The Spitzer c2d survey of weak-line T tauri stars. I. Initial results

Deborah L. Padgett, Lucas Cieza, Karl R. Stapelfeldt, Neal J. Evans, David Koerner, Anneila Sargent, Misato Fukagawa, Ewine F. Van Dishoeck, Jean Charles Augereau, Lori Allen, Geoff Blake, Tim Brooke, Nicholas Chapman, Paul Harvey, Alicia Porras, Shih Ping Lai, Lee Mundy, Philip C. Myers, William Spiesman, Zahed Wahhaj

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Abstract

Using the Spitzer Space Telescope, we have observed 90 weak-line and classical T Tauri stars in the vicinity of the Ophiuchus, Lupus, Chamaeleon, and Taurus star-forming regions as part of the Cores to Disks (c2d) Spitzer Legacy project. In addition to the Spitzer data, we have obtained contemporaneous optical photometry to assist in constructing spectral energy distributions. These objects were specifically chosen as solar-type young stars with low levels of Hα emission, strong X-ray emission, and lithium absorption, i.e., weak-line T Tauri stars, most of which were undetected in the mid- to far-IR by the IRAS survey. Weak-line T Tauri stars are potentially extremely important objects in determining the timescale over which disk evolution may take place. Our objective is to determine whether these young stars are diskless or have remnant disks that are below the detection threshold of previous infrared missions. We find that only 5/83 weak-line T Tauri stars have detectable excess emission between 3.6 and 70 μm, which would indicate the presence of dust from the inner few tenths of an AU out to the planet-forming regions a few tens of AU from the star. Of these sources, two have small excesses at 24 μm consistent with optically thin disks; the others have optically thick disks already detected by previous IR surveys. All of the seven classical T Tauri stars show excess emission at 24 and 70 μm although their properties vary at shorter wavelengths. Our initial results show that disks are rare among young stars selected for their weak Hα emission.

Original languageEnglish (US)
Pages (from-to)1283-1296
Number of pages14
JournalAstrophysical Journal
Volume645
Issue number2 I
DOIs
StatePublished - Jul 10 2006

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Keywords

  • Infrared: stars
  • Planetary systems: protoplanetary disks
  • Stars: pre-main-sequence

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

Cite this

Padgett, D. L., Cieza, L., Stapelfeldt, K. R., Evans, N. J., Koerner, D., Sargent, A., Fukagawa, M., Van Dishoeck, E. F., Augereau, J. C., Allen, L., Blake, G., Brooke, T., Chapman, N., Harvey, P., Porras, A., Lai, S. P., Mundy, L., Myers, P. C., Spiesman, W., & Wahhaj, Z. (2006). The Spitzer c2d survey of weak-line T tauri stars. I. Initial results. Astrophysical Journal, 645(2 I), 1283-1296. https://doi.org/10.1086/504374