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The CARMENES search for exoplanets around M dwarfs : stable radial-velocity variations at the rotation period of AD Leonis: A test case study of current limitations to treating stellar activity
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(2022) The CARMENES search for exoplanets around M dwarfs : stable radial-velocity variations at the rotation period of AD Leonis: A test case study of current limitations to treating stellar activity. Astronomy & Astrophysics, 666 . A143. doi:10.1051/0004-6361/202243773 ISSN 0004-6361.
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WRAP-The-CARMENES-search-exoplanets-around-M-dwarfs-2022.pdf - Published Version - Requires a PDF viewer. Available under License Creative Commons Attribution 4.0. Download (2263Kb) | Preview |
Official URL: http://dx.doi.org/10.1051/0004-6361/202243773
Abstract
Context. A challenge with radial-velocity (RV) data is disentangling the origin of signals either due to a planetary companion or to stellar activity. In fact, the existence of a planetary companion has been proposed, as well as contested, around the relatively bright, nearby M3.0 V star AD Leo at the same period as the stellar rotation of 2.23 days.
Aims. We further investigate the nature of this signal. We introduce new CARMENES optical and near-IR RV data and an analysis in combination with archival data taken by HIRES and HARPS, along with more recent data from HARPS-N, GIANO-B, and HPF. Additionally, we address the confusion concerning the binarity of AD Leo.
Methods. We consider possible correlations between the RVs and various stellar activity indicators accessible with CARMENES. We additionally applied models within a Bayesian framework to determine whether a Keplerian model, a red-noise quasi-periodic model using a Gaussian process, or a mixed model would explain the observed data best. We also exclusively focus on spectral lines potentially associated with stellar activity.
Results. The CARMENES RV data agree with the previously reported periodicity of 2.23 days, correlate with some activity indicators, and exhibit chromaticity. However, when considering the entire RV data set, we find that a mixed model composed of a stable and a variable component performs best. Moreover, when recomputing the RVs using only spectral lines insensitive to activity, there appears to be some residual power at the period of interest. We therefore conclude that it is not possible to determinedly prove that there is no planet orbiting in synchronization with the stellar rotation given our data, current tools, machinery, and knowledge of how stellar activity affects RVs. We do rule out planets more massive than 27 M⊕ (=0.084 MJup). Likewise, we exclude any binary companion around AD Leo with M sin i greater than 3–6 MJup on orbital periods <14 yr.
Item Type: | Journal Article | |||||||||||||||
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Subjects: | Q Science > QB Astronomy Q Science > QC Physics |
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Divisions: | Faculty of Science, Engineering and Medicine > Science > Physics | |||||||||||||||
Library of Congress Subject Headings (LCSH): | Dwarf stars, Stars -- Motion in line of sight, Astrophysics, M stars, Solar activity | |||||||||||||||
Journal or Publication Title: | Astronomy & Astrophysics | |||||||||||||||
Publisher: | EDP Sciences | |||||||||||||||
ISSN: | 0004-6361 | |||||||||||||||
Official Date: | October 2022 | |||||||||||||||
Dates: |
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Volume: | 666 | |||||||||||||||
Article Number: | A143 | |||||||||||||||
DOI: | 10.1051/0004-6361/202243773 | |||||||||||||||
Status: | Peer Reviewed | |||||||||||||||
Publication Status: | Published | |||||||||||||||
Access rights to Published version: | Open Access (Creative Commons) | |||||||||||||||
Date of first compliant deposit: | 21 December 2022 | |||||||||||||||
Date of first compliant Open Access: | 21 December 2022 | |||||||||||||||
RIOXX Funder/Project Grant: |
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