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2MASS J04070752+1546457 (abbreviated to 2MASS J0407+1546) is a rapidly-rotating brown dwarf of spectral class L3.5, located in the constellation Taurus about 119 light-years from Earth. With a photometrically measured rotation period of 1.23 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 over 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.[3] 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]

2MASS J04070752+1546457

Observation data Epoch J2000      Equinox J2000
Constellation	Taurus
Right ascension	04h 07m 07.527s[1]
Declination	+15° 46′ 45.540″[1]
Characteristics
Spectral type	L3.5[2]
Apparent magnitude (G)	20.704 ± 0.014[1]
Apparent magnitude (J)	15.478 ± 0.058[1]
Apparent magnitude (H)	14.354 ± 0.057[1]
Apparent magnitude (K)	13.559 ± 0.038[1]
Astrometry
Radial velocity (Rv)	43.4 ± 2.1[2] km/s
Proper motion (μ)	RA: 61.250 ± 3.490[1] mas/yr Dec.: –53.130 ± 2.712[1] mas/yr
Parallax (π)	27.4408 ± 1.7735 mas[1]
Distance	119 ± 8 ly (36 ± 2 pc)
Details[2]
Mass	0.064+0.009 −0.027 M☉
Radius	0.100+0.024 −0.008 R☉
Surface gravity (log g)	5.2 ± 0.4 cgs
Temperature	1840 ± 210 K
Rotation	1.23±0.01 h
Rotational velocity (v sin i)	82.6 ± 0.2 km/s
Age	0.8+11.2 −0.65 Gyr
Other designations
SDSS J040707.56+154645.2, EPIC 210522262, TIC 348661774[1]
Database references
SIMBAD	data

Discovery

2MASS J0407+1546 was first catalogued as a point source in June 2003 by the Two Micron All-Sky Survey (2MASS) organized by the University of Massachusetts Amherst and the Infrared Processing and Analysis Center under the California Institute of Technology.[4] It was discovered to be a brown dwarf of the spectral class L3.5 by I. Neill Reid and collaborators, based on near-infrared spectra obtained in October 2005 with the Gemini North at the Mauna Kea Observatory, Hawaii. Their discovery and spectroscopic characterization of 430 ultracool dwarfs including 2MASS J0407+1546 was published in The Astronomical Journal in September 2008.[5]

Distance

The trigonometric parallax of 2MASS 1114−2618 was measured to be 27.4408±1.7735 milliarcseconds by the Gaia spacecraft in 2018, corresponding to a distance of 36.4 ± 2.4 parsecs (118.7 ± 7.8 ly).[1] This is in close agreement with Reid et al.'s spectrophotometric estimate of 33.1 ± 3.3 parsecs (108 ± 11 ly) in 2008, calculated from the object's spectral type and near-infrared absolute magnitude.[5]

Proper motion

From Gaia DR2, 2MASS J0407+1546 has a measured net proper motion of 81.0 mas/yr with position angle 139.06 degrees,[lower-alpha 1][lower-alpha 2] indicating motion in south-east direction on the sky.[1]

See also

• 2MASS J12195156+3128497 – L8 spectral class brown dwarf with a period of 1.14+0.03
  −0.01 h
• 2MASS J03480772−6022270 – T7 spectral class brown dwarf with a period of 1.080+0.004
  −0.005 h

Notes

References

External links

• Trio of Fast-Spinning Brown Dwarfs May Reveal a Rotational Speed Limit, Calla Cofield, Jet Propulsion Laboratory, 7 April 2021
• Western space scientists identify fastest-spinning "failed stars" ever found, Jeff Renaud, University of Western Ontario, 7 April 2021
• Caught Speeding: Clocking the Fastest-Spinning Brown Dwarfs, NOIRLab, 7 April 2021

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