Stars, supernovae, black holes and stellar remnants

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Astronomers detect black hole 'starving' its host galaxy to death
https://phys.org/news/2024-09-astronome ... -host.html
by University of Cambridge

Astronomers have used the NASA/ESA James Webb Space Telescope to confirm that supermassive black holes can starve their host galaxies of the fuel they need to form new stars. The results are reported in the journal Nature Astronomy.

The international team, co-led by the University of Cambridge, used Webb to observe a galaxy roughly the size of the Milky Way in the early universe, about two billion years after the Big Bang. Like most large galaxies, it has a supermassive black hole at its center. However, this galaxy is essentially 'dead': it has mostly stopped forming new stars.

"Based on earlier observations, we knew this galaxy was in a quenched state: it's not forming many stars given its size, and we expect there is a link between the black hole and the end of star formation," said co-lead author Dr. Francesco D'Eugenio from Cambridge's Kavli Institute for Cosmology.

[caltrek]

Astronomers Discovered the Biggest Pair of Black Hole Jets Ever, and It's the Stuff of Cosmic Horror
by Kiona Smith
September 18, 2024

Introduction:

(Inverse) Imagine an amoeba blasting out jets of energy that stretched the width of the Earth. That’s what’s happening about 7.5 billion light years away on a much larger scale, where a supermassive black hole at the center of a galaxy is blasting jets of high-speed particles and energy across 23 million light years of space. That’s about 140 times the width of our Milky Way galaxy. It’s the longest pair of black hole jets ever discovered so far, and it could shed light on how supermassive black holes have sculpted not just their host galaxies, but the largest structures in the universe.

Caltech astrophysicist Martijn Oei and his colleagues published their work in the journal Nature.

MEET A COSMIC MONSTER: PORPHYRION

Oei and his colleagues used the Low Frequency Array — a sprawling network of radio dishes spread across 8 European countries — to scan a swath of the sky for long, rolling radio waves from supermassive black holes feasting on the entrails of their host galaxies. They found more than 8,000 pairs of what astronomers call relativistic jets: beams of energy and high-speed charged particles spewing outward from the poles of a supermassive black hole. And one monster pair of relativistic jets has a combined wingspan of about 23 million light years.

In other words, one black hole is continuously erupting energy and plasma into space across a distance more than 140 times longer than our whole galaxy, and it’s carrying the power of trillions of stars. Oei and his colleagues nicknamed the pair Porphyrion.

“The Milky Way would be a little dot in those two giant eruptions,” says Oei in a statement.

Read more of the Eurekalert article here: https://www.inverse.com/science/astron ... jets-ever

For results of the study as published in Nature: https://www.nature.com/articles/s41586-024-07879-y

[wjfox]

^ There's an excellent visualisation of that below.

The scale is hard to imagine...

[wjfox]

NASA’s TESS Spots Record-Breaking Stellar Triplets

Oct 02, 2024

Professional and amateur astronomers teamed up with artificial intelligence to find an unmatched stellar trio called TIC 290061484, thanks to cosmic “strobe lights” captured by NASA’s TESS (Transiting Exoplanet Survey Satellite).

The system contains a set of twin stars orbiting each other every 1.8 days, and a third star that circles the pair in just 25 days. The discovery smashes the record for shortest outer orbital period for this type of system, set in 1956, which had a third star orbiting an inner pair in 33 days.

“Thanks to the compact, edge-on configuration of the system, we can measure the orbits, masses, sizes, and temperatures of its stars,” said Veselin Kostov, a research scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, and the SETI Institute in Mountain View, California. “And we can study how the system formed and predict how it may evolve.”

