期刊
ASTRONOMICAL JOURNAL
卷 154, 期 1, 页码 -出版社
IOP PUBLISHING LTD
DOI: 10.3847/1538-3881/aa74db
关键词
instrumentation: adaptive optics; planets and satellites: atmospheres; planets and satellites: composition; planets and satellites: gaseous planets; stars: individual (51 Eridani)
资金
- NSF [AST1411868, AST-1518332, DGE-1311230]
- NASA [NNX14AJ80G]
- Fonds de Recherche du Quebec
- NASA Exoplanets Research Program (XRP) [NNX16AD44G]
- JPL's ESI program for GPIrelated
- NASA's Science Mission Directorate
- NExSS [NNX15AD95G]
- U.S. Department of Energy by Lawrence Livermore National Laboratory [DE-AC52-07NA27344]
- Direct For Mathematical & Physical Scien
- Division Of Astronomical Sciences [1411868] Funding Source: National Science Foundation
- Division Of Astronomical Sciences
- Direct For Mathematical & Physical Scien [1405505, 1518332] Funding Source: National Science Foundation
We present spectrophotometry spanning 1-5 mu m of 51 Eridani b, a 2-10 M-Jup planet discovered by the Gemini Planet Imager Exoplanet Survey. In this study, we present new K1 (1.90-2.19 mu m) and K2 (2.10-2.40 mu m) spectra taken with the Gemini Planet Imager as well as an updated L-P (3.76 mu m) and new M-S (4.67 mu m) photometry from the NIRC2 Narrow camera. The new data were combined with J (1.13-1.35 mu m) and H (1.50-1.80 mu m) spectra from the discovery epoch with the goal of better characterizing the planet properties. The 51 Eri b photometry is redder than field brown dwarfs as well as known young T-dwarfs with similar spectral type (between T4 and T8), and we propose that 51 Eri b might be in the process of undergoing the transition from L-type to T-type. We used two complementary atmosphere model grids including either deep iron/silicate clouds or sulfide/salt clouds in the photosphere, spanning a range of cloud properties, including fully cloudy, cloud-free, and patchy/intermediate-opacity clouds. The model fits suggest that 51 Eri. b has an effective temperature ranging between 605 and 737 K, a solar metallicity, and a surface gravity of log(g) = 3.5-4.0 dex, and the atmosphere requires a patchy cloud atmosphere to model the spectral energy distribution (SED). From the model atmospheres, we infer a luminosity for the planet of -5.83 to -5.93 (logL/L circle dot),leaving 51 Eri b in the unique position of being one of the only directly imaged planets consistent with having formed via a cold-start scenario. Comparisons of the planet SED against warm-start models indicate that the planet luminosity is best reproduced by a planet formed via core accretion with a core mass between 15 and 127 M-circle plus.
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