Herschel detects oxygen in the ? Pictoris debris disk
Journal article, 2016
The young star β Pictoris is well known for its dusty debris disk produced through collisional grinding of planetesimals, kilometre-sized bodies in orbit around the star. In addition to dust, small amounts of gas are also known to orbit the star; this gas is likely the result of vaporisation of violently colliding dust grains. The disk is seen edge on and from previous absorption spectroscopy we know that the gas is very rich in carbon relative to other elements. The oxygen content has been more difficult to assess, however, with early estimates finding very little oxygen in the gas at a C/O ratio that is 20× higher than the cosmic value. A C/O ratio that high is difficult to explain and would have far-reaching consequences for planet formation. Here we report on observations by the far-infrared space telescope Herschel, using PACS, of emission lines from ionised carbon and neutral oxygen. The detected emission from C+ is consistent withthat previously reported observed by the HIFI instrument on Herschel, while the emission from O is hard to explain without assuming a higher density region in the disk, perhaps in the shape of a clump or a dense torus required to sufficiently excite the O atoms. A possible scenario is that the C/O gas is produced by the same process responsible for the CO clump recently observed by the Atacama Large Millimeter/submillimeter Array in the disk and that the redistribution of the gas takes longer than previously assumed. A more detailed estimate of the C/O ratio and the mass of O will have to await better constraints on the C/O gas spatial distribution.
Stars: individual: beta Pictoris
Circumstellar matter
Stars: early-type
Author
A. Brandeker
Stockholm University
G. Cataldi
Stockholm University
G. Olofsson
Stockholm University
B. Vandenbussche
KU Leuven
B. Acke
KU Leuven
M. J. Barlow
University College London (UCL)
Jadl Blommaert
KU Leuven
Vrije Universiteit Brussel (VUB)
M. Cohen
University of California
W. R. F. Dent
Atacama Large Millimeter-submillimeter Array (ALMA)
C. Dominik
Anton Pannekoek Institute for Astronomy
Radboud University
J. Di Francesco
National Research Council Canada
Malcolm Fridlund
Chalmers, Earth and Space Sciences, Radio Astronomy and Astrophysics
W. K. Gear
Cardiff University
A. M. Glauser
Swiss Federal Institute of Technology in Zürich (ETH)
Royal Observatory
J. S. Greaves
University of St Andrews
P. M. Harvey
The University of Texas at Austin
A. Heras
European Space Research and Technology Centre (ESA ESTEC)
M. R. Hogerheijde
Leiden University
W. S. Holland
Royal Observatory
R. Huygen
KU Leuven
R. J. Ivison
University of Edinburgh
European Southern Observatory (ESO)
S. J. Leeks
STFC Rutherford Appleton Laboratory
T. L. Lim
STFC Rutherford Appleton Laboratory
René Liseau
Chalmers, Earth and Space Sciences, Radio Astronomy and Astrophysics
B. C. Matthews
National Research Council Canada
E. Pantin
The French Alternative Energies and Atomic Energy Commission (CEA)
G.L. Pilbratt
European Space Research and Technology Centre (ESA ESTEC)
P. Royer
KU Leuven
B. Sibthorpe
Netherlands Institute for Space Research (SRON)
C. Waelkens
KU Leuven
H. Walker
STFC Rutherford Appleton Laboratory
Astronomy and Astrophysics
0004-6361 (ISSN) 1432-0746 (eISSN)
Vol. 591 Art. no. A27- A27Subject Categories
Astronomy, Astrophysics and Cosmology
DOI
10.1051/0004-6361/201628395