Type IIP supernova

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A type IIP supernova is a hydrogen-rich core collapse supernova , in the light curve of which there is a 100-day standstill, which is known as the plateau phase. Recent surveys show that 50% of all core collapse supernovae have a plateau phase in the sloping branch of the light curve.

Nuclear collapse supernovae are the final stages of a massive star with an original mass of more than eight solar masses . After the stars have synthesized elements up to iron, the element with the highest binding energy , in their core , they can not generate any further energy through nucleosynthesis and thus build up a pressure that counteracts gravitation. As a result, a core collapse occurs, in which the core collapses into a protoneutron star . The material that continues to fall is reflected on the core and travels outward through the star as a shock wave . In the collision front , the temperature rises to several hundred million degrees and generates heavy elements beyond the iron via the r-process .

Light curve as a function of brightness over time for Type IIL and IIP supernovae

After the shock wave breaks through the stellar atmosphere , the course of brightness is determined by the radioactive decay along the chain 56 Ni → 56 Co → 56 Fe. In the astronomical logarithmic brightness system, this leads to a linear decrease in brightness and the supernovae are referred to as Type IIL (linear). In the case of the IIP supernovae with their plateau lasting a good hundred days, in addition to radioactive decay, additional energy comes from the cooling of the ejecta heated by the shock front from the recombination of hydrogen.

The luminosity during the plateau phase spreads over an order of magnitude between 10 42.5 erg / s up to 10 41.5 erg / s for underluminous supernovae of type IIP. The underluminous IIP supernovae also show both a lower expansion speed of the Balmer lines of 1,000 km / s compared to up to 5,000 km / s and a lower brightness after the plateau phase. This has been linked to a small amount of nickel synthesized in the supernova. In hypoluminous IIP supernovae, only 0.002 to 0.005 solar masses of nickel are produced, while the amount of nickel in normal luminous SN IIP reaches 0.1 solar masses.

The precursor star of a type IIP supernova is a red supergiant or yellow hypergiant . These stars, which can be seen on recordings before the explosion at the location of the supernova, can no longer be detected a few years after the explosion. According to simulation calculations, the mass of the forerunner stars is in the range of 9 to 32 solar masses, while the observed stars seem to have rather lower masses of 9 to 17 solar masses. A un-nova is likely to form in red supergiants with higher mass . This is a failed supernova, the explosion mechanism of which does not release enough energy so that the shell can overcome the gravitational potential of the newly formed black hole .

The plateau phase makes it possible to determine the distance to the supernova with high accuracy, and thus the IIP supernovae are a standard candle for cosmological distances due to their high luminosity . However, the Expanding Photosphere Method , the Spectral-Fitting Expanding Atmosphere Model and the Standardized Candle Method require high-resolution spectra over a long period of time and are therefore more complex than the Phillips relationship for thermonuclear supernovae of type Ia.

Individual evidence

  1. L. Tomasella et al .: Comparison of progenitor mass estimates for the type IIP SN 2012A . In: Astrophysics. Solar and Stellar Astrophysics . 2013, arxiv : 1305.5789v1 .
  2. Roberta M. Humphreys, Kris Davidson, Skyler Grammer, Nathan Kneeland, John C. Martin, Kerstin Weis, Birgitta Burggraf: Luminous and Variable Stars in M31 and M33. I. The Warm Hypergiants and Post-Red Supergiant Evolution . In: Astrophysics. Solar and Stellar Astrophysics . 2013, arxiv : 1305.6051v1 .
  3. Luc Dessart, D. John Hillier, Roni Waldman, Eli Livne: Type II-Plateau supernova radiation: dependencies on progenitor and explosion properties . In: Astrophysics. Solar and Stellar Astrophysics . 2013, arxiv : 1305.3386v1 .
  4. CS Kochanek: Failed Supernovae Explain the Compact Remnant Mass Function . In: Astrophysics. Solar and Stellar Astrophysics . 2013, arxiv : 1308.0013v1 .
  5. Subhash Bose, Brijesh Kumar, Firoza Sutaria, Brajesh Kumar, Rupak Roy, VK Bhatt, SB Pandey, HC Chandola, Ram Sagar, Kuntal Misra, Sayan Chakraborti: Supernova 2012aw - a high-energy clone of archetypal type IIP SN 1999em . In: Astrophysics. Solar and Stellar Astrophysics . 2013, arxiv : 1305.3152v1 .