Gliese 412
Binary star system in the constellation Ursa Major
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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 Location of Gliese 412 in the constellation Ursa Major | |
| Observation data Epoch J2000 Equinox ICRS | |
|---|---|
| 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: HIP 54211, SAO 43609, G 176-11, LAL 21258, LFT 757, LHS 38, LTT 12976, NLTT 26245, Gaia DR2 778947814402405120[4] B: WX UMa, G 176-12, LFT 758, LHS 39, LTT 12977, NLTT 26247, Gaia DR2 778947608243864320[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] From the B component, the A component would appear about as bright as a First Quarter Moon. From the A component, the B component would appear as bright as Venus seen from Earth.
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]