Sökning: onr:"swepub:oai:research.chalmers.se:48b5b3c2-5655-4548-948a-0469fa3ec54e" >
The extended molecu...
The extended molecular envelope of the asymptotic giant branch star π 1 Gruis as seen by ALMA: I. Large-scale kinematic structure and CO excitation properties
-
- Doan, L. (författare)
- Uppsala universitet,Uppsala University
-
- Ramstedt, S. (författare)
- Uppsala universitet,Uppsala University
-
- Vlemmings, Wouter, 1974 (författare)
- Chalmers tekniska högskola,Chalmers University of Technology
-
visa fler...
-
- Höfner, S. (författare)
- Uppsala universitet,Uppsala University
-
- De Beck, Elvire, 1985 (författare)
- Chalmers tekniska högskola,Chalmers University of Technology
-
- Kerschbaum, F. (författare)
- Universität Wien,University of Vienna
-
- Lindqvist, Michael, 1960 (författare)
- Chalmers tekniska högskola,Chalmers University of Technology
-
- Maercker, Matthias, 1979 (författare)
- Chalmers tekniska högskola,Chalmers University of Technology
-
- Mohamed, S. (författare)
- South African Astronomical Observatory,National Institute for Theoretical Physics,University of Cape Town
-
- Paladini, C. (författare)
- Université libre de Bruxelles (ULB)
-
- Wittkowski, M. (författare)
- European Southern Observatory (ESO)
-
visa färre...
-
(creator_code:org_t)
- 2017-09-04
- 2017
- Engelska.
-
Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 605
- Relaterad länk:
-
http://publications.... (primary) (free)
-
visa fler...
-
https://www.aanda.or...
-
https://doi.org/10.1...
-
https://research.cha...
-
visa färre...
Abstract
Ämnesord
Stäng
- Context. The S-type asymptotic giant branch (AGB) star ?1 Gru has a known companion at a separation of 2? 7 (? 400 AU). Previous observations of the circumstellar envelope (CSE) show strong deviations from spherical symmetry. The envelope structure, including an equatorial torus and a fast bipolar outflow, is rarely seen in the AGB phase and is particularly unexpected in such a wide binary system. Therefore a second, closer companion has been suggested, but the evidence is not conclusive. Aims. The aim is to make a 3D model of the CSE and to constrain the density and temperature distribution using new spatially resolved observations of the CO rotational lines. Methods. We have observed the J = 3-2 line emission from 12CO and 13CO using the compact arrays of the Atacama Large Millimeter/submillimeter Array (ALMA). The new ALMA data, together with previously published 12CO J = 2-1 data from the Submillimeter Array (SMA), and the 12CO J = 5-4 and J = 9-8 lines observed with Herschel/Heterodyne Instrument for the Far-Infrared (HIFI), is modeled with the 3D non-LTE radiative transfer code SHAPEMOL. Results. The data analysis clearly confirms the torus-bipolar structure. The 3D model of the CSE that satisfactorily reproduces the data consists of three kinematic components: a radially expanding torus with velocity slowly increasing from 8 to 13 km s-1 along the equator plane; a radially expanding component at the center with a constant velocity of 14 km s-1; and a fast, bipolar outflow with velocity proportionally increasing from 14 km s-1 at the base up to 100 km s-1 at the tip, following a linear radial dependence. The results are used to estimate an average mass-loss rate during the creation of the torus of 7.7 × 10-7 M? yr-1. The total mass and linear momentum of the fast outflow are estimated at 7.3 × 10-4 M? and 9.6 × 1037 g cm s-1, respectively. The momentum of the outflow is in excess (by a factor of about 20) of what could be generated by radiation pressure alone, in agreement with recent findings for more evolved sources. The best-fit model also suggests a 12CO/13CO abundance ratio of 50. Possible shaping scenarios for the gas envelope are discussed.
Ämnesord
- NATURVETENSKAP -- Fysik -- Astronomi, astrofysik och kosmologi (hsv//swe)
- NATURAL SCIENCES -- Physical Sciences -- Astronomy, Astrophysics and Cosmology (hsv//eng)
Nyckelord
- Stars: mass-loss
- Stars: general
- Binaries: general
- Radio lines: stars
- Stars: AGB and post-AGB
- Stars: individual:?1Gru
Publikations- och innehållstyp
- art (ämneskategori)
- ref (ämneskategori)
Hitta via bibliotek
Till lärosätets databas
- Av författaren/redakt...
-
Doan, L.
-
Ramstedt, S.
-
Vlemmings, Woute ...
-
Höfner, S.
-
De Beck, Elvire, ...
-
Kerschbaum, F.
-
visa fler...
-
Lindqvist, Micha ...
-
Maercker, Matthi ...
-
Mohamed, S.
-
Paladini, C.
-
Wittkowski, M.
-
visa färre...
- Om ämnet
-
- NATURVETENSKAP
-
NATURVETENSKAP
-
och Fysik
-
och Astronomi astrof ...
- Artiklar i publikationen
-
Astronomy and As ...
- Av lärosätet
-
Chalmers tekniska högskola