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 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 ...
متن کاملOuter edges of face - on spiral galaxies ⋆
We present deep optical imaging of three face-on disk galaxies together with a detailed description of the reduction and calibration methods used, in order to measure the intrinsic shape of their outer stellar edges. Whereas it is now well accepted that disks of spiral galaxies are not infinite exponential beyond galactocentric distances of about 3-5 radial scalelengths, the genuine structure o...
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ژورنال
عنوان ژورنال: Astronomy & Astrophysics
سال: 2008
ISSN: 0004-6361,1432-0746
DOI: 10.1051/0004-6361:20079133