WISE J072003.20-084651.2: AN OLD AND ACTIVE M9.5 + T5 SPECTRAL BINARY 6 pc FROM THE SUN

We report observations of the recently discovered, nearby late-M dwarf WISE J072003.20-084651.2. With high-resolution optical and near-infrared spectroscopy, we measure a stable radial velocity of +83.8 + or - 0.3 km s super(-1), indicative of old disk kinematics and consistent with the angular sepa...

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Bibliographic Details
Published in:The Astronomical journal 2015-03, Vol.149 (3), p.1-17
Main Authors: Burgasser, Adam J, Gillon, Michael, Melis, Carl, Bowler, Brendan P, Michelsen, Eric L, Gagliuffi, Daniella Bardalez, Gelino, Christopher R, Jehin, E, Delrez, L, Manfroid, J, Blake, Cullen H
Format: Article
Language:English
Subjects:
ASTROPHYSICS, COSMOLOGY AND ASTRONOMY
Aérospatiale, astronomie & astrophysique
binaries: spectroscopic
binaries: visual
Brightness
brown dwarfs
Bursts
Combustion
Disks
DWARF STARS
Flares
Hydrogen
Light curve
MAGNETIC FIELDS
MASS
Physical, chemical, mathematical & earth Sciences
Physique, chimie, mathématiques & sciences de la terre
Rotation
Space science, astronomy & astrophysics
stars: individual: WISE J072003.20-084651.2
stars: low-mass
stars: magnetic field
SUN
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Summary:We report observations of the recently discovered, nearby late-M dwarf WISE J072003.20-084651.2. With high-resolution optical and near-infrared spectroscopy, we measure a stable radial velocity of +83.8 + or - 0.3 km s super(-1), indicative of old disk kinematics and consistent with the angular separation of the possible companion. We measure a projected rotational velocity of v sin i = 8.0 + or - 0.5 km s super(-1) and find evidence of low-level variabilty (~1.5%) in a 13 day TRAPPIST light curve, but cannot robustly constrain the rotational period. We also observe episodic changes in brightness (1%-2%) and occasional flare bursts (4%-8%) with a 0.8% duty cycle, and order-of-magnitude variations in H alpha line strength. Combined, these observations reveal WISE J0720-0846 to be an old, very low-mass binary whose components straddle the hydrogen burning minimum mass, and whose primary is a relatively rapid rotator and magnetically active.
ISSN:1538-3881
0004-6256
1538-3881
DOI:10.1088/0004-6256/149/3/104