What happens to a large star near the end of its lifetime before it explodes as a supernova? This is what a recent study published in The Astrophysical Jou | Space
Category: cosmology
Earth’s Magnetic Field as Dark-Matter Sensor
One candidate for dark matter is a subatomic particle carrying a tiny electric charge many times smaller than that of the electron. This so-called millicharged dark matter would presumably interact with Earth’s magnetic field, generating potentially observable time variations in the magnetic field on Earth’s surface. A new study of archived data looked for this signal but came up empty [1]. The research has thus placed strict limits on the properties that a millicharged dark-matter particle could have if it has a small mass (in the range of 10–18 to 10–15 eV/c2).
Dark matter can’t have a typical electric charge, as it would interact too strongly with normal matter. But a small charge is possible and could produce features in-line with dark-matter models. Astrophysicists have looked for evidence of millicharged dark matter in stellar evolution data, as such particles could cause stars to cool faster than expected. No such signal has been seen, ruling out a large portion of millicharged-dark-matter parameter space.
Lei Wu from Nanjing Normal University in China and colleagues have explored another potential signal in the geomagnetic field. According to the team’s calculations, low-mass millicharged particles could annihilate each other in the presence of the planet’s magnetic-field background, producing an effective electric current that would generate its own magnetic field. This dark-matter-induced field would be small (roughly a million times less than Earth’s field), but it might be detectable owing to its peculiar time variation (at frequencies less than 1 Hz). The researchers failed to find such a signal in previously collected geomagnetic observations. The absence rules out low-mass dark-matter charges in a large range down to 10−30 times the electron charge. Such a small charge may seem implausible, but “nature sometimes surprises us,” Wu says.
High-resolution map shows dark matter’s gravity pulled normal matter into galaxies
Scientists have created the highest resolution map of the dark matter that threads through the universe—showing its influence on the formation of stars, galaxies and planets.
The research, including astronomers from Durham University, UK, tells us more about how this invisible substance helped pull ordinary matter into galaxies like the Milky Way and planets like Earth.
The findings, using new data from NASA’s James Webb Space Telescope (Webb), are published in the journal Nature Astronomy.
Is Betelgeuse about to explode into a supernova? Astronomers finally have an answer
Between late 2019 and early 2020, the red supergiant Betelgeuse showed signs of weakening that led many to wonder whether its long-expected explosion into a supernova just a few hundred light-years from the Solar System might be imminent. Other ideas were put forward, and more recently, fresh data have shed new light on the question.
It’s well established that stars with masses greater than eight to ten times that of the Sun won’t end up as white dwarfs like our Sun will. Instead, they explode as type II supernovae, leaving behind a neutron star and sometimes, if the mass is high enough, a stellar black hole.
Located roughly 650 light-years from Earth in the constellation Orion, Betelgeuse is one of these stars, and it’s clearly nearing the end of its life. It sits in the red supergiant phase, outside the main sequence on the Hertzsprung–Russell diagram.
Can Science Explain Everything? — Sean Carroll
Get all sides of every story and be better informed at https://ground.news/AlexOC — subscribe for 40% off unlimited access.
Come to my UK tour: https://www.livenation.co.uk/alex-o-c…
For early, ad-free access to videos, and to support the channel, subscribe to my Substack: https://www.alexoconnor.com.
To donate to my PayPal (thank you): http://www.paypal.me/cosmicskeptic.
VIDEO NOTES
Sean Carroll is an American theoretical physicist who specializes in quantum mechanics, cosmology, and the philosophy of science.
A Study Appears to Stunningly Contradict Newton and Einstein’s Theory of Gravity
“This systematic deviation agrees with the boost factor that the AQUAL theory predicts for kinematic accelerations in circular orbits under the Galactic external field,” Chae says in the paper.
Similar to how the Newton-Einstein theory relies on the ever-elusive particle known as dark matter, MOND contains its own limitations and challenges. Chae’s study appears to be a big +1 in the pro column for Modified Newtonian Dynamics, but the theory is still just that—a theory. It will need much more observational support before it upends our modern understanding of gravity and the universe we inhabit.
Dark energy survey scientists release analysis of all six years of survey data
The Dark Energy Survey Collaboration collected information on hundreds of millions of galaxies across the universe using the U.S. Department of Energy-fabricated Dark Energy Camera, mounted on the U.S. National Science Foundation Víctor M. Blanco 4-meter Telescope at CTIO, a program of NSF NOIRLab. Their completed analysis combines all six years of data for the first time and yields constraints on the universe’s expansion history that are twice as tight as past analyses.
The Dark Energy Survey (DES) is an international, collaborative effort to map hundreds of millions of galaxies, detect thousands of supernovae, and find patterns of cosmic structure that will help reveal the nature of the mysterious dark energy that is accelerating the expansion of our universe.
From 2013 to 2019, the DES Collaboration carried out a deep, wide-area survey of the sky using the 570-megapixel DOE-fabricated Dark Energy Camera (DECam), mounted on the NSF Víctor M. Blanco 4-meter Telescope at NSF Cerro Tololo Inter-American Observatory (CTIO) in Chile. For 758 nights over six years, the DES Collaboration recorded information from 669 million galaxies that are billions of light-years from Earth, covering an eighth of the sky.
ATLAS confirms collective nature of quark soup’s radial expansion
Scientists analyzing data from heavy ion collisions at the Large Hadron Collider (LHC)—the world’s most powerful particle collider, located at CERN, the European Organization for Nuclear Research—have new evidence that a pattern of “flow” observed in particles streaming from these collisions reflects those particles’ collective behavior. The measurements reveal how the distribution of particles is driven by pressure gradients generated by the extreme conditions in these collisions, which mimic what the universe was like just after the Big Bang.
The research is described in a paper published in Physical Review Letters by the ATLAS Collaboration at the LHC. Scientists from the U.S. Department of Energy’s (DOE) Brookhaven National Laboratory and Stony Brook University played leading roles in the analysis.
The international team used data from the LHC’s ATLAS experiment to analyze how particles flow outward in radial directions when two beams of lead ions—lead atoms stripped of their electrons—collide after circulating around the 17-mile circumference of the LHC at close to the speed of light. The findings offer new insight into the nature of the hot, dense matter generated in these collisions—with temperatures more than 250,000 times hotter than the sun’s core. These extreme conditions essentially melt the protons and neutrons that make up the colliding ions, setting free their innermost building blocks, quarks and gluons, to create a quark-gluon plasma (QGP).
