2020A&A...640A.133R


C.D.S. - SIMBAD4 rel 1.7 - 2020.10.26CET14:46:01

2020A&A...640A.133R - Astronomy and Astrophysics, volume 640A, 133-133 (2020/8-1)

DEATHSTAR: Nearby AGB stars with the Atacama Compact Array. I. CO envelope sizes and asymmetries: A new hope for accurate mass-loss-rate estimates.

RAMSTEDT S., VLEMMINGS W.H.T., DOAN L., DANILOVICH T., LINDQVIST M., SABERI M., OLOFSSON H., DE BECK E., GROENEWEGEN M.A.T., HOFNER S., KASTNER J.H., KERSCHBAUM F., KHOURI T., MAERCKER M., MONTEZ R., QUINTANA-LACACI G., SAHAI R., TAFOYA D. and ZIJLSTRA A.

Abstract (from CDS):


Context. This is the first publication from the DEATHSTAR project. The overall goal of the project is to reduce the uncertainties of the observational estimates of mass-loss rates from evolved stars on the Asymptotic Giant Branch (AGB).Aim. The aim in this first publication is to constrain the sizes of the 12CO emitting region from the circumstellar envelopes around 42 mostly southern AGB stars, of which 21 are M-type and 21 are C-type, using the Atacama Compact Array (ACA) at the Atacama Large Millimeter/submillimeter Array. The symmetry of the outflows is also investigated.
Methods. Line emission from 12CO J=2-1 and 3-2 from all of the sources were mapped using the ACA. In this initial analysis, the emission distribution was fit to a Gaussian distribution in the uv-plane. A detailed radiative transfer analysis will be presented in a future publication. The major and minor axis of the best-fit Gaussian at the line center velocity of the 12CO J=2-1 emission gives a first indication of the size of the emitting region. Furthermore, the fitting results, such as the Gaussian major and minor axis, center position, and the goodness of fit across both lines, constrain the symmetry of the emission distribution. For a subsample of sources, the measured emission distribution is compared to predictions from previous best-fit radiative transfer modeling results.
Results. We find that the CO envelope sizes are, in general, larger for C-type than for M-type AGB stars, which is as expected if the CO/H2 ratio is larger in C-type stars. Furthermore, the measurements show a relation between the measured (Gaussian) 12CO J=2-1 size and circumstellar density that, while in broad agreement with photodissociation calculations, reveals large scatter and some systematic differences between the different stellar types. For lower mass-loss-rate irregular and semi-regular variables of both M- and C-type AGB stars, the 12CO J=2-1 size appears to be independent of the ratio of the mass-loss rate to outflow velocity, which is a measure of circumstellar density. For the higher mass-loss-rate Mira stars, the 12CO J=2-1 size clearly increases with circumstellar density, with larger sizes for the higher CO-abundance C-type stars. The M-type stars appear to be consistently smaller than predicted from photodissociation theory. The majority of the sources have CO envelope sizes that are consistent with a spherically symmetric, smooth outflow, at least on larger scales. For about a third of the sources, indications of strong asymmetries are detected. This is consistent with what was found in previous interferometric investigations of northern sources. Smaller scale asymmetries are found in a larger fraction of sources.
Conclusions. These results for CO envelope radii and shapes can be used to constrain detailed radiative transfer modeling of the same stars so as to determine mass-loss rates that are independent of photodissociation models. For a large fraction of the sources, observations at higher spatial resolution will be necessary to deduce the nature and origin of the complex circumstellar dynamics revealed by our ACA observations.

Abstract Copyright: © ESO 2020

Journal keyword(s): stars: AGB and post-AGB - stars: mass-loss - stars: winds - outflows - circumstellar matter

VizieR on-line data: <Available at CDS (J/A+A/640/A133): stars.dat list.dat fits/*>

Status at CDS : Tables of objects will be appraised for possible ingestion in SIMBAD.