This artist’s concept illustrates how tightly the three stars in the system called TIC 290061484 orbit each other. If they were placed at the center of our solar system, all the stars’ orbits would be contained a space smaller than Mercury’s orbit around the Sun. The sizes of the triplet stars and the Sun are also to scale.

https://www.nasa.gov/missions/tess/nasa ... -triplets/



Credit: NASA’s Goddard Space Flight Center

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Researchers claim to have found the oldest stellar disk in the Milky Way galaxy
https://phys.org/news/2024-10-oldest-st ... alaxy.html
by Bob Yirka , Phys.org

A team of astronomers and astrophysicists at the Chinese Academy of Sciences and the University of Toronto has found what they believe is the oldest stellar disk in the Milky Way galaxy. In their study, reported in the journal Nature Astronomy, the group used high-α stars with substantial orbital angular momentum to conduct age determinations across a wide range of stars in the galaxy.

Prior research has shown that the Milky Way started its life as a single entity. Over time, it has drawn in multiple other galaxies, making it much bigger—remnants of such galaxies have been found throughout the Milky Way. Such additions have made it difficult for astronomers to determine the original structure of the Milky Way.

[wjfox]

[caltrek]

Most Powerful Gamma Rays Ever Seen in Galaxy's Center Detected by Scientists
by Michelle Starr
October 24, 2024

Introduction:

(Science Alert) Although our galaxy's supermassive black hole is relatively placid, the center of the Milky Way wherein it resides is not a placid place. Its extreme location is rife with what can best be described as shenanigans on an epic scale.

Now it can add a powerful cosmic accelerator known as a PeVatron to its list of japes. An observatory high in the mountains of Mexico has recorded repeated emission of some of the highest-energy gamma rays ever recorded from a single point close to the galactic center.

The nature of this source, named HAWC J1746-2856, is unknown – but, over a period of seven years, the High-Altitude Water Cherenkov (HAWC) observatory recorded 98 gamma-ray events with energy levels exceeding 100 teraelectronvolts.

"These results are a glimpse at the center of the Milky Way to an order of magnitude higher energies than ever seen before," says physicist Pat Harding of Los Alamos National Laboratory.

"The research for the first time confirms a PeVatron source of ultrahigh-energy gamma rays at a location in the Milky Way known as the Galactic Center Ridge, meaning the galactic center is home to some of the most extreme physical processes in the Universe."

Read more here: https://www.sciencealert.com/most-powe ... cientists

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Webb Telescope Spots First Brown Dwarfs Outside Our Galaxy
The space telescope peered into the Small Magellanic Cloud to identify these sub-stellar objects.
By Ryan Whitwam October 25, 2024
https://www.extremetech.com/science/web ... our-galaxy

Astronomers have released a stunning new image captured with the James Webb Space Telescope, but this view of NGC 602 is more than a pretty picture. It also depicts the home of the first known population of brown dwarfs outside our galaxy. This discovery could help explain the intricacies of planetary and star formation and provide a window into the conditions in the universe billions of years ago.

Brown dwarfs, sometimes called failed stars, straddle the division between the largest planets and the smallest stars. They are usually between 13 and 75 times the mass of Jupiter, low enough that they cannot sustain nuclear fusion. These objects are often free-floating, untethered from larger stars and smaller exoplanets. That makes them difficult to detect, particularly at greater distances. So far, astronomers have only spotted about 3,000 brown dwarfs, all inside our galaxy.

A team led by the European Space Agency's (ESA) Peter Zeidler has found strong evidence for a population of brown dwarfs in NGC 602. This star cluster in the center of the image is on the outskirts of the Small Magellanic Cloud, a satellite galaxy of the Milky Way about 200,000 light-years away. "Only thanks to the incredible sensitivity and resolution in the right wavelength range we are able to detect these objects at such great distances," says Zeidler. "This has never been possible before and also will remain impossible with telescopes on the ground for the foreseeable future."

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Astronomers Identify First-Ever Black Hole Triple System
One of the first known black holes still has some tricks up its sleeve.
By Ryan Whitwam October 28, 2024

If you know anything about black holes, it's that they have extraordinary gravitational pull, drawing in distant objects and devouring them. Unsurprisingly, many black holes have stellar companions trapped in tight orbits, but perhaps counterintuitively, astronomers have never seen a triple system with a black hole—until now. Scientists from MIT and Caltech have spotted what is believed to be the first system with a black hole and two stable orbiting companions.

