Betelgeuse
Star
Facts
- Distance
- about 550 light-years
- Spectral class
- M1-2 Ia-Iab
- Diameter
- about 760 times the Sun
- Mass
- 16.5 to 19 times the Sun
- Apparent magnitude
- 0.50 (variable)
Betelgeuse is a red supergiant of spectral class M1-2 Ia-Iab, in Orion. It has between 16.5 and 19 times the mass of the Sun and is already fusing helium in its core: it is destined to end in a supernova explosion, although this is unlikely to happen soon.
With its diameter, placed where the Sun is it would reach out to about 3.5 AU, beyond the orbit of Mars; earlier estimates made it even larger, beyond the orbit of Jupiter.
Between late 2019 and mid-February 2020 it lost more than two-thirds of its brightness, a dimming visible to the naked eye, and returned to normal by April 2020. According to Hubble the dimming was caused by a cloud of dust, formed from a huge amount of hot material thrown out of the star, which covered about a quarter of it.
Sources
- Joyce et al. 2020, ApJ 902, 63 (distance of Betelgeuse)
- Hoffleit and Warren 1991, Yale Bright Star Catalogue, 5th Revised Ed. (V magnitudes, positions and spectral classes)
- Montargès et al. 2014, A&A 572, A17 (diameter of Betelgeuse)
- NASA Science, Hubble Finds that Betelgeuse's Mysterious Dimming Is Due to a Traumatic Outburst
- NASA APOD, Rigel Wide (7 April 2023)