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تسجيل مستخدم جديدPredicting the incidence of planets and debris discs as a function of stellar mass
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تأليف
J.S. Greaves
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The mass of solids in a young circumstellar disc may be the key factor in its efficiency in building planetesimals and planetary cores, and dust observed around young T Tauri and Herbig Ae stars can be used as a proxy for this initial solid content. The dust-mass distributions are taken from recent millimetre-wavelength data and fitted using survival analysis to take into account upper limits, and threshold disc-masses for building planets and belts of comets are estimated. Amongst A-stars, 20% gas giant and 55% debris disc systems are predicted, in good agreement with observations. For M-stars, the predicted and observed planet-frequencies agree at ~2-3%, and this low incidence is explained by a lack of massive discs. However, debris is predicted around approx. 14% of M-stars, while only ~2% such systems have so far been found. This suggests that deeper searches such as with Herschel and SCUBA-2 may find a cold disc population previously missed around these low-luminosity stars. Also, an estimate of the efficiency of building millimetre-detected dust into planetary cores suggests that about a third of M-stars could host an Earth-mass planet -- but as the dust is spread over large disc areas, such planets may orbit far from the star.
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We study mass transfers between debris discs during stellar encounters. We carried out numerical simulations of close flybys of two stars, one of which has a disc of planetesimals represented by test particles. We explored the parameter space of the
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Ing-Guey Jiang Department of Physics andn Institute of Astronomy
, National Tsing-Hua University
2009
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Exoplanet surveys of evolved stars have provided increasing evidence that the formation of giant planets depends not only on stellar metallicity ([Fe/H]), but also the mass ($M_star$). However, measuring accurate masses for subgiants and giants is fa
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