Accretion Properties of PDS 70b with MUSE

Jun Hashimoto; Yuhiko Aoyama; Mihoko Konishi; Taichi Uyama; Shinsuke Takasao; Masahiro Ikoma; Takayuki Tanigawa

doi:10.3847/1538-3881/ab811e

paper

Accretion Properties of PDS 70b with MUSE

arXiv:2003.07922 · doi:10.3847/1538-3881/ab811e

Abstract

We report a new evaluation of the accretion properties of PDS~70b obtained with VLT/MUSE. The main difference from previous studies in Haffert et al. (2019) and Aoyama & Ikoma (2019) is in the mass accretion rate. Simultaneous multiple line observations, such as H $α$ and H $β$ , can better constrain the physical properties of an accreting planet. While we clearly detected H $α$ emissions from PDS~70b, no H $β$ emissions were detected. We estimate the line flux of H $β$ with a 3- $σ$ upper limit to be 2.3~ $\times$ ~10 $^{- 16}$ ~erg~s $^{- 1}$ ~cm $^{- 2}$ . The flux ratio $F_{H β}$ / $F_{H α}$ for PDS~70b is $<$ ~0.28. Numerical investigations by Aoyama et al. (2018) suggest that $F_{H β}$ / $F_{H α}$ should be close to unity if the extinction is negligible. We attribute the reduction of the flux ratio to the extinction, and estimate the extinction of H $α$ ( $A_{H α}$ ) for PDS~70b to be $>$ ~2.0~mag using the interstellar extinction value. %The expected $A_{H α}$ value in the gap of the protoplanetary disk at the PDS~70b location is 2.4~mag, which is consistent with the estimated extinction. By combining with the H $α$ linewidth and the dereddening line luminosity of H $α$ , %we derive the PDS~70b dynamical mass and mass accretion rate to be \hashimotor{12~ $\pm$ ~3~ $M_{Jup}$ } and $≳$ ~5~ $\times$ ~10 $^{- 7}$ ~ $M_{Jup}$ ~yr $^{- 1}$ , respectively. we derive the PDS~70b mass accretion rate to be $≳$ ~5~ $\times$ ~10 $^{- 7}$ ~ $M_{Jup}$ ~yr $^{- 1}$ . The PDS~70b mass accretion rate is an order of magnitude larger than that of PDS~70. We found that the filling factor $f_{f}$ (the fractional area of the planetary surface emitting H $α$ ) is $≳$ 0.01, which is similar to the typical stellar value. The small value of $f_{f}$ indicates that the H $α$ emitting areas are localized at the surface of PDS~70b.

arXiv commentAccepted for publication in The Astronomical Journal

Accretion Properties of PDS 70b with MUSE

Abstract

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