Progenitor stars of type IIn supernovae using the NCR method
Välitalo, Milla (2024-12-16)
Progenitor stars of type IIn supernovae using the NCR method
(16.12.2024)
Julkaisu on tekijänoikeussäännösten alainen. Teosta voi lukea ja tulostaa henkilökohtaista käyttöä varten. Käyttö kaupallisiin tarkoituksiin on kielletty.
avoin
Julkaisun pysyvä osoite on:
https://urn.fi/URN:NBN:fi-fe202501133521
https://urn.fi/URN:NBN:fi-fe202501133521
Tiivistelmä
Supernovae are massive stars exploding at the end of their lifetime, when the processes active during their life can no longer maintain a stable star. There are multiple ways for a star to become a supernova, and thus they are classified through their distinct types of spectra. They are classified into two main types based on hydrogen, type I without it and type II SNe including hydrogen.
Type IIn supernovae have been classified into their own subtype since the 1990s. They can be recognized from their narrow Hα emission lines, resulting in fairly similar spectra. The narrow Hα line comes from the interaction between the supernova's ejecta and the surrounding material. The progenitor stars of some supernova types are known, but it is still not fully known what kind of composition of star types forms the progenitors of type IIn supernovae and in which quantity.
One way to study the progenitors of type IIn supernovae is to use the normalized cumulative ranking (NCR) method. The method is used to calculate a value based on the supernova's position and the strength of the Hα emission at that location. The NCR value is calculated for both the type IIn supernovae as well as for different types of stars. Since star formation and Hα emission areas correlate, it is possible to estimate the ages and mass of the progenitors.
This study found multiple different stars to be possible progenitors of type IIn supernovae based on their NCR distribution. Especially interesting is how well correlated yellow supergiants and type IIn supernovae are, although yellow supergiants did not exhibit the same multimodality as type IIn supernovae. The best combination of two progenitors was found to be made of red supergiants and late type WN stars or stars of similar mass.
Type IIn supernovae have been classified into their own subtype since the 1990s. They can be recognized from their narrow Hα emission lines, resulting in fairly similar spectra. The narrow Hα line comes from the interaction between the supernova's ejecta and the surrounding material. The progenitor stars of some supernova types are known, but it is still not fully known what kind of composition of star types forms the progenitors of type IIn supernovae and in which quantity.
One way to study the progenitors of type IIn supernovae is to use the normalized cumulative ranking (NCR) method. The method is used to calculate a value based on the supernova's position and the strength of the Hα emission at that location. The NCR value is calculated for both the type IIn supernovae as well as for different types of stars. Since star formation and Hα emission areas correlate, it is possible to estimate the ages and mass of the progenitors.
This study found multiple different stars to be possible progenitors of type IIn supernovae based on their NCR distribution. Especially interesting is how well correlated yellow supergiants and type IIn supernovae are, although yellow supergiants did not exhibit the same multimodality as type IIn supernovae. The best combination of two progenitors was found to be made of red supergiants and late type WN stars or stars of similar mass.