Greatest Hits, Volume 1

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)

QuickTime™ and aTIFF (Uncompressed) decompressor

are needed to see this picture.

Data from COMPLETE are

made freely available at the

Survey’s web site (take a Post-It

Pad!)

Data from COMPLETE are

made freely available at the

Survey’s web site (take a Post-It

Pad!)

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.]

Naomi RidgeNaomi Ridge

Doug JohnstoneDoug Johnstone

Michelle Borkin

Alyssa Goodman

Alyssa Goodman

“Not all measures of

column density are created

equal.”

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 log-normal, as predicted by many theories of turbulence. (Goodman, Ridge & Schnee 2005)

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Log (Equivalent AV [mag])

IRASlog normal fit to

IRAS column density

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log normal fit to 2MASS column density

(all panels)

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Implied Column Density Distributions and lognormal Fits(Perseus COMPLETE data)

Scott SchneeScott Schnee

“No measure of column density is perfect,

but we can make them

better.”We have created a new method for creating far-infrared-dust-emission-based maps of column density and temperature. The method uses near-infrared 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)

“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)

1313CO in IC348CO in IC3483-D Slicer View3-D Slicer View

(contour overlay (contour overlay shows integrated shows integrated

intensity, B&W image intensity, B&W image is K-band)is K-band)

StandardStandard(J. Williams) (J. Williams)

“CLUMPFIND” “CLUMPFIND” View of Same View of Same

RegionRegion

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.

Data Products, by Resolution

~1J,H,K images of cores (Calar Alto, CTIO)

~10 sub-mm dust emission (JCMT/SCUBA); 1.2 mm dust emission (IRAM/MAMBO,c2d)

~20N2H+ etc. (IRAM)

~4012CO, 13CO, CS, N2H+ (FCRAO); NICER JHK Extinction Maps (Calar Alto, CTIO)

~5 ISSA (IRAS): NICER JHK Extinction (2MASS

The “Coordinated Molecular Probe Line Extinction Thermal Emission Survey of Star Forming Regionsprovides 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 cores in each region.

Jaime PinedaJaime PinedaJaime PinedaJaime Pineda

Coverage in Perseus(background shows COMPLETE NICER Extinction Map, Alves et

al. 2005)

Coverage and Resolutionis similar in

Ophiuchus & Serpens…ask Jaime for details

{Johnstone, DiFrancesco & Kirk 2004}

“Cores like cities.”

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).

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)

Jonathan FosterJonathan Foster

“Cloudshine”Dark Clouds

Shine at 21st mag in J & H

“Red” Outflows & Shining Dust Outflows glowing red with excited hydrogen and a small blue reflection nebula frame L1448 in the southwest of Perseus. Ambient starlight reflects off dust density features in this small star-forming cloud, providing an unprecedented high-resolution view of its complicated structure. (frame is 15 x 15)

Internal Structure of Dust “Blobs” Revealed

This overlay of our 1-mm (MAMBO/IRAM) dust

map (contours) on our deep (Calar Alto) JHK color composite image shows how the near infrared literally highlights the edges

of dense structures within molecular clouds. (frame is 15 x 15)

Both images: J=blue, H=green; K=red

A New Way to Map the Dense

ISM with sub-arcsecResolution

[JHK data: Foster et al. 2005](mm data: Tafalla et al. 2005)

A Giant, Warm, Shell in Perseus is Poking at the Molecular Clouds from Behind

Polarization on Extinction Polarization on Dust Emission

© 2005