Mid-infrared characterization of the planetary-mass companion ROXs 42B b

Sebastian Daemgen, Kamen Todorov, Jasmin Silva, Derek Hand, Eugenio V. Garcia, Thayne Currie, Adam S. Burrows, Keivan G. Stassun, Thorsten Ratzka, John H. Debes, David Lafreniere, Ray Jayawardhana, Serge Correia

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Abstract

We present new Keck/NIRC2 3-5 μm infrared photometry of the planetary-mass companion to ROXS 42B in L′, and for the first time in Brackett-α (Brff) and in Ms-band. We combine our data with existing near-infrared photometry and K-band (2-2.4 μm) spectroscopy and compare these data with models and other directly imaged planetary-mass objects using forward modeling and retrieval methods in order to characterize the atmosphere of ROXS 42B b. The ROXS 42B b 1.25-5 μm spectral energy distribution most closely resembles that of GSC 06214 B and κ And b, although it has a slightly bluer Ks-Ms color than GSC 06214 B and thus currently lacks evidence of a circumplanetary disk. We cannot formally exclude the possibility that any of the tested dust-free/dusty/cloudy forward models describe the atmosphere of ROXS 42B b well. However, models with substantial atmospheric dust/clouds yield temperatures and gravities that are consistent when fit to photometry and spectra separately, whereas dust-free model fits to photometry predict temperatures/gravities inconsistent with the ROXS 42B b K-band spectrum and vice-versa. Atmospheric retrieval on the 1-5 μm photometry places a limit on the fractional number density of CO2 of log (nCO2) < 2.7, but provides no other constraints so far. We conclude that ROXS 42B b has mid-IR photometric features that are systematically different from other previously observed planetary-mass and field objects of similar temperature. It remains unclear whether this is in the range of the natural diversity of targets at the very young (∼2 Myr) age of ROXS 42B b or unique to its early evolution and environment.

Original languageEnglish (US)
Article numberA65
JournalAstronomy and Astrophysics
Volume601
DOIs
StatePublished - May 1 2017

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

Keywords

  • Planets and satellites: detection
  • Planets and satellites: individual: ROXS42Bb
  • Stars: pre-main sequence

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    Daemgen, S., Todorov, K., Silva, J., Hand, D., Garcia, E. V., Currie, T., Burrows, A. S., Stassun, K. G., Ratzka, T., Debes, J. H., Lafreniere, D., Jayawardhana, R., & Correia, S. (2017). Mid-infrared characterization of the planetary-mass companion ROXs 42B b. Astronomy and Astrophysics, 601, [A65]. https://doi.org/10.1051/0004-6361/201629949