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Published August 20, 2008 | Published
Journal Article Open

Spitzer-MIPS observations of the η Chamaeleontis young association


We have mapped the η Chamaeleontis young stellar association in the far-infrared with the Multiband Imaging Photometer for Spitzer (MIPS) on the Spitzer Space Telescope. All 16 members within the map region were detected at 24 μm, along with five members at 70 μm and two at 160 μm. Ten stars show far-infrared excess emission indicating the presence of circumstellar disks; six of these have central clearings as evidenced by the onset of excess emission at λ > 5 μm. No new infrared-excess sources are identified among the 113 2MASS field stars with 24 μm photometry but not seen as X-ray sources, indicating that membership lists derived from X-ray surveys are reasonably complete. Circumstellar disks in the η Cha association span the range from 10^(−1) to 10^(−4) in their fractional infrared luminosity, with a median L_d/L_* of 0.04. The presence of optically thick, optically thin, and intermediate optical depth disks within the same stellar group, in combination with the large fraction of disks with inner holes, indicates that the η Cha association represents a crucial stage in circumstellar disk evolution.

Additional Information

© 2008 The American Astronomical Society. Received 2007 September 8; accepted 2008 April 13. This work is based on observations made with the Spitzer Space Telescope, which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under contract with NASA. Support for this work was provided by NASA through contract 1255094. Gautier was also partially supported under the Research and Technical Development funds at the Jet Propulsion Laboratory. This work also makes use of data products from the Two Micron All Sky Survey, which is a joint project of the University of Massachusetts and the Infrared Processing and Analysis Center/California Institute of Technology, funded by the National Aeronautics and Space Administration and the National Science Foundation.

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