Stellar evolution tagged posts

Why stars spin down, or up, before they die

Why stars spin down, or up, before they die
Illustration of the inner regions of a massive star during its final oxygen (green) and silicon (teal) shell burning phase, before the collapse of the iron core (indigo). The strength and geometry of the magnetic field, combined with the properties of convection in the oxygen region can cause the rotation rate to speed up or slow down. Credit KyotoU / Lucy McNeill

From birth to death, stars generally slow by 100 to 1,000 times their initial rotation rates; in other words, they “spin down.” The sun’s total angular momentum has declined as material is gradually blown off at the surface as solar wind. By observing this, astronomers have theorized the interaction between magneticfields and plasma flow to be the most efficient way to spin down stars.

Why and how this happens has long int...

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First Pairs of White Dwarf–main sequence binaries discovered in clusters shine new light on stellar evolution

Astronomers discover first pairs of white dwarf and main sequence stars in clusters, shining new light on stellar evolution
This image from the ALMA telescope shows star system HD101584 and the complex gas clouds surrounding the binary. It is the result of a pair of stars sharing a common outer layer during their last moments. Credit: ALMA (ESO/NAOJ/NRAO), Olofsson et al / Robert Cumming

Astronomers at the University of Toronto (U of T) have discovered the first pairs of white dwarf and main sequence stars—”dead” remnants and “living” stars—in young star clusters. Described in a new study published in The Astrophysical Journal, this breakthrough offers new insights into an extreme phase of stellar evolution, and one of the biggest mysteries in astrophysics.

Scientists can now begin to bridge the gap between the earliest and final stages of binary star systems—two stars that orbit a shared center of g...

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‘Triple Star’ Discovery could Revolutionize Understanding of Stellar Evolution

Large ball of light surrounded by blue disc of light and smaller ball of light hovering above
Artist’s impression composed of a star with a disc around it (a Be “vampire” star; foreground) and its companion star that has been stripped of its outer parts (background). Credit: ESO/L. Calçada

A ground-breaking new discovery by University of Leeds scientists could transform the way astronomers understand some of the biggest and most common stars in the Universe.

Research by PhD student Jonathan Dodd and Professor René Oudmaijer, from the University’s School of Physics and Astronomy, points to intriguing new evidence that massive Be stars — until now mainly thought to exist in double stars — could in fact be “triples.”

The remarkable discovery could revolutionise our understanding of the objects — a subset of B stars — which are considered an important “test bed” for d...

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Researchers Measure the Inner Structure of Distant Suns from their Pulsations

A glimpse into the heart: Artist's impression of the interior of the star, which was studied through its surface oscillations. Credit: Earl Bellinger / ESA

A glimpse into the heart: Artist’s impression of the interior of the star, which was studied through its surface oscillations. Credit: Earl Bellinger / ESA

At first glance, it would seem to be impossible to look inside a star. An international team has, for the first time, determined the deep inner structure of two stars based on their oscillations. Our sun, and most other stars, experience pulsations that spread through the star’s interior as sound waves. The frequencies of these waves are imprinted on the light of the star, and can be later seen by astronomers here on Earth.

Astronomers determine the properties of stars from their pulsations—a field called asteroseismology...

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