2022A&A...666A..69J


Query : 2022A&A...666A..69J

2022A&A...666A..69J - Astronomy and Astrophysics, volume 666A, 69 (2022/10-1)

Vibrationally excited HCN transitions in circumstellar envelopes of carbon-rich AGB stars.

JESTE M., GONG Y., WONG K.T., MENTEN K.M., KAMINSKI T. and WYROWSKI F.

Abstract (from CDS):


Context. The most abundant molecule after H2 and CO in the circumstellar envelopes (CSEs) of carbon-rich asymptotic giant branch (AGB) stars is HCN. Its rotational lines within vibrationally excited states are exceptional tracers of the innermost region of carbon-rich CSEs.
Aims. We aim to constrain the physical conditions of CSEs of carbon-rich stars using thermal lines of the HCN molecule. Additionally, we also search for new HCN masers and probe the temporal variations for HCN masers, which should shed light on their pumping mechanisms.
Methods. We observed 16 carbon-rich AGB stars in various HCN rotational transitions, within the ground and 12 vibrationally excited states, with the Atacama Pathfinder Experiment (APEX) 12-metre sub-millimetre telescope.
Results. We detect 68 vibrationally excited HCN lines from 13 carbon-rich stars, including 39 thermal transitions and 29 maser lines, suggesting that vibrationally excited HCN lines are ubiquitous in carbon-rich stars. Population diagrams constructed for two objects from the sample, for thermal transitions from different vibrationally excited states, give excitation temperatures around 800-900 K, confirming that they arise from the hot innermost regions of CSEs (i.e. r <20 R*). Among the detected masers, 23 are newly detected, and the results expand the total number of known HCN masers lines towards carbon-rich stars by 47%. In particular, the J = 2-1 (0, 3le, 0), J = 3-2 (0, 2, 0), and J = 4-3 (0, 11f, 0) masers are detected in an astronomical source for the first time. Our observations confirm temporal variations of the 2-1 (0, 11e, 0) maser on a timescale of a few years. Our analysis of the data suggests that all detected HCN masers are unsaturated. A gas kinetic temperature of ≳700 K and an H2 number density of >108 cm–3 are required to excite the HCN masers. In some ways, HCN masers in carbon-rich stars might be regarded as an analogy of SiO masers in oxygen-rich stars.

Abstract Copyright: © M. Jeste et al. 2022

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

Simbad objects: 39

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Number of rows : 39
N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2024
#notes
1 V* R Scl C* 01 26 58.0939182720 -32 32 35.439234828 17.26 9.59 5.72 3.69 2.30 C-N5+ 332 0
2 V* R For C* 02 29 15.3077617632 -26 05 55.646585700   12.94 7.50 8.01   C4,3e 196 0
3 LEE 259 C* 03 26 29.5037418864 +47 31 48.551540844       10.70   N 175 0
4 RAFGL 618 pA* 04 42 53.6242032600 +36 06 53.400902220   16.32   12.59   C-rich 1002 0
5 V* R Lep C* 04 59 36.3486921120 -14 48 22.502479140 15.06 13.51 7.76 4.90 3.42 C7,6e 339 0
6 V* W Ori C* 05 05 23.7190712856 +01 10 39.454639032 16.36 9.52 6.10 3.83 2.35 C-N5 287 0
7 V* S Aur C* 05 27 07.4585545416 +34 08 58.849073880   13.48 8.20 9.61   C-N5+ 129 0
8 V* Y Tau C* 05 45 39.4101366456 +20 41 42.148590324 15.71 9.90 6.90 4.69 3.19 C-N5- 224 1
9 * alf Ori s*r 05 55 10.30536 +07 24 25.4304 4.38 2.27 0.42 -1.17 -2.45 M1-M2Ia-Iab 1673 0
10 V* TU Gem C* 06 10 53.1027504240 +26 00 53.311175640   10.688 8.694 7.400   C-N5+ 118 0
11 V* V636 Mon C* 06 25 01.4305200360 -09 07 15.963301164       11.78 8.83 C-N5 57 0
12 V* UU Aur C* 06 36 32.8371036984 +38 26 43.819021608   7.89 5.25 3.31 1.90 C-N5- 304 1
13 V* R Vol C* 07 05 36.2081474688 -73 00 52.034502960   14.24 8.70     Ce 85 0
14 V* VY CMa s*r 07 22 58.3261352189 -25 46 03.194390594 12.01 10.068 8.691 7.938   M5Iae 1104 0
15 V* AL Vol RR* 08 16 09.4380163272 -66 44 47.895677412     12.36   11.94 ~ 9 0
16 RAFGL 5254 C* 09 13 53.9370704592 -24 51 25.217250948           C-rich 50 0
17 IRC +10216 C* 09 47 57.40632 +13 16 43.5648           C9,5e 2344 0
18 V* X Vel C* 09 55 26.1116280096 -41 35 12.779975508   10.29 10.30 7.13 8.80 C-N3 73 0
19 V* RW LMi C* 10 16 02.2777043904 +30 34 19.045098516       15.27   C4,3e 396 0
20 V* V Hya C* 10 51 37.2615873024 -21 15 00.333928044   12.23 6.80 7.42   C-N:6 366 0
21 V* Y CVn C* 12 45 07.8260815656 +45 26 24.926308404 14.03 7.41 4.87 3.12 1.74 C-N5 477 0
22 RAFGL 4211 C* 15 11 41.4444649944 -48 19 58.949705172           C-rich 53 0
23 V* X TrA C* 15 14 19.1755012584 -70 04 46.113298104 15.88 9.19 5.81     C5,5 120 0
24 WOS 48 C* 15 23 05.0730770544 -51 25 58.762691652   17.85 16.66 14.51 10.18 C 134 1
25 V* T Dra C* 17 56 23.3288487384 +58 13 06.783372804   18.08 7.20 9.39   C6,2e 191 0
26 RAFGL 2047 C* 18 01 06.4659268968 -17 44 22.798921308         12.28 C-rich 31 0
27 V* FX Ser C* 18 06 50.2066800624 -09 41 16.576025784     14.80 15.62 11.20 C 70 0
28 IRC +20370 C* 18 41 54.5501446200 +17 41 08.425834728       13.56   C7,3e 118 0
29 V* V Aql C* 19 04 24.1544971752 -05 41 05.444321424   11.09 6.90     C-N5 215 0
30 IRC +30374 C* 19 34 10.0570246440 +28 04 08.361228288       16.22   C 79 0
31 V* AQ Sgr C* 19 34 18.9945475487 -16 22 27.048908541 13.85 9.48 6.70     C-N5 119 0
32 RAFGL 2477 S* 19 56 48.4423076904 +30 44 02.604494580   17.9 14.8 14.1   M6SIII 55 1
33 RAFGL 2513 C* 20 09 14.2555901784 +31 25 44.830603344           C-rich 49 0
34 V* V Cyg C* 20 41 18.2676815496 +48 08 28.810980420   14.05 7.70 6.67   C7,4eJ 306 0
35 V* V1610 Cyg pA* 21 02 18.27 +36 41 37.0           F5Iae 873 1
36 V* RV Aqr C* 21 05 51.7376905368 -00 12 42.121057536     11.5     C6,3e 107 0
37 V* Y Pav C* 21 24 16.7499375384 -69 44 01.960245204 12.63 9.23 6.41     C7,3 87 0
38 V* S Cep C* 21 35 12.8233100592 +78 37 28.185141792   12.13 7.40     C7,3e 261 0
39 RAFGL 3068 C* 23 19 12.60744 +17 11 33.1332           C 270 0

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