Importance of Supernovae in the Enrichment of Planetary Systems

Figure: Called the Veil Nebula, the debris is one of the best-known supernova remnants, deriving its name from its delicate, draped filamentary structures. This view is a mosaic of six Hubble pictures of a small area roughly two light-years across, covering only a tiny fraction of the nebula’s vast structure. Credit: NASA/ESA/Hubble Heritage Team

The presence and abundance of short lived radioisotopes in chondritic meteorites implies that the Sun formed in the vicinity of one or more massive stars that exploded as supernovae (SNe).

Massive stars are more likely to form in massive star clusters (>1000 M⊙) than lower mass clusters. However, photoevaporation of protoplanetary discs from massive stars and dynamical interactions with passing stars can inhibit planet formation in clusters with radii of ∼1 pc.

In a recent paper (Nicholson & Parker 2016) the authors investigate whether low-mass (50 - 200 M⊙) star clusters containing one or two massive stars are a more likely avenue for early Solar system enrichment as they are more dynamically quiescent.

They analyze N-body simulations of the evolution of these low-mass clusters and find that a similar fraction of stars experience supernova enrichment than in high mass clusters, despite their lower densities.

This is due to two-body relaxation, which causes a significant expansion before the first supernova even in clusters with relatively low initial densities. However, because of the high number of low mass clusters containing one or two massive stars, the absolute number of enriched stars is the same, if not higher than for more populous clusters.

Their results show that direct enrichment of protoplanetary discs from supernovae occurs as frequently in low mass clusters containing one or two massive stars (>20 M⊙) as in more populous star clusters (1000 M⊙).

This relaxes the constraints on the direct enrichment scenario and therefore the birth environment of the Solar System.

Nicholson & Parker 2016 (accepted in MNRAS) - Supernova enrichment of planetary systems in low-mass star clusters (arXiv)

Comments

A METHOD TO TEST THE EXISTENCE OF REGULAR BLACK HOLES

Illustration of a black hole. Image Credit & Copyright: Alain Riazuelo The existence of the singularity is an intrinsic problem of the General Relativity (GR). At the fundamentally level, the resolution of the problem of the singularity lies with the expectation that under situations where quantum effects become strong, the behavior of gravity could possibly greatly deviate from that predicted by the classical theory of GR. Regular black hole solution are proposed with the same spacetime geometry outside the horizon as the traditional black hole, but bears no singularity inside. Whether or not black hole singularities should exist, they would be covered by the black hole horizon. The black hole horizon serves as an information curtain hindering outside observers from directly observing the interior structure of the black hole, and determining that whether or not the black hole singularity does really exist. A method is needed to check the correctness of the new constructions ...

Dark Neutron Stars

Illustration of a neutron star. Credit: NASA/Dana Berry There is good evidence that electron-positron pair formation is not present in that section of the pulsar open magnetosphere which is the source of coherent radio emission, but the possibility of two-photon pair creation in an outer gap remains. Calculation of transition rates for this process based on measured whole-surface temperatures, combined with a survey of gamma-ray, X-ray and optical luminosities, expressed per primary beam lepton, shows that few Fermi LAT pulsars have significant outer-gap pair creation. For radio-loud pulsars with positive polar-cap corotational charge density and an ion-proton plasma there must be an outward flow of electrons from some other part of the magnetosphere to maintain a constant net charge on the star. In the absence of pair creation, it is likely that this current is the source of GeV gamma-emission observed by the Fermi LAT and its origin is in the region of the outer gap. With n...

SUPERNOVAE FROM WD-WD DIRECT COLLISIONS

Image: Supernova remnant N 63A. Credit: NASA/ESA/HEIC and The Hubble Heritage Team (STScI/AURA) Models for supernovae (SNe) related to thermonuclear explosions of white dwarfs (WDs) have been extensively studied over the last few decades, mostly focusing on single degenerate (accretion of material of a WD) and double degenerate (WD-WD merger) scenarios.

SpaceTime

Search This Blog