The effect of interstellar matter on climatic variation

Abstract

The effect of interstellar matter on the sun's radiation is considered with a view to explaining changes in terrestrial climate. It appears that a star in passing through a nebulous cloud will capture an amount of material which by the energy of its fall to the solar surface can bring about considerable changes in the quantity of radiation emitted. The quantity of matter gathered in by the star depends directly on the density of the cloud and inversely on the cube of its velocity relative to the cloud. Thus vastly different effects on the solar radiation can be brought about under fairly narrow ranges of density and relative velocity (ranges that are in accordance with astronomical evidence). In this way the process is able to explain the small changes in the solar radiation that are necessary to produce an ice age and, under conditions less likely to have taken place frequently, the high increase in radiation required for the Carboniferous Epoch. Despite the large effects that the mechanism can bring about, it is shown that the mass of the sun does not undergo appreciable change and hence reverts to its former luminosity once the cloud has been traversed.

Scaling relations between black holes and their host galaxies: comparing theoretical and observational measurements, and the impact of selection effects

“…Bromm sertion, BHs grow in mass by accretion of surrounding gas and by merging with other black holes. Gas is accreted ac- (Hoyle & Lyttleton 1939;Bondi & Hoyle 1944;Bondi 1952), where ρ is the local gas density, cs is the local sound speed, v is the velocity of the BH relative to the surrounding gas, and α is introduced to correct for the reduction of the gas density close to the BH due to our effective sub-resolution model for the ISM. To allow for the initial rapid BH growth necessary to produce sufficiently massive BHs at early time (∼ 10 9 M⊙ by z ∼ 6) we allow for mildly super-Eddington accretion (consistent with Begelman et al 2006), but limit it to a maximum of 3 ×Ṁ Edd to prevent artificially high values.…”

Star formation in mergers with cosmologically motivated initial conditions

“…BH particles accrete mass by Eddington limited Bondi-Hoyle accretion (Hoyle & Lyttleton 1939;Bondi & Hoyle 1944;Bondi 1952), and this accretion is assumed to deposit thermal energy into the surrounding medium at a rate proportional to the accretion rate: E feed = ǫ f ǫrṀBH c 2 where ǫ f is the coupling strength of the feedback, and is adopted from Di , and ǫr is the standard conversion factor of rest-mass to energy for a standard thin accretion disk from Shakura & Sunyaev (1973).…”

Dynamics of jets during the common-envelope phase

“…The Bondi-Hoyle-Lyttleton (BHL, Bondi & Hoyle 1944;Hoyle & Lyttleton 1939) accretion radius can be a considerable fraction of the stellar radius. The accretion rate estimated by Brown (1995) and Chevalier (1996), when including highly-efficient neutrino cooling, is large enough to favour the formation of BH-NS systems over NS-NS systems.…”