At the American Astronomical Society meeting during June 10-14, 1996 astronomers George Gatewood and colleagues at the University of Pittsburgh's Allegheny Observatory presented astrometric data of the nearby star Lalande 21185 that seemed to show a wobble due to the orbit of an unseen, Jupiter- sized planet orbiting every 30-35 years in an orbit similar to our Jupiter from its star. For 66 years, the Alleheney Observatory's telescope has been keeping meticulous track of the position of Lalande 21185 as it moves gradually across the sky at a rate of 4.78 arc seconds each year.
Lalande 21185, also called BD +36 2147 or HD95735, is a faint, +7.48 magnitude star, in the constellation Ursa Major. It is at a distance of 2.52 parsecs and has a proper motion of 4.78 arc seconds per year. It is an M2.1 V red dwarf, main sequence star with a luminosity about 0.0055 of the Sun, and a mass of about 0.3 times the Sun. Its coordinates in the 2000.0 epoch are Right Ascension = 11h 0.34m and Declination= +35d 57'. It is the fourth closest star to the Sun after the Alpha Centauri / Proxima Centauri system, Barnard's Star and Wolf 359. It's parallax is 0.395 arc seconds corresponding to a distance of 8.3 light years; about half a light year closer than Sirius.
Variations in the proper motion of this star were discovered by astronomer G. Land in 1941, and since then the presence of an unseen companion has become increasingly well established. S. Lippincott analyzed proper motion measurements from 1912 to 1959 and deduced a period of 8 years and a mass of 1/100 the Sun for the unseen companion with a maximum separation of 0.04 arc seconds. The eccentricity of the orbit was 0.30 making it very elliptical, and inclined at about 79 degrees to the line of sight.
The recent observations suggest that the unseen companion has a mass definitely below that of a brown dwarf, making it a bonefide planet candidate. There may also be some indication of one or two other bodies orbiting the star. We will have to keep a watch on these results, because astrometric detection of planets by the wobble they produce is notoriously tricky business. Confirmation of these results would strengthen the claim. The problem is that the purported orbital period of 30 - 35 years means that lots of data will have to be taken over nearly a century of time to follow several orbits of the body and make certain that they lead to consistent, periodic results.