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Table 8

Line intensity ratios IMB(12CO)/IMB(13CO) for the sample stars give first order estimates of their isotope abundance ratio 12C/13C.

IMB(12CO)/IMB(13CO) M09
Target 2−1 3−2 4−3 6−5 12C/13C 12C/13C

O-rich
RX Boo 12.0 10.5 9.8
EP Aqr 9.5 6.2 12.3 8.1
T Cet 11.5 14.4 11.2
o Cet 12.2 8.0 - 3.3 6.8
IK Tau 8.7 6.8 6.7 10
TX Cam 17.1 13.3 13.2 31
NV Aur 5.4 4.7
R Hya 6.1 5.3
R Cas 20.8 12.4 14.4
WX Psc 6.2 5.5 - 5.1
AFGL 5379 8.3 7.2
OH 44.8-2.3 3.8 7.6 4.9
NML Cyg 10.0 8.7 13
α Ori 6.5 - 5.7 8
VY CMa 19.7 14.3 14.8 25, 33, 46
VX Sgr 22.0 - 19.2
IRC +10420 9.0 9.7 8.1 14
AFGL 2343 3.8 3.3
S-type
π1 Gru 35.3 30.7
W Aql 16.1 12.8 12.6
χ Cyg 16.2 14.1 33
C-rich
V Hya 30.7 26.7 71, 72
R Scl 10.6 9.2
II Lup 4.6 4.0
IRC +20370 8.1 7.1
V Cyg 13.8 12.0
LL Peg 4.2 3.6

Notes. An absolute flux error of 20% for transitions J = 2−1, 3−2, and 4−3 gives an error of 28% on the respective line intensity ratios. For J = 6−5, the absolute flux error is of the order of 30%, so the error on the line intensity ratio is about 42%. The 12C/13C-value listed in the second to last column is the mean line intensity ratio, corrected with a factor 0.87 for the difference in line strengths (Eq. (15)). The last column (M09) lists the values derived by Milam et al. (2009) from CO data.

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