The black hole in question is known as V404 Cygni, which is somewhat famous among dead stars. This object, about 8,000 light-years away from Earth, was surveyed in 1992 and confirmed as one of the first known black holes. It has gotten plenty of attention since then, being mentioned in more than 1,300 scientific papers. However, no one noticed its stellar companion until lead author Kevin Burdge of MIT spotted something unexpected buried in a repository of astronomical data.

https://www.extremetech.com/science/ast ... ple-system

[caltrek]

Meet Algol, the Demon Star
by Daniel Johnson
October 31, 2024

Introduction:

(Sky & Telescope) If you need a touch of trick-or-treat in the sky this season — or anytime — seek out Algol, a bright star in the constellation Perseus.

The notoriety of Algol, also called the Demon Star, stretches back thousands of years because of a notable “trick”: The star dims over the course of a few hours before rebrightening, a feat it repeats precisely every 2.87 days. When Algol performs its trick, it fades from a vivid magnitude 2.1 (almost as bright as Polaris, the North Star) to a dim magnitude-3.4. At its faintest, it’s still visible without optical aid. The behavior may have startled ancient stargazers (see link below for their stories). Happily, today we have the tools to pull the treat out of the trick.

Algol is a terrific example of an eclipsing binary variable star. Algol itself never changes in brightness at all, but is eclipsed by a larger and dimmer companion, whose orbital plane is aligned just so in Earth’s direction. When the fainter star passes in front of Algol, we see the system’s brightness drop until the companion moves back out of the way. (Ten hours is enough to view the whole event).

Read more here: https://skyandtelescope.org/observing/ ... on-star/

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Black Hole Eats One Star ant the Remains Pummel a Second
by Monica Young
October 28, 2024

Introduction:

(Sky & Telescope) In 2019 a supermassive black hole ate a star. It’s incredible that such an incredible event is now commonplace — not in individual galaxies, where such stellar meals happen only every 10,000 to 100,000 years, but in our telescopes, through which astronomers can monitor millions of galaxies to observe their feeding habits.

But in the course of studying this particular stellar feast, Matt Nicholl (Queen’s University Belfast, UK) and colleagues discovered something else: bright spikes of X-rays that recurred roughly every 48 hours. Those kinds of spikes have been observed elsewhere, and astronomers call them quasi-periodic emissions — a vague term that reflects the fact that we don’t know why they happen.

Now, they have an important clue. The Zwicky Transient Facility, a wide field-of-view camera that scans the whole sky every two days, found a visible flash of light that it dubbed AT2019qiz on September 19, 2019. That burst came from the center of a barred spiral galaxy some 210 million years ago, taking that long to travel to Earth. The flare marked the end of a star that had passed too close to that galaxy’s million-solar-mass black hole, and it was sheared apart in the extreme gravitational field.

The black hole takes time to eat, and the stellar gas was still swirling inward as astronomers turned the Chandra X-ray Observatory to watch high-energy emission from the meal in 2023. They found an unexpected spike in X-ray emission that prompted follow-up observations with the Neutron Star Interior Composition Explorer (NICER) onboard the International Space Station as well as observations from two other space telescopes, the Neil Gehrels Swift Telescope and India’s AstroSat.

In all, they found nine X-ray bursts that recurred roughly every two days. Hubble Space Telescope observations showed that the emissions are coming from a source less than 82 light-years across — in other words, too small to be a star cluster in the galaxy’s center. More likely, the source is material swirling around the black hole in an accretion disk.

Read more here: https://skyandtelescope.org/astronomy- ... cond-one/

[Time_Traveller]

Black holes that form in 'reverse Big Bang replays' could account for dark energy

published 31 minutes ago

Scientists have strengthened the potential connection between dark energy and black holes. New research suggests that as more black holes were born in "little Big Bang reverse replays" in the 14.6 billion-year-old cosmos, the strength of dark energy grew to dominance and continues to change to this day.

