but the first orbital periods for such systems were published just recently. Current observations suggest that most have long periods, on the order of years, and that some are or once were hierarchical triple systems. As part of a survey with the Hobby-Eberly Telescope, we have been monitoring the radial velocities of several composite-spectra binaries since 2005 in order to determine their periods, velocities, and eccentricities. Here we present observations and orbital solutions for two of these systems, PG 1449+653 and PG 1701+359. Similar to the other sdB+F/G/K binaries with solved orbits, their periods are long, 909 and 734 days, respectively, and pose a challenge to current binary population synthesis models of hot subdwarf stars. Intrigued by their relatively large systemic velocities, we also present a kinematical analysis of both targets and find that neither is likely a member of the Galactic thin disk.

Original languageEnglish (US)
Article number23
JournalAstrophysical Journal
Volume771
Issue number1
DOIs
StatePublished - Jul 1 2013
Externally publishedYes

Keywords

  • binaries: spectroscopic
  • ephemeredes
  • subdwarfs
  • techniques: radial velocities

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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