Are periodic mass extinctions driven by a distant solar companion?

  title={Are periodic mass extinctions driven by a distant solar companion?},
  author={Daniel P. Whitmire and Albert A. Jackson},
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 this extinction cycle is associated with the orbital period of a solar companion star. The required semi-major axis is (a*), semi-major axis) ≈ 8.8 × 104 AU = 1.4 light yr. Its highly eccentric orbit (e* \[gsims] 0.9) periodically brings the companion into the dense inner region (\[lsims]2 × 104 AU) of… 

Orbital stability of the unseen solar companion linked to periodic extinction events

Recent suggestions of astronomical causes for the closely periodic extinction events in the geological record1 and the possible periodicities in the cratering record2 have involved two basic ideas.

Cometary showers and unseen solar companions

The possibility that an invisible solar companion passing through the Oort cloud every 28 Myr precipitates a sufficiently high rate of cometary collisions with the earth to account for periodic mass

Periodic mass extinctions and the Planet X model reconsidered

The 27 Myr periodicity in the fossil extinction record has been confirmed in modern data bases dating back 500 Myr, which is twice the time interval of the original analysis from thirty years ago.

How stable is an astronomical clock that can trigger mass extinctions on Earth?

  • P. Hut
  • Physics, Geology
  • 1984
The periodicity in mass extinctions observed in the fossil record1,2 may be driven by an astronomical clock consisting of a companion star to the Sun3,4. Each perihelion passage of the companion star

Periodic comet showers and planet X

The discovery1 that Pluto's mass is insufficient to explain the discrepancies in the motions of the outer planets has led to the prediction of a tenth planet (planet X) of mass ∼1–5 M⊕ beyond the

Dynamical constraints on the mass and perihelion distance of Nemesis and the stability of its orbit

It has been suggested1,2 that the observed periodic extinction of species at intervals of 26 Myr (ref. 3) may be catalysed by a hypothetical stellar companion of the Sun, Nemesis, with an orbital

The Closest Known Flyby of a Star to the Solar System

Passing stars can perturb the Oort Cloud, triggering comet showers and potentially extinction events on Earth. We combine velocity measurements for the recently discovered, nearby, low-mass binary

Arguments for the presence of a distant large undiscovered Solar system planet

Aphelion distances of long-period comets show a slight excess around 30 000 to 50 000 au from the Sun. Positions of cometary aphelia within these distance limits are aligned along a great circle

Statistical and Evolutionary Aspects of Cometary Orbits

The observed frequency of passages of Earth-crossing long-period (LP) comets (P > 200 yr) is about three per year for comets brighter than absolute magnitude H10 ~ 10.5. About one out of six LP



Comets, Planet X and the orbit of Neptune

The recent discovery that Pluto's mass is negligible compared with that of the Earth1 has raised again the question of the cause of the important discrepancies between the observed and computed

Evidence from crater ages for periodic impacts on the Earth

Recent evidence has indicated that the impact of a comet or asteroid may have been responsible for mass extinction at the ends of both the Cretaceous1 and the Eocene2–4. Quantitative analysis by Raup

Comet showers and the steady-state infall of comets from the Oort cloud

The appearance of an inner edge to the Oort comet cloud at a semimajor axis of a = (1--2) x 10/sup 4/ AU is an observational artifact. Stellar perturbations are frequent enough and strong enough to

On companions and comets

HARRISON1 has recently hypothesised that the Sun possesses a companion star, in order to explain an anomaly in the distribution on the sky of pulsars which lose speed very slowly. This is a

Stellar perturbations of the cometary cloud

The existence of a cloud of ∼2 × 1011 comets surrounding the Solar System and extending out to interstellar distances has been suggested by Oort1 based on the observed distribution of inverse

Has the Sun really got a companion star?

HARRISON1 has pointed out that the six radio pulsars with the smallest observed spin-down rates (\Ṗ) are grouped together in a relatively small region of the sky, roughly in the direction of

Has the Sun a companion star?

PULSARS are accurate timekeepers. They are believed to be rotating neutron stars, with strong magnetic fields, and the energy they radiate is at the expense of their rotational kinetic energy1. As

Energetic comets versus the Sun's companion

The conjecture1 that another star is near the Sun (at a distance R of the order of 103 AU) has provoked much discussion2–4. Subsequent work has tended to rule out all possibilities except for a

Brown and Black Dwarfs: their Structure, Evolution and Contribution to the Missing Mass

  • D. Stevenson
  • Physics, Geology
    Publications of the Astronomical Society of Australia
  • 1978
According to Oort (1965), the mass density in the solar neighbourhood (inferred from the gravity component normal to the galactic plane) is between 50% and 150% greater than the mass density inferred