2014A&A...566A.145R


Query : 2014A&A...566A.145R

2014A&A...566A.145R - Astronomy and Astrophysics, volume 566A, 145-145 (2014/6-1)

The 12CO/13CO ratio in AGB stars of different chemical type. Connection to the 12C/13C ratio and the evolution along the AGB.

RAMSTEDT S. and OLOFSSON H.

Abstract (from CDS):

The aim of this paper is to investigate the evolution of the 12C/13C ratio along the AGB through the circumstellar 12CO/13CO abundance ratio. This is the first time a sample including a significant number of M- and S-type stars is analysed together with a carbon-star sample of equal size, making it possible to investigate trends among the different types and establish evolutionary effects. The circumstellar 12CO/13CO abundance ratios are estimated through a detailed radiative transfer analysis of single-dish radio line emission observations. Several different transitions have been observed for each source to ensure that a large extent of the circumstellar envelope is probed and the radiative transfer model is well constrained. The radiative transfer model is based on the Monte Carlo method and has been benchmarked against a set of similar codes. It assumes that the radiation field is non-local and solves the statistical equilibrium equations in full non-local thermodynamic equilibrium. The energy balance equation, determining the gas temperature distribution, is solved self-consistently, and the effects of thermal dust radiation (as estimated from the spectral energy distribution) are taken into account. First, the 12CO radiative transfer is solved, assuming an abundance (dependent on the chemical type of the star), to give the physical parameters of the gas, i.e. mass-loss rate, {dot}(M), gas expansion velocity, υe, and gas temperature distribution. Then, the 13CO radiative transfer is solved using the results of the 12CO model giving the 13CO abundance. Finally, the 12CO/13CO abundance ratio is calculated. The circumstellar 12CO/13CO abundance ratio differs between the three spectral types. This is consistent with what is expected from stellar evolutionary models assuming that the spectral types constitute an evolutionary sequence; however, this is the first time this has been shown observationally for a relatively large sample covering all three spectral types. The median value of the 13CO abundance in the inner circumstellar envelope is 1.6x10–5, 2.3x10–5, and 3.0x10–5 for the M-type, S-type, and carbon stars of the sample, respectively, corresponding to 12CO/13CO abundance ratios of 13, 26, and 34, respectively. The spread in the 13CO abundance, quantified by the ratio between the 90th and 10th percentile, is 4, 3, and 15 for the M-type, S-type, and carbon stars, respectively. Interestingly, the abundance ratio spread of the carbon stars is much larger than for the M- and S-type stars, even when excluding J-type carbon stars, in line with what could be expected from evolution on the AGB. We find no correlation between the isotopologue ratio and the mass-loss rate, as would be expected if both increase as the star evolves.

Abstract Copyright:

Journal keyword(s): stars: AGB and post-AGB - circumstellar matter - stars: evolution

