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arXiv · 1905.06370

Evidence for a circumplanetary disk around protoplanet PDS 70 b

V. Christiaens·F. Cantalloube·S. Casassus·D. J. Price·O. Absil·C. Pinte·J. Girard·M. Montesinos
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Abstract

We present the first observational evidence for a circumplanetary disk around the protoplanet PDS~70~b, based on a new spectrum in the $K$ band acquired with VLT/SINFONI. We tested three hypotheses to explain the spectrum: Atmospheric emission from the planet with either (1) a single value of extinction or (2) variable extinction, and (3) a combined atmospheric and circumplanetary disk model. Goodness-of-fit indicators favour the third option, suggesting circumplanetary material contributing excess thermal emission --- most prominent at $\lambda \gtrsim 2.3 \mu$m. Inferred accretion rates ($\sim 10^{-7.8}$--$10^{-7.3} M_J$ yr$^{-1}$) are compatible with observational constraints based on the H$\alpha$ and Br$\gamma$ lines. For the planet, we derive an effective temperature of 1500--1600 K, surface gravity $\log(g)\sim 4.0$, radius $\sim 1.6 R_J$, mass $\sim 10 M_J$, and possible thick clouds. Models with variable extinction lead to slightly worse fits. However, the amplitude ($\Delta A_V \gtrsim 3$mag) and timescale of variation ($\lesssim$~years) required for the extinction would also suggest circumplanetary material.

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V. Christiaens, F. Cantalloube, S. Casassus, D. J. Price, O. Absil, C. Pinte, J. Girard, M. Montesinos. 2019-05-15. Evidence for a circumplanetary disk around protoplanet PDS 70 b. https://doi.org/10.3847/2041-8213/ab212b

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