The changing face of AU Mic b: Stellar spots, spin-orbit commensurability, and transit timing variations as seen by CHEOPS and TESS
(2021) In Astronomy & Astrophysics 654.- Abstract
- AU Mic is a young planetary system with a resolved debris disc showing signs of planet formation and two transiting warm Neptunes near mean-motion resonances. Here we analyse three transits of AU Mic b observed with the CHaracterising ExOPlanet Satellite (CHEOPS), supplemented with sector 1 and 27 Transiting Exoplanet Survey Satellite (TESS) photometry, and the All-Sky Automated Survey from the ground. The refined orbital period of AU Mic b is 8.462995 ± 0.000003 d, whereas the stellar rotational period is Prot = 4.8367 ± 0.0006 d. The two periods indicate a 7:4 spin-orbit commensurability at a precision of 0.1%. Therefore, all transits are observed in front of one of the four possible stellar central longitudes. This is strongly supported... (More)
- AU Mic is a young planetary system with a resolved debris disc showing signs of planet formation and two transiting warm Neptunes near mean-motion resonances. Here we analyse three transits of AU Mic b observed with the CHaracterising ExOPlanet Satellite (CHEOPS), supplemented with sector 1 and 27 Transiting Exoplanet Survey Satellite (TESS) photometry, and the All-Sky Automated Survey from the ground. The refined orbital period of AU Mic b is 8.462995 ± 0.000003 d, whereas the stellar rotational period is Prot = 4.8367 ± 0.0006 d. The two periods indicate a 7:4 spin-orbit commensurability at a precision of 0.1%. Therefore, all transits are observed in front of one of the four possible stellar central longitudes. This is strongly supported by the observation that the same complex star-spot pattern is seen in the second and third CHEOPS visits that were separated by four orbits (and seven stellar rotations). Using a bootstrap analysis we find that flares and star spots reduce the accuracy of transit parameters by up to 10% in the planet-to-star radius ratio and the accuracy on transit time by 3-4 min. Nevertheless, occulted stellar spot features independently confirm the presence of transit timing variations (TTVs) with an amplitude of at least 4 min. We find that the outer companion, AU Mic c, may cause the observed TTVs. © ESO 2021. (Less)
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https://lup.lub.lu.se/record/b93cc9ae-941d-4727-a475-311d1c750456
- author
- Szabó, Gy. M. ; Davies, Melvyn B LU and Wilson, T. G.
- author collaboration
- organization
- publishing date
- 2021-10-01
- type
- Contribution to journal
- publication status
- published
- subject
- keywords
- Planetary systems, Extrasolar planets, Gold, Orbits, Surveys, Timing circuits, Debris disk, Exo-planets, Neptune, Planet formation, Planetary system, Spin orbits, Star spots, Stellars, Timing variations, Transit timing, Stars
- in
- Astronomy & Astrophysics
- volume
- 654
- article number
- A159
- publisher
- EDP Sciences
- external identifiers
-
- scopus:85118444840
- ISSN
- 1432-0746
- DOI
- 10.1051/0004-6361/202140345
- language
- English
- LU publication?
- yes
- id
- b93cc9ae-941d-4727-a475-311d1c750456
- date added to LUP
- 2021-12-02 09:19:35
- date last changed
- 2024-04-20 16:47:26
@article{b93cc9ae-941d-4727-a475-311d1c750456,
abstract = {{AU Mic is a young planetary system with a resolved debris disc showing signs of planet formation and two transiting warm Neptunes near mean-motion resonances. Here we analyse three transits of AU Mic b observed with the CHaracterising ExOPlanet Satellite (CHEOPS), supplemented with sector 1 and 27 Transiting Exoplanet Survey Satellite (TESS) photometry, and the All-Sky Automated Survey from the ground. The refined orbital period of AU Mic b is 8.462995 ± 0.000003 d, whereas the stellar rotational period is Prot = 4.8367 ± 0.0006 d. The two periods indicate a 7:4 spin-orbit commensurability at a precision of 0.1%. Therefore, all transits are observed in front of one of the four possible stellar central longitudes. This is strongly supported by the observation that the same complex star-spot pattern is seen in the second and third CHEOPS visits that were separated by four orbits (and seven stellar rotations). Using a bootstrap analysis we find that flares and star spots reduce the accuracy of transit parameters by up to 10% in the planet-to-star radius ratio and the accuracy on transit time by 3-4 min. Nevertheless, occulted stellar spot features independently confirm the presence of transit timing variations (TTVs) with an amplitude of at least 4 min. We find that the outer companion, AU Mic c, may cause the observed TTVs. © ESO 2021.}},
author = {{Szabó, Gy. M. and Davies, Melvyn B and Wilson, T. G.}},
issn = {{1432-0746}},
keywords = {{Planetary systems; Extrasolar planets; Gold; Orbits; Surveys; Timing circuits; Debris disk; Exo-planets; Neptune; Planet formation; Planetary system; Spin orbits; Star spots; Stellars; Timing variations; Transit timing; Stars}},
language = {{eng}},
month = {{10}},
publisher = {{EDP Sciences}},
series = {{Astronomy & Astrophysics}},
title = {{The changing face of AU Mic b: Stellar spots, spin-orbit commensurability, and transit timing variations as seen by CHEOPS and TESS}},
url = {{http://dx.doi.org/10.1051/0004-6361/202140345}},
doi = {{10.1051/0004-6361/202140345}},
volume = {{654}},
year = {{2021}},
}