Type Ib and Ic supernovae

A Stripped - Envelope Supernova is a core-collapse supernova, the spectrum shows during the eruption little or no hydrogen. The progenitor star of the supernova has lost its outer atmosphere due to strong stellar winds or due to mass transfer in close binary systems before the explosion.

Core-collapse supernova

Star act against the gravitational force by the thermal gas, wherein the temperature is a consequence of thermonuclear reactions at or near the star cores. In the nuclear fusion as a function of the mass of the star, heavy elements are produced up to iron. Since iron has the highest binding energy of all the chemical elements, the star can no longer escape the gravitational collapse by a further contraction and increasing the temperature in its core. Gamma rays are produced instead by a temperature rise that destroy existing iron atoms by photo disintegration in an endothermic reaction. Furthermore, neutrinos are produced by the inverse beta decay, leaving due to their low interaction cross -section almost unhindered the star and thus lead to a further cooling of the core. This allows the star to Gravitational collapse not avoid and the core collapses into a proto- neutron star. This reflects the incoming matter, by the star running as a shock front to the outside and appears as a supernova after emerging from the atmosphere.

Properties of Stripped - Envelope Supernovae

In some core collapse supernovae little or no hydrogen can be detected in their spectra. This Stripped - Envelope Supernovae are according to their range further divided into subclasses

• Ib with strong helium lines and no hydrogen lines
• Ic, in which no helium lines nor hydrogen lines can be detected

In the first 100 days after the eruption, the expansion velocity of Stripped - Envelope Supernovae is remarkably uniform at 4,500 km / s. , With only minor differences from star to star A separate group is formed by the hydrogen- poor hypernovae whose expansion speed can reach up to a tenth of the speed of light. Stripped - Envelope Supernovae are in maximum with Mv = -17.8 likes fainter than the thermonuclear supernovae of type Ia, with lows like up to 2 is.

Progenitor star

Stripped - Envelope Supernovae occur preferentially in interacting galaxies, where it is millions of years ago came through the gravitational interaction between the islands of stars in a starburst. Therefore, the progenitor star should also only an age of a few tens of million years before they explode. From the development of the radio light curve can be concluded that dense circumstellar matter, which does not correspond to the observed density of the presumed progenitor stars, the Wolf -Rayet star.

For modulations of the radio light curves of some of Stripped - Envelope Supernovae and spektropolarimetrischen observations has been closed on a double-star nature of the progenitor star, after which the outer atmosphere has been transmitted through mass exchange in a close binary system to a companion. These conclusions, however, are controversial. Alternatively, the outer layers could be lost by strong winds Rochester as the light Strengthening Blue Variables that may directly explode as a supernova.

Numerical simulations can expect that all progenitor star of Stripped - Envelope Supernovae had an initial mass of about 25 solar masses and have lost before the explosion about 20 solar masses. To reproduce the observed spectra, the II-b and Ib supernovae in interacting binary stars seem to arise because only there that the mixing can be achieved. The hydrogen-and helium- poor supernovae Ic appear to originate from massive single stars, however. While no progenitor star for Type I supernovae were identified Yellow hypergiants have been found at the site of SN IIb in two cases that could not be detected after the explosion. They can not yet be wandered far from their place of origin, since the supernovae of stars come with a high mass. Spectroscopic observations of stars in the vicinity of Type Ib and Ic supernovae show that these are unusually metal rich rich.

Associated with gamma ray bursts

In a number of long gamma -ray bursts in the same place a Stripped - Envelope supernova has been observed. These show no signs of helium or hydrogen in the spectra, but they are somewhat more luminous than the corresponding supernova type Ic. This relationship between a subset of gamma ray bursts and the stripped - envelope supernovae produced by the collapsar model. After that, it comes in a core-collapse supernova to a gravitational collapse in a massive star, which shows a proto - neutron star with a rotation period of the order of a millisecond and a strong magnetic field with a magnetic flux density of more than 1011 t. For this proto- neutron star, an energy of up to 1045 J within a period of 100 s can be extracted. This energy occurs under certain conditions along the axis of rotation of a massive star and a jet accelerated to relativistic speeds. If such jets directed towards the earth, they are registered here as gamma-ray bursts of long duration. The magnetar collapses probably due to back- falling matter within a short time into a black hole after exceeding the Tolman -Oppenheimer - Volkoff limit.

However Stripped - envelope supernovae are probably only for a subset of the long gamma -ray bursts the cause. So far supernova have been found at the site of GRBs only for low luminosity bursts whose average luminosity under which lies in the field of gamma radiation by a factor of 100 to 10,000 by distant bursts. Furthermore, the eruptions of gamma -ray bursts associated with a Stripped - envelope supernovae are unusually long and may not represent the entire population of long GRBs.

Ultra - Stripped supernovae of type Ic

A small group of supernovae that are discovered during surveys, show the spectral properties of a Stripped - Envelope supernova at a luminosity that is a factor of 100 or more below a typical supernovae of type Ic. Examples are 2005ek SN, SN 2010X and SN 2005E, the ejected mass is only 0.05 to 0.2 solar masses. The properties of these ultra - Stripped suspect let supernovae that the gravitational collapse occurs in a star with a mass of 1.5 solar masses. Such a helium star can evolve in a close binary system where can form a star with an iron core of 1.4 solar masses and a thin helium atmosphere during a common- envelope phase. With an ultra - Stripped supernova close binary consisting of two neutron stars could like the pulsar PSR 1913 16 Doppelpulsarsystem arise.

Itemization

• Supernova