MIX OF OLD AND NEW OBSERVATIONS REVEALS EXOTIC BINARY STAR European Southern Observatory Spots Largest Yellow Hypergiant Star
ESO’s Very Large Telescope Interferometer has revealed the largest yellow star — and one of the ten largest stars found so far.
This hypergiant has been found to measure more than 1300 times the diameter of the Sun,
and to be part of a double star system, with the second component so close that it is in contact with the main star.
Observations spanning over sixty years, some from amateur observers, also indicate that this rare and remarkable object is changing very rapidly and has been caught during a very brief phase of its life.
Using the European Southern Observatory’s (ESO) Very Large Telescope Interferometer (VLTI), Olivier Chesneau (Observatoire de la Côte d’Azur, Nice, France) and an international team of collaborators have found that the yellow hypergiant star HR 5171 A is absolutely huge — 1300 times the diameter of the Sun and much bigger than was expected. This makes it the largest yellow star known. It is also in the top ten of the largest stars known — 50% larger than the famous red supergiant Betelgeuse — and about one million times brighter than the Sun. [ESO United States]
TOP IMAGE: HR 5171 [a/ka/ V766 Centauri] — the brightest star just below the centre of this wide-field image — is a yellow hypergiant, a very rare type of star with only a dozen known in our galaxy. [ESO United States] Image credit: ESO/Digitized Sky Survey 2
BOTTOM IMAGE: Roche-lobe model of HR 5171 A. The model consists of two stars with a total mass of 39 solar masses separated by 9.6 AU, an orbital period of 1304d (3.57yr). [O. Chesneau, et al. The yellow hypergiant HR 5171 A: Resolving a massive interacting binary in the common envelope phase. arxiv.org/abs/1401.2628v2 // Accepted in Astronomy & Astrophysics (Jan 2014)
Open access PDF: arxiv.org/pdf/1401.2628v2.pdf
[Observation with the ESO's VLTI in 2012; further analysis, including comparison with archives, 2012-2013; publication, January 2014]
Revised