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Habitable zones around main sequence stars.
A one-dimensional climate model is used to estimate the width of the habitable zone (HZ) around our Sun and around other main sequence stars. Our basic premise is that we are dealing with Earth-likeExpand
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A slightly more massive young Sun as an explanation for warm temperatures on early Mars.
The valley network channels on the heavily cratered ancient surface of Mars suggest the presence of liquid water approximately 3.8 Gyr ago. However, the implied warm climate is difficult to explainExpand
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Persistent evidence of a jovian mass solar companion in the Oort cloud
Abstract We present updated dynamical and statistical analyses of outer Oort cloud cometary evidence suggesting that the Sun has a wide-binary jovian mass companion. The results support a conjectureExpand
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Are periodic mass extinctions driven by a distant solar companion?
Raup and Sepkoski1–3 have recently reported evidence for a 26-Myr cycle in biological mass extinctions which, if real, requires an astronomical explanation. Here we investigate a model in which thisExpand
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Habitable Planet Formation in Binary Star Systems
Abstract Assuming current models of terrestrial planet formation in the Solar System, we numerically investigate the conditions under which the secondary star in a binary system will inhibit planetExpand
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Cometary Evidence of a Massive Body in the Outer Oort Clouds
Approximately 25% of the 82 new class I Oort cloud comets have an anomalous distribution of orbital elements that can best be understood if there exists a bound perturber in the outer Oort cloud.Expand
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Planet X and the origins of the shower and steady state flux of short-period comets
Abstract In the planet X model periodic comet showers are associated with passages of the planet's perihelion and aphelion points through a primordial disk of comets believed to lie beyond the orbitExpand
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The slaved disc model for SS 433
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