MIRI MRS Observations of β Pictoris. I. The Inner Dust, the Planet, and the Gas

Kadin Worthen; Christine H. Chen; David R. Law; Cicero X. Lu; Kielan Hoch; Yiwei Chai; G. C. Sloan; B. A. Sargent; Jens Kammerer; Dean C. Hines; Isabel Rebollido; William Balmer; Marshall D. Perrin; Dan M. Watson; Laurent Pueyo; Julien H. Girard; Carey M. Lisse; Christopher C. Stark

doi:10.3847/1538-4357/ad2354

The Astrophysical Journal (Jan 2024)

MIRI MRS Observations of β Pictoris. I. The Inner Dust, the Planet, and the Gas

Kadin Worthen,
Christine H. Chen,
David R. Law,
Cicero X. Lu,
Kielan Hoch,
Yiwei Chai,
G. C. Sloan,
B. A. Sargent,
Jens Kammerer,
Dean C. Hines,
Isabel Rebollido,
William Balmer,
Marshall D. Perrin,
Dan M. Watson,
Laurent Pueyo,
Julien H. Girard,
Carey M. Lisse,
Christopher C. Stark

Affiliations

Kadin Worthen: ORCiD; William H. Miller III Department of Physics and Astronomy, John’s Hopkins University , 3400 N. Charles Street, Baltimore, MD 21218, USA ; [email protected]
Christine H. Chen: ORCiD; William H. Miller III Department of Physics and Astronomy, John’s Hopkins University , 3400 N. Charles Street, Baltimore, MD 21218, USA ; [email protected]; Space Telescope Science Institute , 3700 San Martin Drive, Baltimore, MD 21218, USA
David R. Law: ORCiD; Space Telescope Science Institute , 3700 San Martin Drive, Baltimore, MD 21218, USA
Cicero X. Lu: ORCiD; Gemini Observatory/NSF's NOIRLab , 670 N. A’ohoku Place, Hilo, HI 96720, USA
Kielan Hoch: ORCiD; Space Telescope Science Institute , 3700 San Martin Drive, Baltimore, MD 21218, USA
Yiwei Chai: William H. Miller III Department of Physics and Astronomy, John’s Hopkins University , 3400 N. Charles Street, Baltimore, MD 21218, USA ; [email protected]
G. C. Sloan: ORCiD; Space Telescope Science Institute , 3700 San Martin Drive, Baltimore, MD 21218, USA; Department of Physics and Astronomy, University of North Carolina , Chapel Hill, NC 27599-3255, USA
B. A. Sargent: ORCiD; William H. Miller III Department of Physics and Astronomy, John’s Hopkins University , 3400 N. Charles Street, Baltimore, MD 21218, USA ; [email protected]; Space Telescope Science Institute , 3700 San Martin Drive, Baltimore, MD 21218, USA
Jens Kammerer: ORCiD; Space Telescope Science Institute , 3700 San Martin Drive, Baltimore, MD 21218, USA; European Southern Observatory , Karl-Schwarzschild-Strae 2, 85748 Garching, Germany
Dean C. Hines: ORCiD; Space Telescope Science Institute , 3700 San Martin Drive, Baltimore, MD 21218, USA
Isabel Rebollido: ORCiD; Centro de Astrobiología (CAB) , INTA-CSIC, Camino Bajo del Castillo s/n—Villafranca del Castillo, 28692 Villanueva de la Cañada, Madrid, Spain
William Balmer: ORCiD; William H. Miller III Department of Physics and Astronomy, John’s Hopkins University , 3400 N. Charles Street, Baltimore, MD 21218, USA ; [email protected]
Marshall D. Perrin: ORCiD; Space Telescope Science Institute , 3700 San Martin Drive, Baltimore, MD 21218, USA
Dan M. Watson: ORCiD; Department of Physics and Astronomy, University of Rochester , 500 Wilson Boulevard, Rochester, NY 14627, USA
Laurent Pueyo: ORCiD; Space Telescope Science Institute , 3700 San Martin Drive, Baltimore, MD 21218, USA
Julien H. Girard: ORCiD; Space Telescope Science Institute , 3700 San Martin Drive, Baltimore, MD 21218, USA
Carey M. Lisse: ORCiD; Johns Hopkins University Applied Physics Laboratory , 11100 Johns Hopkins Road, Laurel, MD 20723, USA
Christopher C. Stark: NASA Goddard Space Flight Center , Exoplanets & Stellar Astrophysics Laboratory, Code 667, Greenbelt, MD 20771, USA

DOI: https://doi.org/10.3847/1538-4357/ad2354
Journal volume & issue: Vol. 964, no. 2
p. 168

Abstract

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We present JWST MIRI Medium Resolution Spectrograph (MRS) observations of the β Pictoris system. We detect an infrared excess from the central unresolved point source from 5 to 7.5 μ m which is indicative of dust within the inner ∼7 au of the system. We perform point-spread function (PSF) subtraction on the MRS data cubes and detect a spatially resolved dust population emitting at 5 μ m. This spatially resolved hot dust population is best explained if the dust grains are in the small grain limit (2 π a ≪ λ ). The combination of unresolved and resolved dust at 5 μ m could suggest that dust grains are being produced in the inner few astronomical units of the system and are then radiatively driven outwards, where the particles could accrete onto the known planets in the system, β Pictoris b and c. We also report the detection of an emission line at 6.986 μ m that we attribute to [Ar ii ]. We find that the [Ar ii ] emission is spatially resolved with JWST and appears to be aligned with the dust disk. Through PSF-subtraction techniques, we detect β Pictoris b at the 5 σ level in our MRS data cubes and present the first mid-infrared spectrum of the planet from 5 to 7 μ m. The planet’s spectrum is consistent with having absorption from water vapor between 5 and 6.5 μ m. We perform atmosphere model grid fitting of the spectra and photometry of β Pictoris b and find that the planet’s atmosphere likely has a substellar C/O ratio.

Published in The Astrophysical Journal

ISSN: 1538-4357 (Online)
Publisher: IOP Publishing
Country of publisher: United Kingdom
LCC subjects: Science: Astronomy: Astrophysics
Website: https://iopscience.iop.org/journal/0004-637X

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