Observations at 70 μm with the Spitzer Space Telescope have detected several stellar systems within 65 pc of the Sun. Of 18 presumably young systems detected in this study, as many as 15 have 70 μm emission in excess of that expected from their stellar photospheres. Five of the systems with excesses are members of the Tucanae association. The 70 μm excesses range from a factor of ∼2 to nearly 30 times the expected photospheric emission from these stars. In contrast to the 70 μm properties of these systems, there is evidence for an emission excess at 24 μm for only HD 3003, confirming previous results for this star. The lack of a strong 24 μm excess in most of these systems suggests that the circumstellar dust producing the IR excesses is relatively cool (Tdust ≲ 150 K) and that there is little IR-emitting material within the inner few AU of the primary stars. Many dust of these systems lie close enough to Earth that the distribution of the dust producing the IR excesses might be imaged in scattered light at optical and near-IR wavelengths.
Bibliographical noteFunding Information:
This work is based on observations made with Spitzer, which is operated by the Jet Propulsion Laboratory (JPL), California Institute of Technology (CIT), under National Aeronautics and Space Administration (NASA) contract 1407. We thank NASA, JPL, and the Spitzer Science Center for support through contracts 960785, 959969, and 1256424 to The University of Arizona and contracts 1256406 and 1215746 to the University of Minnesota. This research has made use of the SIMBAD database, operated at CDS, Strassbourg, France, and data products from the 2MASS, which is a joint project of the University of Massachusetts and the Infrared Processing and Analysis Center/ CIT, funded by NASA and the National Science Foundation.
- Circumstellar matter
- Infrared: stars
- Planetary systems: formation