Gliese 412

Gliese 412 is a binary star system in the constellation Ursa Major. Among the nearest stars, they lie at a distance of 16.0 light-years (4.9 parsecs). The pair have an angular separation of 31.4″ at a position angle of 126.1°.^[16] Both components are relatively dim red dwarf stars.

Gliese 412 A/B

Gliese 412 Location of Gliese 412 in the constellation Ursa Major
Observation data Epoch J2000      Equinox J2000
Constellation	Ursa Major[1][2]
Gliese 412 A
Right ascension	11h 05m 28.57695s[3]
Declination	+43° 31′ 36.3869″[3]
Apparent magnitude (V)	8.68[4]
Gliese 412 B
Right ascension	11h 05m 30.88558s[5]
Declination	+43° 31′ 17.8852″[5]
Apparent magnitude (V)	14.45[6]
Characteristics
Gliese 412 A
Spectral type	M1.0V[4]
U−B color index	+1.16[7]
B−V color index	+1.54[7]
Gliese 412 B
Spectral type	M6.0V[6]
B−V color index	+2.08[8]
Astrometry
Gliese 412 A
Radial velocity (Rv)	+68.41±0.12[3] km/s
Proper motion (μ)	RA: −4,406.469 mas/yr[3] Dec.: +938.527 mas/yr[3]
Parallax (π)	203.8876±0.0332 mas[3]
Distance	15.997 ± 0.003 ly (4.9047 ± 0.0008 pc)
Absolute magnitude (MV)	10.34[9]
Gliese 412 B
Radial velocity (Rv)	+67.94±0.74[5] km/s
Proper motion (μ)	RA: −4,339.850 mas/yr[5] Dec.: +960.696 mas/yr[5]
Parallax (π)	203.8323±0.0500 mas[5]
Distance	16.001 ± 0.004 ly (4.906 ± 0.001 pc)
Absolute magnitude (MV)	16.05[9]
Details
Gliese 412 A
Mass	0.387±0.010[10] M☉
Radius	0.398±0.009[10] R☉
Luminosity	0.0223±0.0004[10] L☉
Surface gravity (log g)	4.860±0.031[10] cgs
Temperature	3,639±51[10] K
Metallicity [Fe/H]	−0.30±0.16[10] dex
Rotation	36.9±2.5 d[11]
Rotational velocity (v sin i)	<3[12] km/s
Age	3[13] Gyr
Gliese 412 B
Mass	0.0952±0.0095[13] M☉
Radius	0.1262±0.0054[13] R☉
Luminosity	0.000915±0.000024[14] L☉
Temperature	2,863±60[13] K
Metallicity [Fe/H]	−0.32±0.08[13] dex
Rotational velocity (v sin i)	7.7±1.7[12] km/s
Other designations
BD+44°2051, GJ 412, CCDM J11055+4332AB, WDS J11055+4332AB[15][4] A: Gaia DR2 778947814402405120, HIP 54211, SAO 43609, G 176-11, LAL 21258, LFT 757, LHS 38, LTT 12976, NLTT 26245[4] B: WX UMa, Gaia DR2 778947608243864320, G 176-12, LFT 758, LHS 39, LTT 12977, NLTT 26247[6]
Database references
SIMBAD	A
	B

History of observations

This system, also known as Lalande 21258, was announced in 1860 as a high apparent proper motion star by Friedrich Wilhelm Argelander as a result of work on the Bonner Durchmusterung (BD).^[17] Adalbert Krueger, an assistant to the BD project, was tasked with measuring its parallax. In Krueger's paper reporting the result, he dubbed it Argelander's Third Star.^[18]

The primary star was monitored for radial velocity (RV) variations caused by a Jupiter-mass companion in a short-period orbit. It displayed no significant excess of RV variation that could be attributed to a planet.^[19] A search of the system using near-infrared speckle interferometry also failed to detect a companion orbiting at distances of 1–10 AU.^[20] Nor has a brown dwarf been detected orbiting within this system.^[21]

Characteristics

The two stellar components of this system have a projected separation of about 152 AU, and an estimated orbital semimajor axis of 190 AU.^[22]

The primary has 0.387 times the mass of the Sun, 0.398 times the Sun's radius and 2.23% of the Sun's luminosity.^[10] It is spinning at a rotation velocity at the equator of less than 3 km/s.^[12] The secondary is smaller and fainter, at 9.52% of the Sun's mass, 12.62% of the Sun's radius^[13] and luminosity only 0.09% solar.^[14] It is spinning at a rotation velocity of 7.7±1.7 km/s.^[12] Gliese 412 A has a temperature of 3,639 K,^[10] while Gliese 412 B has 2,863 K.^[13]

The space velocity components of this system are U = 141, V = –7 and W = 7. They are members of the halo population of the Milky Way galaxy.^[12]

X-ray source

The secondary is a flare star that is referred to as WX Ursae Majoris. It is characterized as a UV Ceti-type variable star that displays infrequent increases in luminosity. This star was observed to flare as early as 1939 by the Dutch astronomer Adriaan van Maanen.^[23]

Component B (WX Ursae Majoris) has been identified as an X-ray source, while no significant X-ray emission was detected from component A.^[24] This system had not been studied in X-rays prior to ROSAT.^[24]