Constraining Planetary Gas Accretion Rate from Hα Line Width and Intensity: Case of PDS 70 b and c
Abstract
Recent observations of protoplanets embedded in circumstellar disks have shed light on the planet formation process. In particular, detection of hydrogen Balmer-line (Hα) emission gives direct constraints on late-stage accretion onto gas giants. Very recently Haffert et al. measured the spectral line widths, in addition to intensities, of {{H}}α emission from the two protoplanets orbiting PDS 70. Here, we study these protoplanets by applying radiation-hydrodynamic models of the shock-heated accretion flow onto protoplanets that Aoyama et al. have recently developed. As a result, we demonstrate that Hα line widths combined with intensities lead to narrowing down the possible ranges of the protoplanetary accretion rate and/or mass significantly. While the current spectral resolution is not high enough to derive a definite conclusion regarding their accretion process, high-resolution spectral imaging of growing protoplanets is highly promising.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- November 2019
- DOI:
- 10.3847/2041-8213/ab5062
- arXiv:
- arXiv:1909.08175
- Bibcode:
- 2019ApJ...885L..29A
- Keywords:
-
- Accretion;
- Shocks;
- Extrasolar gas giants;
- Planet formation;
- Exoplanet formation;
- H I line emission;
- Line intensities;
- 14;
- 2086;
- 509;
- 1241;
- 492;
- 690;
- 2084;
- Astrophysics - Earth and Planetary Astrophysics
- E-Print:
- 8 pages, 5 figures