Tightening the (Asteroid) Belt around Zeta Leporis (Forwarded)

Gemini Observatory
Hilo, Hawaii

19 January 2007

Tightening the (Asteroid) Belt around Zeta Leporis

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.

The team, lead by University of Florida Ph.D. student Margaret Moerchen
and her advisor Charles Telesco, observed Zeta Leporis as part of a
broader research program centered on the search for resolved circumstellar
disks. The Gemini observations supplement previous observations made in
2001 that placed a strong limit on the size of the disk, but did not
resolve the dust emission from that of the central star.

The team using Gemini, which included UF researchers Chris Packham and Tom
Kehoe, found that the majority of the dust grains in the system reside
within 3 AU from the central star, exactly where the asteroids orbit in
our own Solar system. The fact that the dust emission comes from so close
to the central star makes this type of observation very difficult to carry
out. It is the combination of the excellent mid-IR performance of Gemini
South and the ingenuity of the researchers that makes this type of
discovery possible.

The result will appear in an upcoming issue of ApJL and was featured in
the January 8, 2007 issue of ScienceNews. In the ScienceNews article
Charles Beichman of NASA's JPL says, "The high angular resolution
measurement of the Zeta Leporis disk is a very exciting result. We now
have direct evidence for structures around other stars that are directly
analogous to the asteroid belt in our solar system."

A pre-print of this paper can be found on astro-ph at
http://arxiv.org/abs/astro-ph/0612550

Gemini is an international partnership managed by the Association of
Universities for Research in Astronomy under a cooperative agreement with
the National Science Foundation.

The Gemini Observatory provides the astronomical communities in each
partner country with state-of-the-art astronomical facilities that
allocate observing time in proportion to each country's contribution. in
addition to financial support, each country also contributes significant
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(NSF), the UK Particle Physics and Astronomy Research Council (PPARC), the
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investigación Cientifica y Tecnológica (CONiCYT), the Australian Research
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managed by the Association of Universities for Research in Astronomy, inc.
(AURA) under a cooperative agreement with the NSF. The NSF also serves as
the executive agency for the international partnership.

[NOTE: Images supporting this release are available at
http://www.gemini.edu/index.php?opti...sk=view&id=222 ]