1. The Eroding Disk of AU Microscopii
C. Grady (Eureka Scientific), J.P. Wisniewski (U.Oklahoma), G. Schneider (U. Arizona),
A. Boccaletti (LESIA - Observatoire de Paris), A. Gaspar (U. Arizona), J.H. Debes, D.C. Hines,
& C.C. Stark (STScI), A.-M. Lagrange (U. Grenoble I), C. Thalmann (ETH Zurich),
J.-C. Augereau (IPAG) J. Milli (ESO- Chile ), T. Henning (MPIA, Heidelberg), E. Sezestre (IPAG), M.J. Kuchner (NASA’s GSFC)

2. AU Mic the Star Distance 9.79 pc or 31.93 Lyr Gaia Consortium 2016
Spectral Type
M1Ve
SIMBAD database
Age
24±3 Myr
Bell et al. 2014
Stellar activity cycle
5 years
Ibańez Bustos et al (2018)
Disk viewed
Edge-on
Fitzgerald et al. (2004)
Krist et al. (2005)
planet
1 month period
Plavchan (tweet TESS data)

3. The Disk as seen by HST since 2010

4. Mass Loss Rate
Disk mass from ALMA data (Daley et al 2018) earth masses including larger bodies
Mass Estimate per feature (Chiang & Fung 2017) - 4x10-7 earth masses
Number of features with proper motion indicating escape (Boccaletti et al. 2015) – 3 decade-1
Remaining Lifetime of disk is estimated to be ~1.4 Myr

5. Mechanism responsible for ejecting features still unknown, as is source of changing aspect ratios of some features
10 au
10 au

6. Implications
Disk lifetime consistent with deficit in debris disks with M- star hosts after 30 Myr (Binks & Jeffries 2017)
Markedly different from A stars where disks can be imaged through most of MS lifetime, or G stars where disks can be imaged to at least 2.3 Gyr (Schneider et al ).
Processes which depend on disk survival may be inhibited in these systems, including veneering of terrestrial planets with volatiles and organics
This may result in smaller planets in the Habitable Zone which are far from habitable.

7. Next Steps
Scale of Features comparable to size of Coronal Mass Ejections in our outer solar system, which may indicate a link to stellar activity – see poster by Kowalski et al. on Wednesday
Data for this program were obtained under HST-GO and 15219