The close circumstellar environment of Betelgeuse V. Rotation velocity and molecular envelope properties from ALMA
We observed Betelgeuse using ALMA’s extended configuration in band 7 (f ≈ 340 GHz, λ ≈ 0.88 mm), resulting in a very high angular resolution of 18 mas. Using a solid body rotation model of the 28 SiO(ν= 2, J = 8−7) line emission, we show that the supergiant is rotating with a projected equatorial ve...
Published in: | Astronomy & Astrophysics |
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2018
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Online Access: | https://research.manchester.ac.uk/en/publications/e2186d60-6275-41a3-b2c6-8dd5a1a329e8 https://doi.org/10.1051/0004-6361/201731761 https://pure.manchester.ac.uk/ws/files/65100909/KervellaBeteleuseRotation1711.07983.pdf |
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ftumanchesterpub:oai:pure.atira.dk:publications/e2186d60-6275-41a3-b2c6-8dd5a1a329e8 2023-11-12T04:23:03+01:00 The close circumstellar environment of Betelgeuse V. Rotation velocity and molecular envelope properties from ALMA Kervella , Pierre Decin, Leen Richards, Anita Harper, Graham M Mcdonald, Iain O'Gorman, Eamon Montargès, Miguel Homan, Ward Ohnaka, Keiichi 2018-01 application/pdf https://research.manchester.ac.uk/en/publications/e2186d60-6275-41a3-b2c6-8dd5a1a329e8 https://doi.org/10.1051/0004-6361/201731761 https://pure.manchester.ac.uk/ws/files/65100909/KervellaBeteleuseRotation1711.07983.pdf eng eng info:eu-repo/semantics/openAccess Kervella , P , Decin , L , Richards , A , Harper , G M , Mcdonald , I , O'Gorman , E , Montargès , M , Homan , W & Ohnaka , K 2018 , ' The close circumstellar environment of Betelgeuse V. Rotation velocity and molecular envelope properties from ALMA ' , Astronomy and Astrophysics . https://doi.org/10.1051/0004-6361/201731761 Stars: individual: Betelgeuse Stars: supergiants Stars: rotation Stars: circumstellar matter Techniques: high angular resolution Stars: imaging article 2018 ftumanchesterpub https://doi.org/10.1051/0004-6361/201731761 2023-10-30T09:11:28Z We observed Betelgeuse using ALMA’s extended configuration in band 7 (f ≈ 340 GHz, λ ≈ 0.88 mm), resulting in a very high angular resolution of 18 mas. Using a solid body rotation model of the 28 SiO(ν= 2, J = 8−7) line emission, we show that the supergiant is rotating with a projected equatorial velocity of ν eq sini = 5.47 ± 0.25 km s -1 at the equivalent continuum angular radius R star = 29.50 ± 0.14 mas. This corresponds to an angular rotation velocity of ω sini = (5.6 ± 1.3) × 10 -9 rad s -1 . 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 ≈ 10 au (45 mas or 1.5 × 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. Article in Journal/Newspaper North Pole The University of Manchester: Research Explorer Astronomy & Astrophysics 609 A67 |
institution |
Open Polar |
collection |
The University of Manchester: Research Explorer |
op_collection_id |
ftumanchesterpub |
language |
English |
topic |
Stars: individual: Betelgeuse Stars: supergiants Stars: rotation Stars: circumstellar matter Techniques: high angular resolution Stars: imaging |
spellingShingle |
Stars: individual: Betelgeuse Stars: supergiants Stars: rotation Stars: circumstellar matter Techniques: high angular resolution Stars: imaging Kervella , Pierre Decin, Leen Richards, Anita Harper, Graham M Mcdonald, Iain O'Gorman, Eamon Montargès, Miguel Homan, Ward Ohnaka, Keiichi The close circumstellar environment of Betelgeuse V. Rotation velocity and molecular envelope properties from ALMA |
topic_facet |
Stars: individual: Betelgeuse Stars: supergiants Stars: rotation Stars: circumstellar matter Techniques: high angular resolution Stars: imaging |
description |
We observed Betelgeuse using ALMA’s extended configuration in band 7 (f ≈ 340 GHz, λ ≈ 0.88 mm), resulting in a very high angular resolution of 18 mas. Using a solid body rotation model of the 28 SiO(ν= 2, J = 8−7) line emission, we show that the supergiant is rotating with a projected equatorial velocity of ν eq sini = 5.47 ± 0.25 km s -1 at the equivalent continuum angular radius R star = 29.50 ± 0.14 mas. This corresponds to an angular rotation velocity of ω sini = (5.6 ± 1.3) × 10 -9 rad s -1 . 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 ≈ 10 au (45 mas or 1.5 × 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. |
format |
Article in Journal/Newspaper |
author |
Kervella , Pierre Decin, Leen Richards, Anita Harper, Graham M Mcdonald, Iain O'Gorman, Eamon Montargès, Miguel Homan, Ward Ohnaka, Keiichi |
author_facet |
Kervella , Pierre Decin, Leen Richards, Anita Harper, Graham M Mcdonald, Iain O'Gorman, Eamon Montargès, Miguel Homan, Ward Ohnaka, Keiichi |
author_sort |
Kervella , Pierre |
title |
The close circumstellar environment of Betelgeuse V. Rotation velocity and molecular envelope properties from ALMA |
title_short |
The close circumstellar environment of Betelgeuse V. Rotation velocity and molecular envelope properties from ALMA |
title_full |
The close circumstellar environment of Betelgeuse V. Rotation velocity and molecular envelope properties from ALMA |
title_fullStr |
The close circumstellar environment of Betelgeuse V. Rotation velocity and molecular envelope properties from ALMA |
title_full_unstemmed |
The close circumstellar environment of Betelgeuse V. Rotation velocity and molecular envelope properties from ALMA |
title_sort |
close circumstellar environment of betelgeuse v. rotation velocity and molecular envelope properties from alma |
publishDate |
2018 |
url |
https://research.manchester.ac.uk/en/publications/e2186d60-6275-41a3-b2c6-8dd5a1a329e8 https://doi.org/10.1051/0004-6361/201731761 https://pure.manchester.ac.uk/ws/files/65100909/KervellaBeteleuseRotation1711.07983.pdf |
genre |
North Pole |
genre_facet |
North Pole |
op_source |
Kervella , P , Decin , L , Richards , A , Harper , G M , Mcdonald , I , O'Gorman , E , Montargès , M , Homan , W & Ohnaka , K 2018 , ' The close circumstellar environment of Betelgeuse V. Rotation velocity and molecular envelope properties from ALMA ' , Astronomy and Astrophysics . https://doi.org/10.1051/0004-6361/201731761 |
op_rights |
info:eu-repo/semantics/openAccess |
op_doi |
https://doi.org/10.1051/0004-6361/201731761 |
container_title |
Astronomy & Astrophysics |
container_volume |
609 |
container_start_page |
A67 |
_version_ |
1782337945130237952 |