Lifeboat Foundation

Neutron stars are normally extremely fast-spinning stellar corpses left over from the intense violence of a supernova, but researchers have found one in a “stellar graveyard” where one should not be – and it spins at a relatively glacial rate of once every 76 seconds.

Researchers with the University of Sydney found the bizarre radio signal, designated PSR J0901-4046, emitted by the neutron star thanks to the MeerKAT radio telescope in South Africa and weren’t even expecting to see it. The region of the sky they were observing was thought to be free of pulsars, since none had been observed there before.

Now they might know why. Capturing eight-second-long samples of the sky, they caught sight of a single pulse from the star, which had to be confirmed with subsequent observation due to its unexpectedly long rotational period.

What do you do when a tried-and-true method for determining the sun’s chemical composition appears to be at odds with an innovative, precise technique for mapping the sun’s inner structure? That was the situation facing astronomers studying the sun—until new calculations that have now been published by Ekaterina Magg, Maria Bergemann and colleagues, and that resolve the apparent contradiction.

The decade-long solar abundance crisis is the conflict between the internal structure of the sun as determined from solar oscillations (helioseismology) and the structure derived from the fundamental theory of stellar evolution, which in turn relies on measurements of the present-day sun’s chemical composition. The new calculations of the physics of the sun’s atmosphere yield updated results for abundances of different chemical elements, which resolve the conflict. Notably, the sun contains more oxygen, silicon and neon than previously thought. The methods employed also promise considerably more accurate estimates of the chemical compositions of stars in general.

When we look out into space, all of the astrophysical objects that we see are embedded in magnetic fields. This is true not only in the neighborhood of stars and planets, but also in the deep space between galaxies and galactic clusters. These fields are weak—typically much weaker than those of a refrigerator magnet—but they are dynamically significant in the sense that they have profound effects on the dynamics of the universe. Despite decades of intense interest and research, the origin of these cosmic magnetic fields remains one of the most profound mysteries in cosmology.

In previous research, scientists came to understand how turbulence, the churning motion common to fluids of all types, could amplify preexisting magnetic fields through the so-called dynamo process. But this remarkable discovery just pushed the mystery one step deeper. If a turbulent dynamo could only amplify an existing field, where did the “seed” magnetic field come from in the first place?

We wouldn’t have a complete and self-consistent answer to the origin of astrophysical magnetic fields until we understood how the seed fields arose. New work carried out by MIT graduate student Muni Zhou, her advisor Nuno Loureiro, a professor of nuclear science and engineering at MIT, and colleagues at Princeton University and the University of Colorado at Boulder provides an answer that shows the basic processes that generate a field from a completely unmagnetized state to the point where it is strong enough for the dynamo mechanism to take over and amplify the field to the magnitudes that we observe.

Although the universe is expanding at an accelerating rate today, this paper presents a simple mechanism by which a dynamical form of dark energy (known as quintessence) could cause the acceleration to come to end and smoothly transition from expansion to a phase of slow contraction. That raises questions, How soon could this transition occur? And at what point would it be detectable? The conclusions are that the transition could be surprisingly soon, maybe less than 100 million y from now, and yet, for reasons described in the main text, it is not yet detectable today. The scenario is not far-fetched. In fact, it fits naturally with recent theories of cyclic cosmology and conjectures about quantum gravity.

NASA is being forced to end its Mars lander mission early because of dust.

NASA’s InSight Mars lander is shutting down after four years and scientists have seen our galaxy’s black hole for the first time. Here’s May 11–18 in science images.

Continue reading “NASA InSight shutting down and more: Understand the world through 9 images” »

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The recently-released image shows how Sagittarius A is both mundane and very strange, all at once.