The Exemplar T8 Subdwarf Companion of Wolf 1130

November 2013 • 2013ApJ...777...36M

Authors • Mace, Gregory N. • Kirkpatrick, J. Davy • Cushing, Michael C. • Gelino, Christopher R. • McLean, Ian S. • Logsdon, Sarah E. • Wright, Edward L. • Skrutskie, Michael F. • Beichman, Charles A. • Eisenhardt, Peter R. • Kulas, Kristin R.

Abstract • We have discovered a wide separation (188.''5) T8 subdwarf companion to the sdM1.5+WD binary Wolf 1130. Companionship of WISE J200520.38+542433.9 is verified through common proper motion over a ~3 yr baseline. Wolf 1130 is located 15.83 ± 0.96 pc from the Sun, placing the brown dwarf at a projected separation of ~3000 AU. Near-infrared colors and medium resolution (R ≈ 2000-4000) spectroscopy establish the uniqueness of this system as a high-gravity, low-metallicity benchmark. Although there are a number of low-metallicity T dwarfs in the literature, WISE J200520.38+542433.9 has the most extreme inferred metallicity to date with [Fe/H] = -0.64 ± 0.17 based on Wolf 1130. Model comparisons to this exemplar late-type subdwarf support it having an old age, a low metallicity, and a small radius. However, the spectroscopic peculiarities of WISE J200520.38+542433.9 underscore the importance of developing the low-metallicity parameter space of the most current atmospheric models.


IPAC Authors

Chris Gelino

Associate Scientist


Davy Kirkpatrick

Senior Scientist