NEW DEBRIS DISKS AROUND YOUNG, LOW-MASS STARS DISCOVERED WITH THE SPITZER SPACE TELESCOPE

By P. Plavchan, M. Werner, Christine Chen, K. Stapelfeldt, K. Su, J. Stauffer, Inseok Song. 2009

150 citations recorded by the source corpus.

We present 24 μm and 70 μm Multiband Imaging Photometer for Spitzer (MIPS) observations of 70 A through M-type dwarfs with estimated ages from 8 Myr to 1.1 Gyr, as part of a Spitzer guaranteed time program, including a re-analysis of some previously published source photometry. Our sample is selected from stars with common youth indicators such as lithium abundance, X-ray activity, chromospheric activity, and rapid rotation. We compare our MIPS observations to empirically derived Ks–[24] colors as a function of the stellar effective temperature to identify 24 μm and 70 μm excesses. We place constraints or upper limits on dust temperatures and fractional infrared luminosities with a simple blackbody dust model. We confirm the previously published 70 μm excesses for HD 92945, HD 112429, and AU Mic, and provide updated flux density measurements for these sources. We present the discovery of 70 μm excesses for five stars: HD 7590, HD 10008, HD 59967, HD 73350, and HD 135599. HD 135599 is also a known Spitzer IRS (InfraRed Spectrograph) excess source, and we confirm the excess at 24 μm. We also present the detection of 24 μm excesses for 10 stars: HD 10008, GJ 3400A, HD 73350, HD 112429, HD 123998, HD 175742, AT Mic, BO Mic, HD 358623 and Gl 907.1. We find that large 70 μm excesses are less common around stars with effective temperatures of less than 5000 K (3.7+7.6−1.1%) than around stars with effective temperatures between 5000 K and 6000 K (21.4+9.5−5.7%), despite the cooler stars having a younger median age in our sample (12 Myr vs. 340 Myr). We find that the previously reported excess for TWA 13A at 70 μm is due to a nearby background galaxy, and the previously reported excess for HD 177724 is due to saturation of the near-infrared photometry used to predict the mid-infrared stellar flux contribution. In the Appendix, we present an updated analysis of dust grain removal timescales due to grain–grain collisions and radiation pressure, Poynting–Robertson (P–R) drag, stellar wind drag, and planet–dust dynamical interaction. We find that drag forces can be important for disk dynamics relative to grain–grain collisions for LIR/L* < 10−4, and that stellar wind drag is more important than P–R drag for K and M dwarfs, and possibly for young (<1 Gyr) G dwarfs as well.

Subfields: Astronomy and Astrophysics, Education, Instrumentation

View Paper: https://www.semanticscholar.org/paper/7f5fba86b6dab4fade5a95c1ae2160e977960bed

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In Astronomy and Astrophysics

1. Michael C. Liu
2. B. Bowler
3. E. Shkolnik
4. K. Allers
5. R. Doyon
6. T. Dupuy
7. A. Kraus
8. B. Macintosh

In Education

1. K. Allers
2. Michael C. Liu
3. E. Shkolnik
4. M. Bessell
5. A. Kraus
6. B. Bowler

In Instrumentation

1. Michael C. Liu
2. K. Allers
3. E. Shkolnik
4. R. Doyon
5. B. Macintosh
6. A. Kraus
7. C. Marois
8. J. Graham

Citations in the corpus

• A STELLAR CENSUS OF THE TUCANA–HOROLOGIUM MOVING GROUP (2014, background): “The low distances also result in additional sensitivity for flux-limited studies of disks (Low et al. 2005; Bouwman et al. 2006; Plavchan et al. 2009) and the (sub)stellar mass function (Gizis 2002; Lyo et al. 2006; Murphy et al. 2010; Shkolnik et al. 2011).”
• The VAST Survey - III. The multiplicity of A-type stars within 75 pc (2013, background): “Both of these systems have indications of youth (Plavchan et al. 2009; De Rosa et al. 2012), which would be consistent with an unstable dynamical configuration (Zhuchkovet al. 2012).”