ppt

Report
Alyssa A. Goodman, Principal Investigator (CfA), João Alves (ESO, Germany),
Héctor Arce (AMNH), Michelle Borkin (Harvard College), Paola Caselli (Arcetri,
Italy), James DiFrancesco (NRC-HIA, Canada), Jonathan Foster (CfA, PhD
Student),
Mark Heyer (UMASS/FCRAO), Helen Kirk (U. Victoria, Canada), Di Li (CfA/JPL),
Doug Johnstone (NRC-HIA, U. Victoria, Canada), Jaime Pineda (CfA, PhD
Student),
Naomi Ridge (CfA), Scott Schnee (CfA, PhD student), Mario Tafalla (OAN, Spain)
Greatest Hits, Volume 1
The “Coordinated Molecular Probe Line Extinction Thermal Emission Survey of Star Forming
Regions
provides spectral-line, dust emission and dust absorption maps of the Perseus, Ophiuchus,
and Serpens regions being observed by Spitzer in the c2d Legacy Survey. “Phase 1” of
COMPLETE, now nearly done, provides fully-sampled maps at arcmin resolution; “Phase 2,”
now well-underway, includes higher-resolution mapping of the most prominent star-forming
Data Products, by Resolution
cores in eachCoverage
region.
in Perseus
(background shows COMPLETE NICER Extinction Map, Alves et al.
2005)
Data from
COMPLETE are
made freely available
at the Survey’s web
site
(take a Post-It Pad!)
~1
J,H,K images of cores (Calar Alto, CTIO)
~10
sub-mm dust emission (JCMT/SCUBA);
1.2 mm dust emission
(IRAM/MAMBO,c2d)
Coverage and Resolution
is similar in
Ophiuchus & Serpens…
ask Jaime for details
QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture.
~20
N2H+ etc. (IRAM)
~40
12CO, 13CO, CS, N H+ (FCRAO);
2
NICER JHK Extinction Maps (Calar Alto,
CTIO)
~5
ISSA (IRAS): NICER JHK Extinction
(2MASS
“No measure
of column
density is
perfect, but
we can make
them better.”
Implied Column Density Distributions and lognormal Fits
(Perseus COMPLETE data)
140
log normal fit to
2MASS column density
(all panels)
120
100
Number
“Not all measures
of column density
are created equal.”
Jaime Pineda
80
60
40
20
2M ASS/NICER
0
140
Alyssa Goodman
120
Number
100
80
60
40
13
CO
20
0
140
120
100
Number
Intercomparison of column density maps based on 13CO
integrated intensity, far-infrared dust emission, and near-infrared
extinction mapping reveals that: extinction mapping is most
intrinsically accurate;, far-infrared emission maps can be
corrected to nearly match extinction maps (see panel at right);
but 13CO maps cannot be corrected to represent column
density faithfully. The 13CO emission is subject to both
opacity and depletion effects at high column densities, and is
sub-thermally excited at low column density, leading to column
density maps that are impressionistically, but not quantitatively,
accurate. The near-infrared extinction maps show that, at least
over the 10-square pc area of Perseus mapped in COMPLETE
(see panel above), the distribution of column density is lognormal, as predicted by many theories of turbulence.
(Goodman, Ridge & Schnee 2005)
80
60
40
IRAS
log normal fit to
IRAS column density
20
0
-1.0
-0.5
0.0
0.5
1.0
Scott Schnee
Log (Equiv alent A
V [ mag] )
We have created a new method for creating farinfrared-dust-emission-based maps of column
density and temperature. The method uses nearinfrared maps of dust extinction to calibrate
emission-based column density maps, thus also
allowing for the most accurate derivation of dust
color temperature. Note (above) that even after this
“optimization,” however, the point-to-point match in
extinction measures still has very significant
scatter. (Schnee et al. 2005, submitted)
“Cloudshine”
A Giant, Warm, Shell in Perseus is Poking at the Molecular Clouds from Behind
Dark Clouds
Shine at 21st mag
in J & H
Even though we often think of Perseus as a long chain of dark
clouds (e.g. as it appears in CO maps), its dust emission is
dominated by a giant shell, filled with H emission. The
“finger”
of extinction bifurcating the H emission clearly indicates that
the shell is behind the molecular clouds. Spectral-line and 8
m (MSX) data, not shown here, show that the shell &
molecular gas are interacting on the “backside” of the clouds.
