Document Type

Article

Publication Date

8-1-2022

Publication Title

Astrophysical Journal Letters

Abstract

Accretion signatures from bound brown dwarf and protoplanetary companions provide evidence for ongoing planet formation, and accreting substellar objects have enabled new avenues to study the astrophysical mechanisms controlling the formation and accretion processes. Delorme 1 (AB)b, a ?1/430-45 Myr circumbinary planetary-mass companion, was recently discovered to exhibit strong Hα emission. This suggests ongoing accretion from a circumplanetary disk, somewhat surprising given canonical gas disk dispersal timescales of 5-10 Myr. Here, we present the first NIR detection of accretion from the companion in Paβ, Pa?3, and Br?3 emission lines from SOAR/TripleSpec 4.1, confirming and further informing its accreting nature. The companion shows strong line emission, with L line ≈ 1-6 × 10-8 L ? across lines and epochs, while the binary host system shows no NIR hydrogen line emission (L line < 0.32-11 × 10-7 L ?). Observed NIR hydrogen line ratios are more consistent with a planetary accretion shock than with local line excitation models commonly used to interpret stellar magnetospheric accretion. Using planetary accretion shock models, we derive mass accretion rate estimates of Ṁpla?1/43 -4 × 10-8 M J yr-1, somewhat higher than expected under the standard star formation paradigm. Delorme 1 (AB)b's high accretion rate is perhaps more consistent with formation via disk fragmentation. Delorme 1 (AB)b is the first protoplanet candidate with clear (signal-to-noise ratio ?1/45) NIR hydrogen line emission.

Volume

935

Issue

1

DOI

10.3847/2041-8213/ac85ef

ISSN

20418205

Creative Commons License

Creative Commons Attribution 4.0 International License
This work is licensed under a Creative Commons Attribution 4.0 International License.

Rights

© 2022. The Author(s)

Comments

Archived as published.

Download

Share

COinS
 
 

To view the content in your browser, please download Adobe Reader or, alternately,
you may Download the file to your hard drive.

NOTE: The latest versions of Adobe Reader do not support viewing PDF files within Firefox on Mac OS and if you are using a modern (Intel) Mac, there is no official plugin for viewing PDF files within the browser window.