Astrobites | 2018 Dec 10
Jessica Roberts wrote:
Sitting at only 6 light years from us, Barnard’s star is the closest single star from us and the second closest M dwarf (Proxima Centauri being the closest). This little 0.16 solar mass star has also been the subject of some serious debate and controversy over the possible existence of a planetary system. In the 1960s, Peter van de Kamp claimed a detection of not one but two planets orbiting at 12 and 20 days, with similar masses to Jupiter. However, multiple groups have been unable to reproduce these results. One study, highlighted in this bite, also ruled out planets with masses greater than 10 Earth masses and periods less than 2 years. If there are planets of smaller masses or on longer orbits, the observations up to this point just haven’t been precise enough to detect them.
But the authors of today’s paper didn’t give up on this tiny star. They observed Barnard’s star every possible night between 2016 and 2017 with CARMENES, HARPS, and HARPS-N instruments. These measurements were then combined with all the other observations of this star over the last 20 years. By using the radial velocity technique, the authors searched for possible “wobbles” in the star’s movement as it is pulled towards and away from us by the undetected planet. And lo and behold, not one, but two signals emerged from the dataset (Figure 1)! One was a repeating or periodic signal at 233 days and another one at >4000 days (or about 11 years). Something (or multiple things) appeared to be playing a gravitational tug-of-war with Barnard’s star. ...
These dusty young stars are changing the rules of planet-building
Nature News | 04 Dec 2018
A Candidate Super-Earth Planet Orbiting near the Snow-Line of Barnard’s Star ~ I. Ribas et al
- Nature 563(7731):365 (15 Nov 2018) DOI: 10.1038/s41586-018-0677-y
arXiv.org > astro-ph > arXiv:1811.05955 > 14 Nov 2018 (v1), 23 Nov 2018 (v2)