A NEW VLA-HIPPARCOSDISTANCE TO BETELGEUSE AND ITS IMPLICATIONS

Abstract

The distance to the M supergiant Betelgeuse is poorly known, with the Hipparcos parallax having a significant uncertainty. For detailed numerical studies of M supergiant atmospheres and winds, accurate distances are a prerequisite to obtaining reliable estimates for many stellar parameters. New high spatial resolution, multiwavelength, NRAO 3 Very Large Array (VLA) radio positions of Betelgeuse have been obtained and then combined with Hipparcos Catalogue Intermediate Astrometric Data to derive new astrometric solutions. These new solutions indicate a smaller parallax, and hence greater distance (197 ± 45 pc), than that given in the original Hipparcos Catalogue (131 ± 30 pc) and in the revised Hipparcos reduction. They also confirm smaller proper motions in both right ascension and declination, as found by previous radio observations. We examine the consequences of the revised astrometric solution on Betelgeuse's interaction with its local environment, on its stellar properties, and its kinematics. We find that the most likely star-formation scenario for Betelgeuse is that it is a runaway star from the Ori OB1 association and was originally a member of a high-mass multiple system within Ori OB1a.

3D simulations of Betelgeuse’s bow shock

“…Estimates for Betelgeuse's age are highly uncertain, ranging from 8-13 million years depending on the stellar evolution model and distance assumed (Harper et al 2008). The core helium-burning phase lasts about 10% of the total lifetime, thus τ He = 0.8−1.3 Myr.…”

“…Betelgeuse has an average radial (heliocentric) velocity of V rad = +20.7 ± 0.4 km s −1 away from the sun, and the tangential velocities are V α cos δ = 23.7(D [pc]/200) km s −1 and V δ = 9.1(D [pc]/200) km s −1 (Harper et al 2008, and references therein). The distance D to Betelgeuse is not yet well established, the most recent estimate being 197 ± 45 pc (see Harper et al 2008, for a detailed discussion).…”

“…Betelgeuse has an average radial (heliocentric) velocity of V rad = +20.7 ± 0.4 km s −1 away from the sun, and the tangential velocities are V α cos δ = 23.7(D [pc]/200) km s −1 and V δ = 9.1(D [pc]/200) km s −1 (Harper et al 2008, and references therein). The distance D to Betelgeuse is not yet well established, the most recent estimate being 197 ± 45 pc (see Harper et al 2008, for a detailed discussion). For this range of distances, Betelgeuse is moving supersonically relative to the local ISM, and the collision of its stellar wind with this medium has resulted in the formation of a cometary structure, a bow shock, pointing in the direction of motion (at a position angle of 69.0 • east of north).…”

The next-generation liquid-scintillator neutrino observatory LENA

“…While this effect requires the star to be close, the red supergiant Betelgeuse at about 200 pc [89] is a possible candidate. The neutrino burst after collapse would trigger about 10 7 events in LENA.…”

Imaging the spotty surface of Betelgeuse in theHband

“…Classified as semi-regular, it shows periodicity in its brightness changes, accompanied or sometimes interrupted by various irregularities (Guinan 1984). According to a recent reanalysis of a Hipparcos satellite dataset, its distance is now estimated at 197 ± 45 pc (Harper et al 2008). The observations up to now have identified at least 7 components of the complex Betelgeuse atmosphere: two outer shells, a dust environment, a chromosphere, a gaseous envelope, a molecular shell also known as MOLsphere (Tsuji 2000a), and finally the photosphere.…”