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.


infrared: stars

globular clusters: individual: NGC 104

stars: mass-loss

circumstellar matter

stars: AGB and post-AGB

stars: winds


I. McDonald

University of Manchester

A. Zijlstra

University of Manchester

E. Lagadec

Observatoire de la Cote d'Azur

Cornell University

G. C. Sloan

Cornell University

M. Boyer

NASA Goddard Space Flight Center

M. Matsuura

Cardiff University

University College London (UCL)

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 4324-4336


Astronomi, astrofysik och kosmologi