2006ApJ...649..389P -
Astrophys. J., 649, 389-398 (2006/September-3)
Masses of astrometrically discovered and imaged binaries: G78-28AB and GJ 231.1BC.
PRAVDO S.H., SHAKLAN S.B., WIKTOROWICZ S.J., KULKARNI S., LLOYD J.P., MARTINACHE F., TUTHILL P.G. and IRELAND M.J.
Abstract (from CDS):
The Stellar Planet Survey (STEPS) is an ongoing astrometric search for giant planets and brown dwarfs around a sample of ∼30 M dwarfs. We have discovered several low-mass companions by measuring the motion of our target stars relative to their reference frames. The highest mass discovery thus far is G78-28B, a companion to the M dwarf G78-28A. The orbital period is 4.18±0.03 yr, the system mass is 0.565±0.055 M☉, and the semimajor axis is 2.19±0.10 AU. Imaging observations with the Keck laser guide star adaptive optics (LGSAO) and the Palomar AO instruments resolved the system and also yielded JHK-band delta magnitudes. We use the orbital solution, light ratios, and mass-luminosity relationships to derive component masses of MA=0.370±0.034 M☉and MB=0.195±0.021 M☉. G78-28B is of type M4 V based on its colors and mass. We also discovered GJ 231.1C, a companion to GJ 231.1B, with STEPS and imaged the companion with LGSAO and Palomar AO, but the orbital period is longer than our observing baseline; thus, the system parameters are less constrained. In GJ 231.1BC the masses are MB=0.25±0.06 M☉and MC=0.12±0.02 M☉. The inferred spectral type of GJ 231.1C is M5 V. We demonstrate the results of the current state of mass estimation techniques with our data.
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Journal keyword(s):
Stars: Planetary Systems - stars: individual (G78-28A)
Simbad objects:
3
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