A COMBINED VERY LARGE TELESCOPE AND GEMINI STUDY OF THE ATMOSPHERE OF THE DIRECTLY IMAGED PLANET, β PICTORIS b
- Department of Astronomy and Astrophysics, University of Toronto, 50 St. George Street, Toronto, Ontario M5S 3H4 (Canada)
- Department of Astrophysical Sciences, Princeton University, 4 Ivy Lane, Peyton Hall, Princeton, NJ 08544 (United States)
- Department of Astronomy, Yale University, 260 Whitney Avenue, New Haven, CT 06511 (United States)
- Osaka University, Machikaneyama 1-1, Toyonaka, Osaka 560-0043 (Japan)
- European Southern Observatory, Alonso de Cordova 3107, Vitacura, Cassilla 19001, Santiago (Chile)
- Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, MS 10, Cambridge, MA 02138 (United States)
- NASA-Goddard Space Flight Center, Exoplanets and Stellar Astrophysics Laboratory Code 667, Greenbelt, MD 20771 (United States)
- Department of Astronomy, University of Maryland, College Park, MD 20742-2421 (United States)
- Department of Terrestrial Magnetism, Carnegie Institution of Washington, 5241 Broad Branch Road, NW Washington, DC 20015-1305 (United States)
- Department of Physics, University of Utah, Salt Lake City, UT (United States)
We analyze new/archival VLT/NaCo and Gemini/NICI high-contrast imaging of the young, self-luminous planet β Pictoris b in seven near-to-mid IR photometric filters, using advanced image processing methods to achieve high signal-to-noise, high precision measurements. While β Pic b's near-IR colors mimic those of a standard, cloudy early-to-mid L dwarf, it is overluminous in the mid-infrared compared to the field L/T dwarf sequence. Few substellar/planet-mass objects—i.e., κ And b and 1RXJ 1609B—match β Pic b's JHK{sub s}L' photometry and its 3.1 μm and 5 μm photometry are particularly difficult to reproduce. Atmosphere models adopting cloud prescriptions and large (∼60 μm) dust grains fail to reproduce the β Pic b spectrum. However, models incorporating thick clouds similar to those found for HR 8799 bcde, but also with small (a few microns) modal particle sizes, yield fits consistent with the data within the uncertainties. Assuming solar abundance models, thick clouds, and small dust particles ((a) = 4 μm), we derive atmosphere parameters of log (g) = 3.8 ± 0.2 and T{sub eff} = 1575-1650 K, an inferred mass of 7{sup +4}{sub -3} M{sub J} , and a luminosity of log(L/L{sub ☉}) ∼–3.80 ± 0.02. The best-estimated planet radius, ≈1.65 ± 0.06 R{sub J} , is near the upper end of allowable planet radii for hot-start models given the host star's age and likely reflects challenges constructing accurate atmospheric models. Alternatively, these radii are comfortably consistent with hot-start model predictions if β Pic b is younger than ≈7 Myr, consistent with a late formation well after its host star's birth ∼12{sup +8}{sub -4} Myr ago.
- OSTI ID:
- 22270893
- Journal Information:
- Astrophysical Journal, Vol. 776, Issue 1; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
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