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Published December 2018 | Published + Accepted Version
Journal Article Open

SCExAO/CHARIS Near-IR High-contrast Imaging and Integral Field Spectroscopy of the HIP 79977 Debris Disk


We present new, near-infrared (1.1–2.4 μm) high-contrast imaging of the bright debris disk surrounding HIP 79977 with the Subaru Coronagraphic Extreme Adaptive Optics system (SCExAO) coupled with the CHARIS integral field spectrograph. SCExAO/CHARIS resolves the disk down to smaller angular separations of (0farcs11; r ~ 14 au) and at a higher significance than previously achieved at the same wavelengths. The disk exhibits a marginally significant east–west brightness asymmetry in H band that requires confirmation. Geometrical modeling suggests a nearly edge-on disk viewed at a position angle of ~114fdg6 east of north. The disk is best-fit by scattered-light models assuming strongly forward-scattering grains (g ~ 0.5–0.65) confined to a torus with a peak density at r_0 ~ 53–75 au. We find that a shallow outer density power law of α_(out) = −1 to −3 and flare index of β = 1 are preferred. Other disk parameters (e.g., inner density power law and vertical scale height) are more poorly constrained. The disk has a slightly blue intrinsic color and its profile is broadly consistent with predictions from birth ring models applied to other debris disks. While HIP 79977's disk appears to be more strongly forward-scattering than most resolved disks surrounding 5–30 Myr old stars, this difference may be due to observational biases favoring forward-scattering models for inclined disks versus lower inclination, ostensibly neutral-scattering disks like HR 4796A's. Deeper, higher signal-to-noise SCExAO/CHARIS data can better constrain the disk's dust composition.

Additional Information

© 2018. The American Astronomical Society. Received 2018 May 24; revised 2018 October 15; accepted 2018 October 16; published 2018 November 28. We thank the anonymous referee for helpful suggestions that improved the quality of this work. We also thank Laurent Pueyo for helpful conversations about KLIP forward modeling. T.C. is supported by a NASA Senior Postdoctoral Fellowship. M.T. is partly supported by the JSPS Grant-in-Aid (15H02063). S.G. is supported from NSF award AST 1106391 and NASA Roses APRA award NNX 13AC14G. The development of SCExAO was supported by the JSPS (Grant-in-Aid for Research #23340051, #26220704, #23103002), the Astrobiology Center (ABC) of the National Institutes of Natural Sciences, Japan, the Mt Cuba Foundation and the directors contingency fund at Subaru Telescope. CHARIS was built at Princeton University in collaboration with the National Astronomical Observatory of Japan under a Grant-in-Aid for Scientific Research on Innovative Areas from MEXT of the Japanese government (#23103002). We wish to emphasize the pivotal cultural role and reverence that the summit of Maunakea has always had within the indigenous Hawaiian community. We are most fortunate to have the privilege to conduct scientific observations from this mountain. Facility: Subaru Telescope - (SCExAO, CHARIS). Software: CHARIS Data Reduction Pipeline.

Attached Files

Published - Goebel_2018_AJ_156_279.pdf

Accepted Version - 1810.09458


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