Constraining accretion signatures of exoplanets in the TW Hya transitional disk

Abstract

We present a near-infrared direct imaging search for accretion signatures of possible protoplanets around the young stellar object (YSO) TW Hya, a multi-ring disk exhibiting evidence of planet formation. The Pa$\beta$ line (1.282 $\mu$m) is an indication of accretion onto a protoplanet, and its intensity is much higher than that of blackbody radiation from the protoplanet. We focused on the Pa$\beta$ line and performed Keck/OSIRIS spectroscopic observations. Although spectral differential imaging (SDI) reduction detected no accretion signatures, the results of the present study allowed us to set 5$\sigma$ detection limits for Pa$\beta$ emission of $5.8\times 10^{-18}$ and $1.5\times 10^{-18}$ erg/s/cm${}^2$ at 0\farcs4 and 1\farcs6, respectively. We considered the mass of potential planets using theoretical simulations of circumplanetary disks and hydrogen emission. The resulting masses were $1.45\pm 0.04$ M${}_{\mathrm{J}}$ and $2.29_{-0.04}^{+0.03}$ M${}_{\mathrm{J}}$ at 25 and 95 AU, respectively, which agree with the detection limits obtained from previous broadband imaging. The detection limits should allow the identification of protoplanets as small as $\sim$1 M${}_{\mathrm{J}}$, which may assist in direct imaging searches around faint YSOs for which extreme adaptive optics instruments are unavailable.

6 pages, 3 figures, accepted for publication in AJ

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Cited by in corpus (1)

• Analyzing JWST/NIRSpec Hydrogen Line Detections at TWA 27B: Constraining Accretion Properties and Geometry