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2MASS J12195156+3128497
Brown dwarf in the constellation Coma Berenices / From Wikipedia, the free encyclopedia
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2MASS J12195156+3128497 (abbreviated to 2MASS J1219+3128) is a rapidly-rotating brown dwarf of spectral class L8, located in the constellation Coma Berenices about 66 light-years from Earth. With a photometrically measured rotation period of 1.14 hours, it is one of the fastest-rotating known brown dwarfs announced by a team of astronomers led by Megan E. Tannock in March 2021. With a rotational velocity of about 80 km/s (50 mi/s), it is approaching the predicted rotational speed limit beyond which it would break apart due to centripetal forces. As a consequence of its rapid rotation, the brown dwarf is slightly flattened at its poles to a similar degree as Saturn, the most oblate planet in the Solar System.[5] Its rapid rotation may enable strong auroral radio emissions via particle interactions in its magnetic field, as observed in other known rapidly-rotating brown dwarfs.[2]
Observation data Epoch J2000 Equinox J2000 | |
---|---|
Constellation | Coma Berenices |
Right ascension | 12h 19m 51.561s[1] |
Declination | +31° 28′ 49.714″[1] |
Characteristics | |
Spectral type | L8[2] |
Apparent magnitude (J) | 15.913 ± 0.082[1] |
Apparent magnitude (H) | 14.907 ± 0.074[1] |
Apparent magnitude (K) | 14.305 ± 0.072[1] |
Astrometry | |
Radial velocity (Rv) | −19.0 ± 4.2[2] km/s |
Proper motion (μ) | RA: –233.0 ± 23.7[3] mas/yr Dec.: –49.6 ± 14.7[3] mas/yr |
Distance | 66.2 ± 9.8 ly (20.3 ± 3.0[4] pc) |
Details[2] | |
Mass | 0.047+0.022 −0.025 M☉ |
Radius | 0.100+0.027 −0.013 R☉ |
Surface gravity (log g) | 5.1 ± 0.5 cgs |
Temperature | 1330 ± 140 K |
Rotation | 1.14+0.03 −0.01 h |
Rotational velocity (v sin i) | 79.0 ± 3.4 km/s |
Age | 0.9+12.8 −0.8 Gyr |
Other designations | |
Database references | |
SIMBAD | data |