According tomedia reports, a new theory could explain one of the biggest mysteries about how the Milky Way and other galaxies were created, exploring the role of white dwarfs in creating the building blocks of the universe. Carbon is not only a tool for galaxy formation, but also a tool for life, but its origins in the Milky Way are still unclear. Carbon atoms are produced by stars and are the product of the fusion process of helium. But exactly how it got into the galaxy from there has been debate.
One possibility is that low-mass stars may be worn by stellar winds and lose their carbon wrap as they mature into white dwarfs. Dense stars that collapse over billions of years will eventually emit carbon from other elements when they eventually die. But another theory is that larger stars explode, creating supernovaes that spread carbon, forming the Milky Way where Earth is located.
Backtracking time is obviously not something astronomers can do, but by analyzing the white dwarfs found in open clusters in the Milky Way, they have a better idea. Astronomers used the Keck Observatory to observe the cluster in 2018 — made up of thousands of stars, roughly the same age– and remain the same through mutual gravitational attraction. Importantly, the stars in these clusters all come from the same molecular cloud. By measuring the mass of white dwarfs, astronomers were able to derive the mass at birth. Because this advance is a known amount in astrophysics, the so-called initial-final mass relationship.
But what I didn’t expect was that the white dwarf of the Open Star cluster did not fit in with that relationship. Instead, these old stars weigh more than they “should” weigh. The result is a new mass boundary, on both sides, that revolves differently around how carbon is stripped out of evolving stars and how their own mass is affected. Stars larger than two solar masses produce new carbon atoms, which are transferred to the surface and then spread through the stellar wind through the universe. However, stars with less than 1.5 solar masses do not.
“In other words, 1.5 solar masses represent the smallest mass of carbon-rich ash transmitted by a star after death,” concluded researchers led by Paola Marigo of the University of Padua in Italy and Enrico Ramirez-Ruiz, professor of astronomy and astrophysics at the University of California, Santa Cruz. “These findings impose strict limits on how and when carbon is generated by the stars of our milky way, eventually trapped in the raw materials that formed by the sun and its planetary systems 4.6 billion years ago,” he said.
While this study clearly explains some of the history of our own galaxy, it also has implications for the wider universe. “The relationship between initial mass and final mass is also the reason why supernovae are large explosions that they see at large distances and are really important for understanding the nature of the universe,” explained study co-author Pier-Emmanuel Tremblay of the University of Warwick.