منابع مشابه
Vertical structure of debris discs
Context. The vertical thickness of debris discs is often used as a measure of these systems’ dynamical excitation, and as clues to the presence of hidden massive perturbers such as planetary embryos. However, this argument might be flawed because the observed dust should be naturally placed on inclined orbits by the combined effect of radiation pressure and mutual collisions. Aims. We criticall...
متن کاملAtomic gas in debris discs
We have conducted a search for optical circumstellar absorption lines in the spectra of 16 debris disc host stars. None of the stars in our sample showed signs of emission line activity in either Hα, Ca II or Na I, confirming their more evolved nature. Four stars were found to exhibit narrow absorption features near the cores of the photospheric Ca II and Na I D lines (when Na I D data were ava...
متن کاملVertical Structure of Accretion Discs with Hot Coronae in AGN
We study vertical structure of radiation pressure dominated disc with a hot corona. We include all the relevant processes like bound–free opacity and convection. We show that the presence of the corona modifies considerably the density and the opacity of the disc surface layers which are important from the point of view of spectrum formation. The surface of the disc with a corona is much denser...
متن کاملCollisional Dust Avalanches in Debris Discs
We quantitatively investigate how collisional avalanches may develop in debris discs, as the result of the initial break-up of a planetesimal or comet-like object, triggering a collisional chain reaction due to outward escaping small dust grains. We use a specifically developed numerical code that follows both the spatial distribution of the dust grains and the evolution of their size-frequency...
متن کاملDebris discs around nearby Solar analogues
An unbiased search for debris discs around nearby Sun-like stars is reported. Thirteen G-dwarfs at 12-15 parsecs distance were searched at 850 μm wavelength, and a disc is confirmed around HD 30495. The estimated dust mass is 0.008 M⊕ with a net limit . 0.0025 M⊕ for the average disc of the other stars. The results suggest there is not a large missed population of substantial cold discs around ...
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ژورنال
عنوان ژورنال: Astronomy & Astrophysics
سال: 2009
ISSN: 0004-6361,1432-0746
DOI: 10.1051/0004-6361/200912396