A Mini-Neptune and a Venus-Zone Planet in the Radius Valley Orbiting the Nearby M2-dwarf TOI-1266: Validation with the Habitable-zone Planet Finder

Transit photometry of TOI-1266. a) Short-cadence (2-minute) TESS photometry is shown in black. The blue points show the data binned to 10 minutes. The red curve shows our best-fit joint model including both planets b and c. The blue and red triangles denote transits of planets b and c, respectively. b-c) Phase-folded photometry from TESS of the transits of TOI-1266b and TOI-1266c, respectively. d) Ground-based photometry from the 0.4m Perkin Telescope showing the transit of TOI-1266b. e) Diffuser-assisted photometry during the transit of TOI-1266c using the Engineered Diffuser on the 3.5m Telescope at Apache Point Observatory.

We report on the validation of two planets orbiting the nearby (36pc) M2 dwarf TOI-1266 observed by the TESS mission.

The inner planet is sub-Neptune-sized (R=2.46±0.08R⊕) with an orbital period of 10.9 days. The outer planet has a radius of 1.67+0.09−0.11R⊕ and resides in the exoplanet Radius Valley---the transition region between rocky and gaseous planets. With an orbital period of 18.8 days, the outer planet receives an insolation flux of 2.4 times that of Earth, similar to the insolation of Venus. Using precision near-infrared radial velocities with the Habitable-zone Planet Finder Spectrograph, we place upper mass limits of 15.9M⊕ and 6.4M⊕ at 95% confidence for the inner and outer planet, respectively. A more precise mass constraint of planet c, achievable with current RV instruments given the host star brightness (V=12.9, J=9.7), will yield further insights into the dominant processes sculpting the exoplanet Radius Valley.

Gudmundur Stefansson, Ravi Kopparapu, Andrea Lin, Suvrath Mahadevan, Caleb Cañas, Shubham Kanodia, Joe Ninan, William Cochran, Michael Endl, Leslie Hebb, John Wisniewski, Arvind Gupta, Mark Everett, Chad Bender, Scott Diddams, Eric Ford, Connor Fredrick, Samuel Halverson, Fred Hearty, Eric Levi, Marissa Maney, Andrew Metcalf, Andrew Monson, Lawrence Ramsey, Paul Robertson, Arpita Roy, Christian Schwab, Ryan Terrien, Jason Wright

Comments: Submitted to AAS Journals. 21 pages, 8 figures. Comments welcome
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Cite as: arXiv:2006.11180 [astro-ph.EP] (or arXiv:2006.11180v1 [astro-ph.EP] for this version)
Submission history
From: Gudmundur Stefansson
[v1] Fri, 19 Jun 2020 15:13:01 UTC (2,589 KB)
Astrobiology, Astrochemistry

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