New Measurements of Galaxy Rotation Lean Towards Modified Gravity as an Explanation for Dark Matter

Although dark matter is a central part of the standard cosmological model, it’s not without its issues. There continue to be nagging mysteries about the stuff, not the least of which is the fact that scientists have found no direct particle evidence of it. Despite numerous searches, we have yet to detect dark matter particles. So some astronomers favor an alternative, such as Modified Newtonian Dynamics (MoND) or modified gravity model. And a new study of galactic rotation seems to support them.

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Rubble Pile Asteroids Might be the Best Places to Build Space Habitats

Illustration: SpaceX Crew Dragon at ISS
An illustration shows SpaceX's Crew Dragon capsule approaching the International Space Station. (Credit: SpaceX)

The stars call to us, as Carl Sagan once said. Given the human drive to explore our world and expand our reach, it is likely only a matter of time before we begin to build our homes in the solar system. The Moon and Mars could be acceptable destinations, but nearby asteroids could also become homes, as a recent study shows.

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The Formation of the Southern Ring Nebula was Messier Than the Death of a Single Star

JWST images of the Southern Ring Nebula as seen from the telescope's NIRCam (left) and MIRI (right). Credit: NASA, ESA, CSA, and STScI

Two thousand five hundred years ago, during the height of the bronze age, an old red star died. Its outer layers expanded over time, becoming what is now known as the Southern Ring Nebula, or less romantically, NGC 3132. By the looks of it, this planetary nebula looks like many others. As Sun-like stars die, they swell to become red giants before becoming a white dwarf, and their outer layers typically become a planetary nebula. But a recent study finds that this particular nebula formed in a way quite messier than we had thought.

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Want to Learn More About Dark Matter? Send an Atomic Clock Close to the Sun

Artist's impression of a space atomic clock used to uncover dark matter. Credit: Kavli IPMU

Dark matter continues to vex astronomers around the world. We see its effects in the clustering of galaxies and the gravitational lensing of light within galaxies, and it seems to comprise about 80% of the matter in the universe, but we still haven’t detected it on Earth. So what about at least detecting it in our solar system? That might be possible according to a new study in Nature Astronomy.

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Mapping the Interiors of Meteorites to Learn how Earth got its Water

A composite image of Earth as a watery world. Credit: Reto Stöckli, Robert Simmon, MODIS/NASA

Earth is a strange world. A warm, rocky planet covered with oceans of liquid water. This strangeness is central to life on Earth, but it has been a longstanding puzzle for astronomers. Just why is our planet wet while other terrestrial worlds are dry? Where did all of Earth’s water come from?

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Astronomers Spot the Debris From Planets That Formed 10 Billion Years ago

Artist's view of old white dwarfs surrounded by planetary debris. Credit: University of Warwick/Dr Mark Garlick

The fate of the Sun is sealed. It was sealed by gravity in the earliest days of its formation. In several billion years the Sun will swell to a red giant, cast off much of its thin outer layers, then collapse to become a white dwarf. The white dwarfs we see in the nearby galaxy tell us of our Sun’s future. Its core will collapse to about the size of Earth, and then it will gradually cool as it fades into the dark. It’s a tale we’ve long known, but astronomers continue to learn learning interesting details, particularly regarding what might be the fate of the Sun’s planets.

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Can JWST see Galaxies Made of Primordial Stars?

The distance of first generation stars. Credit: STScI

All stars are composed of mostly hydrogen and helium, but most stars also have measurable amounts of heavier elements, which astronomers lump into the category of “metals.” Our Sun has more metals than most stars because the nebula from which it formed was the remnant debris of earlier stars. These were in turn children of even earlier stars, and so on. Generally, each new generation of stars has a bit more metal than the last. The very first stars, those born from the primordial hydrogen and helium of the cosmos, had almost no metal in them. We’ve never seen one of these primordial stars, but with the power of the Webb and a bit of luck, we might catch a glimpse of them soon.

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A Black Hole’s X-Rays are Coming From a Region 2,000 km Away From the Singularity Itself

Artist’s conception of the Cygnus X-1 system. Credit: John Paice

In 1961 astronomers discovered a powerful x-ray source coming from the constellation Cygnus. Not knowing what it was, they named the source Cygnus X-1. It’s one of the strongest x-ray sources in the sky, and we now know it is powered by a stellar-mass black hole. Since it is only about 7,000 light-years away, it also gives astronomers an excellent view of how stellar-mass black holes behave. Even after six decades of study, it continues to teach us a few things, as a recent study in Science shows.

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Not Just Gold. Colliding Neutron Stars Forge Strontium, Lanthanum, and Cerium

Artist’s conception of a neutron star merger. Credit: Tohoku University

In the beginning, there was hydrogen and helium. Other than some traces of things such as lithium, that’s all the matter the big bang produced. Everything other than those two elements was largely produced by astrophysical rather than cosmological processes. The elements we see around us, those that comprise us, were mostly formed within the hearts of stars. They were created in the furnace of stellar cores, then cast into space when the star died. But there are a few elements that are created differently. The most common one is gold.

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JWST Sees the Same Galaxy From Three Different Angles Thanks to a Gravitational Lens

This illustration shows how gravitational lensing works. The gravity of a large galaxy cluster is so strong, it bends, brightens and distorts the light of distant galaxies behind it. The scale has been greatly exaggerated; in reality, the distant galaxy is much further away and much smaller. Credit: NASA, ESA, L. Calcada

One of the great tragedies of the night sky is that we will never travel to much of what we see. We may eventually travel to nearby stars, and even distant reaches of our galaxy, but the limits of light speed and cosmic expansion make it impossible for us to travel beyond our local group. So we can only observe distant galaxies, and we can only observe them from our home in the universe. You might think that means we can only see one face of those galaxies, but thanks to the James Webb Space Telescope that isn’t entirely true.

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