Abundances of HCN from Shimajiri + 2015

Ok, so one thing I'm working on today is compiling numbers on the molecular column density & fractional abundance of HCN towards the intermediate-mass protostar OMC-2 FIR 4. It's the subject of a lot of study - it's a very bright prominent infrared-revealed protostar in the Orion region, and is the prototype intermediate mass protostar that the CHESS Herschel program selected.

Here's the paper I'm working with:
http://adsabs.harvard.edu/abs/2015ApJS..221...31S
Spectral-line Survey at Millimeter and Submillimeter Wavelengths toward an Outflow-shocked Region, OMC 2-FIR 4

Observations:

Nobeyama 45m and Atacama submillimeter telescope experiment (ASTE)
82–106GHz and 335–355GHz

This means they can see the H13CN and HC15N J=1–0 and 4–3 transitions, from which they make rotation diagrams.

Here's the rotation diagrams for H13CN and HC15N towards this source.

 

The difference between Tables 10 and 11:
Table 10 assumes FIR 4 is 19'' in size. Table 11 assumes that the emission filling factor is 1, with a beam of 15'' to 19.7''.

Table 10 gives the following numbers. N_mol is given in cm^-2. X_mol is given relative to H₂, as estimated via 1.1mm dust continuum measurements under two different temperature assumptions.

H¹³CN

N_mol = 6.4 x 10¹³

X_mol = 1.4 – 6.4 x 10^-10

HC¹⁵N

N_mol = 2.9 x 10¹²

X_mol = 0.6 – 2.9 x 10^-11

Table 11 gives the following numbers

H¹³CN

N_mol = 3.4 x 10¹³

X_mol = 7.6 – 34 x 10^-11

HC¹⁵N

N_mol = 1.5 x 10¹²

X_mol = 0.3 – 1.5 x 10^-11

If I use averaged ISM isotopic ratios to scale these X values to what is expected for HCN, they look like this:

Table 10

H¹³CN - SCALED to HCN

N_mol = 4.4 x 10¹⁵

X_mol = 9.7 – 44 x 10^-9

HC¹⁵N - SCALED to HCN

N_mol = 1.1 x 10¹⁵

X_mol = 2.3 – 11 x 10^-9

Table 11 gives the following numbers

H¹³CN - SCALED to HCN

N_mol = 2.3 x 10¹⁵

X_mol = 5.2 – 23 x 10^-9

HC¹⁵N - SCALED to HCN

N_mol = 5.8 x 10¹⁴

X_mol = 1.2 – 5.8 x 10^-9