Published July 31, 2023 | Version v1

Products and Models for "A JWST transmission spectrum of the nearby Earth-sized exoplanet LHS 475 b"

  • 1. JHU Applied Physics Laboratory
  • 2. JHU Department of Physics & Astronomy
  • 3. Center for Astrophysics | Harvard & Smithsonian
  • 4. University of Arizona
  • 5. University of Maryland
  • 6. Imperial College London

Description

OVERVIEW: The critical first step in the search for life on exoplanets over the next decade is to determine whether rocky planets transiting small M-dwarf stars possess atmospheres and, if so, what processes sculpt them over time. Because of its broad wavelength coverage and improved resolution compared to previous instruments, spectroscopy with JWST offers a new capability to detect and characterize the atmospheres of Earth-sized, M-dwarf planets. Here we use JWST to independently validate the discovery of LHS 475 b, a warm (586 K), 0.99 Earth-radius exoplanet, interior to the habitable zone, and report a precise 2.9 − 5.3 μm transmission spectrum using the NIRSpec G395H instrument. With two transit observations, we rule out primordial hydrogen-dominated and cloudless pure methane atmospheres. Thus far, the featureless transmission spectrum remains consistent with a planet that has a high-altitude cloud deck (similar to Venus), a tenuous atmosphere (similar to Mars), or no appreciable atmosphere at all (akin to Mercury). There are no signs of stellar contamination due to spots or faculae. Our observations demonstrate that JWST has the requisite sensitivity to constrain the secondary atmospheres of terrestrial exoplanets with absorption features < 50 ppm, and that our current atmospheric constraints speak to the nature of the planet itself, rather than instrumental limits.

Files

LHS47b_Zenodo_Files.zip

Files (312.4 kB)

Name Size Download all
md5:fe9d81e069fbef4787506fb78a389876
312.4 kB Preview Download

Additional details

Related works

Is documented by
Preprint: 10.48550/arXiv.2301.04191 (DOI)
Is published in
Journal article: 10.1038/s41550-023-02064-z (DOI)

References