Planetesimals around stars with TESS (PAST) - II. An M dwarf 'dipper' star with a long-lived disc in the TESS continuous viewing zone

Autor(en): Eric Gaidos, Andrew W. Mann, Bárbara Rojas-Ayala, Gregory A. Feiden, Mackenna L. Wood, Suchitra Narayanan, Megan Ansdell, Tom Jacobs, Daryll LaCourse
Abstrakt: Studies of T Tauri discs inform planet formation theory; observations of variability due to occultation by circumstellar dust are a useful probe of unresolved, planet-forming inner discs, especially around faint M dwarf stars. We report observations of 2M0632, an M dwarf member of the Carina young moving group that was observed by Transiting Exoplanet Survey Satellite over two 1-yr intervals. The combined light curve contains >300 dimming events, each lasting a few hours, and as deep as 40 per cent (0.55 magnitudes). These stochastic events are correlated with a distinct, stable 1.86-d periodic signal that could be stellar rotation. Concurrent ground-based, multiband photometry show reddening consistent with interstellar medium-like dust. The star's excess emission in the infrared and emission lines in optical and infrared spectra reveal a T Tauri-like accretion disc around the star. We confirm membership of 2M0632 in the Carina group by a Bayesian analysis of its Galactic space motion and position. We combine stellar evolution models with Gaia photometry and constraints on T_eff, luminosity, and the absence of detectable lithium in the photosphere to constrain the age of the group and 2M0632 to 40-60 Myr, consistent with earlier estimates. 2M0632 joins a handful of long-lived discs which challenge the canon that disc lifetimes are ≲10 Myr. All known examples surround M dwarfs, suggesting that lower X-ray/ultraviolet irradiation and slower photoevaporation by these stars can dramatically affect disc evolution. The multiplanet systems spawned by long-lived discs probably experienced significant orbital damping and migration into close-in, resonant orbits, and perhaps represented by the TRAPPIST-1 system.
Organisation(en): Institut für Astrophysik
Externe Organisation(en): Universität Bern, University of Hawaii at Manoa, University of North Carolina at Chapel Hill, Universidad de Tarapacá, University of North Georgia, National Aeronautics & Space Administration (NASA), Visual Survey Group
Journal: Monthly Notices of the Royal Astronomical Society
Band: 514
Seiten: 1386-1402
Anzahl der Seiten: 17
ISSN: 0035-8711
DOI: https://doi.org/10.1093/mnras/stac1433
Publikationsdatum: 07-2022
Peer-reviewed: Ja
ÖFOS 2012: 103003 Astronomie, 103004 Astrophysik
Schlagwörter
ASJC Scopus Sachgebiete: Astronomy and Astrophysics, Space and Planetary Science
Link zum Portal: https://ucrisportal.univie.ac.at/de/publications/42cab8cf-428a-4cff-beb3-37e327bfa3c2

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