ALMA reveals sunburn: CO dissociation around AGB stars in the globular cluster 47 Tucanae
Artikel i vetenskaplig tidskrift, 2015
Atacama Large Millimetre Array observations show a non-detection of carbon monoxide around the four most luminous asymptotic giant branch (AGB) stars in the globular cluster 47 Tucanae. Stellar evolution models and star counts show that the mass-loss rates from these stars should be similar to 1.2-3.5x10(-7) M-circle dot yr(-1). We would naively expect such stars to be detectable at this distance (4.5 kpc). By modelling the ultraviolet radiation field from post-AGB stars and white dwarfs in 47 Tuc, we conclude that CO should be dissociated abnormally close to the stars. We estimate that the CO envelopes will be truncated at a few hundred stellar radii from their host stars and that the line intensities are about two orders of magnitude below our current detection limits. The truncation of CO envelopes should be important for AGB stars in dense clusters. Observing the CO (3-2) and higher transitions and targeting stars far from the centres of clusters should result in the detections needed to measure the outflow velocities from these stars.
stars: winds
circumstellar matter
stars: AGB and post-AGB
infrared: stars
globular clusters: individual: NGC 104
outflows
stars: mass-loss
Författare
I. McDonald
University of Manchester
A. Zijlstra
University of Manchester
E. Lagadec
Cornell University
Observatoire de la Cote d'Azur
G. C. Sloan
Cornell University
M. Boyer
National Aeronautics and Space Administration (NASA)
M. Matsuura
University College London (UCL)
Cardiff University
R. J. Smith
University of Manchester
C. L. Smith
University of Manchester
J. A. Yates
University College London (UCL)
J. T. van Loon
Keele University
O. C. Jones
University of Manchester
Space Telescope Science Institute (STScI)
S. Ramstedt
Uppsala universitet
A Avison
University of Manchester
Kay Justtanont
Chalmers, Rymd- och geovetenskap, Radioastronomi och astrofysik
Hans Olofsson
Chalmers, Rymd- och geovetenskap, Radioastronomi och astrofysik
Jadl Blommaert
Vrije Universiteit Brüssel (VUB)
S. R. Goldman
Keele University
M. A. T. Groenewegen
Royal Observatory of Belgium
Monthly Notices of the Royal Astronomical Society
0035-8711 (ISSN) 1365-2966 (eISSN)
Vol. 453 4 4324-4336Ämneskategorier (SSIF 2011)
Astronomi, astrofysik och kosmologi
DOI
10.1093/mnras/stv1968