Spitzer IRS Spectroscopy of IRAS-discovered Debris Disks

By Christine H. Chen, B. Sargent, C. Bohac, K. H. Kim, E. Leibensperger, Michael Jura, J. Najita, W. Forrest, D. Watson, G. Sloan and 1 more. 2006

244 citations recorded by the source corpus.

We have obtained Spitzer Space Telescope Infrared Spectrograph (IRS) 5.5-35 μm spectra of 59 main-sequence stars that possess IRAS 60 μm excess. The spectra of five objects possess spectral features that are well-modeled using micron-sized grains and silicates with crystalline mass fractions 0%-80%, consistent with T Tauri and Herbig AeBe stars. With the exception of η Crv, these objects are young with ages ≤50 Myr. Our fits require the presence of a cool blackbody continuum, Tgr = 80-200 K, in addition to hot, amorphous, and crystalline silicates, Tgr = 290-600 K, suggesting that multiple parent body belts are present in some debris disks, analogous to the asteroid and Kuiper belts in our solar system. The spectra for the majority of objects are featureless, suggesting that the emitting grains probably have radii a > 10 μm. We have modeled the excess continua using a continuous disk with a uniform surface density distribution, expected if Poynting-Robertson and stellar wind drag are the dominant grain removal processes, and using a single-temperature blackbody, expected if the dust is located in a narrow ring around the star. The IRS spectra of many objects are better modeled with a single-temperature blackbody, suggesting that the disks possess inner holes. The distribution of grain temperatures, based on our blackbody fits, peaks at Tgr = 110-120 K. Since the timescale for ice sublimation of micron-sized grains with Tgr > 110 K is a fraction of a Myr, the lack of warmer material may be explained if the grains are icy. If planets dynamically clear the central portions of debris disks, then the frequency of planets around other stars is probably high. We estimate that the majority of debris disk systems possess parent body masses, MPB < 1 M⊕. The low inferred parent body masses suggest that planet formation is an efficient process.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/fdc9f4916d53b2aef5a3a8d55bcb31a7b4afced6

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In Astronomy and Astrophysics

1. J. Farihi
2. M. C. Wyatt
3. Eric Mamajek
4. Michael Jura
5. S. Kenyon
6. B. Bromley
7. K. Luhman
8. B. Zuckerman

In Instrumentation

1. J. Farihi
2. K. Luhman
3. M. C. Wyatt
4. Eric Mamajek
5. S. Kenyon
6. B. Bromley
7. Michael Jura
8. A. Bolatto

Citations in the corpus

• NEW DEBRIS DISKS AROUND YOUNG, LOW-MASS STARS DISCOVERED WITH THE SPITZER SPACE TELESCOPE (2009, unknown): “…consistent with the ring geometry (e.g., Kalas et al. 2008; Fitzgerald et al. 2007; Telesco et al. 2005; Krist et al. 2005a,b; Kalas et al. 2004; Stapelfeldt et al. 2004), and the IRS excess spectra consistent with a single-temperature blackbody (e.g., Morales et al. 2009; Chen et al. 2006).”
• THE DISK POPULATION OF THE UPPER SCORPIUS ASSOCIATION (2012, methodology): “Excesses in [4.5]/W2 are present for only a few stars, which may be some of the youngest debris disks in the association (Sylvester & Mannings 2000; Honda et al. 2004; Smith et al. 2008; Chen et al. 2006, 2011).”
• Steady State Evolution of Debris Disks around A Stars (2007, unknown): “…eleven sources were taken from the literature (HD1438 from Wyatt et al. 2003; HD3003 from Song et al. 2001; HD9672, HD21997, HD110058, HD158352, HD172555, and HD176638 from Rhee et al. 2007; HD109573 from Stauffer et al. 1995; HD141569 from Weinberger et al. 2000; HD153053 from Chen et al. 2006).”
• Transience of Hot Dust around Sun-like Stars (2006, background): “Silicate features have been detected in the mid-IR spectrum of all of the transient hot dust stars (Song et al. 2005; Beichman et al. 2005; Beichman et al. 2006a; Chen et al. 2006).”
• Long-Term Collisional Evolution of Debris Disks (2007, methodology): “These observations were done mostly at 24 and 70µm with the MIPS photometer, but also between 5 and 40µm with the IRS spectrometer (Jura et al. 2004; Chen et al. 2006).”
• Debris Disks in Main-Sequence Binary Systems (2006, background): “Indeed, Chen et al. (2006) provide observational evidence that IRAS-discovered debris disks are dominated by collisions and not PR drag.”
• The Spitzer Survey of the Small Magellanic Cloud: S3MC Imaging and Photometry in the Mid- and Far-Infrared Wave Bands (2006, background): “The low IR luminosity of these SMC stars in comparison to their photospheric stellar luminosity is characteristic of systems hosting debris disks (e.g., Rieke et al. 2005; Gorlova et al. 2006; Chen et al. 2006).”
• THE LINK BETWEEN PLANETARY SYSTEMS, DUSTY WHITE DWARFS, AND METAL-POLLUTED WHITE DWARFS (2012, background): “Current observations of main sequence stars with warm dust in the terrestrial planet forming region are rare and represent either recent collisions or high mass asteroidal belts (e.g. Chen et al. 2006; Lisse et al. 2009; Currie et al. 2011, and references therein).”
• Variations on Debris Disks: Icy Planet Formation at 30-150 AU for 1-3 M☉ Main-Sequence Stars (2008, background): “For systems with submillimeter observations, the measured fluxes suggest grains with sizes 1 mY1 cm and total mass 0.01 M (Wyatt et al. 2003; Liu et al. 2004a; Najita & Williams 2005; Chen et al. 2006; Williams & Andrews 2006).”
• INFRARED SIGNATURES OF DISRUPTED MINOR PLANETS AT WHITE DWARFS (2009, background): “Collisions among parent bodies result in dust production rates around main-sequence A-type stars in excess of 1010g s−1 (Chen et al. 2006).”
• Debris Disks around Sun-like Stars (2007, methodology): “…of these has excesses at both 24 and 70 m (D. E. Backman et al., in preparation); the second is photospheric at 24 m and has an excess at 70 m (Chen et al. 2006; Stapelfeldt et al. 2006); and the third has no excess at either 24 or 70 m (Chen et al. 2006; Stapelfeldt et al. 2006; Trilling et…”
• The Chemical Composition of an Extrasolar Minor Planet (2007, background): “Analysis of the 10Y20 m spectra of these stars reveals the nature of some silicate materials in the dust (Song et al. 2005; Beichman et al. 2005; Chen et al. 2006; Weinberger et al. 2007) but not the relative abundance of the elements.”