Stars, supernovae, black holes and stellar remnants

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caltrek
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Re: Stars, supernovae, black holes and stellar remnants

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Study Explains How Supermassive Black Holes Develop
February 15, 2023

Introduction:
(EurekAlert) The second paper (published in The Astrophysical Journal Letters finds that the growth in mass of these black holes matches predictions for black holes that not only cosmologically couple, but also enclose vacuum energy—material that results from squeezing matter as much as possible without breaking Einstein's equations, thus avoiding a singularity…

“Here's a toy analogy. You can think of a coupled black hole like a rubber band, being stretched along with the universe as it expands," said Croker. "As it stretches, its energy increases. Einstein's E = mc2 tells you that mass and energy are proportional, so the black hole mass increases, too."

How much the mass increases depends on the coupling strength, a variable the researchers call k.

"The stiffer the rubber band, the harder it is to stretch, so the more energy when stretched. In a nutshell, that's k," Croker said.

Because mass growth of black holes from cosmological coupling depends on the size of the universe, and the universe was smaller in the past, the black holes in the first study must be less massive by the correct amount in order for the cosmological coupling explanation to work.
Read more here: https://www.eurekalert.org/news-releases/979797
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Re: Stars, supernovae, black holes and stellar remnants

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A star is born: Images of nearby galaxies provide clues about star formation
https://phys.org/news/2023-02-star-born ... axies.html
by Michelle Franklin, University of California - San Diego
It is a popular notion that aside from large celestial objects like planets, stars and asteroids, outer space is empty. In fact, galaxies are filled with something called the interstellar medium (ISM)—that is, the gas and dust that permeate the space in between those large objects. Importantly, under the right conditions, it is from the ISM that new stars are formed.

Now researchers from the University of California San Diego, in collaboration with a worldwide project team, have released their findings in a special issue of The Astrophysical Journal Letters dedicated to their work using advanced telescope images through the JWST Cycle 1 Treasury Program.

"With JWST, you can make incredible maps of nearby galaxies at very high resolution that provide amazingly detailed images of the interstellar medium," stated Associate Professor of Physics Karin Sandstrom who is a co-principal investigator on the project.

Although JWST can look at very distant galaxies, the ones Sandstrom's group studied are relatively close at about 30 million light years away, including one known as the Phantom Galaxy. Also known as M74 or NGC 628, astronomers have known of the Phantom Galaxy's existence since at least the 18th century.

Sandstrom, along with postdoctoral scholar Jessica Sutter and former postdoctoral scholar Jeremy Chastenet (now at University of Ghent), focused on a specific component of the ISM called polycyclic aromatic hydrocarbons (PAHs). PAHs are small particles of dust—the size of a molecule—and it's their small size that makes them so valuable to researchers.

When PAHs absorb a photon from a star, they vibrate and produce emission features that can be detected in the mid-infrared electromagnetic spectrum—something that typically doesn't happen with larger dust grains from the ISM. The vibrational features of PAHs allow researchers to observe many important characteristics including size, ionization and structure.
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Re: Stars, supernovae, black holes and stellar remnants

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Re: Stars, supernovae, black holes and stellar remnants

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'Runaway' black hole the size of 20 million suns found speeding through space with a trail of newborn stars behind it

By Robert Lea
published 5 days ago

Astronomers have discovered a "runaway" black hole, potentially the first observational evidence that supermassive black holes can be ejected from their host galaxies.

https://www.space.com/runaway-black-hol ... born-stars


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Re: Stars, supernovae, black holes and stellar remnants

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Supermassive black hole in Milky Way centre will consume large object in 2036

5th March 2023

A mysterious object called X7 has evolved dramatically in a relatively short time as it approaches the centre of our galaxy. Astronomers now say it is likely to be a large cloud of dust and gas, created when two stars collided.

Read more: https://www.futuretimeline.net/blog/202 ... e-2036.htm


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Re: Stars, supernovae, black holes and stellar remnants

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'Missing link' protostar may prove solar system's water is older than the sun
published 1 day ago

Astronomers have detected an abundance of water in the form of gas in a disk of planet-forming material that surrounds a distant star. The disk appears to contain hundreds of times more water than in all of Earth's oceans.

The discovery could give clues as to how water moves from star-forming clouds of gas and dust to planets, and could also indicate that Earth's water may be older than the sun.

The team of astronomers reached their conclusion as a result of observations of V883 Orionis, an infant star or "protostar" located around 1,300 light-years from Earth in the Orion constellation using the Atacama Large Millimeter/submillimeter Array (ALMA) in Northern Chile.

"We can now trace the origins of water in our solar system to before the formation of the sun," National Radio Astronomy Observatory (NRAO) astronomer and research lead author, John J. Tobin, said in a statement.(opens in new tab) "V883 Orionis is the missing link in this case."
https://www.space.com/solar-system-wate ... =space.com
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Re: Stars, supernovae, black holes and stellar remnants

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Nearly 300 variable stars detected with Kepler spacecraft
https://phys.org/news/2023-03-variable- ... craft.html
by Tomasz Nowakowski , Phys.org
Using data from NASA's Kepler spacecraft, astronomers from the Pedagogical University of Cracow, Poland, and elsewhere have detected 278 variable stars in the open cluster NGC 6791 and its surroundings. The finding was reported in a paper published March 13 on the arXiv pre-print repository.

