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A Layered Debris Disk around M Star TWA 7 in Scattered Light

Ren, Bin and Choquet, Élodie and Perrin, Marshall D. and Mawet, Dimitri and Chen, Christine H. and Milli, Julien and Debes, John H. and Rebollido, Isabel and Stark, Christopher C. and Hagan, J. Brendan and Hines, Dean C. and Millar-Blanchaer, Maxwell A. and Pueyo, Laurent and Roberge, Aki and Schneider, Glenn and Serabyn, Eugene and Soummer, Rémi and Wolff, Schuyler G. (2021) A Layered Debris Disk around M Star TWA 7 in Scattered Light. Astrophysical Journal, 914 (2). Art. No. 95. ISSN 0004-637X. doi:10.3847/1538-4357/ac03b9.

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We have obtained Hubble Space Telescope (HST) coronagraphic observations of the circumstellar disk around M star TWA 7 using the Space Telescope Imaging Spectrograph (STIS) instrument in visible light. Together with archival observations, including HST/NICMOS using the F160W filter and Very Large Telescope/SPHERE at the H-band in polarized light, we investigate the system in scattered light. By studying this nearly face-on system using geometric disk models and Henyey–Greenstein phase functions, we report a new discovery of a tertiary ring and a clump. We identify a layered architecture: three rings, a spiral, and an ≈150 au² elliptical clump. The most extended ring peaks at 28 au, and the other components are on its outskirts. Our point-source detection-limit calculations demonstrate the necessity of disk modeling in imaging fainter planets. Morphologically, we witness a clockwise spiral motion, and the motion pattern is consistent with both solid body motion and local Keplerian motion; we also observe underdensity regions for the secondary ring that might result from mean-motion resonance or moving shadows: both call for re-observations to determine their nature. Comparing multi-instrument observations, we obtain blue STIS-NICMOS color, a STIS-SPHERE radial distribution peak difference for the tertiary ring, and a high SPHERE-NICMOS polarization fraction; these aspects indicate that TWA 7 could retain small dust particles. By viewing the debris disk around M star TWA 7 at a nearly face-on vantage point, our study allows for the understanding of such disks in scattered light in both system architecture and dust property.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Ren, Bin0000-0003-1698-9696
Choquet, Élodie0000-0002-9173-0740
Perrin, Marshall D.0000-0002-3191-8151
Mawet, Dimitri0000-0002-8895-4735
Chen, Christine H.0000-0002-8382-0447
Milli, Julien0000-0001-9325-2511
Debes, John H.0000-0002-1783-8817
Rebollido, Isabel0000-0002-4388-6417
Hines, Dean C.0000-0003-4653-6161
Millar-Blanchaer, Maxwell A.0000-0001-6205-9233
Pueyo, Laurent0000-0003-3818-408X
Roberge, Aki0000-0002-2989-3725
Schneider, Glenn0000-0002-4511-5966
Soummer, Rémi0000-0003-2753-2819
Wolff, Schuyler G.0000-0002-9977-8255
Additional Information:© 2021. The American Astronomical Society. Received 2021 March 1; revised 2021 May 18; accepted 2021 May 19; published 2021 June 18. We thank the anonymous referee for useful suggestions that make this paper more thorough. We thank useful discussions with Johan Olofsson and Rob van Holstein. This paper was based on observations made with the NASA/ESA Hubble Space Telescope, obtained from the data archive at the Space Telescope Science Institute. STScI is operated by the Association of Universities for Research in Astronomy, Inc. under NASA contract NAS 5-26555. This research has made use of data reprocessed as part of the ALICE program, which was supported by NASA through grants HST-AR-12652 (PI: R. Soummer), HST-GO-11136 (PI: D. Golimowski), HST-GO-13855 (PI: E. Choquet), HST-GO-13331 (PI: L. Pueyo), and STScI Director's Discretionary Research funds, and was conducted at STScI, which is operated by AURA under NASA contract NAS5-26555. The input images to ALICE processing are from the recalibrated NICMOS data products produced by the Legacy Archive project, "A Legacy Archive PSF Library And Circumstellar Environments (LAPLACE) Investigation," (HST-AR-11279, PI: G. Schneider). Based on observations collected at the European Organisation for Astronomical Research in the Southern Hemisphere under ESO program 198.C-0209(F). Part of the computations presented here were conducted on the Caltech High Performance Cluster, partially supported by a grant from the Gordon and Betty Moore Foundation. Facilities: HST (NICMOS - , STIS) - , VLT:Melipal (SPHERE) - . Software: DebrisDiskFM (Ren et al. 2019), emcee (Foreman-Mackey et al. 2013), IRDAP (van Holstein et al. 2020), nmf_imaging (Ren 2020), pysynphot (STScI Development Team 2013), TinyTim (Krist et al. 2011).
Group:Astronomy Department
Funding AgencyGrant Number
NASANAS 5-26555
STScI Director's Discretionary Research fundsUNSPECIFIED
Gordon and Betty Moore FoundationUNSPECIFIED
Subject Keywords:Debris disks; Coronagraphic imaging; Planetary system formation; Orbital motion
Issue or Number:2
Classification Code:Unified Astronomy Thesaurus concepts: Debris disks (363); Coronagraphic imaging (313); Planetary system formation (1257); Orbital motion (1179)
Record Number:CaltechAUTHORS:20210628-191053670
Persistent URL:
Official Citation:Bin Ren et al 2021 ApJ 914 95
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:109630
Deposited By: George Porter
Deposited On:29 Jun 2021 14:19
Last Modified:16 Nov 2021 19:37

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