Dark energy is the placeholder name given to the mysterious force driving the acceleration of the universe's expansion in its current epoch. It is troubling because scientists have no idea what dark energy is, yet it dominates our universe, accounting for around 70% of the cosmic matter/energy budget. This wasn't always the case, however. Prior to the dark energy-dominated epoch, matter and gravity had ruled the universe and had succeeded in slowing its initial Big Bang-driven expansion to a near stop. Dark energy then staged its cosmic coup around 5 billion years ago, "hitting the gas" on the expansion of the universe again. The problem is that no one knows where it came from or how that switch from matter to dark energy happened.

To address this mystery, a team of scientists has been asking themselves where in the modern-day universe is gravity as strong as it was at the beginning of the universe? The answer is only at the heart of black holes. Thus, the team determined that black holes could be "cosmically coupled" to dark energy.

"According to the cosmological coupling hypothesis, black holes are coupled to the expanding universe and are filled with dark energy that grows as the universe expands," team member Gregory Tarlé, professor of physics at the University of Michigan, told Space.com. "This new development provides confirming evidence that cosmologically coupled black holes may very well be the dark energy of the universe."

https://www.space.com/dark-energy-black-hole-connection

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Astronomers Find Black Hole Gobbling Matter Impossibly Fast
The hungry hungry black hole could help explain how supermassive black holes grew in the early universe.
By Ryan Whitwam November 8, 2024

https://www.extremetech.com/science/ast ... sibly-fast
As we gaze into the universe, we've discovered most galaxies have a supermassive black hole lurking near the center. Astronomers have even found these enormous celestial monsters in the early universe, which has raised an important question: How did they get so big so fast? A new observation may offer some hints. A team from the National Science Foundation NOIRLab has spotted a supermassive black hole from the early universe that is devouring stars at an unfathomable rate.

The work was led by NOIRLab astronomer Hyewon Suh, who used the James Webb Space Telescope to check out a sampling of galaxies from a survey conducted with the Chandra X-ray Observatory. One of those objects, LID-568, stood out immediately. LID-568 has high X-ray emission from its central black hole, but Webb is the only instrument capable of gathering this data.

[Time_Traveller]

A Star Disappeared in Andromeda, Replaced by a Black Hole

NOVEMBER 8, 2024

Massive stars about eight times more massive than the Sun explode as supernovae at the end of their lives. The explosions, which leave behind a black hole or a neutron star, are so energetic they can outshine their host galaxies for months. However, astronomers appear to have spotted a massive star that skipped the explosion and turned directly into a black hole.

Stars are balancing acts between the outward force of fusion and the inward force of their own gravity. When a massive star enters its last evolutionary stages, it begins to run out of hydrogen, and its fusion weakens. The outward force from its fusion can no longer counteract the star’s powerful gravity, and the star collapses in on itself. The result is a supernova explosion, a calamitous event that destroys the star and leaves behind a black hole or a neutron star.

However, it appears that sometimes these stars fail to explode as supernovae and instead turn directly into black holes.

New research shows how one massive, hydrogen-depleted supergiant star in the Andromeda galaxy (M31) failed to detonate as a supernova. The research is “The disappearance of a massive star marking the birth of a black hole in M31.” The lead author is Kishalay De, a postdoctoral scholar at the Kavli Institute for Astrophysics and Space Research at MIT.

These types of supernovae are called core-collapse supernovae, also known as Type II. They’re relatively rare, with one occurring about every one hundred years in the Milky Way. Scientists are interested in supernovae because they are responsible for creating many of the heavy elements, and their shock waves can trigger star formation. They also create cosmic rays that can reach Earth.

https://www.universetoday.com/169204/a- ... lack-hole/

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Colossal cosmic collision clocked at 2 million mph
By Michael Irving
November 24, 2024

https://newatlas.com/space/stephan-quin ... ion-weave/
Astronomers have clocked a cosmic collision at 3.2 million km/h (2 million mph). A new instrument has spotted a galaxy crashing through a group of others at incredible speeds, creating a shock wave that’s changing the region completely.

