HD 32297
After the discovery of the extended disk of HD 32297 with near-IR
coronagraphic observations
(Schneider et al. 2005) and subsequent optical coronagraphic
observations (Kalas 2005), we imaged
the disk at 12 and 18 microns with T-ReCS at Gemini South. We find an
apparent nearly edge-on dust disk ~300 AU in diameter at both
wavelengths. (We note the independent resolution of the disk at 12
microns by Fitzgerald et al. with Michelle at the Gemini North
facility.) With a radial profile of the dust color temperatures
estimated from the images at two mid-IR wavelengths, we see that the
dust temperature stays constant out to ~80 AU. We propose that this
implies that there is not actually a substantial amount of dust
interior to this location. Thus, the temperatures determined for radii
closer to the star correspond to dust seen in projection through the
edge-on disk, such that anywhere closer to the star than 80 AU, we are
seeing the inner edge of the dust disk's cleared central
region.
Radial color temperature profile of HD 32297, as derived from 11.7
and 18.3 micron flux density measurements along the disk. This figure
is discussed in greater detail in Moerchen et al. 2007b,
as seen below.
HD32297 Article (PDF)
2007 ApJ 666, L109
Zeta Leporis
Following the initial suggestion of extended structure (Chen and
Jura 2001) and the higher-than-expected
infrared excess brightness of Zeta Lep (Rieke et al. 2005), we imaged
the A-star system with T-ReCS at Gemini South at 11 and 18 microns. The
source appears point-like at 11 microns, but through a careful
comparison at 18 microns of Zeta Lep with a point source, we find a
subarcsecond extended dust disk. The radial profile comparison suggests
that the bulk of the dust resides at 3 AU, or 3 times the Earth-Sun
distance -- the same distance as the asteroid belt in our own system.
This is the first resolved disk that is more akin to an asteroid belt
in size, rather than the much more extended Kuiper Belt analogs
previously revealed by imaging observations. We continue to investigate
how common such "small" debris disks may be.
Profiles of azimuthally averaged normalized intensity for Zeta Lep
(red diamonds) and reference PSF star (black dots); vertical lines
indicate the FWHM values of profile fits to the PSF star and Zeta Lep.
The FWHM of each nodset pair in the total integration time was also
measured to ensure the certainty of this resolution, since longer
integration times on-source (compared to the relatively short time on
the point source reference) tend to introduce smearing effects due to, e.g.,
pupil rotation and sky variations.
ZetaLep Article (PDF) 2007 ApJ 655, L109
The following are two public audience articles written on Zeta
Leporis.
Science
News Online
Sciene News ZetaLep (PDF) (Print Version)
Outreach Article
(PDF) June 2007 Gemini Focus (observatory newsletter)
The Galactic Center
In 2004, in collaboration with Dan Gezari and Eli Dwek at Goddard
SFC, we obtained high-resolution
images of the central parsec of the Galactic center over a wide range
of mid-IR wavelengths with T-ReCS at Gemini South. By having images at
many wavelengths, a line-of-sight radiative transfer code (Frank Varosi
and Eli Dwek) enables the study of not only the varying brightness
throughout this region, but also parameters such as emitting dust
optical depth, line-of-sight optical depth, and dust temperature. This
work is still in progress.
Color composite image from observations at 3.8 microns
(blue), 12.3 microns (green), and
24.5 microns
(red).
Galactic Center movie
This movie is a composite view of the GC images
taken with T-ReCS, from 4-25 microns.
GC Poster (PDF)
A poster reviewing progress on this work as of Dec.
2004, presented at the Jan. 2005 AAS
meeting in Washington, D.C.
