Lalande 21185 is the fourth nearest star system to the Sun after Alpha Centauri, Barnard's Star, and Wolf 359. Lalande 21185 is located in the southeastern corner of Ursa Major, northwest of Alula Borealis (Nu UMa). It is about three times too faint to be seen with the unaided eye.
Although Lalande 21185 is almost 200 times dimmer than the Sun, it is among the brightest red dwarfs in the solar neighborhood. Moving perpendicular to the galactic plane at a high velocity of 47 km/s, Lalande 21185 appears to belong to the Galaxy's thick disk population and to be considerably older than the Sun. It has both a high radial velocity, of 86 kilometers per second toward the Sun, and a high tangential velocity (proper motion) of 57 kilometers per second. The former is bringing the star 0.028 light-year closer to us each century and to a closest approach of about 4.6 light-years in 22,000 AD.
After analyzing 50 years of astrometric observations of the star, George Gatewood and colleagues of the Allegheny Observatory suggested (1996) that Lalande 21185 is orbited by two Jupiter-like
planets, a and b, though the evidence for b is weaker than
|Distance||8.29 light-years (2.54 parsecs)|
|Position||R.A. 11h 03m 20.2s; Dec. +35° 58' 11"|
|Other designations||HD 95735, BD +36 2147, G 119-052, PLX 2576, GJ 411, LHS 37, MCC 594, SAO 62377, LTT 12960, LFT 756, HIP 54035|
|Planets (to be confirmed and in doubt)|
|Mass (Jupiter=1)||0.9||1.6 ?|
|Semimajor axis||2.5 AU||10 AU ?|
|Orbital period||5.8 years||30 years ?|
|Discovery||1996, Gatewood et al, Allegheny Observatory||1996, Gatewood et al, Allegheny Observatory|
|Method of discovery||astrometry||astrometry|
Lalande 21185 in fiction
In Star Light, a novel by Hal Clement, Lalande 21185 is orbited by a planet called Dhrawn, which has an extremely high gravitational pull.
In the fictional universe of Star Trek, on several occasions in the year 2364, viewscreen readouts aboard the starship USS Enterprise-D show the location of Lalande 21185 in the form of charts from the Enterprise library computer. (TNG: "The Naked Now", "The Last Outpost", "Conspiracy").
1. Gatewood, G. D. "Lalande 21185," Bulletin of the American Astronomical Society, 28, 885 (1996).