Observations of fast-moving features in the debris disk of AU Mic on a three-year timescale: Confirmation and new discoveries
Maire, A. L.
Coroller, H. Le
AffiliationUniv Arizona, Steward Observ
Keywordsstars: individual: AU Mic
techniques: high angular resolution
techniques: image processing
MetadataShow full item record
PublisherEDP SCIENCES S A
CitationBoccaletti, A., Sezestre, E., Lagrange, A. M., Thébault, P., Gratton, R., Langlois, M., ... & Schneider, G. (2018). Observations of fast-moving features in the debris disk of AU Mic on a three-year timescale: Confirmation and new discoveries. Astronomy & Astrophysics, 614, A52. DOI: https://doi.org/10.1051/0004-6361/201732462
JournalASTRONOMY & ASTROPHYSICS
Rights© ESO 2018. Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License.
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AbstractContext. The nearby and young M star AU Mic is surrounded by a debris disk in which we previously identified a series of large-scale arch-like structures that have never been seen before in any other debris disk and that move outward at high velocities. Aims. We initiated a monitoring program with the following objectives: (1) track the location of the structures and better constrain their projected speeds, (2) search for new features emerging closer in, and ultimately (3) understand the mechanism responsible for the motion and production of the disk features. Methods. AU Mic was observed at 11 different epochs between August 2014 and October 2017 with the IR camera and spectrograph of SPHERE. These high-contrast imaging data were processed with a variety of angular, spectral, and polarimetric differential imaging techniques to reveal the faintest structures in the disk. We measured the projected separations of the features in a systematic way for all epochs. We also applied the very same measurements to older observations from the Hubble Space Telescope (HST) with the visible cameras STIS and ACS. Results. The main outcomes of this work are (1) the recovery of the five southeastern broad arch-like structures we identified in our first study, and confirmation of their fast motion (projected speed in the range 4-12 km s(-1) ); (2) the confirmation that the very first structures observed in 2004 with ACS are indeed connected to those observed later with STIS and now SPHERE; (3) the discovery of two new very compact structures at the northwest side of the disk (at 0.40 '' and 0.55 '' in May 2015) that move to the southeast at low speed; and (4) the identification of a new arch-like structure that might be emerging at the southeast side at about 0.4" from the star (as of May 2016). Conclusions. Although the exquisite sensitivity of SPHERE allows one to follow the evolution not only of the projected separation, but also of the specific morphology of each individual feature, it remains difficult to distinguish between possible dynamical scenarios that may explain the observations. Understanding the exact origin of these features, the way they are generated, and their evolution over time is certainly a significant challenge in the context of planetary system formation around M stars.
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VersionFinal published version
SponsorsESO; CNRS (France); MPIA (Germany); INAF (Italy); FINES (Switzerland); NOVA (Netherlands); European Commission Sixth as part of the Optical Infrared Coordination Network for Astronomy (OPTICON) [RII3-Ct-2004-001566, 226604, 312430]; European Commission Seventh Framework Programmes as part of the Optical Infrared Coordination Network for Astronomy (OPTICON) [RII3-Ct-2004-001566, 226604, 312430]; Programme National de Planetologie (PNP) of CNRS-INSU in France; Programme National de Physique Stellaire (PNPS) of CNRS-INSU in France; French Labex OSUG@2020 (Investissements d'avenir) [ANR10 LABX56]; CNRS; Agence Nationale de la Recherche [ANR-14-CE33-0018]; "Progetti Premiali" funding scheme of the Italian Ministry of Education, University, and Research; project PRIN-INAF 2016 The Cradle of Life - GENESIS - SKA (General Conditions in Early Planetary Systems for the rise of life with SKA); SNSF; Universidad de Valparaiso; ICM Nucleo Milenio de Formacion Planetaria, NPF; STFC via the Institute of Astronomy, Cambridge Consolidated Grant; NASA [NAS 5-26555]