Variable stars could offer important hints into aspects of stellar structure and evolution. They could also be helpful for better understanding the distance scale of the universe. In particular, studies of variable stars in star clusters are of special interest for astronomers as they have the potential to help identify systematic errors that affect stellar distance indicators.

Located about 13,300 light years from the Earth in the Lyra constellation, NGC 6791 is one of the most studied open clusters (OCs). It has an estimated age of approximately 8 billion years and an iron to hydrogen abundance ratio that is more than twice that of our sun. This makes it one of the oldest and most metal-rich clusters in the Milky Way galaxy. With a mass of approximately 4,000 solar masses, it is also one of the most massive OCs known to date.
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Re: Stars, supernovae, black holes and stellar remnants

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Astronomers discover helium-burning white dwarf
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https://phys.org/news/2023-03-astronome ... dwarf.html
by University of Bonn
A white dwarf star can explode as a supernova when its mass exceeds the limit of about 1.4 solar masses. A team led by the Max Planck Institute for Extraterrestrial Physics (MPE) in Garching and involving the University of Bonn has now found a binary star system in which matter flows onto the white dwarf from its companion.

The system was found due to bright, so-called super-soft X-rays, which originate in the nuclear fusion of the overflowed gas near the surface of the white dwarf. The unusual thing about this source is that it is helium and not hydrogen that overflows and burns. The measured luminosity suggests that the mass of the white dwarf is growing more slowly than previously thought possible, which may help to understand the number of supernovae caused by exploding white dwarfs. The results have been published in the journal Nature.
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Re: Stars, supernovae, black holes and stellar remnants

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Flattest Explosion In Space Is Bizarre Phenomenon Never Seen Before
by Dr. Alfredo Carpineti
March 31, 2023

Introduction:
(IFL Science) Back in 2018, astronomers discovered a very peculiar stellar explosion, which got the automatic name of AT2018cow. Since then, it's become known simply as the “cow” and it is the prototype of a new class of objects called Fast Blue Optical Transients (FBOTs). And researchers have now realized that the event was even weirder than previously assumed.

This explosion appeared to be extremely flat, spreading through a thick disk, with a thickness about one-tenth of the radius of the disk a handful of days after the explosion was recorded. Explosions in space can have a level of asymmetry, but this is the most aspherical ever recorded, which could be an indication of the properties of all FBOTs.

“Very little is known about FBOT explosions - they just don’t behave like exploding stars should, they are too bright and they evolve too quickly. Put simply, they are weird, and this new observation makes them even weirder,” lead author Dr Justyn Maund, from the University of Sheffield, said in a statement.

“What we now know for sure is that the levels of asymmetry recorded are a key part of understanding these mysterious explosions, and it challenges our preconceptions of how stars might explode in the Universe,” Dr Maund continued.

The crucial element in this work was the polarization of light. Light is made by oscillating electric and magnetic fields, and these oscillations can point in any direction. If the light is polarized, it means the oscillation is happening in a specific direction. This approach is what is used in 3D cinema. Light with two polarizations is sent out and each lens filters part of it out, giving the impression to our brains that we are seeing something in 3D.

Read more here: https://www.iflscience.com/flattest-ex ... ore-68264
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Re: Stars, supernovae, black holes and stellar remnants

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Hubble telescope spies mysterious celestial object that defies classification
published 5 days ago

Space is hard, the adage goes. And we'd extrapolate that sentiment to the classification of celestial objects, particularly ones like Z 229-15.

A newly released image taken by the Hubble Space Telescope shows Z 229-15, which, at first glance, simply appears to be a spiral galaxy, given its two spiraling arms of stars emanating from a bright core. But it's far, far more than that.

Z 229-15 is one of those objects that fits several classifications, according to a statement released by the European Space Agency (ESA). "Z 229-15 is one of those interesting celestial objects that, should you choose to research it, you will find defined as several different things," the statement reads. While it's impossible to pin down a singular classification for Z 229-15, there are several overlapping definitions that together describe this wondrous celestial object.

First and foremost, Z 229-15 is indeed a galaxy, which is a gravitationally bound collection of stars.

Second, it's an active galactic nucleus (AGN), or rather, it contains an AGN. An AGN is a region at the center of a galaxy that is exceptionally bright due to a supermassive black hole at its core. It's not the black hole itself that's so luminous, but rather all the material from the galaxy that has been trapped in a spinning disk around it, having been drawn toward the black hole by its intense gravitational pull. That disk heats up and emits massive amounts of energy across the electromagnetic spectrum, resulting in the brightness.
https://www.space.com/hubble-telescope- ... cebook.com
"We all have our time machines, don't we. Those that take us back are memories...And those that carry us forward, are dreams."

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