Super massive star
Super massive stars (also supermassive stars , after English supermassive stars ) were hypothetical stars with a mass in the order of 100,000 solar masses in the early phase of the universe . Their collapse currently provides the only satisfactory explanation for the formation of supermassive black holes (up to 10 9 solar masses) some 100 million years after the Big Bang ; such supermassive black holes can already be detected at a redshift of z> 7.
Formation of supermassive black holes
Super-massive black holes in the cores of galaxies lead to the various manifestations of active galactic nuclei as quasar , blazar , Seyfert galaxy , etc. The effects of active galactic nuclei on their environment have been proven in the early phase of the universe at an age of less than a billion years. From a theoretical point of view, this is a problem because stellar black holes with 100 solar masses cannot have built up that much mass per accretion in this relatively short period of time ; the accretion rate is limited to the Eddington limit.
In contrast, supermassive stars could have a much higher accretion rate after their gravitational collapse. Hence, they are the preferred hypothesis for the rapid formation of supermassive black holes.
Other hypotheses about the formation of supermassive black holes, such as the direct collapse of a gas cloud into a black hole, the collapse of star clusters and clusters of black holes, are largely rejected on the basis of theoretical considerations.
Special conditions in the early phase of the cosmos
No stars with more than a few hundred solar masses are detectable in the local universe. The difference is attributed to the special conditions in the early phase of the cosmos:
- The low metallicity in combination with a gas temperature of 10,000 Kelvin allowed the formation of supermassive stars without fragmentation of the protostar .
- Also due to the low metallicity, no stellar winds were formed , which would drive stars with more than 100 solar masses apart again in the local universe. In addition, there were no pulsation instabilities.
- Due to a high accretion rate, the protostar rotated at great speed. This led to an avoidance of the gravitational collapse by centrifugal forces and to a constant mixture of fresh material in the core, which therefore could generate energy longer by means of thermonuclear reactions and prevent the collapse.
Observation of supermassive stars
Simulations of supermassive stars have shown that they should be surprisingly cool at 6000 to 8000 Kelvin. Because of this, and because of their enormous size, they should be observable in the infrared range for future telescopes such as the James Webb Space Telescope .
See also
Web links
literature
- Kohei Inayoshi, Kazuyuki Omukai, Elizabeth J. Tasker: Formation of an embryonic supermassive star in the first galaxy . In: Astrophysics. Solar and Stellar Astrophysics . 2014, arxiv : 1404.4630v1 .
- Takashi Hosokawa, Harold W. Yorke, Kohei Inayoshi, Kazuyuki Omukai, Naoki Yoshida: Formation of Primordial Supermassive Stars by Rapid Mass Accretion . In: Astrophysics. Solar and Stellar Astrophysics . 2013, arxiv : 1308.4457v2 .
- Dominik RG Schleicher, Francesco Palla, Andrea Ferrara, Daniele Galli, Muhammad Latif: Massive black hole factories: Supermassive and quasi-star formation in primordial halos . In: Astrophysics. Solar and Stellar Astrophysics . 2013, arxiv : 1305.5923v1 .
- C. Reisswig et al .: Formation and Coalescence of Cosmological Supermassive Black Hole Binaries in Supermassive Star Collapse . In: Astrophysics. Solar and Stellar Astrophysics . 2013, arxiv : 1304.7787v2 .
Individual evidence
- ↑ On the Detection of Supermassive Primordial Stars . Cornell University. December 12, 2018. Retrieved August 2, 2019.
- ↑ For The First Time, We're Close to Seeing Supermassive Stars From The Early Universe . sciencealtert. December 2, 2018. Retrieved August 2, 2019.