Simbad objects: 56

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Number of rows : 56
N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2023
#notes
1 V* KU And Mi* 00 06 52.7571912336 +43 05 02.363566416       14.12   M10 82 0
2 V* T Cet S* 00 21 46.2731778 -20 03 28.884826   7.32 5.74     M5-6Se 144 0
3 V* R And S* 00 24 01.9457463096 +38 34 37.370144352 10.61 9.36 7.39 4.45 2.30 S5-7/4-5e 346 0
4 IRC +10011 OH* 01 06 25.9879717848 +12 35 52.896392052   20.7   18.26 14.01 M8 414 0
5 V* S Cas S* 01 19 41.9796588720 +72 36 40.850697240           S3-54-8 120 1
6 V* R Scl C* 01 26 58.0939182720 -32 32 35.439234828 17.26 9.59 5.72 3.69 2.30 C-N5+ 322 0
7 CIT 4 OH* 02 35 44.6711866704 +65 08 58.922331000       11.78   M9.5III 61 0
8 LEE 259 C* 03 26 29.5037418864 +47 31 48.551540844       10.70   N 173 0
9 V* IK Tau OH* 03 53 28.8924743304 +11 24 21.895183368 16.99 17.03 13.39 7.29 3.20 M7-11 617 0
10 V* R Dor AB* 04 36 45.59127 -62 04 37.7974 7.84 6.98 5.40 2.71 -0.44 M8III:e 330 0
11 V* TV Aur S* 04 58 08.2129478880 +48 33 37.067023224   11.47 9.32     S5/6 60 0
12 V* R Lep C* 04 59 36.3486921120 -14 48 22.502479140 15.06 13.51 7.76 4.90 3.42 C7,6e 329 0
13 V* TX Cam Mi* 05 00 51.1627935408 +56 10 54.041462220       14.02   M9-9.5 345 0
14 V* W Ori C* 05 05 23.7190712856 +01 10 39.454639032 16.36 9.52 6.10 3.83 2.35 C-N5 283 0
15 IRC +50137 OH* 05 11 19.4506093584 +52 52 33.235824324           M10 173 0
16 IRC +70066 Mi* 05 46 44.3288397432 +69 58 24.422766636           M9.5 83 0
17 V* AP Lyn Mi* 06 34 33.3992529912 +60 56 27.812508252   12.51 11.15 11.90   M7+ 113 0
18 V* UU Aur C* 06 36 32.8371036984 +38 26 43.819021608   7.89 5.25 3.31 1.90 C-N5- 299 1
19 V* GX Mon OH* 06 52 47.0423680104 +08 25 19.097958468   15.40 15.46 10.56   M9 116 0
20 V* R Gem S* 07 07 21.2705134872 +22 42 12.747215448 11.74 9.89 7.68 3.75 0.39 S3.5-6.5/6e 194 0
21 V* AA Cam S* 07 14 52.0696706376 +68 48 15.359511204   9.23 7.79     M5S 68 0
22 V* Y Lyn S* 07 28 11.6165714400 +45 59 26.229456564 9.88 8.71 6.98 4.25 1.96 M6S 138 0
23 V* X Cnc C* 08 55 22.8819374952 +17 13 52.583009880   9.63 6.40 4.29 2.90 C-N4.5 264 1
24 V* R Leo Mi* 09 47 33.4839808805 +11 25 43.823283729 9.22 8.94 7.53 3.39 0.12 M7-9e 895 1
25 IRC +10216 C* 09 47 57.40632 +13 16 43.5648           C9,5e 2275 0
26 V* RW LMi C* 10 16 02.2777043904 +30 34 19.045098516       15.27   C4,3e 389 0
27 V* U Hya C* 10 37 33.2729535 -13 23 04.352923 13.29 7.51 4.82 3.05 1.78 C-N5 293 0
28 V* Y CVn C* 12 45 07.8260815656 +45 26 24.926308404 14.03 7.41 4.87 3.12 1.74 C-N5 471 0
29 V* RY Dra C* 12 56 25.9112361600 +65 59 39.811665876 15.56 9.44 6.34 4.34 2.91 C-N3III: 233 0
30 V* RT Vir AB* 13 02 37.9814644272 +05 11 08.362884984 10.07 9.07 7.41     M8III 310 0
31 V* SW Vir AB* 13 14 04.3830437280 -02 48 25.130666916 9.24 8.52 6.85     M7III: 257 0
32 V* TT Cen S* 13 19 35.0158771776 -60 46 46.295369400     11.50     SC5:/8+ 53 0
33 V* W Hya Mi* 13 49 02.0018313132 -28 22 03.532006894   8.97 7.70     M7.5-9e 628 0
34 V* RX Boo AB* 14 24 11.6253191184 +25 42 13.394221596   9.23 8.60     M7.5-M8 432 0
35 WOS 48 C* 15 23 05.0730770544 -51 25 58.762691652   17.85 16.66 14.51 10.18 C 129 1
36 V* ST Her S* 15 50 46.6232210160 +48 28 58.850853780   9.09 7.75     M6S-M7SIII: 160 0
37 V* RT Sco S* 17 03 32.5593710616 -36 55 13.694502792     7.00     S7,2 71 0
38 V* T Lyr C* 18 32 20.0767626264 +36 59 55.635218376   12.74 7.84 7.30   C-J4:p 178 1
39 IRC +10365 OH* 18 37 19.2583829328 +10 25 42.492195300       9.97   M9 144 0
40 IRC -30398 AB* 18 59 13.8469390704 -29 50 20.513684796   14.35 14.19 15.46   M9 46 0
41 V* V Aql C* 19 04 24.1544971752 -05 41 05.444321424   11.09 6.90     C-N5 210 0
42 V* S Lyr S* 19 13 11.8046954880 +26 00 27.853438788       11.35   SC 73 0
43 V* W Aql S* 19 15 23.3572741560 -07 02 50.333886492   12.72 10.14 10.21   S6/6e 223 0
44 V* T Sgr S* 19 16 14.4361485576 -16 58 17.076889992   11.81 7.10     S4.5-6/5.5-6e 131 0
45 V* UX Dra C* 19 21 35.5182299784 +76 33 34.557161688   8.81 5.94     C-N5 196 0
46 V* EP Vul S* 19 33 17.8371536064 +23 39 19.506133512   15.65 11.00 7.79   S6.5/5 56 1
47 V* AQ Sgr C* 19 34 18.9945475487 -16 22 27.048908541 13.85 9.48 6.70     C-N5 117 0
48 V* R Cyg S* 19 36 49.3579856496 +50 11 59.727536988   9.96 6.10 8.96 6.447 S4-8/6e 270 1
49 * chi Cyg S* 19 50 33.9213430345 +32 54 50.575531294 7.02 6.06 4.24 1.81 -0.01 S6-9/1-2e 683 0
50 V* DK Vul S* 20 06 33.9524469312 +24 26 00.133136196   12.76 10.99     S4,2 37 0
51 IRC -10529 OH* 20 10 27.8731455576 -06 16 13.758742596         15.49 M: 137 0
52 V* V Cyg C* 20 41 18.2676815496 +48 08 28.810980420   14.05 7.70 6.67   C7,4eJ 302 0
53 V* RV Aqr C* 21 05 51.7376905368 -00 12 42.121057536     11.5     C6,3e 102 0
54 RAFGL 3068 C* 23 19 12.60744 +17 11 33.1332           C 267 0
55 IRC +40540 C* 23 34 27.5185864392 +43 33 01.323347256     15.12     C8,3.5eJ 176 0
56 V* R Cas Mi* 23 58 24.8682785040 +51 23 19.713029388 6.71 6.63 4.80     M6.5-9e 694 0

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2023.02.01-07:08:43

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