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http://inaoe.repositorioinstitucional.mx/jspui/handle/1009/2241| HERSCHEL’S “COLD DEBRIS DISKS”: BACKGROUND GALAXIES OR QUIESCENT RIMS OF PLANETARY SYSTEMS? | |
| Carlos del Burgo Díaz | |
| Acceso Abierto | |
| Atribución-NoComercial-SinDerivadas | |
| Stars: individual: (HIP 29271, HIP 49908, HIP 109378, HIP 92043, HIP 171, HIP 73100) Circumstellar matter Planetary systems: formation Planetary systems: protoplanetary disks Galaxies: statistics | |
| Infrared excesses associated with debris disk host stars detected so far, peak at wavelengths around ~100 μm or shorter. However, six out of 31 excess sources studied in the Herschl ͣ Open Time Key Programme, DUNES, have been seen to show significant – and in some cases extended – excess emission at 160 μm, which is larger than the 100 μm excess. This excess emission has been attributed to circumstellar dust and has been suggested to stem from debris disks colder than those known previously. Since the excess emission of the cold disk candidates is extremely weak, challenging even the unrivaled sensitivity of Herschel, it is prudent to carefully consider whether some or even all of them may represent unrelated galactic or extragalactic emission, or even instrumental noise. We readdress these issues using several distinct methods and conclude that it is highly unlikely that none of the candidates represents a true circumstellar disk. For true disks, both the dust temperatures inferred from the spectral energy distributions and the disk radii estimated from the images suggest that the dust is nearly as cold as a blackbody. This requires the grains to be larger than ~100 μm, even if they are rich in ices or are composed of any other material with a low absorption in the visible. The dearth of small grains is puzzling, since collisional models of debris disks predict that grains of all sizes down to several times the radiation pressure blowout limit should be present. We explore several conceivable scenarios: transport-dominated disks, disks of low dynamical excitation, and disks of unstirred primordial macroscopic grains. Our qualitative analysis and collisional simulations rule out the first two of these scenarios, but show the feasibility of the third one. We show thatsuch disks can indeed survive for gigayears, largely preserving the primordial size distribution. They should be composed of macroscopic solids larger than millimeters, but smaller than a few kilometers in size. If larger planetesimals were present, they would stir the disk, triggering a collisional cascade and thus causing production of small debris, which is not seen. Thus planetesimal formation, at least in the outer regions of the systems, has stopped before “cometary” or “asteroidal” sizes were reached. | |
| The Astrophysical Journal | |
| 12-06-2013 | |
| Artículo | |
| Inglés | |
| Estudiantes Investigadores Público en general | |
| Krivov, A. V., et al., (2013), Herschel’s “cold debris disks”: background galaxies or quiescent rims of planetary systems?, The Astrophysical Journal, Vol. 772(1):1-22 | |
| ASTRONOMÍA Y ASTROFÍSICA | |
| Versión aceptada | |
| acceptedVersion - Versión aceptada | |
| Aparece en las colecciones: | Artículos de Astrofísica |
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| Fichero | Tamaño | Formato | |
|---|---|---|---|
| 23. Cold Debris Disks-Background Galaxies or Quiescent Rims of Planetary Systems.pdf | 797.96 kB | Adobe PDF | Visualizar/Abrir |