SCExAO/CHARIS High-Contrast Imaging of Spirals and Darkening Features in the HD 34700 A Protoplanetary Disk

TL;DR

This study uses high-contrast imaging to analyze the HD 34700 A protoplanetary disk, revealing spiral structures, darkening features, and setting limits on potential substellar companions, with implications for disk geometry and dynamics.

Contribution

First high-contrast integral field spectroscopy of HD 34700 A's disk, confirming spirals and analyzing disk features and potential origins of observed structures.

Findings

Confirmed multiple spiral arms with large pitch angles (~30-50°)

Set mass limits for substellar companions (~12 M_Jup at 0.3" and ~5 M_Jup at 0.75" )

Detected darkening effects and inferred disk properties such as scale height and dust distribution.

Abstract

We present Subaru/SCExAO+CHARIS broadband ($JHK$-band) integral field spectroscopy of HD 34700 A. CHARIS data recover HD 34700 A's disk ring and confirm multiple spirals discovered in Monnier et al. (2019). We set limits on substellar companions of $\sim12\ M_{\rm Jup}$ at $0\farcs3$ (in the ring gap) and $\sim5\ M_{\rm Jup}$ at $0\farcs75$ (outside the ring). The data reveal darkening effects on the ring and spiral, although we do not identify the origin of each feature such as shadows or physical features related to the outer spirals. Geometric albedoes converted from the surface brightness suggests a higher scale height and/or prominently abundant sub-micron dust at position angle between $\sim45^\circ$ and $90^\circ$. Spiral fitting resulted in very large pitch angles ($\sim30-50^\circ$) and a stellar flyby of HD 34700 B or infall from a possible envelope is perhaps a reasonable scenario to explain the large pitch angles.