Clumpfind: Determining Structure in Molecular Clouds

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owlice
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Clumpfind: Determining Structure in Molecular Clouds

Post by owlice » Sat Jul 16, 2011 12:25 pm

[c]Clumpfind: Determining Structure in Molecular Clouds[/c][/b]
Abstract: We describe an automatic, objective routine for analyzing the clumpy structure in a spectral line position-position-velocity data cube. The algorithm works by first contouring the data at a multiple of the rms noise of the observations, then searches for peaks of emission which locate the clumps, and then follows them down to lower intensities. No a proiri clump profile is assumed. By creating simulated data, we test the performance of the algorithm and show that a contour map most accurately depicts internal structure at a contouring interval equal to twice the rms noise of the map. Blending of clump emission leads to small errors in mass and size determinations and in severe cases can result in a number of clumps being misidentified as a single unit, flattening the measured clump mass spectrum. The algorithm is applied to two real data sets as an example of its use. The Rosette molecular cloud is a 'typical' star-forming cloud, but in the Maddalena molecular cloud high-mass star formation is completely absent. Comparison of the two clump lists generated by the algorithm show that on a one-to-one basis the clumps in the star-forming cloud have higher peak temperatures, higher average densities, and are more gravitationally bound than in the non-star-forming cloud. Collective properties of the clumps, such as temperature-size-line-width-mass relations appear very similar, however. Contrary to the initial results reported in a previous paper (Williams & Blitz 1993), we find that the current, more thoroughly tested analysis finds no significant difference in the clump mass spectrum of the two clouds.

Credit: Williams, Jonathan P.; de Geus, Eugene J.; Blitz, Leo

Site: http://www.ifa.hawaii.edu/users/jpw/clumpfind.shtml
http://adsabs.harvard.edu/abs/1994ApJ...428..693W

Bibcode: 2011ascl.soft07014W

Preferred citation method: http://adsabs.harvard.edu/abs/1994ApJ...428..693W

ID: ascl:1107.014
Last edited by Ada Coda on Sun Nov 05, 2017 7:52 pm, edited 1 time in total.
Reason: Updated code entry.
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teuben
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Re: Clumpfind: Determining Structure in Molecular Clouds

Post by teuben » Wed Jan 23, 2013 8:55 pm

The clumpfind programs are implemented as clfind, clstats and clplot in the MIRIAD package (ascl:1106.007). There is a BIMA memo available describing the technical aspect of this program,as well as a test dataset. See http://carma.astro.umd.edu/memo/abstracts.html#56

The CPROPS package (ascl:1102.012) has been derived from clumpfind.

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