Stephan’s Quintet is a structure made up of five galaxies in close proximity to each other in the sky, which was first discovered by French astronomer Édouard Stephan in 1877. But it’s not quite as peaceful as its name and images suggest – this is the scene of a slow-motion smash.

Stephan’s Quintet is the cosmic equivalent of glass and metal scattered across a road after a car crash. The four galaxies involved have already hit each other and sent some of their material flying into a debris field, and are slowly skidding back together where they’ll probably merge into one giant galaxy eventually.

[caltrek]

To Map the Vibration of the Universe, Astronomers Use a Detector the Size of the Galaxy
December 2, 2024

Introduction:

(The Conversation) Using the largest gravitational wave detector ever made, we have confirmed earlier reports that the fabric of the universe is constantly vibrating. This background rumble is likely caused by collisions between the enormous black holes that reside in the hearts of galaxies.

The results from our detector – an array of rapidly spinning neutron stars spread across the galaxy – show this “gravitational wave background” may be louder than previously thought. We have also made the most detailed maps yet of gravitational waves across the sky, and found an intriguing “hot spot” of activity in the Southern Hemisphere.

Read more here: https://theconversation.com/to-map-the ... xy-244157

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Astronomers discover magnetic loops around supermassive black hole
https://phys.org/news/2024-12-astronome ... black.html
by National Radio Astronomy Observatory

NGC 1068 is a well-known, relatively nearby, bright galaxy with a supermassive black hole at its center. Despite its status as a popular target for astronomers, however, its accretion disk is obscured by thick clouds of dust and gas. A few light-years in diameter, the outer accretion disk is dotted by hundreds of distinct water maser sources that hinted for decades at deeper structures.

Masers are distinct beacons of electromagnetic radiation that shine in microwave or radio wavelengths; in radio astronomy, water masers observed at a frequency of 22 GHz are particularly useful because they can shine through much of the dust and gas that obscures optical wavelengths.

Led by astronomer Jack Gallimore of Bucknell University, an international team of astronomers and students set out to observe NGC 1068 with twin goals in mind: astrometric mapping of the galaxy's radio continuum and measurements of polarization for its water masers.

"NGC 1068 is a bit of a VIP among active galaxies," says co-author C. M. Violette Impellizzeri. "It is unusually powerful, with a black hole and an edge-on accretion disk. And because it is so nearby, it has been really, really well-studied in detail." Gallimore and his team set out to look at NGC 1068 in a completely new way, however. Their paper is published in The Astrophysical Journal Letters.

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Observations suggest sun-like stars emit superflares once per century
https://phys.org/news/2024-12-sun-stars ... ntury.html
by Max Planck Society

There is no question that the sun is a temperamental star, as this year's unusually strong solar storms show. Some of them led to remarkable auroras even at low latitudes. But can our star become even more furious?

Evidence of the most violent solar "tantrums" can be found in prehistoric tree trunks and in samples of millennia-old glacial ice. However, from these indirect sources, the frequency of superflares cannot be determined. And direct measurements of the amount of radiation reaching the Earth from the sun have only been available since the beginning of the space age.

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MIT Astronomers Trace Source of Fast Radio Burst in Another Galaxy
For the first time, scientists have shown an FRB probably originated in the magnetosphere of a neutron star.
By Ryan Whitwam January 3, 2025

After nearly 20 years of study, scientists are beginning to understand a bizarre celestial phenomenon known as fast radio bursts (FRBs). These signals last just a fraction of a second but can outshine entire galaxies. Research in recent years has pointed to neutron stars as the likely source of FRBs, but the mechanism is still a bone of contention among astronomers. A new study from MIT could shed light on that—the team managed to trace one FRB back to its source, some 200 million light years away.

FRBs have been happening for as long as there have been stars in the sky, but humanity only noticed in 2007. Since then, new instruments have identified thousands of fast radio bursts, some of which repeat on set intervals. This has allowed scientists to narrow the list of possible sources to intensely magnetic neutron stars known as magnetars and possibly black holes.

https://www.extremetech.com/science/mit ... her-galaxy