Planetesimals Around Stars with TESS (PAST): II. An M Dwarf "Dipper" Star with a Long-Lived Disk in the TESS Continuous Viewing Zone

• DOI: 10.48550/arxiv.2204.14163
• Publication Date: 2022-01-01
• Authors: Eric Gaidos; Andrew W. Mann; Bárbara Rojas-Ayala; Gregory A. Feiden; Mackenna L. Wood; Suchitra Narayanan; Megan Ansdell; Thomas L. Jacobs; Daryll M. LaCourse
• Keywords: Photoevaporation; Stellar rotation

Studies of T Tauri disks inform planet formation theory; observations variability due to occultation by circumstellar dust are a useful probe unresolved, planet-forming inner disks, especially around faint M dwarf stars. We report 2M0632, an member the Carina young moving group that was observed TESS over two one-year intervals. The combined light curve contains >300 dimming events, each lasting few hours, and as deep 40% (0.55 magnitudes). These stochastic events correlated with distinct, stable 1.86-day periodic signal could be stellar rotation. Concurrent ground-based, multi-band photometry show reddening consistent ISM-like dust. star's excess emission in infrared lines optical spectra, reveal Tauri-like accretion disk star. confirm membership 2M0632 Bayesian analysis its Galactic space motion position. combine evolution models Gaia constraints on Teff, luminosity, absence detectable lithium photosphere constrain age 40-60 Myr, earlier estimates. joins handful long-lived which challenge canon lifetimes <10 Myr. All known examples surround dwarfs, suggesting lower X-ray/UV irradiation slower photoevaporation these stars can dramatically affect evolution. multi-planet systems spawned probably experienced significant orbital damping migration into close-in, resonant orbits, perhaps represented TRAPPIST-1 system.