2018A&A...609A..67K


Query : 2018A&A...609A..67K

2018A&A...609A..67K - Astronomy and Astrophysics, volume 609A, 67-67 (2018/1-1)

The close circumstellar environment of Betelgeuse. V. Rotation velocity and molecular envelope properties from ALMA.

KERVELLA P., DECIN L., RICHARDS A.M.S., HARPER G.M., McDONALD I., O'GORMAN E., MONTARGES M., HOMAN W. and OHNAKA K.

Abstract (from CDS):

We observed Betelgeuse using ALMA's extended configuration in band 7 (f~=340GHz, λ~=0.88mm), resulting in a very high angular resolution of 18 mas. Using a solid body rotation model of the 28SiO(ν=2, J=8-7) line emission, we show that the supergiant is rotating with a projected equatorial velocity of νeqsini=5.47±0.25km/s at the equivalent continuum angular radius Rstar=29.50±0.14mas. This corresponds to an angular rotation velocity of ωsini=(5.6±1.3)x10–9rad/s. The position angle of its north pole is PA = 48.0±3.5°. The rotation period of Betelgeuse is estimated to P/sini=36±8-years. The combination of our velocity measurement with previous observations in the ultraviolet shows that the chromosphere is co-rotating with the star up to a radius of ~=10au (45mas or 1.5x the ALMA continuum radius). The coincidence of the position angle of the polar axis of Betelgeuse with that of the major ALMA continuum hot spot, a molecular plume, and a partial dust shell (from previous observations) suggests that focused mass loss is currently taking place in the polar region of the star. We propose that this hot spot corresponds to the location of a particularly strong "rogue" convection cell, which emits a focused molecular plume that subsequently condenses into dust at a few stellar radii. Rogue convection cells therefore appear to be an important factor shaping the anisotropic mass loss of red supergiants.

Abstract Copyright: © ESO, 2018

Journal keyword(s): stars: individual: Betelgeuse - supergiants - stars: rotation - circumstellar matter - techniques: high angular resolution - stars: imaging

Simbad objects: 4

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Number of rows : 4
N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2023
#notes
1 ICRF J055250.1+031327 Bz? 05 52 50.1013410696 +03 13 27.242707260       22.79   ~ 53 1
2 * alf Ori s*r 05 55 10.30536 +07 24 25.4304 4.38 2.27 0.42 -1.17 -2.45 M1-M2Ia-Iab 1582 0
3 ICRF J060510.1+093913 QSO 06 05 10.1131750728 +09 39 13.608958968           ~ 16 1
4 * alf Sco s*r 16 29 24.45970 -26 25 55.2094 4.08 2.75 0.91 -0.64 -1.87 M1.5Iab+B2Vn 729 0

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2022.11.27-16:27:10

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