Electron capture supernova

An electron capture supernova (German: electron capture supernova ) is a core collapse supernova of a super AGB star with a main sequence mass of 7 to 9.5  solar masses . In contrast to the Fe core collapse supernovae, the core of the precursor star does not consist of iron, but mainly of oxygen, neon and magnesium.

Origin and course

In red giants on the asymptotic giant branch  (AGB) the core is an O + Ne + Mg- white dwarf , which stabilizes the gravitational forces acting on it by means of degenerative pressure . The mass and pressure of the core increase due to the temporary burning of the shell of the hydrogen and helium , the star develops into a super AGB star.

When the density in the core exceeds a value of 4 × 10 ¹² kg / m³, the electrons are captured by the magnesium atoms and the core collapse begins. The core collapses into a proton neutron star , the incident matter is reflected on the dense crust. The shock wave , which is accelerated by neutrinos emitted from the core , runs through the star and generates a UV flash when it breaks through the photosphere . The outer layers of the atmosphere and parts of the core are accelerated to escape speed due to the low density of the AGB star and ejected into the interstellar matter . According to computational simulations, only about 2 × 10 ⁻³  solar masses of radioactive nickel are generated in the collision front .

Light curve

The radioactive decay of nickel and its isotopic sequence controls the further course of the light curve . In addition, the luminosity is supported by the recombination of the ionized hydrogen in the ejecta of the supernova. Together, the two energy sources result in a brightness curve that is characteristic of the subtype IIn-P of the subluminous IIP supernova : they achieve a maximum luminosity of 2 × 10 ⁴⁴ erg / s and a brightness plateau of 10 ⁴²  erg / s lasting around 100 days .

Copies

Examples of electron capture supernovae are:

• the supernova 1054
• SN 1994W
• SN 2009kn
• SN 2011ht.

Individual evidence

1. ↑ Nozomu Tominaga, Sergei I. Blinnikov, Ken'ichi Nomoto: Supernova Explosions of Super-Asymptotic Giant Branch Stars: Multicolor Light Curves of Electron-Capture Supernovae . In: Astrophysics. Solar and Stellar Astrophysics . 2013, arxiv : 1305.6813v1 .
2. ↑ Koh Takahashi et al .: Evolution of progenitors for electron capture supernovae . In: Astrophysics. Solar and Stellar Astrophysics . 2013, arxiv : 1302.6402v1 .
3. ^ RD Ferdman et al .: The double pulsar: evidence for neutron star formation without an iron core-collapse supernova . In: Astrophysics. Solar and Stellar Astrophysics . 2013, arxiv : 1302.2914v1 .
4. ^ Nathan Smith: The Crab Nebula and the class of Type IIn-P supernovae caused by sub-energetic electron capture explosions . In: Astrophysics. Solar and Stellar Astrophysics . 2013, arxiv : 1304.0689v1 .