TOI-3884 b: A rare 6-R<SUB>E</SUB> planet that transits a low-mass star with a giant and likely polar spot

Almenara, J. M.; Bonfils, X.; Forveille, T.; Astudillo-Defru, N.; Ciardi, D. R.; Schwarz, R. P.; Collins, K. A.; Cointepas, M.; Lund, M. B.; Bouchy, F.; Charbonneau, D.; Díaz, R. F.; Delfosse, X.; Kidwell, R. C.; Kunimoto, M.; Latham, D. W.; Lissauer, J. J.; Murgas, F.; Ricker, G.; Seager, S.; Vezie, M.; Watanabe, D.
Bibliographical reference

Astronomy and Astrophysics

Advertised on:
11
2022
Number of authors
22
IAC number of authors
1
Citations
17
Refereed citations
14
Description
The Transiting Exoplanet Survey Satellite mission identified a deep and asymmetric transit-like signal with a periodicity of 4.5 days orbiting the M4 dwarf star TOI-3884. The signal has been confirmed by follow-up observations collected by the ExTrA facility and Las Cumbres Observatory Global Telescope, which reveal that the transit is chromatic. The light curves are well modelled by a host star having a large polar spot transited by a 6-RE planet. We validate the planet with seeing-limited photometry, high-resolution imaging, and radial velocities. TOI-3884 b, with a radius of 6.00 ± 0.18 RE, is the first sub-Saturn planet transiting a mid-M dwarf. Owing to the host star's brightness and small size, it has one of the largest transmission spectroscopy metrics for this planet size and becomes a top target for atmospheric characterisation with the James Webb Space Telescope and ground-based telescopes.
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