PACS and SPIRE spectroscopy of the red supergiant VY CMa
Pierre Royer
(1)
,
Leen Decin
(1)
,
R. Wesson
(2)
,
Michael J. Barlow
(2)
,
Edward T. Polehampton
(3)
,
Mikako Matsuura
(2)
,
Marcelino Agúndez
(4, 5, 6, 7)
,
J. A. D. L. Blommaert
(1)
,
José Cernicharo
(4)
,
Mathieu Cohen
(8)
,
Fabien Daniel
(4)
,
Pieter Degroote
(1)
,
W. de Meester
(1)
,
K. M. Exter
(1)
,
Helmut Feuchtgruber
(9)
,
Walter K. Gear
(10)
,
H. L. Gomez
(10)
,
M. A. T. Groenewegen
(11)
,
Peter C. Hargrave
(10)
,
R. Huygen
(1)
,
P. Imhof
(12)
,
Robert J. Ivison
(13)
,
C. Jean
(1)
,
Franz Kerschbaum
(14)
,
Sarah J. Leeks
(3)
,
Tanya L. Lim
(3)
,
R. Lombaert
(1)
,
Goran Olofsson
(15)
,
Thomas Posch
(14)
,
S. Regibo
(1)
,
Giorgio Savini
(2)
,
B. Sibthorpe
(13)
,
Bruce Swinyard
(3)
,
Bart Vandenbussche
(1)
,
Christoffel Waelkens
(1)
,
D. K. Witherick
(2)
,
J. A. Yates
(2)
1
Instituut voor Sterrenkunde, Katholieke Universiteit Leuven
2 UCL - University College of London [London]
3 Space Science and Technology Department, Rutherford Appleton Laboratory
4 CAB - Centro de Astrobiología, Consejo Superior de Investigaciones Científicas (CSIC)/Instituto Nacional de Técnica Aeroespacial (INTA)
5 LUTH (UMR_8102) - Laboratoire Univers et Théories
6 LERMA - Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique
7 Molécules dans l'Univers
8 Radio Astronomy Laboratory, University of California, Berkeley
9 MPE - Max-Planck-Institut für Extraterrestriche Physik
10 Cardiff University
11 ROB - Royal Observatory of Belgium = Observatoire Royal de Belgique
12 BSS - Blue Sky Spectroscopy
13 UKATC - UK Astronomy Technology Centre, Royal Observatory Edinburgh
14 IfA - Institut für Astronomie, Universität Wien
15 Stockholm University
2 UCL - University College of London [London]
3 Space Science and Technology Department, Rutherford Appleton Laboratory
4 CAB - Centro de Astrobiología, Consejo Superior de Investigaciones Científicas (CSIC)/Instituto Nacional de Técnica Aeroespacial (INTA)
5 LUTH (UMR_8102) - Laboratoire Univers et Théories
6 LERMA - Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique
7 Molécules dans l'Univers
8 Radio Astronomy Laboratory, University of California, Berkeley
9 MPE - Max-Planck-Institut für Extraterrestriche Physik
10 Cardiff University
11 ROB - Royal Observatory of Belgium = Observatoire Royal de Belgique
12 BSS - Blue Sky Spectroscopy
13 UKATC - UK Astronomy Technology Centre, Royal Observatory Edinburgh
14 IfA - Institut für Astronomie, Universität Wien
15 Stockholm University
Résumé
With a luminosity >10<SUP>5</SUP> L<SUB>&sun;</SUB> and a mass-loss rate of ~2 × 10<SUP>-4</SUP> M<SUB>&sun;</SUB> yr<SUP>-1</SUP>, the red supergiant VY CMa truly is a spectacular object. Because of its extreme evolutionary state, it could explode as supernova any time. Studying its circumstellar material, into which the supernova blast will run, provides interesting constraints on supernova explosions and on the rich chemistry taking place in such complex circumstellar envelopes. We have obtained spectroscopy of VY CMa over the full wavelength range offered by the PACS and SPIRE instruments of Herschel, i.e. 55-672 micron. The observations show the spectral fingerprints of more than 900 spectral lines, of which more than half belong to water. In total, we have identified 13 different molecules and some of their isotopologues. A first analysis shows that water is abundantly present, with an ortho-to-para ratio as low as ~1.3:1, and that chemical non-equilibrium processes determine the abundance fractions in the inner envelope.