Free Astronomy Magazine January-February 2019

JANUARY-FEBRUARY 2019 The fast motion and the relative proximity of that star made Barnard even more famed, to the point that his name has since been in- dissolubly linked to the star. Today we know that Barnard’s Star is a typi- cal red dwarf, considerably older than the Sun and therefore quieter than younger red dwarfs, whose surface often shows particu- larly severe flares. The last of these events at Barnard’s Star occurred about twenty years ago and doubled the surface temperature. In the decades following the discovery by Barnard, astrometry continued to be funda- mental to the work on this star by many as- tronomers, who continued to measure the positions of the star on photographic plates in order to improve es- timates of parallax and proper motion. Among those as- tronomers was Peter van de Kamp, Dutch by birth and American by adoption, who was director of observato- ries and a university professor. In the late 1960s, van de Kamp became quite famous for announcing the discovery of a planet in orbit around Barnard’s Star. Examining photo- graphic plates taken between 1916 and 1962, the astronomer no- ticed small oscillations in the straight motion of the star, explainable with the presence of a body 1.6 times more massive than Jupiter, that from a distance of 4.4 AU pulled the star towards itself by rotating around it. The announcement of the discovery had a re- markable resonance because at that time the only known planets were those in our Solar System, and to tell the truth little was known even of them. As usual, other astronomers went to work to verify the discovery, and in the 1970s it be- came clear that the anomalies found by van de Kamp were not attributable to a planet, but to a problem of the 24-inch refractor op- G raphical repre- sentation of the relative dis- tances between the nearest stars and the Sun. Barnard’s Star is the second closest star system to the Sun and the near- est single star to our Solar System. On the left, the high apparent mo- tion of V2500 Ophiuchi, or Bar- nard’s Star, from the 1950s to 2018.