Herschel imaging of 61Vir: implications for the prevalence of debris in low-mass planetary systems

Wyatt, M. C. and Kennedy, G. and Sibthorpe, B. and Moro-Martin, A. and Lestrade, J. -F. and Ivison, R. J. and Matthews, B. and Udry, S. and Greaves, J. S. and Kalas, P. and Lawler, S. and Su, K. Y. L. and Rieke, G. H. and Booth, M. and Bryden, G. and Horner, J. and Kavelaars, J. J. and Wilner, D. (2012) Herschel imaging of 61Vir: implications for the prevalence of debris in low-mass planetary systems. Monthly Notices of the Royal Astronomical Society, 424 (2). pp. 1206-1223. ISSN 0035-8711

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This paper describes Herschel observations of the nearby (8.5pc) G5V multi-exoplanet host star 61Vir at 70, 100, 160, 250, 350 and 500m carried out as part of the DEBRIS survey. These observations reveal emission that is significantly extended out to a distance of >15arcsec with a morphology that can be fitted by a nearly edge-on (77° inclination) radially broad (from 30au out to at least 100au) debris disc of fractional luminosity 2.7 × 10 -5, with two additional (presumably unrelated) sources nearby that become more prominent at longer wavelengths. Chance alignment with a background object seen at 1.4GHz provides potential for confusion, however, the star's 1.4arcsecyr -1 proper motion allows archival Spitzer 70m images to confirm that what we are interpreting as disc emission really is circumstellar. Although the exact shape of the disc's inner edge is not well constrained, the region inside 30au must be significantly depleted in planetesimals. This is readily explained if there are additional planets outside those already known (i.e. in the 0.5-30au region), but is also consistent with collisional erosion. We also find tentative evidence that the presence of detectable debris around nearby stars correlates with the presence of the lowest mass planets that are detectable in current radial velocity surveys. Out of an unbiased sample of the nearest 60G stars, 11 are known to have planets, of which six (including 61Vir) have planets that are all less massive than Saturn, and four of these have evidence for debris. The debris towards one of these planet hosts (HD20794) is reported here for the first time. This fraction (4/6) is higher than that expected for nearby field stars (15per cent), and implies that systems that form low-mass planets are also able to retain bright debris discs. We suggest that this correlation could arise because such planetary systems are dynamically stable and include regions that are populated with planetesimals in the formation process where the planetesimals can remain unperturbed over Gyr time-scales.

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Item Type: Article (Commonwealth Reporting Category C)
Refereed: Yes
Item Status: Live Archive
Additional Information: © 2012 The Authors. This publication is copyright. It may be reproduced in whole or in part for the purposes of study, research, or review, but is subject to the inclusion of an acknowledgment of the source.
Faculty / Department / School: Historic - Faculty of Engineering and Surveying - No Department
Date Deposited: 22 Jul 2014 01:09
Last Modified: 09 Feb 2017 01:36
Uncontrolled Keywords: cCircumstellar matter; planet-disc interactions; planetary systems; planets and satellites formation
Fields of Research : 02 Physical Sciences > 0201 Astronomical and Space Sciences > 020110 Stellar Astronomy and Planetary Systems
02 Physical Sciences > 0201 Astronomical and Space Sciences > 020105 General Relativity and Gravitational Waves
02 Physical Sciences > 0201 Astronomical and Space Sciences > 020108 Planetary Science (excl. Extraterrestrial Geology)
Socio-Economic Objective: E Expanding Knowledge > 97 Expanding Knowledge > 970102 Expanding Knowledge in the Physical Sciences
Identification Number or DOI: 10.1111/j.1365-2966.2012.21298.x
URI: http://eprints.usq.edu.au/id/eprint/25587

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