TOI 540 b: A Planet Smaller than Earth Orbiting a Nearby Rapidly Rotating Low-mass Star
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Ment_2021_AJ_161_23.pdf
Description
Published version
Size
1.79 MB
Format
Adobe PDF
Checksum (MD5)
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Author(s)
Ment, Kristo
Irwin, Jonathan
Charbonneau, David
Winters, Jennifer G
Medina, Amber
Cloutier, Ryan
Díaz, Matías R
Jenkins, James S
Ziegler, Carl
Law, Nicholas
Date Issued
2020
Journal
Astronomical Journal
Publisher
American Astronomical Society
Version
Final published version
Abstract
© 2020. The American Astronomical Society. All rights reserved. We present the discovery of TOI 540 b, a hot planet slightly smaller than Earth orbiting the low-mass star 2MASS J05051443-4756154. The planet has an orbital period of P = 1.239149 days (±170 ms) and a radius of r = 0.903 ± 0.052R⊕, and is likely terrestrial based on the observed mass-radius distribution of small exoplanets at similar insolations. The star is 14.008 pc away and we estimate its mass and radius to be M = 0.159 ± 0.014 M⊙ and R = 0.1895 ± 0.0079R⊙, respectively. The star is distinctive in its very short rotational period of Prot = 17.4264 ± 0.0094 hr and correspondingly small Rossby number of 0.007 as well as its high X-ray-to-bolometric luminosity ratio of LX/LboI = 0.0028 based on a serendipitous XMM-Newton detection during a slew operation. This is consistent with the X-ray emission being observed at a maximum value of as predicted for the most rapidly rotating M dwarfs. TOI 540 b may be an alluring target to study atmospheric erosion due to the strong stellar X-ray emission. It is also among the most accessible targets for transmission and emission spectroscopy and eclipse photometry with the James Webb Space Telescope, and may permit Doppler tomography with high-resolution spectroscopy during transit. This discovery is based on precise photometric data from the Transiting Exoplanet Survey Satellite and ground-based follow-up observations by the MEarth team.
MIT Department
Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences
MIT Kavli Institute for Astrophysics and Space Research
Massachusetts Institute of Technology. Department of Aeronautics and Astronautics
Massachusetts Institute of Technology. Department of Physics
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DOI of Published Version
https://doi.org/10.3847/1538-3881/ABBD91
