Gorlova, N.; Balog, Z.; Rieke, G. H.; Muzerolle, J.; Su, K. Y. L.; Ivanov, V. D.; Young, E. T., 2007, Debris Disks in NGC 2547 ApJ, 670, 516 (Stellar/Galactic) Engelbracht, C. W.; Blaylock, M.; Su, K. Y. L.; Rho, J.; Rieke, G. H.; Muzerolle, J.; Padgett, D. L.; Hines, D. C.; Gordon, K. D.; Fadda, D.; Noriega-Crespo, A.; Kelly, D. M.; Latter, W. B.; Hinz, J. L.; Misselt, K. A.; Morrison, J. E.; Stansberry, J. A.; Shupe, D. L.; Stolovy, S.; Wheaton, Wm. A.; Young, E. T.; Neugebauer, G.; Wachter, S.; Pérez-González, P. G.; Frayer, D. T.; Marleau, F. R., 2007, Absolute Calibration and Characterization of the Multiband Imaging Photometer for Spitzer. I. The Stellar Calibrator Sample and the 24 micron Calibration PASP, 119, 994 (Stellar/Galactic) Gautier, Thomas N., III; Rieke, G. H.; Stansberry, John; Bryden, Geoffrey C.; Stapelfeldt, Karl R.; Werner, Michael W.; Beichman, Charles A.; Chen, Christine; Su, Kate; Trilling, David; Patten, Brian M.; Roellig, Thomas L., 2007, Far-Infrared Properties of M Dwarfs ApJ, 667, 527 (Stellar/Galactic) Banerjee, D. P. K.; Misselt, K. A.; Su, K. Y. L.; Ashok, N. M.; Smith, P. S., 2007, Spitzer Observations of V4332 Sagittarii: Detection of Alumina Dust ApJL, 666, 25 (Stellar/Galactic) Chen, C. H.; Li, A.; Bohac, C.; Kim, K. H.; Watson, D. M.; van Cleve, J.; Houck, J.; Stapelfeldt, K.; Werner, M. W.; Rieke, G.; Su, K.; Marengo, M.; Backman, D.; Beichman, C.; Fazio, G., 2007, The Dust and Gas Around β Pictoris ApJ, 666, 466 (Stellar/Galactic) Wyatt, M. C.; Smith, R.; Su, K. Y. L.; Rieke, G. H.; Greaves, J. S.; Beichman, C. A.; Bryden, G., 2007, Steady State Evolution of Debris Disks around A Stars ApJ, 663, 365 (Stellar/Galactic) Balog, Zoltan; Muzerolle, James; Rieke, G. H.; Su, Kate Y. L.; Young, Eric T.; Megeath, S. Tom, 2007, Spitzer/IRAC-MIPS Survey of NGC 2244: Protostellar Disk Survival in the Vicinity of Hot Stars ApJ, 660, 1532 (Stellar/Galactic) Trilling, D. E.; Stansberry, J. A.; Stapelfeldt, K. R.; Rieke, G. H.; Su, K. Y. L.; Gray, R. O.; Corbally, C. J.; Bryden, G.; Chen, C. H.; Boden, A.; Beichman, C. A., 2007, Debris disks in main-sequence binary systems ApJ, 658, 1289 (Stellar/Galactic) Su, K. Y. L.; Chu, Y.-H.; Rieke, G. H.; Huggins, P. J.; Gruendl, R.; Napiwotzki, R.; Rauch, T.; Latter, W. B.; Volk, K., 2007, A Debris Disk around the Central Star of the Helix Nebula? ApJL, 657, 41 (Stellar/Galactic) Siegler, Nick; Muzerolle, James; Young, Erick T.; Rieke, George H.; Mamajek, Eric E.; Trilling, David E.; Gorlova, Nadya; Su, Kate Y. L., 2007, Spitzer 24 micron Observations of Open Cluster IC 2391 and Debris Disk Evolution of FGK Stars ApJ, 654, 580 (Stellar/Galactic)
K. Su, in collaboration with G. Rieke, J. Stansberry, D. Trilling (Arizona), K. Stapelfeldt, G. Bryden (Caltech/JPL), investigated the debris disk evolution around main-sequence stars based on the Spitzer Space Telescope data. By measuring infrared photometry around 160 A-type stars with ages of 5-850 Myr, we found the infrared excess rate at 24 and 70 μm is 32% and >=33%, considerably higher than what has been found for old solar analogs and M dwarfs. We found that older stars tend to have lower fractional dust luminosity than younger ones. While the fractional luminosity from the excess infrared emission follows a general 1/t relationship, the values at a given stellar age vary by at least 2 orders of magnitude. We also found that (1) older stars possess a narrow range of temperature distribution peaking at colder temperatures, and (2) the disk emission at 70 μm persists longer than that at 24 μm. Both results suggest that the debris disk clearing process is more effective in the inner regions. (Stellar/galactic, observational) K. Su, in collaboration with Z. Balog, G. Rieke, J. Muzerolle, E. Young (Arizona), presented 24 μm images of three protoplanetary disks being photoevaporated around high-mass O-type stars. These objects have cometary structure where the dust pulled away from the disk by the photoevaporating flow is forced away from the O star by photon pressure on the dust and heating and ionization of the gas. (Stellar/galactic, observational) K. Su, in collaboration with D. Trilling, J. Stansberry, G. Rieke, C. Corbally (Arizona), K. Stapelfeldt, G. Bryden, C. Beichman (Caltech/JPL), C. Chen (NOAO), investigated the debris disk study around main-sequence binary systems. We found a very large fraction (nearly 60%) of observed binary systems with small (<3 AU) separations have excess thermal emission. The incidence of debris disks around main-sequence A3-F8 binaries is marginally higher than that for single old AFGK stars. (Stellar/galactic, observational) K. Su, in collaboration with Y.-H. Chu, R. Gruendl (UIUC), G. Rieke, (Arizona), P. Huggins (New York University), R. Napiwotzki (University of Hertfordshire, UK), T. Rauch (Universität Tübingen, Germany), K. Volk (Gemini Observatory), B. Latter (Herschel Science Center), discovered an infrared excess around the hot white dwarf, WD 2226-210, the central star of the Helix Nebula. Based on the observations and disk modeling, we found the infrared excess is attributed to dust distributed in a ring between ~35 and ~150 AU from the central star, possibly arising from collisions of Kuiper Belt-like objects or the breakup of comets from an Oort-like cloud that have survived from the post-main-sequence evolution of the central star. (Stellar/galactic) K. Su, in collaboration with D. Banerjee, N. Ashok (PRL, India), K. Misselt, and P. Smith (Arizona), investigated dust emission around a Nova-like star, V4332 Sgr, using the Spitzer Space Telescope data. We found a distinguishing feature in the spectrum of 5-35 μm, an unusually broad absorption feature near 10 μm, which is at the position generally associated with silicate-rich dust. Through radiative transfer modeling, we showed that this broad feature cannot arise from silicates alone but requires the inclusion of alumina (Al2O3) as a dust condensate. We discussed how further observations of V4332 Sgr may have the potential of verifying some general predictions of the dust condensation process. (Stellar/galactic)