Author(s): C. Grady, Eureka Scientific , Laurel, Maryland, UNITED STATES|J. Wisniewski, University of Oklahoma, Norman, Oklahoma, UNITED STATES|G. Schneider, A. Gaspar, University of Arizona, Tucson, Arizona, UNITED STATES|J. Debes, D. Hines, C. Stark, STScI, Baltimore, Maryland, UNITED STATES|A. Boccaletti, LESIA, Observatoire de Paris , Paris, MEUDON Cedex, FRANCE|J. Augereau, E. Sezestre, Institut Planetologie et d'Astrophysique de Grenoble, Paris, Grenoble Cédex 9, FRANCE|A. Lagrange, Universite de Grenoble I., Saint-Martin-d'Hères, Grenoble Cédex 9, FRANCE|C. Thalmann, Eidgenossiche Technische Hochschule (ETH), Zurich, Grenoble Cédex 9, SWITZERLAND|T.K. Henning, Max-Planck-Institut fur Astronomie, Heidelberg, Grenoble Cédex 9, GERMANY|M.J. Kuchner, NASA Goddard Space Flight Center, Greenbelt, Maryland, UNITED STATES|J. Milli, European Southern Observatory, Santiago, Maryland, CHILE|
Institution(s): 1. Eureka Scientific , Laurel, MD, United States. 2. University of Oklahoma, Norman, OK, United States. 3. University of Arizona, Tucson, AZ, United States. 4. STScI, Baltimore, MD, United States. 5. LESIA, Observatoire de Paris , Paris, MEUDON Cedex, France. 6. Institut Planetologie et d'Astrophysique de Grenoble, Paris, Grenoble Cédex 9, France. 7. Universite de Grenoble I., Saint-Martin-d'Hères, France. 8. Eidgenossiche Technische Hochschule (ETH), Zurich, Switzerland. 9. Max-Planck-Institut fur Astronomie, Heidelberg, Germany. 10. NASA Goddard Space Flight Center, Greenbelt, MD, United States. 11. European Southern Observatory, Santiago, Chile.
Contributing team(s): (none)
AU Mic (M1V) is a young star (BPMG, 23+/-3 Myrs old) hosting the first M-star debris disk to be imaged. At d=9.72 pc, HST and ground-based imagery offers unprecedented detail. A distinctive feature of the disk is the presence of a series of out-of-plane arc-like features first seen in the SE arm in 2004. In 2014, comparison of SPHERE commissioning data with HST coronagraphy from 2010/2011 revealed that the features were moving outward in the disk, and that 3 had projected velocities greater than escape velocity. The motion has continued into 2017/2018. The disk features seen previously are now more diffuse. A small velocity component vertical to the disk midplane is now resolved. Using the disk mass estimate of Daley et al. (2018), the feature mass estimate of Chiang & Fung (2017), and the number of escaping features noted by Boccaletti et al. (2015), we estimate the residual lifetime of the disk and find the disk can be exhausted in ~1.4 Myr. This has implications for delivery of water and organics to planets in the Habitable Zone. In particular, if AU Mic is representative, it implies that little will remain in the disk at the time when planets in the habitable zone have cooled sufficiently to retain volatiles, and suggests that the evolution of HZ planets with M star hosts may be very different from terrestrial planets around G stars. Our remaining lifetime estimate is consistent with the previously known paucity of IR Excess detections around M stars (Binks & Jeffries 2017). We discuss the implications for future HST coronagraphic studies. Support for this work was provided by NASA through grant number HST-GO-15219 from the Space Telescope Science Institute, which is operated by AURA, Inc., under NASA contract NAS 5-26555.