MILLIMETER EMISSION STRUCTURE IN THE FIRST ALMA IMAGE OF THE AU Mic DEBRIS DISK
- Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)
- Herzberg Institute of Astrophysics, 5072 West Saanich Road, Victoria, BC V9E 2E7 (Canada)
- Department of Astronomy, 601 Campbell Hall, University of California, Berkeley, CA 94720 (United States)
- Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA (United Kingdom)
- SRON Netherlands Institute for Space Research, NL-9747 AD Groningen (Netherlands)
We present 1.3 mm ALMA Cycle 0 observations of the edge-on debris disk around the nearby, {approx}10 Myr old, M-type star AU Mic. These observations obtain 0.''6 (6 AU) resolution and reveal two distinct emission components: (1) the previously known dust belt that extends to a radius of 40 AU and (2) a newly recognized central peak that remains unresolved. The cold dust belt of mass {approx}1 M{sub Moon} is resolved in the radial direction with a rising emission profile that peaks sharply at the location of the outer edge of the 'birth ring' of planetesimals hypothesized to explain the midplane scattered light gradients. No significant asymmetries are discerned in the structure or position of this dust belt. The central peak identified in the ALMA image is {approx}6 times brighter than the stellar photosphere, which indicates an additional emission process in the inner regions of the system. Emission from a stellar corona or activity may contribute, but the observations show no signs of temporal variations characteristic of radio-wave flares. We suggest that this central component may be dominated by dust emission from an inner planetesimal belt of mass {approx}0.01 M{sub Moon}, consistent with a lack of emission shortward of 25 {mu}m and a location {approx}<3 AU from the star. Future millimeter observations can test this assertion, as an inner dust belt should be readily separated from the central star at higher angular resolution.
- OSTI ID:
- 22078344
- Journal Information:
- Astrophysical Journal Letters, Vol. 762, Issue 2; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 2041-8205
- Country of Publication:
- United States
- Language:
- English
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