Spectroscopic Characterization of HD 95086 b with the Gemini Planet Imager
Abstract
We present new H (1.5-1.8 μm) photometric and K 1 (1.9-2.2 μm) spectroscopic observations of the young exoplanet HD 95086 b obtained with the Gemini Planet Imager. The H-band magnitude has been significantly improved relative to previous measurements, whereas the low-resolution K 1 (λ /δ λ ≈ 66) spectrum is featureless within the measurement uncertainties and presents a monotonically increasing pseudo-continuum consistent with a cloudy atmosphere. By combining these new measurements with literature L\prime photometry, we compare the spectral energy distribution (SED) of the planet to other young planetary-mass companions, field brown dwarfs, and to the predictions of grids of model atmospheres. HD 95086 b is over a magnitude redder in {K}1-L\prime color than 2MASS J12073346-3932539 b and HR 8799 c and d, despite having a similar L\prime magnitude. Considering only the near-infrared measurements, HD 95086 b is most analogous to the brown dwarfs 2MASS J2244316+204343 and 2MASS J21481633+4003594, both of which are thought to have dusty atmospheres. Morphologically, the SED of HD 95086 b is best fit by low temperature ({T}{{eff}} = 800-1300 K), low surface gravity spectra from models which simulate high photospheric dust content. This range of effective temperatures is consistent with field L/T transition objects, but the spectral type of HD 95086 b is poorly constrained between early L and late T due to its unusual position the color-magnitude diagram, demonstrating the difficulty in spectral typing young, low surface gravity substellar objects. As one of the reddest such objects, HD 95086 b represents an important empirical benchmark against which our current understanding of the atmospheric properties of young extrasolar planets can be tested.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- June 2016
- DOI:
- 10.3847/0004-637X/824/2/121
- arXiv:
- arXiv:1604.01411
- Bibcode:
- 2016ApJ...824..121D
- Keywords:
-
- infrared: planetary systems;
- instrumentation: adaptive optics;
- planets and satellites: atmospheres;
- stars: individual: HD 95086;
- Astrophysics - Earth and Planetary Astrophysics
- E-Print:
- 20 pages, 12 figures, accepted for publication in ApJ