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Published October 2020 | Published + Submitted
Journal Article Open

SCExAO/CHARIS Near-infrared Integral Field Spectroscopy of the HD 15115 Debris Disk


We present new, near-infrared (1.1–2.4 μm) high-contrast imaging of the debris disk around HD 15115 with the Subaru Coronagraphic Extreme Adaptive Optics (SCExAO) system coupled with the Coronagraphic High Angular Resolution Imaging Spectrograph (CHARIS). The SCExAO/CHARIS resolves the disk down to ρ ~ 0."2 (r_(proj) ~ 10 au), a factor of ~3–5 smaller than previous recent studies. We derive a disk position angle of PA ~ 279 4–280 5 and an inclination of i ~ 85.°3–86.2.°. While recent SPHERE/IRDIS imagery of the system could suggest a significantly misaligned two-ring disk geometry, CHARIS imagery does not reveal conclusive evidence for this hypothesis. Moreover, optimizing models of both one- and two-ring geometries using differential evolution, we find that a single ring having a Hong-like scattering phase function matches the data equally well within the CHARIS field of view (ρ ≾ 1''). The disk's asymmetry, well evidenced at larger separations, is also recovered; the west side of the disk appears, on average, around 0.4 mag brighter across the CHARIS bandpass between 0."25 and 1''. Comparing Space Telescope Imaging Spectrograph (STIS) 50CCD optical photometry (2000–10500 Å) with CHARIS near-infrared photometry, we find a red (STIS/50CCD−CHARIS broadband) color for both sides of the disk throughout the 0."4–1'' region of overlap, in contrast to the blue color reported at similar wavelengths for regions exterior to ~2''. Further, this color may suggest a smaller minimum grain size than previously estimated at larger separations. Finally, we provide constraints on planetary companions and discuss possible mechanisms for the observed inner disk flux asymmetry and color.

Additional Information

© 2020 The American Astronomical Society. Received 2020 May 28; revised 2020 July 23; accepted 2020 July 31; published 2020 September 11. We thank our referee for providing helpful comments that improved this manuscript. The authors wish to acknowledge the very significant cultural role and reverence that the summit of Maunakea has always had within the indigenous Hawaiian community. We are most fortunate to have the opportunity to conduct observations from this mountain. We wish to acknowledge the critical importance of the current and recent Subaru telescope operators, day crew, computer support, and office staff employees. Their expertise, ingenuity, and dedication are indispensable to the continued successful operation of Subaru. We acknowledge funding support from the NASA XRP program via grants 80NSSC20K0252 and NNX17AF88G. T.C. was supported by a NASA Senior Postdoctoral Fellowship. Based partially on observations made with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555. These observations are associated with program No. 12228. E.A. is supported by MEXT/JSPS KAKENHI grant No. 17K05399.

Attached Files

Published - Lawson_2020_AJ_160_163.pdf

Submitted - 2008.00309.pdf


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September 15, 2023
October 23, 2023