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Research
Here is a brief summary of
my research activities past and present, with links to some of the relevant
papers.
NOTE: this page is largely out of date. To get an
idea of my current research, check out my
recent Publications.
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Young
Circumstellar Debris Disks
The evolution from primordial disks of gas
and dust to debris disks is intimately associated with the formation
of planetesimals and planets. However, relatively little is known
about the nature of this transition. We are using sensitive IR and
sub-mm observations of young stars near Earth to better understand
the crucial 10-100 Myr epoch. A highlight from this work is the
discovery and characterization of the disk around the young M dwarf
AU Microscopii, a low-mass coeval version of the archetypical debris
disk system beta Pictoris. |
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| Adaptive
Optics Imaging of Extrasolar Planetary Systems
Little is known about the substellar constituents
in the outer regions of other solar systems. Exploring this domain
calls out for direct imaging, as radial velocity and astrometric
surveys of these regions are hampered by the very long orbital periods.
Adaptive optics (AO) systems on the largest ground-based telescopes
(Keck, Gemini, and Subaru) provides a powerful new capability towards
direct imging of brown dwarfs and planets around other stars. AO
systems correct for the blurring of astronomical images due to the
atmospheric turbulence, leading to angular resolution many times
better than even the Hubble Space Telescope.  I
am leading the the
new Gemini Planet-Finding campaign, which will be the largest
ground-based program ever devoted to direct imaging of exoplanets. |
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Origins
of Brown Dwarfs
Brown dwarfs are now being found in abundance, but their origins
remain a mystery. Current and future deep field surveys can place
the old field brown dwarf population in the context of the stellar
components of galactic structure. Another potential insight
is whether these objects possess circumstellar disks in their youth.
We have found that disks around young brown dwarfs are just as common
as disks around the higher mass stars. Finally, we are using
new laser guide
star adaptive optics systems on large 8-10m telescopes to study
brown dwarf binaries with near diffraction-limited imaging in the
IR. |
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Surface
Brightness Fluctuations
Surface brightness fluctuations (SBFs) of early-type
galaxies provide a unique tool for cosmological distance measurements
and stellar population studies. We have been pursuing near-IR SBFs
measurements using data from a variety ground and space-based telescopes,
from as large as the 10-meter Keck Telescope to as small as the
1.3-meter 2MASS telescopes. Our observational efforts have been
closely coupled with testing and employing the latest stellar population
synthesis models. |
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Formation
of Elliptical Galaxies
Elliptical galaxies are key laboratories for understanding galaxy
formation and evolution: their high luminosities mean they can be
detected at high redshifts (if they exist), and their star formation
histories are believed to be simple compared to other galaxies.
We have used multi-wavelength measurements of surface brightness
fluctuations as a novel probe of recent star formation in early-type
cluster galaxies in the local Universe. At high redshift (z~1),
spectroscopic studies of extremely red galaxies (EROs) find that
some EROs are spatially concentrated, perhaps indicative of young
massive clusters. |
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Go back to my
home page.
Last modified on
May 11, 2006
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