Dodd, J.M., Oudmaijer, R.D. orcid.org/0000-0001-7703-3992, Radley, I.C. et al. (2 more authors) (2023) Gaia uncovers difference in B and Be star binarity at small scales: evidence for mass transfer causing the Be phenomenon. Monthly Notices of the Royal Astronomical Society, 527 (2). pp. 3076-3086. ISSN 0035-8711
Abstract
Be stars make up almost 20 per cent of the B star population, and are rapidly rotating stars surrounded by a disc; however the origin of this rotation remains unclear. Mass transfer within close binaries provides the leading hypothesis, with previous detections of stripped companions to Be stars supporting this. Here, we exploit the exquisite astrometric precision of Gaia to carry out the largest to date comparative study into the binarity of matched samples of nearby B and Be stars from the Bright Star Catalogue. By utilizing new ‘proper motion anomaly’ values, derived from Gaia DR2 and DR3 astrometric data alongside previous values calculated using Hipparcos and Gaia data, and the Gaia-provided RUWE, we demonstrate that we can identify unresolved binaries down to separations of 0.02 arcsec. Using these measures, we find that the binary fractions of B and Be stars are similar between 0.04 and 10 arcsec, but the Be binary fraction is significantly lower than that of the B stars for separations below 0.04 arcsec. As the separation range of these ‘missing’ binaries is too large for mass transfer, and stripped companions are not retrieved by these measures, we suggest the companions migrate inwards via binary hardening within a triple system. This confirms statistically for the first time the hypothesis that binary interaction causes the Be phenomenon, with migration causing the dearth of Be binaries between 0.02 and 0.04 arcsec. Furthermore, we suggest that triplicity plays a vital role in this migration, and thus in the formation of Be stars as a whole.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | © The Author(s) 2023. This is an open access article under the terms of the Creative Commons Attribution License (CC-BY 4.0), which permits unrestricted use, distribution and reproduction in any medium, provided the original work is properly cited. |
Keywords: | proper motions, binaries: close, stars: emission-line, Be |
Dates: |
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Institution: | The University of Leeds |
Academic Units: | The University of Leeds > Faculty of Engineering & Physical Sciences (Leeds) > School of Physics and Astronomy (Leeds) > Astrophysics (Leeds) |
Funding Information: | Funder Grant number STFC (Science and Technology Facilities Council) ST/X001016/1 STFC (Science and Technology Facilities Council) ST/T000287/1 STFC (Science and Technology Facilities Council) ST/P00041X/1 EU - European Union 823734 EU - European Union 676036 |
Depositing User: | Symplectic Publications |
Date Deposited: | 07 Dec 2023 12:12 |
Last Modified: | 07 Dec 2023 12:12 |
Status: | Published |
Publisher: | Oxford University Press |
Identification Number: | 10.1093/mnras/stad3105 |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:206306 |