Simbad objects: 47

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Number of rows : 47

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2020
#notes
1 V* UY Cet AB* 00 27 06.4484430547 -06 36 16.871502759   10.61 9.32     M7 44 0
2 IRC +10011 OH* 01 06 25.9889735162 +12 35 52.890666456   20.7   18.26 14.01 M8 402 0
3 V* R Scl C* 01 26 58.0946233986 -32 32 35.437732667 17.26 9.59 5.72 3.69 2.30 C-N5+ 301 0
4 V* R For C* 02 29 15.3081251463 -26 05 55.647016467   12.94 7.50     C4,3e 181 0
5 V* R Hor Mi* 02 53 52.7746504509 -49 53 22.732999275     3.92 4.99 1.51 M5-7e 173 0
6 V* TW Hor C* 03 12 33.1606201355 -57 19 17.571043687   7.93 5.71 3.78 2.40 C-N5IIIb: 126 0
7 V* R Lep C* 04 59 36.3480393629 -14 48 22.511432606 15.06 13.51 7.76 4.90 3.42 C7,6e 318 0
8 V* W Ori C* 05 05 23.7201883024 +01 10 39.459119918 16.36 9.52 6.10 3.83 2.35 C-N5 275 0
9 IRC +70066 Mi* 05 46 44.3250774318 +69 58 24.408023024           M9.5 76 0
10 RAFGL 865 C* 06 04 00.04728 +07 25 52.0104           C-rich 97 0
11 RAFGL 971 C* 06 36 54.2442987630 +03 25 28.677658825       18.4   C5,9e 64 0
12 V* NP Pup C* 06 54 26.6836612589 -42 21 56.056266157   8.49 6.27 4.55 3.28 C-N4.5 74 0
13 V* R Vol C* 07 05 36.2092864981 -73 00 52.021676008   14.24 8.70     Ce 79 0
14 V* W CMa C* 07 08 03.4363216943 -11 55 23.793216538 13.44 8.98 6.56 4.86 3.51 C-N5 112 0
15 * L02 Pup AB* 07 13 32.3181035 -44 38 23.062946 7.90 6.66 5.10 2.49 0.07 M5IIIe 193 0
16 V* CW Cnc LP* 09 08 26.5427117208 +13 13 13.612715596   10.23 9.15     M6 47 0
17 V* R Leo Mi* 09 47 33.4839808805 +11 25 43.823283729 9.22 8.94 7.53 3.39 0.12 M7-9e 879 1
18 V* SU Vel LP* 09 50 02.5610278528 -42 01 13.317351720   10.20 8.95     M5(III) 20 0
19 V* Y Hya C* 09 51 03.7183623740 -23 01 02.359218355 17.75 10.45 6.63     C-N4.5III: 103 0
20 V* X Vel C* 09 55 26.1119127674 -41 35 12.790399779   10.29 10.30 7.13 8.80 C-N3 63 0
21 V* CZ Hya C* 10 27 18.0392236186 -25 32 56.308014871   12.44 9.71 10.55   Ce 51 0
22 V* U Ant C* 10 35 12.8508908507 -39 33 45.320533564 15.32 8.22 5.38 3.18 1.86 C-N3 138 0
23 V* U Hya C* 10 37 33.2729535 -13 23 04.352923 13.29 7.51 4.82 3.05 1.78 C-N5 287 0
24 V* R Crt AB* 11 00 33.8541158313 -18 19 29.574953304   10.33 9.80     M7/8III 197 0
25 V* SS Vir C* 12 25 14.3952079722 +00 46 10.946733968 15.84 10.79 6.60     C-N4.5: 192 1
26 V* BK Vir AB* 12 30 21.0150535628 +04 24 59.159360514 9.60 8.82 7.28     M7-III: 133 0
27 V* RT Vir AB* 13 02 37.9836301550 +05 11 08.360733054 10.07 9.07 7.41     M8III 297 0
28 V* SW Vir AB* 13 14 04.3908742003 -02 48 25.155302846 9.24 8.52 6.85     M7III: 248 0
29 V* R Hya Mi* 13 29 42.7818674 -23 16 52.774679 7.26 6.58 4.97 2.27 -0.15 M6-9e 463 0
30 V* W Hya Mi* 13 49 02.0018313132 -28 22 03.532006894   8.97 7.70     M7.5-9e 604 0
31 V* TW Oph C* 17 29 43.6641693394 -19 28 22.867073875   12.95 8.79 7.54 8.70 C-N5 109 0
32 IRC +10365 Mi* 18 37 19.2595666948 +10 25 42.492197977           M9 135 0
33 V* V Aql C* 19 04 24.1548619887 -05 41 05.434251344   11.09 6.90     C-N5 204 0
34 V* V Tel LP* 19 18 14.6117223850 -50 26 48.373405167   10.93 10.30     M6/8 28 0
35 V* AQ Sgr C* 19 34 18.9945475487 -16 22 27.048908541 13.85 9.48 6.70     C-N5 109 0
36 V* RR Aql Mi* 19 57 36.0628075265 -01 53 11.322802573     7.80     M7.5e 280 2
37 V* V1943 Sgr AB* 20 06 55.2458545503 -27 13 29.754314126   9.25 8.04     M7/8III 70 0
38 IRC -10529 OH* 20 10 27.8733409252 -06 16 13.757843352         15.49 M: 133 0
39 V* RT Cap C* 20 17 06.5288478069 -21 19 04.462721142   12.92 8.90     C6,4 115 0
40 V* T Mic AB* 20 27 55.1872307024 -28 15 39.798200611   8.33 6.74     M7/8III 83 0
41 V* RV Aqr C* 21 05 51.7378981699 -00 12 42.121668132     11.5     C6,3e 97 0
42 V* T Ind C* 21 20 09.4831019700 -45 01 18.812718120 12.08 8.33 6.00     C7,2 83 0
43 V* Y Pav C* 21 24 16.7498446696 -69 44 01.965339111 12.63 9.23 6.41     C7,3 78 0
44 V* EP Aqr AB* 21 46 31.8467491729 -02 12 45.901666975   7.93 6.78     M7-III: 214 0
45 * pi.01 Gru S* 22 22 44.2112214756 -45 56 52.780402708 10.52 8.62 6.55 3.19 0.52 S5,7: 162 0
46 V* Y Scl LP* 23 09 05.5603140187 -30 08 02.144630134   9.86 8.70     M6III 46 0
47 V* SV Aqr LP* 23 22 45.3625989510 -10 49 00.065968329   10.91 9.83     M8 28 0

    Equat.    Gal    SGal    Ecl

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2020.10.26-14:46:01

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