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Category: cosmology – Page 178

Red giants are dying stars, in advanced stages of stellar evolution, which have depleted the hydrogen in their cores. In a study published today in Nature Communications, a team of astronomers mainly from Instituto de Astrofísica e Ciências do Espaço (IA), have found new evidence that red giant stars experience “glitches”—sharp structural variations—in their inner core.

Unfortunately, it is impossible to look directly inside a star. However, a technique dubbed asteroseismology, which measures oscillations similar to “earthquakes” in stars, can provide indirect glimpses of stellar interiors. The “glitches” can affect these oscillations, or the frequencies and paths of gravity and traveling through the stellar interior.

As IA researcher Margarida Cunha explains, “Waves propagating inside stars induce minute stellar brightness variations that can be detected with highly precise space-based instruments. These waves reveal the conditions of the medium where they propagate, which is to say, the physical properties of the stellar interiors.”

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The European Space Agency recently announced a new mission of its science program: a small telescope orbiting the Earth dubbed Arrakhis.

The European Space Agency (ESA) recently announced a new mission of its science.

Amriphoto/iStock.

Instead, this nimble satellite will punch hugely above its weight and try to track down one of the most elusive and mysterious substances in the universe: dark matter. This is the term given to the hypothetical invisible matter that is thought to be more abundant than normal matter and has a similar gravitational effect on its surroundings.

Continue reading “Dark matter: How the ESA’s tiny telescope will reveal more about this mystery” | >

Summary: Findings support the theory that microRNAs are essential for the development and evolution of intelligent life.

Source: Dartmouth College.

Octopuses have captured the attention of scientists and the public with their remarkable intelligence, including the use of tools, engaging in creative play and problem-solving, and even escaping from aquariums.

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A temperature not seen since the first microsecond of the birth of the universe has been recreated by scientists, and they discovered that the event did not unfold quite the way they expected. The interaction of energy, matter, and the strong nuclear force in the ultra-hot experiments conducted at the Relativistic Heavy Ion Collider (RHIC) was thought to be well understood. However, a detailed investigation has revealed that physicists are missing something in their model of how the universe works. A recent paper detailing the findings appears in the journal Physical Review Letters.

“It’s the things you weren’t expecting that are really trying to tell you something in science,” says Steven Manly, associate professor of physics and astronomy at the University of Rochester and co-author of the paper. “The basic nature of the interactions within the hot, dense medium, or at least the manifestation of it, changes depending on the angle at which it’s viewed. We don’t know why. We’ve been handed some new pieces to the puzzle and we’re just trying to figure out how this new picture fits together.”

“They said, ‘This can’t be. You’re violating boost invariance.’ But we’ve gone over our results for more than a year, and it checks out.” —

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Using a chain of atoms in single-file to simulate the event horizon of a black hole, a team of physicists has observed the equivalent of what we call Hawking radiation – particles born from disturbances in the quantum fluctuations caused by the black hole’s break in spacetime.

This, they say, could help resolve the tension between two currently irreconcilable frameworks for describing the Universe: the general theory of relativity, which describes the behavior of gravity as a continuous field known as spacetime; and quantum mechanics, which describes the behavior of discrete particles using the mathematics of probability.

For a unified theory of quantum gravity that can be applied universally, these two immiscible theories need to find a way to somehow get along.

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The cosmic optical background (COB) is the visible light emitted by all sources outside of the Milky Way. This faint glow of light, which can only be observed using very precise and sophisticated telescopes, could help astrophysics to learn more about the origins of the universe and what lies beyond our galaxy.

Last year, physicists working at different institutes across the United States published the most precise COB measurements collected so far, gathered by the New Horizons spacecraft, an interplanetary space probe launched by NASA over a decade ago. These measurements suggested that the COB is two times brighter than theoretical predictions.

Researchers at Johns Hopkins University have recently carried out a theoretical study exploring the possibility that this observed excess light could be caused by the of a hypothesized type of dark matter particles, known as axions. In their paper, published in Physical Review Letters, they showed that axions with masses between 8 and 20 eV could potentially account for the excess COB flux measured by the New Horizons team.

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