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A Layered Debris Disk around M Star TWA 7 in Scattered Light
- Source :
- ApJ 914 (2021) 95
- Publication Year :
- 2021
-
Abstract
- We have obtained Hubble Space Telescope (HST) coronagraphic observations of the circumstellar disk around M star TWA 7 using the STIS instrument in visible light. Together with archival observations including HST/NICMOS using the F160W filter and Very Large Telescope/SPHERE at $H$-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 new discovery of a tertiary ring and a clump. We identify a layered architecture: three rings, a spiral, and an ${\approx}150$ au$^2$ 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 and local Keplerian; 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, STIS-SPHERE radial distribution peak difference for the tertiary ring, and 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.<br />Comment: 20 pages, 10 figures, 3 tables, ApJ accepted. Data and animation available in the ancillary folder. Citation fixed, author list updated
Details
- Database :
- arXiv
- Journal :
- ApJ 914 (2021) 95
- Publication Type :
- Report
- Accession number :
- edsarx.2105.09949
- Document Type :
- Working Paper
- Full Text :
- https://doi.org/10.3847/1538-4357/ac03b9