Core Selection
By Elijah Bernstein-Cooper, September 27, 2015, 0 comments.

Core Selection

One essential step in the paper I need to address is the selection of the cores with which we will test the steady state models. Currently I just chose regions based on Lombardi et al. (2010) regions. I split several of their identified regions into multiple regions because I found multiple $A_V$ peaks within some of their identified regions.

One perhaps more justifiable method would be to use sources identified by the Planck Cold Clump catalogue in Planck Collaboration 2011. The catalogue includes 10,000 sources which stand out against a nearby warm environment. The table includes locations, SNR, sizes, distances, masses, and more statistics for each identified core. There are on order of 100 core clumps found in each of the three clouds.

My first idea for identifying core regions in our sample was to include the top ten or so cold clumps with the highest SNR. This would correspond to the cores with the most drastic temperature difference from the surrounding environment, thus likely have the most developed molecular components. If we wanted to test the steady-state models against a variety of maturity, the SNR-selected sample would bias the sample towards more more mature cores. See Figure 1 for the distribution of the top 15 SNR cold clumps for each cloud.

To see the statistics are available in the Planck Cold Clump Catalogue, visit the table description. After choosing individual cores based on some criteria with this catalogue I will manually draw the core regions to include diffuse $A_V$ lines of sight.

Figure 1

$A_V$ map overplotted with fifteen highest SNR cold clumps in each cloud.

$\phi_{\rm CNM}$ Map

Below is a plot of the $\phi_{\rm CNM}$ parameter and $\alpha G$ parameter as a function of position.

Figure 2

$A_V$ contour plot of three clouds. Overplotted are $\phi_{\rm CNM}$ values for each core in the top panel and $\alpha G$ values in the bottom panel. The contours are at 2, 4, 8, and 16 mag. Neither parameter seems to show a clear trend as a function of position.