Published March 2025 | Published
Journal Article Open

JWST 1.5 μm and 4.8 μm Photometry of Y Dwarfs

  • 1. ROR icon University of Montreal
  • 2. ROR icon NOIRLab
  • 3. ROR icon University of Michigan–Ann Arbor
  • 4. ROR icon California Institute of Technology
  • 5. ROR icon Amherst College
  • 6. ROR icon American Museum of Natural History
  • 7. ROR icon The University of Texas at Austin
  • 8. ROR icon Jet Propulsion Lab
  • 9. ROR icon University of California, San Diego
  • 10. ROR icon University of Toledo
  • 11. ROR icon University of Delaware
  • 12. ROR icon Infrared Processing and Analysis Center
  • 13. ROR icon Lagrange Laboratory
  • 14. ROR icon University of Queensland
  • 15. ROR icon University of Southern Queensland
  • 16. ROR icon Ames Research Center
  • 17. ROR icon European Space Astronomy Centre
  • 18. ROR icon Space Telescope Science Institute
  • 19. ROR icon Johns Hopkins University

Abstract

Brown dwarfs lack nuclear fusion and cool with time; the coldest known have an effective temperature below 500 K, and are known as Y dwarfs. We present a James Webb Space Telescope (JWST) photometric data set of Y dwarfs: 23 were imaged in wide-field mode, 20 using NIRCam with the F150W and F480M filters, and three using NIRISS with the F480M filter. We present an F480M versus F150W – F480M color–magnitude diagram for our sample, and other brown dwarfs with F150W and F480M colors synthesized from JWST spectra by S. A. Beiler et al. For one target, WISEA J083011.95+283716.0, its detection in the near-infrared confirms it as one of the reddest Y dwarfs known, with F150W – F480M = 9.62 mag. We provide its updated parallax and proper motion. One of the Beiler et al. Y dwarfs, CWISEP J104756.81+545741.6, is unusually blue, consistent with strong CO absorption seen in its spectrum, which the F480M filter is particularly sensitive to. The strong CO and the kinematics of the object suggest it may be very low mass and young. We update the resolved photometry for the close binary system WISE J033605.05–014350.4 AB, and find that the secondary is almost as cold as WISE 085510.83–071442.5, with Teff ≲ 300 K, however the F150W – F480M color is significantly bluer, possibly suggesting the presence of water clouds. Astrometry is measured at the JWST epoch for the sample which is consistent with parallax and proper motion values reported by J. D. Kirkpatrick et al. and F. Marocco et al.

Copyright and License

© 2025. The Author(s). Published by the American Astronomical Society.

Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.

Acknowledgement

L.A. acknowledges support from the Canadian Space Agency funding program #22JWGO1-11. M.R.M., P.C., D.C.B.G., C.A.B., A.J.B., and J.A.G. gratefully acknowledge support through NASA grant No. JWST-GO-02473.002-A. M.D.F. is supported by an NSF Astronomy and Astrophysics Postdoctoral Fellowship under award AST-2303911. T.R would like to acknowledge support from NASA through the JWST NIRCam project through contract number NAS5-02105 (PI: M. Rieke, University of Arizona). C.F. acknowledges support from the Trottier Family Foundation and the Trottier Institute for Research on Exoplanets through her Trottier Postdoctoral Fellowship. Part of the work by C.A.B. was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration (grant No. 80NM0018D0004). This work was authored by A.Z.G. of Caltech/IPAC under Contract No. 80GSFC21R0032 with the National Aeronautics and Space Administration. This research made use of Photutils, an Astropy package for detection and photometry of astronomical sources (L. Bradley et al. 2023).

Software References

This research made use of Photutils, an Astropy package for detection and photometry of astronomical sources (L. Bradley et al. 2023).

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Additional details

Created:
February 28, 2025
Modified:
February 28, 2025