Childhood of stars shapes stellar evolution

Scientists are now showing that star biography is already forming through its early stages.

In classical models of stellar evolution, little importance has yet been given to the early evolution of stars. Scientists are now showing that star biography is already forming through its early stages.

From kids to teens: the stars in their “younger years” present a major challenge to science. The process of star formation is particularly complex and difficult to determine in theoretical models. One of the few ways to learn more about a star’s composition, structure, or age is by observing its vibrations. “Compared with the exploration of the Earth’s interior with the help of seismology, we can also make statements about its internal structure, and thus also about the age of stars based on their oscillations,” says Konstanze Zwintz. The astronomer is a pioneer in the field of young stellar mercury science and leads the research group “Stellar Evolution and Stellar Seismology” at the Institute for Astrophysics and Particles at the University of Innsbruck. The study of stellar oscillations has developed greatly in recent years due to the possibilities of careful observation through telescopes in outer space Like TESS, Kepler and James Webb have improved on several levels. These developments are now also shedding new light on decades-old theories of stellar evolution.

Stars are called “children” as long as they have not yet burned hydrogen to helium in their cores. At this point, they are in the pre-major sequence; After ignition, they become adults and move to the main sequence. “searching for stars So far focused mainly on adults stars Like our sun “says Thomas Steindl, a member of the research group at Konstanze Zwintz and lead author of the study.” The sequence is because the phase is very turbulent and difficult to model. What allows this is only technological progress in recent years we A closer look at the childhood of the stars – and thus in that moment in which he was star It begins fusing hydrogen into helium. In their current study, the researchers in Innsbruck now present a model that can be used to realistically depict the early stages of a star. life Long before they become adults. The model is based on the open source stellar evolution program MESA (Modules for Experiments in Stellar Astrophysics).

Inspired by a talk given by astronomer Eduard Vorobyov of the University of Vienna at the 2019 meeting, Thomas Steindl spent months refining the way he used this stellar evolution code to recreate the chaotic phase of early star formation and then predict their specific oscillations. “Our data shows that stars in the pre-main sequence take a very chaotic path in their evolution. Despite their complexity, we can now use them in our new theoretical model.” Steindl said. Thus, the astronomer explains that the way a star forms has an effect on the oscillation behavior even after nuclear fusion ignites in the main sequence: “Childhood has an effect on the subsequent pulsations of the star: this seems very simple, but there was great doubt. Classical theory assumes that the time during which Preceding ignition is simply irrelevant. This is not true: compared to a musical instrument, even minute differences in composition lead to significant changes in tone. Thus, our modern models best describe oscillations in real stars.”

Konstanze Zwintz is pleased with this discovery and is very optimistic about the future: “I was already convinced about 20 years ago, when I first saw a young star swing in front of me on the screen, One Being able to demonstrate the importance of early stellar evolution on an “adult” star. Thanks to the wonderful work of Thomas Steindl, we are now successful: definitely an eureka moment for our research group and another milestone for a better understanding of the steps in star growth.