HD 76920 b pinned down: A detailed analysis of the most eccentric planetary system around an evolved star
Article
Article Title | HD 76920 b pinned down: A detailed analysis of the most eccentric planetary system around an evolved star |
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ERA Journal ID | 40237 |
Article Category | Article |
Authors | Bergmann, C. (Author), Jones, M. I. (Author), Zhao, J. (Author), Mustill, A. J. (Author), Brahm, R. (Author), Torres, P. (Author), Wittenmyer, R. A. (Author), Gunn, F. (Author), Pollard, K. R. (Author), Zapata, A. (Author), Vanzi, L. (Author) and Wang, Songhu (Author) |
Journal Title | Publications of the Astronomical Society of Australia |
Journal Citation | 38, pp. 1-12 |
Article Number | e019 |
Number of Pages | 12 |
Year | 2021 |
Publisher | Cambridge University Press |
Place of Publication | United Kingdom |
ISSN | 1323-3580 |
1448-6083 | |
Digital Object Identifier (DOI) | https://doi.org/10.1017/pasa.2021.8 |
Web Address (URL) | https://www.cambridge.org/core/journals/publications-of-the-astronomical-society-of-australia/article/hd-76920-b-pinned-down-a-detailed-analysis-of-the-most-eccentric-planetary-system-around-an-evolved-star/5CB05802612F9105247395C0A4E3DBC2 |
Abstract | We present 63 new multi-site radial velocity (RV) measurements of the K1III giant HD 76920, which was recently reported to host the most eccentric planet known to orbit an evolved star. We focused our observational efforts on the time around the predicted periastron passage and achieved near-continuous phase coverage of the corresponding RV peak. By combining our RV measurements from four different instruments with previously published ones, we confirm the highly eccentric nature of the system and find an even higher eccentricity of , an orbital period of 415.891(-0.039)(+0.043) d, and a minimum mass of 3.13(-0.43)(+0.41) M-J for the planet. The uncertainties in the orbital elements are greatly reduced, especially for the period and eccentricity. We also performed a detailed spectroscopic analysis to derive atmospheric stellar parameters, and thus the fundamental stellar parameters (M-*, R-*, L-*) taking into account the parallax from Gaia DR2, and independently determined the stellar mass and radius using asteroseismology. Intriguingly, at periastron, the planet comes to within 2.4 stellar radii of its host star's surface. However, we find that the planet is not currently experiencing any significant orbital decay and will not be engulfed by the stellar envelope for at least another 50-80 Myr. Finally, while we calculate a relatively high transit probability of 16%, we did not detect a transit in the TESS photometry. |
Keywords | planetary systems; stars: individual: HD; 76920; techniques: radial; velocities; Astrophysics - Earth and Planetary Astrophysics |
ANZSRC Field of Research 2020 | 510109. Stellar astronomy and planetary systems |
Byline Affiliations | University of New South Wales |
European Southern Observatory (ESO), Chile | |
University of New South Wales | |
Lund University, Sweden | |
Millennium Institute of Astrophysics, Chile | |
Pontifical Catholic University of Chile, Chile | |
Centre for Astrophysics | |
University of Canterbury, New Zealand | |
Indiana University, United States | |
Institution of Origin | University of Southern Queensland |
https://research.usq.edu.au/item/q6x84/hd-76920-b-pinned-down-a-detailed-analysis-of-the-most-eccentric-planetary-system-around-an-evolved-star
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