Appreciation of the shell’s existence allows understanding of
the apparently bi-modal magnetic field distribution, with one
component associated with the warm ring (blue vectors) and
the other with the cool clouds (red vectors).
(Ridge et al. 2005, submitted)
Polarization on Extinction
Polarization on Dust Emission
Naomi Ridge
“Cores like
cities.”
Doug Johnstone
COMPLETE SCUBA Mapping of Ophiuchus 20 times more extensive than
earlier work (and only twice as shallow) showed that nearly all cores are
found above a threshold of roughly AV=15 mag. (Notice how “empty” the
850 m map looks, above.)
Modeling the clumps as Bonnor-Ebert spheres shows the lack of objects at
low extinction is not due to detection sensitivity (see Fig. 1, at left).
{Johnstone, DiFrancesco & Kirk 2004}
Jonathan Foster
A New Way to
“Red” Outflows & Shining Dust
Internal Structure of Dust “Blobs” Revealed
Map
the
Dense
Outflows glowing red with excited hydrogen and a
This overlay of our 1-mm (MAMBO/IRAM) dust
small blue reflection nebula frame L1448 in the ISM with sub-arcsec map (contours) on our deep (Calar Alto) JHK
southwest of Perseus. Ambient starlight reflects off
color composite image shows how the near
Resolution
dust density features in this small star-forming
infrared literally highlights the edges of dense
cloud, providing an unprecedented high-resolution [JHK data: Foster et al. 2005] structures within molecular clouds. (frame is 15
view of its complicated structure. (frame is 15 x (mm data: Tafalla et al. 2005)
x 15)
15)
Both images: J=blue, H=green; K=red
“Astronomical Medicine”
In our quest to make the large (e.g. nearly
200,000 spectra in one Perseus map alone)
COMPLETE data set intelligible to humans,
we have, in collaboration with researchers
at the Harvard-affiliated Brigham and
Women’s Hospital in Boston, used the
medical imaging tool known as “3-D Slicer”
to interactively visualize spectral-line data
cubes. This coming Summer, we will also
use the “segmentation” features of 3-D
Slicer to develop a new clumpfinding
algorithm that will allow for the identification
and characterization of hierarchical features,
rather than requiring a “space-filling”
approach like the widely-used routine
“CLUMPFIND” (by J. Williams). It is our
expectation that the new clumpfinding
procedure will be able to automatically
identify more meaningful (e.g. bound)
clumps, and will alter our understanding of
the so-called
“clump mass function” in molecular clouds.
(Borkin et al. 2005, astro-ph; Goodman et
al. 2005, for Nature)
This work is also a pilot
project of a new
“Initiative in Innovative
Computing” at Harvard.
Ask Alyssa Goodman
for more information,
and for a 3-D Slicer
Demo.
Michelle Borkin
13CO
in IC348
3-D Slicer View
(contour overlay shows
integrated intensity, B&W
image is K-band)
Standard
(J. Williams)
“CLUMPFIND”
View of Same
Region
Coming Attractions: “A COMPLETE Overview” (Ridge et al.); “All the Outflows in Perseus” (Arce et al.); COMPLETE Extinction Mapping (Alves et al.);
Atomic Gas in the COMPLETE Molecular Clouds” (Li et al.); “The Real Rho-Oph Cluster, and Ring” (Li et al.); “Angular Momentum & Bulk Motion in Star-Forming Regions” (Schnee et al.
“Astronomical Medicine” (Goodman et al.); “Cloudshine” (Foster et al.); “Clumpfinding in Molecular Clouds” (Pineda et al.); Triggered Star Formation in Perseus [Kirk et al.]
© 2005

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