* Astronomy

Blobrana · L

RE: Zeta Leporis

Blobrana · L

New mid-infrared images of the Zeta Leporis circumstellar disk obtained with T-ReCS on Gemini South have for the first time revealed what researchers are calling an "exo-asteroid belt" around another star. Far from a passive dust disk, the new data shows that there must be some sort of ongoing collisional activity within a few astronomical units (AU) of the star. These collisions sustain the replenishment of the small dust grains detected in the T-ReCS images. The results also lend support to the theory that the Zeta Leporis system contains a large reservoir of asteroid-sized bodies as well as the possibility of rocky planets.

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Blobrana · L

Title; Mid-infrared resolution of a 3 AU-radius debris disk around Zeta Leporis
Authors: M. M. Moerchen, C. M. Telesco, C. Packham, T. J. J. Kehoe

We present subarcsecond-resolution mid-infrared images of the debris disk surrounding the 230 Myr- old A star Zeta Lep. Our data obtained with T-ReCS at Gemini South show the source to be unresolved at 10.4 microns but clearly extended at 18.3 microns. Quadratic subtraction of the PSF profile from that of Zeta Lep implies a characteristic radius for the dust disk of 3 AU, which is comparable in size to our solar system's asteroid belt. Simple models suggest that the 18 micron flux is well approximated by two contiguous annuli of mid-infrared-emitting dust from 2-4 and 4-8 AU with a 3:1 flux ratio for the annuli, respectively. We consider two scenarios for the collisions that must be resupplying the dust population: (1) continuous "steady state" grinding of planetesimals, and (2) an isolated cataclysmic collision. We determine that radiation pressure and subsequent collisions are the dominant determinants of the disk morphology in either case, and that Poynting-Robertson drag is comparatively insignificant.

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Position(2000): RA = 05 46 57.3408 Dec = -14 49 19.020