The Herschel DIGIT Survey of Weak-line T Tauri Stars: Implications for Disk Evolution and Dissipation
- Author(s)
- Lucas A. Cieza, Johan Olofsson, Paul M. Harvey, Neal J., II Evans, Joan Najita, Thomas Henning, Bruno Merín, Armin Liebhart, Manuel Güdel, Jean-Charles Augereau, Christophe Pinte
- Abstract
As part of the "Dust, Ice, and Gas In Time (DIGIT)" Herschel Open Time
Key Program, we present Herschel photometry (at 70, 160, 250, 350, and
500 μm) of 31 weak-line T Tauri star (WTTS) candidates in order to
investigate the evolutionary status of their circumstellar disks. Of the
stars in our sample, 13 had circumstellar disks previously known from
infrared observations at shorter wavelengths, while 18 of them had no
previous evidence for a disk. We detect a total of 15 disks as all
previously known disks are detected at one or more Herschel wavelengths
and two additional disks are identified for the first time. The spectral
energy distributions (SEDs) of our targets seem to trace the dissipation
of the primordial disk and the transition to the debris disk regime. Of
the 15 disks, 7 appear to be optically thick primordial disks, including
2 objects with SEDs indistinguishable from those of typical Classical T
Tauri stars, 4 objects that have significant deficit of excess emission
at all IR wavelengths, and 1 "pre-transitional" object with a known gap
in the disk. Despite their previous WTTS classification, we find that
the seven targets in our sample with optically thick disks show evidence
for accretion. The remaining eight disks have weaker IR excesses similar
to those of optically thin debris disks. Six of them are warm and show
significant 24 μm Spitzer excesses, while the last two are newly
identified cold debris-like disks with photospheric 24 μm fluxes, but
significant excess emission at longer wavelengths. The Herschel
photometry also places strong constraints on the non-detections, where
systems with F 70/F 70, sstarf >~ 5-15 and L
disk/L sstarf >~ 10-3 to
10-4 can be ruled out. We present preliminary models
for both the optically thick and optically thin disks and discuss our
results in the context of the evolution and dissipation of circumstellar
disks.
Herschel is an ESA space observatory with science instruments provided
by European-led Principal Investigator consortia and with important
participation from NASA. Based in part on observations made with the
CFHT, under program 11AH96.
- Organisation(s)
- Department of Astrophysics
- External organisation(s)
- University of Hawaii at Manoa, University of Texas, Austin, National Aeronautics & Space Administration (NASA), Max-Planck-Institut für Astronomie, National Optical Astronomy Observatory, Tucson, European Space Astronomy Centre (ESA), Université Joseph-Fourier (Grenoble-I)
- Journal
- The Astrophysical Journal: an international review of astronomy and astronomical physics
- Volume
- 762
- No. of pages
- 20
- ISSN
- 0004-637X
- DOI
- https://doi.org/10.1088/0004-637X/762/2/100
- Publication date
- 01-2013
- Peer reviewed
- Yes
- Austrian Fields of Science 2012
- 103004 Astrophysics, 103003 Astronomy
- Keywords
- Portal url
- https://ucrisportal.univie.ac.at/en/publications/b9a19424-c4e3-41ad-86d2-de924b46cb84