TOI-3884 b: A rare 6-R$_{\oplus}$ planet that transits a low-mass star with a giant and likely polar spot [EPA]

http://arxiv.org/abs/2210.10909


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-R${\oplus}$ planet. We validate the planet with seeing-limited photometry, high-resolution imaging, and radial velocities. TOI-3884 b, with a radius of $6.00 \pm 0.18$ R${\oplus}$, 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.

Read this paper on arXiv…

J. Almenara, X. Bonfils, T. Forveille, et. al.
Fri, 21 Oct 22
26/76

Comments: 13 pages, 13 figures, accepted for publication in A&A Letters