2MASS J15404341−5101357 (abbreviated 2M1540) is a red dwarf of spectral type M7, located in Norma at approximately 17 light-years from Earth. It is the nearest known M7 dwarf.[2]

2MASS J15404341−5101357

Observation data Epoch J2000      Equinox J2000
Constellation	Norma
Right ascension	15h 40m 43.537s[1]
Declination	−51° 01′ 35.968″[1]
Apparent magnitude (V)	15.26[2]
Characteristics
Evolutionary stage	main-sequence star[2]
Spectral type	M7V[2]
Apparent magnitude (J)	8.96[3]
Astrometry
Radial velocity (Rv)	50.0[3] km/s
Proper motion (μ)	RA: +1.954[2] mas/yr Dec.: −0.330[2] mas/yr
Parallax (π)	187.7290 ± 0.0496 mas[4]
Distance	17.374 ± 0.005 ly (5.327 ± 0.001 pc)
Absolute bolometric magnitude (Mbol)	12.81[2]
Details[2]
Mass	0.090±0.010 M☉
Luminosity	0.000603 L☉
Temperature	2621±100 K
Other designations
2MASS J154043.42-510135.7, WISEA J154045.67-510139.3, UCAC4 195-119117, Gaia DR2 5985290231327158144
Database references
SIMBAD	data
2M1540 Location of 2M1540 in the constellation Norma

Discovery

Its discovery was announced in 2014 by Kirkpatrick et al.[5] and independently by Pérez Garrido et al.[2]

Kirkpatrick and colleagues found a few thousand new high proper motion objects under the AllWISE program of study of images, taken by Wide-field Infrared Survey Explorer (WISE). 2M1540 was one of these high proper motion objects. They named it WISEA J154045.67-510139.3 and assigned it spectral type M6.[5]

Pérez Garrido and colleagues were looking for high proper motion sources in the 2MASS–WISE cross-match. They named it 2MASS J154043.42-510135.7 (2M1540 for short) and classified it as an M7.0±0.5 dwarf.[2]

Since the trigonometric distance of 2M1540 agreed with its spectrophotometric distances, computed for a single object, it was concluded that it is not an equal-mass binary.[2]

References