Being a Star: Nature vs Nurture

Sep 21, 2022 | Daily Space, Spacecraft, Stars

Being a Star: Nature vs Nurture
IMAGE: The young star in the centre is in a molecular cloud and is enveloped by a disk. In the first stages of its life, the star attracts numerous materials, for example, through magnetic fields, which are constantly remixed in the turbulence. The interior of the young star is permeated by pulsations. CREDIT: Mirjana Keser

This next story left me wondering what “young” means in astronomy. It’s about trying to understand the lives of stars prior to that point where stable nuclear reactions begin in their cores. This work is led by Konstanze Zwintz, who is described as a leader in the “young” field of astroseismology. 

When I was a youngling at Michigan State University, we learned about the then new field of astroseismology my senior year, which, somehow, was more than 25 years ago. In computer science that would make astroseismology a mature field of research, but in astronomy, where our New General Catalogue of objects was first published in 1888, astroseismology is pretty much a toddler learning to run, while fields like exoplanetary research are just starting to sit up.

Anyway, in the toddling field of asteroseismology, researchers like Zwintz and his colleagues are combining data on stellar oscillations in infant stars from TESS and Kepler, and looking forward to data from JWST, and using these oscillations they are developing computer models that look at how the interior of these object change as they form, condense and eventually ignite. I love this research because it uses concepts I’ve used in my research in elder stars in a totally new way.

Thomas Steindl, a member of Zwintz’s group, explains: Research on stars has so far focused mainly on adult stars – such as our Sun. Even if it sounds counterintuitive at first glance, so far little attention has been paid to the evolution of the pre-main sequence because the phase is very turbulent and difficult to model. It’s only the technological advances of recent years that allow us a closer look at the infancy of stars – and thus at that moment when the star begins to fuse hydrogen into helium.

Asteroseismology and the study of pulsating stars both share a basic concept: They look at how a star vibrates like a tuning fork in response to various forces. These vibrations are directly related to the volume and density of the material they are passing through. While senior stars like the variable ones I looked at may have simple pulsations that expand and contract entire stars, asteroseismologists look at complex waves that look more like vibrations of an orchestra on the head of a speaker horn, and each of the different waves can reflect different resonances in the star.

Steidl goes on to explain: The classical theory assumes that the time before ignition is simply irrelevant. This is not true: Comparable to a musical instrument, even subtle differences in the composition lead to significant changes in the tone. Thus, our modern models better describe the oscillations in real stars.

This is amazing work, and it is a lifetime of work. Team leader Zwintz explains: I was already convinced about 20 years ago, when I first saw the oscillation of a young star in front of me on the screen, that I would one day be able to prove the significance of early stellar evolution on the ‘adult’ star. Thanks to the great work of Thomas Steindl, we have now succeeded: Definitely a eureka moment for our research group and another milestone for a better understanding of the growth steps of stars.

It is amazing to watch both a star and a research field get all grown up.

More Information

University of Innsbruck press release

The imprint of star formation on stellar pulsations,” Thomas Steindl, Konstanze Zwintz, and Eduard Vorobyov, 2022 September 19, Nature Communications

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