GASPS-A Herschel Survey of Gas and Dust in Protoplanetary Disks: Summary and Initial Statistics
Journal article, 2013
We describe a large-scale far-infrared line and continuum survey of protoplanetary disk through to young debris disk systems carried out using the ACS instrument on the Herschel Space Observatory. This Open Time Key program, known as GASPS (Gas Survey of Protoplanetary Systems), targeted similar to 250 young stars in narrow wavelength regions covering the [OI] fine structure line at 63 mu m the brightest far-infrared line in such objects. A subset of the brightest targets were also surveyed in [OI]145 mu m, [CII] at 157 mu m, as well as several transitions of H2O and high-excitation CO lines at selected wavelengths between 78 and 180 mu m. Additionally, GASPS included continuum photometry at 70, 100 and 160 mu m, around the peak of the dust emission. The targets were SED Class II-III T Tauri stars and debris disks from seven nearby young associations, along with a comparable sample of isolated Herbig AeBe stars. The aim was to study the global gas and dust content in a wide sample of circumstellar disks, combining the results with models in a systematic way. In this overview paper we review the scientific aims, target selection and observing strategy of the program. We summarise some of the initial results, showing line identifications, listing the detections, and giving a first statistical study of line detectability. The [OI] line at 63 mu m was the brightest line seen in almost all objects, by a factor of similar to 10. Overall [OI]63 mu m detection rates were 49%, with 100% of HAeBe stars and 43% of T Tauri stars detected. A comparison with published disk dust masses (derived mainly from sub-mm continuum, assuming standard values of the mm mass opacity) shows a dust mass threshold for [OI] 63 mu m detection of similar to 10(-5) M-circle dot. Normalising to a distance of 140 pc, 84% of objects with dust masses >= 10(-5) M-circle dot can be detected in this line in the present survey; 32% of those of mass 10(-6)-10(-5) M-circle dot, and only a very small number of unusual objects with lower masses can be detected. This is consistent with models with a moderate UV excess and disk flaring. For a given disk mass, [OI] detectability is lower for M stars compared with earlier spectral types. Both the continuum and line emission was, in most systems, spatially and spectrally unresolved and centred on the star, suggesting that emission in most cases was from the disk. Approximately 10 objects showed resolved emission, most likely from outflows. In the GASPS sample, [OI] detection rates in T Tauri associations in the 0.3-4 Myr age range were similar to 50%. For each association in the 5-20 Myr age range, similar to 2 stars remain detectable in [OI]63 mu m, and no systems were detected in associations with age >20 Myr. Comparing with the total number of young stars in each association, and assuming a ISM-like gas/dust ratio, this indicates that similar to 18% of stars retain a gas-rich disk of total mass similar to 1 M-Jupiter for 1-4 Myr, 1-7% keep such disks for 5-10 Myr, but none are detected beyond 10-20 Myr. The brightest [OI] objects from GASPS were also observed in [OI]145 mu m, [CII]157 mu m and CO J = 18 - 17, with detection rates of 20-40%. Detection of the [CII] line was not correlated with disk mass, suggesting it arises more commonly from a compact remnant envelope.
Author
W. R. F. Dent
Atacama Large Millimeter-submillimeter Array (ALMA)
W. F. Thi
Grenoble Alpes University
University of Groningen
I. Kamp
University of Groningen
J. P. Williams
University of Hawaii
F. Menard
Grenoble Alpes University
S. Andrews
Harvard-Smithsonian Center for Astrophysics
D. R. Ardila
National Aeronautics and Space Administration (NASA)
G. Aresu
University of Groningen
J. C. Augereau
Grenoble Alpes University
D. Barrado
Spanish National Research Council (CSIC)
S. Brittain
Clemson University
A. Carmona
Grenoble Alpes University
D. R. Ciardi
National Aeronautics and Space Administration (NASA)
W. Danchi
National Aeronautics and Space Administration (NASA)
J. Donaldson
University of Maryland
G. Duchene
University of California
Grenoble Alpes University
C. Eiroa
Universidad Autonoma de Madrid (UAM)
D. Fedele
Max Planck Society
C. A. Grady
Eureka Scientific
I. de Gregorio-Molsalvo
Atacama Large Millimeter-submillimeter Array (ALMA)
C. D. Howard
National Aeronautics and Space Administration (NASA)
N. Huelamo
Spanish National Research Council (CSIC)
A. Krivov
Friedrich Schiller University Jena
J. Lebreton
Grenoble Alpes University
René Liseau
Chalmers, Earth and Space Sciences, Radio Astronomy and Astrophysics
C. Martin-Zaidi
Grenoble Alpes University
G. Mathews
University of Hawaii
G. Meeus
Universidad Autonoma de Madrid (UAM)
I. Mendigutia
Spanish National Research Council (CSIC)
B. Montesinos
Spanish National Research Council (CSIC)
M. Morales-Calderon
Spanish National Research Council (CSIC)
A. Mora
European Space Astronomy Centre (ESAC)
H. Nomura
Kyoto University
E. Pantin
The French Alternative Energies and Atomic Energy Commission (CEA)
I. Pascucci
University of Arizona
N. Phillips
Atacama Large Millimeter-submillimeter Array (ALMA)
C. Pinte
Grenoble Alpes University
L. Podio
Atacama Large Millimeter-submillimeter Array (ALMA)
S. Ramsay
European Southern Observatory (ESO)
B. Riaz
University of Hertfordshire
P. Riviere-Marichalar
Spanish National Research Council (CSIC)
A. Roberge
National Aeronautics and Space Administration (NASA)
G. Sandell
National Aeronautics and Space Administration (NASA)
E. Solano
Spanish National Research Council (CSIC)
I. Tilling
University of Edinburgh
J. M. Torrelles
University of Barcelona
B. Vandenbusche
KU Leuven
S. Vicente
University of Groningen
G. J. White
Open University
STFC Rutherford Appleton Laboratory
P. Woitke
University of St Andrews
Publications of the Astronomical Society of the Pacific
0004-6280 (ISSN) 1538-3873 (eISSN)
Vol. 125 927 477-505Subject Categories (SSIF 2011)
Astronomy, Astrophysics and Cosmology
DOI
10.1086/670826