FIGURE 2. Comparison of the 'dendrogram' and 'CLUMPFIND' feature-identification algorithms as applied to 13CO emission from the L1448 region of Perseus.
From the following article:
A role for self-gravity at multiple length scales in the process of star formation
Alyssa A. Goodman, Erik W. Rosolowsky, Michelle A. Borkin, Jonathan B. Foster, Michael Halle, Jens Kauffmann & Jaime E. Pineda
Nature 457, 63-66(1 January 2009)
doi:10.1038/nature07609
a, 3D visualization of the surfaces indicated by colours in the dendrogram shown in c. Purple illustrates the smallest scale self-gravitating structures in the region corresponding to the leaves of the dendrogram; pink shows the smallest surfaces that contain distinct self-gravitating leaves within them; and green corresponds to the surface in the data cube containing all the significant emission. Dendrogram branches corresponding to self-gravitating objects have been highlighted in yellow over the range of Tmb (main-beam temperature) test-level values for which the virial parameter is less than 2. The x–y locations of the four 'self-gravitating' leaves labelled with billiard balls are the same as those shown in Fig. 1. The 3D visualizations show position–position–velocity (p–p–v) space. RA, right ascension; dec., declination. For comparison with the ability of dendrograms (c) to track hierarchical structure, d shows a pseudo-dendrogram of the CLUMPFIND segmentation (b), with the same four labels used in Fig. 1 and in a. As 'clumps' are not allowed to belong to larger structures, each pseudo-branch in d is simply a series of lines connecting the maximum emission value in each clump to the threshold value. A very large number of clumps appears in b because of the sensitivity of CLUMPFIND to noise and small-scale structure in the data. In the online PDF version, the 3D cubes (a and b) can be rotated to any orientation, and surfaces can be turned on and off (interaction requires Adobe Acrobat version 7.0.8 or higher). In the printed version, the front face of each 3D cube (the 'home' view in the interactive online version) corresponds exactly to the patch of sky shown in Fig. 1, and velocity with respect to the Local Standard of Rest increases from front (-0.5 km s-1) to back (8 km s-1).
Download file
If the slide opens in your browser, select "File > Save As" to save it.
Download Power Point slide (574K)Slides may be downloaded for educational use, according to the terms described in Nature Publishing Group's licensing policy.
BACK TO ARTICLE