A Search for Polarized Thermal Emission from Directly Imaged Exoplanets and Brown Dwarf Companions to Nearby Stars

Journal Article · Tue Dec 01 00:00:00 EST 2020 · Astronomical Journal (Online)

DOI:https://doi.org/10.3847/1538-3881/ABC33D· OSTI ID:23013463

Jensen-Clem, Rebecca; Wiktorowicz, Sloane J. ^[1]; Millar-Blanchaer, Maxwell A.; Mawet, Dimitri ^[2]; Van Holstein, Rob G.; Snik, Frans; Boer, Jos de ^[3]; Graham, James ^[4]; Sengupta, Sujan ^[5]; Marley, Mark S. ^[6]; Vigan, Arthur ^[7]; Hinkley, Sasha ^[8]; Girard, Julien H. ^[9]; De Rosa, Robert J. ^[10]; Bowler, Brendan P. ^[11]; Perrin, Marshall D. ^[12]; Crepp, Justin R. ^[13]; Macintosh, Bruce ^[14]

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1. Astronomy Department, University of California Santa Cruz, 1156 High St., Santa Cruz, CA 95064 (United States)
2. Department of Astrophysics, California Institute of Technology, 1200 E. California Boulevard, Pasadena, CA 91101 (United States)
3. Leiden Observatory, Leiden University, P.O. Box 9513, 2300 RA Leiden (Netherlands)
4. Astronomy Department, University of California, Berkeley, CA 94720 (United States)
5. Indian Institute of Astrophysics, Koramangala 2nd Block, Sarjapura Road, Bangalore 560034 (India)
6. NASA Ames Research Center, MS 245-3, Moffett Field, CA 94035 (United States)
7. Aix Marseille Univ, CNRS, CNES, LAM, Marseille (France)
8. University of Exeter, Physics Department, Stocker Road, Exeter EX4 4QL (United Kingdom)
9. Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States)
10. European Southern Observatory, Alonso de Córdova 3107, Casilla 19001, Vitacura, Santiago (Chile)
11. Department of Astronomy, The University of Texas at Austin, Austin, TX 78712 (United States)
12. Space Telescope Science Institute, Baltimore, MD 21218 (United States)
13. Department of Physics, University of Notre Dame, Notre Dame, IN 46556 (United States)
14. Kavli Institute for Particle Astrophysics and Cosmology, Stanford University, Stanford, CA 94305 (United States)

Aerosols in the atmospheres of cloudy gas giant exoplanets and brown dwarfs scatter and polarize these objects’ thermal emission. If such an object has an oblate shape or nonuniform cloud distribution, the net degree of linear polarization can show an increase ranging from several tenths of a percent to a few percent. Modern high-contrast imaging polarimeters are now poised to detect such low-polarization signals, opening up a new window into the rotational velocities and cloud properties of substellar companions to nearby stars. In this paper, we present the results of a near-IR survey searching for linearly polarized thermal emission from a sample of two planetary-mass companions and five brown dwarf companions using GPI and SPHERE-IRDIS. We probe the subpercent linear polarization regime that typifies polarized free-floating brown dwarfs and place limits on each object’s degree of linear polarization. We relate our upper limits on each target’s degree of linear polarization to its rotation rate, and place our results in the context of rotation rates measured using high-resolution spectroscopy.

• OSTI ID: 23013463
• Journal Information: Astronomical Journal (Online), Vol. 160, Issue 6; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 1538-3881
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTROPHYSICS
COSMOLOGY AND ASTRONOMY
DISTRIBUTION
DWARF STARS
EMISSION
MASS
POLARIMETERS
POLARIZATION
ROTATION
STELLAR ATMOSPHERES