A Sub-Neptune-sized Planet Transiting the M2.5 Dwarf G 9-40: Validation with the Habitable-zone Planet Finder

We validate the discovery of a 2-Earth-radii sub-Neptune-sized planet around the nearby high-proper-motion M2.5 dwarf G 9-40 (EPIC 212048748), using high-precision, near-infrared (NIR) radial velocity (RV) observations with the Habitable-zone Planet Finder (HPF), precision diffuser-assisted ground-based photometry with a custom narrowband photometric filter, and adaptive optics imaging. At a distance of d = 27.9 pc, G 9-40b is the second-closest transiting planet discovered by K2 to date. The planet's large transit depth (∼3500 ppm), combined with the proximity and brightness of the host star at NIR wavelengths (J = 10, K = 9.2), makes G 9-40b one of the most favorable sub-Neptune-sized planets orbiting an M dwarf for transmission spectroscopy with James Webb Space Telescope, ARIEL, and the upcoming Extremely Large Telescopes. The star is relatively inactive with a rotation period of ∼29 days determined from the K2 photometry. To estimate spectroscopic stellar parameters, we describe our implementation of an empirical spectral-matching algorithm using the high-resolution NIR HPF spectra. Using this algorithm, we obtain an effective temperature of Teff = 3404 ± 73 K and metallicity of [Fe/H] = -0.08 ± 0.13. Our RVs, when coupled with the orbital parameters derived from the transit photometry, exclude planet masses above 11.7M ⊕ with 99.7% confidence assuming a circular orbit. From its radius, we predict a mass of M =5.0-1.9+3.8inf>M⊕ and an RV semiamplitude of K= 4.1-1.6+3.1 m s-1, making its mass measurable with current RV facilities. We urge further RV follow-up observations to precisely measure its mass, to enable precise transmission spectroscopic measurements in the future.

Files

Metadata

Work Title A Sub-Neptune-sized Planet Transiting the M2.5 Dwarf G 9-40: Validation with the Habitable-zone Planet Finder
Access
Open Access
Creators
  1. Gudmundur Stefansson
  2. Caleb Cañas
  3. John Wisniewski
  4. Paul Robertson
  5. Suvrath Mahadevan
  6. Marissa Maney
  7. Shubham Kanodia
  8. Corey Beard
  9. Chad F. Bender
  10. Peter Brunt
  11. J. Christopher Clemens
  12. William Cochran
  13. Scott A. Diddams
  14. Michael Endl
  15. Eric B. Ford
  16. Connor Fredrick
  17. Samuel Halverson
  18. Fred Hearty
  19. Leslie Hebb
  20. Joseph Huehnerhoff
  21. Jeff Jennings
  22. Kyle Kaplan
  23. Eric Levi
  24. Emily Lubar
  25. Andrew J. Metcalf
  26. Andrew Monson
  27. Brett Morris
  28. Joe P. Ninan
  29. Colin Nitroy
  30. Lawrence Ramsey
  31. Arpita Roy
  32. Christian Schwab
  33. Steinn Sigurdsson
  34. Ryan Terrien
  35. Jason T. Wright
Keyword
  1. Planets and satellites: detection
  2. Planetary systems
  3. Stars: fundamental parameters
License In Copyright (Rights Reserved)
Work Type Article
Publisher
  1. Astronomical Journal
Publication Date February 12, 2020
Publisher Identifier (DOI)
  1. https://doi.org/10.3847/1538-3881/ab5f15
Deposited January 26, 2024

Versions

Analytics

Collections

This resource is currently not in any collection.

Work History

Version 1
published

  • Created
  • Added 1912.00291-1.pdf
  • Added Creator Gudmundur Stefansson
  • Added Creator Caleb Cañas
  • Added Creator John Wisniewski
  • Added Creator Paul Robertson
  • Added Creator Suvrath Mahadevan
  • Added Creator Marissa Maney
  • Added Creator Shubham Kanodia
  • Added Creator Corey Beard
  • Added Creator Chad F. Bender
  • Added Creator Peter Brunt
  • Added Creator J. Christopher Clemens
  • Added Creator William Cochran
  • Added Creator Scott A. Diddams
  • Added Creator Michael Endl
  • Added Creator Eric B. Ford
  • Added Creator Connor Fredrick
  • Added Creator Samuel Halverson
  • Added Creator Fred Hearty
  • Added Creator Leslie Hebb
  • Added Creator Joseph Huehnerhoff
  • Added Creator Jeff Jennings
  • Added Creator Kyle Kaplan
  • Added Creator Eric Levi
  • Added Creator Emily Lubar
  • Added Creator Andrew J. Metcalf
  • Added Creator Andrew Monson
  • Added Creator Brett Morris
  • Added Creator Joe P. Ninan
  • Added Creator Colin Nitroy
  • Added Creator Lawrence Ramsey
  • Added Creator Arpita Roy
  • Added Creator Christian Schwab
  • Added Creator Steinn Sigurdsson
  • Added Creator Ryan Terrien
  • Added Creator Jason T. Wright
  • Published
  • Updated Keyword, Publication Date Show Changes
    Keyword
    • Planets and satellites: detection, Planetary systems, Stars: fundamental parameters
    Publication Date
    • 2020-03-01
    • 2020-02-12
  • Updated