Lalande 21185
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| Observation data Epoch J2000 | |
|---|---|
| Constellation (pronunciation) | Ursa Major |
| Right ascension | 11h 03m 20.2s |
| Declination | +35° 58' 11" |
| Apparent magnitude (V) | 7.47 |
| Characteristics | |
| Spectral type | M2 V |
| U-B color index | 1.13 |
| B-V color index | 1.51 |
| Variable type | Flare star |
| Astrometry | |
| Radial velocity (Rv) | -84.8 km/s |
| Proper motion (μ) | RA: -580.20 mas/yr Dec.: -4767.09 mas/yr |
| Parallax (π) | 393.42 ± 0.70 mas |
| Distance | 8.29 ± 0.01 ly (2.542 ± 0.005 pc) |
| Absolute magnitude (MV) | 10.46 |
| Details | |
| Mass | 0.46 M☉ |
| Radius | 0.46 R☉ |
| Luminosity | 0.0016 L☉ |
| Temperature | 3,400 K |
| Metallicity | 63% Sun |
| Rotation | ? |
| Age | 5-10 × 109 years |
| Other designations | |
Lalande 21185 is a red dwarf star approximately 2.5 pc or 8.21 light years from Earth's Solar System, and is the fourth closest known star system to the Sun and the closest in the constellation Ursa Major. It has a relatively high velocity and is moving in an orbit perpendicular to the plane of the galaxy. Its closest neighbour is Wolf 359, 1.24 pc or 4.03 ly away. It is also a variable flare star that sometimes increases in brightness. Based on the analysis of astrometric perturbations, this star is thought to possess at least two Jupiter-sized planets in orbit. The first planetary candidate, Lalande 21185b, is 2.2 AU from its primary and may have about nine-tenths of Jupiter's mass. Lalande 21185c, the second planetary candidate, has a mass about 1.6 times that of Jupiter and is thought to lie 11 AU from Lalande 21185b.
This earliest recording of the star was by Joseph-Jérôme Lefrançais de Lalande at the Paris Observatory some time before 1801.
[edit] See also
[edit] External links
- SolStation.com: Lalande 21185br:Lalande 21185
ca:Lalande 21185 de:Lalande 21185 es:Lalande 21185 fr:Lalande 21185 it:Lalande 21185 nl:Lalande 21185 ja:ラランド21185 pl:Lalande 21185 sk:Lalande 21185 fi:Lalande 21185 zh:拉蘭德21185
