Category Astronomy/Space

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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Two blazing quasars caught waltzing into a merger

Two blazing quasars caught waltzing into a merger
Artist’s concept of two quasars in the process of merging. Credit: International Gemini Observatory/NOIRLab/NSF/AURA/M. Garlick

Astronomers, using the Atacama Large Millimeter/submillimeter Array (ALMA), have confirmed the existence of a close quasar pair housed in a pair of merging galaxies seen when the universe was less than a billion years old, at a redshift of 5.7. The system, designated J2037–4537, is one of only two confirmed quasar pairs at redshift greater than 5 ever found. A paper outlining this work was submitted to the preprint server arXiv on April 7.

Quasars are among the most luminous objects in the universe. They belong to the family of active galactic nuclei (AGN)—galaxies that are powered by supermassive black holes at their centers...

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Self-regulating process governs cosmic order inside star clusters

A large number of small molecular clouds (left) cannot form the same population of stars as one very large cloud (right). – This has a significant influence on the evolution of galaxies. © Copyright: Eda Gjergo

A team of astrophysicists from Nanjing University and University of Bonn have demonstrated that, rather than being random, the mass of new stars born inside a star cluster is actually governed by a defined process of self-regulation. Their work has been published in the journal Research in Astronomy and Astrophysics.

How galaxy size shapes newborn stars
When a galaxy welcomes new stars, they are usually formed in star clusters inside vast gas clouds...

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3I/ATLAS contains 30 times more semi-heavy water than comets in our solar system

This artist’s impression compares the semi-heavy water content of the interstellar comet 3I/ATLAS (left) and Earth (right). Insets illustrate the relative abundance of deuterated water (HDO) molecules, showing that 3I/ATLAS contains over 30 times more HDO than is found in Earth’s oceans. This elevated ratio suggests the comet formed in an extremely cold environment, very different from the conditions that shaped our Solar System.
Credit: NSF/AUI/NSF NRAO/M.Weiss

New observations of the interstellar comet 3I/ATLAS include the first measurement of the abundance of deuterated water relative to ordinary water in an interstellar object...

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