Supernova triggers for end-Devonian extinctions.

The Late Devonian was a protracted period of low speciation resulting in biodiversity decline, culminating in extinction events near the Devonian-Carboniferous boundary. Recent evidence indicates that the final extinction event may have coincided with a dramatic drop in stratospheric ozone, possibly due to a global temperature rise. Here we study an alternative possible cause for the postulated ozone drop: a nearby supernova explosion that could inflict damage by accelerating cosmic rays that can deliver ionizing radiation for up to [Formula: see text] ky.

Hypothesis: Muon Radiation Dose and Marine Megafaunal Extinction at the End-Pliocene Supernova.

Considerable data and analysis support the detection of one or more supernovae (SNe) at a distance of about 50 pc, ∼2.6 million years ago. This is possibly related to the extinction event around that time and is a member of a series of explosions that formed the Local Bubble in the interstellar medium.

Terrestrial effects of moderately nearby supernovae.

Recent data indicate one or more moderately nearby supernovae in the Early Pleistocene, with additional events likely in the Miocene. This has motivated more detailed computations, using new information about the nature of supernovae and the distances of these events to describe in more detail the sorts of effects that are indicated at the Earth. This short communication/review is designed to describe some of these effects so that they may possibly be related to changes in the biota around these times.

A Supernova at 50 pc: Effects on the Earth's Atmosphere and Biota.

Recent Fe results have suggested that the estimated distances of supernovae in the last few million years should be reduced from ∼100 to ∼50 pc. Two events or series of events are suggested, one about 2.7 million years to 1.

A Possible Role for Stochastic Astrophysical Ionizing Radiation Events in the Systematic Disparity between Molecular and Fossil Dates.

Major discrepancies have been noted for some time between fossil ages and molecular divergence dates for a variety of taxa. Recently, systematic trends within avian clades have been uncovered. The trends show that the disparity is much larger for mitochondrial DNA than for nuclear DNA, also that it is larger for crown fossil dates than stem fossil dates.

TERRESTRIAL EFFECTS OF NEARBY SUPERNOVAE IN THE EARLY PLEISTOCENE.

Recent results have strongly confirmed that multiple supernovae happened at distances of ∼100 pc, consisting of two main events: one at 1.7-3.2 million years ago, and the other at 6.

Astrophysical ionizing radiation and Earth: a brief review and census of intermittent intense sources.

Cosmic radiation backgrounds are a constraint on life, and their distribution will affect the Galactic Habitable Zone. Life on Earth has developed in the context of these backgrounds, and characterizing event rates will elaborate the important influences. This in turn can be a base for comparison with other potential life-bearing planets.

Long-term cycles in the history of life: periodic biodiversity in the paleobiology database.

Time series analysis of fossil biodiversity of marine invertebrates in the Paleobiology Database (PBDB) shows a significant periodicity at approximately 63 My, in agreement with previous analyses based on the Sepkoski database. I discuss how this result did not appear in a previous analysis of the PBDB. The existence of the 63 My periodicity, despite very different treatment of systematic error in both PBDB and Sepkoski databases strongly argues for consideration of its reality in the fossil record.

Superluminous supernovae: no threat from eta Carinae.

Recently, Supernova 2006gy was noted as the most luminous ever recorded, with a total radiated energy of approximately 10(44) Joules. It was proposed that the progenitor may have been a massive evolved star similar to eta Carinae, which resides in our own Galaxy at a distance of about 2.3 kpc.

Considering the case for biodiversity cycles: re-examining the evidence for periodicity in the fossil record.

We re-examine the evidence for a 62 million year (Myr) periodicity in biodiversity throughout the Phanerozoic history of animal life reported by, as well as related questions of periodicity in origination and extinction. We find that the signal is robust against variations in methods of analysis, and is based on fluctuations in the Paleozoic and a substantial part of the Mesozoic. Examination of origination and extinction is somewhat ambiguous, with results depending upon procedure.

Peculiar velocity surveys: optimal moments analysis.

A new formalism to analyze peculiar velocity surveys is presented. Results from these surveys are shown to be dominated by small-scale noise, aliasing, and incomplete cancellations. The formalism allows us to filter out the signal from scales that are not of interest and thus provides us with a clean signal that probe large scales.

Environmental Dependence of the Fundamental Plane of Galaxy Clusters.

Galaxy clusters approximate a planar distribution in a three-dimensional parameter space that can be characterized, for example, by an optical luminosity, half-light radius, and X-ray luminosity. We find the nearest neighbor clusters for those common to either of two previous fundamental-plane studies and a high-quality cluster redshift catalog. Examining scatter about one plane in parameter space, we find a 2 sigma result that it is dependent on the nearest neighbor distance.