Newfound Star(s) Challenges our Theory of Stellar Evolution
Newfound Star(s) Challenges our Theory of Stellar Evolution
Ben Tubiello, March 29, 2022
The Stars
A controversial pair of stars, PG1654+322 (10,000 light years from Earth) and PG1528+025 (25,000 light years from Earth), were recently discovered by a team of researchers, led by Professor Klaus Werner of the University of Tübingen. Their discovery through the Large Binocular Telescope in Arizona, however, is causing a bit of a stir due to the stars’ extremely peculiar features. Both stars are covered in an ash-like substance that is produced when helium burns inside the stars to provide fuel, which gives them a surface composition of carbon and oxygen due to the nuclear fusion process. The temperatures and radii of each implies that the stars are still burning helium in their cores. The rarity of the combination of these components led the researchers to believe that these stars formed from a stellar merger of two white dwarfs, as shown in Figure 1. Mergers between two white dwarfs, or white dwarfs with binary systems, have occurred before, but there has never been an outcome like PG1654+322 and PG1528+025. Another author of the study, Miller Bertolami, explained a possibility for how a product like these two stars could be created– “For binary systems formed with very specific masses, a carbon and oxygen-rich white dwarf might be disrupted and end up on top of a helium-rich one, leading to the formation of these stars.” As of right now, this is the only possible explanation for the formation of these stars that has been developed, but the situation is still managing to make astronomers question our theory of stellar evolution.
Figure 1. An artist’s interpretation of a stellar merger between two white dwarf stars
How is it peculiar?
Typically, stars of similar size have barely any traces of heavier elements like carbon and oxygen and have tons of helium and hydrogen in their surfaces, but these stars have a surface composition of which about 20% is carbon and oxygen. The size and temperature of the stars also decrease over time as this process of burning helium collapses the star’s center, which cools it down and makes it smaller. Stars of this surface composition have usually already undergone nuclear fusion reactions that burn up the helium and hydrogen in its core. The two new discoveries counter each of these assumptions, disrupting our current understanding of stellar properties. These stars aren’t close to the end of their life, and still burn helium in their core while being extremely hot and relatively large, as previously stated. The discovery resulted in a new type of star being classified, but further research is needed in our theory for stellar evolution in order to properly assess the situations of the subdwarfs, PG1654+322 and PG1528+025. Until astronomers gather more information on the later evolutionary stages of binary stars, there is no definite answer for the origin of these interesting stars.
Links to references:
https://bgr.com/science/scientists-discovered-a-strange-new-type-of-star-that-has-them-puzzled/
https://www.republicworld.com/science/space/newly-born-stars-with-never-before-seen-properties-in-milky-way-baffle-astronomers-articleshow.html
As astronomers have to wait to gather more information on the later evolutionary stages of binary stars, it makes me wonder how long it might take for us to know more about this interesting discovery. I also wonder if anything might be produced from these stars from either its remnants or the burning of its elements.
ReplyDelete- Emma Levy
DeleteWhat an interesting article! Certainly, there is so much more to learn about these "zombie stars" and the process that drives their continuation of fusion. It certainly makes you wonder what other bizarre and weird objects that are out there still awaiting discovery and explanations.
ReplyDeleteI find it fascinating that astronomers are constantly unveiling more information about the evolution process of stars through new discoveries
ReplyDeleteIt is also fascinating to see theories being challenged as we discover more in a field. I wonder what could this mean if we find a star so peculiar. Should we create another standard to categorize stars?
ReplyDelete