Smallest, densest white dwarf ever discovered packs the sun's mass into a moon-size stellar corpse - Space.com | Canada News Media
Connect with us

Science

Smallest, densest white dwarf ever discovered packs the sun's mass into a moon-size stellar corpse – Space.com

Published

 on


Astronomers may have discovered the smallest and heaviest white dwarf star ever seen, a smoldering ember about the size of our moon but 450,000 times more massive than Earth, a new study finds.

White dwarfs are usually about the size of Earth and are the cool, dim cores of dead stars that are left behind after average-size stars have exhausted their fuel and shed their outer layers. Our sun will one day become a white dwarf, as will about 97% of all stars.

Although the sun is alone in space without a stellar partner, many stars orbit around each other in pairs. If these binary stars are both less than eight times the mass of the sun, they will both evolve into white dwarfs over time.

Related: Oddball giant white dwarf may have formed in epic crash of smaller stars

The newfound white dwarf, designated ZTF J1901+1458, is located about 130 light-years from Earth and may be an example of what can happen when white dwarf pairs merge. If the white dwarfs were more massive, they would explode in a powerful thermonuclear explosion known as a Type Ia supernova. However, if their combined masses fell below a certain threshold, they could form a new white dwarf heavier than either of its parents, which is what scientists think happened in the case of ZTF J1901+1458.

“Our discovery is the most massive and smallest white dwarf ever found,” study lead author Ilaria Caiazzo, an astrophysicist at the California Institute of Technology in Pasadena, told Space.com.

The discovery was made using the Zwicky Transient Facility at the Palomar Observatory in California, which scans the entire northern sky every two nights looking for cosmic bodies that blink, erupt, move or similarly change in brightness. Study co-author Kevin Burdge, an astrophysicist at the California Institute of Technology in Pasadena, first spotted the new white dwarf based on its high mass and rapid spin.

The researchers used a host of telescopes to help analyze the dead star, which is about 100 million years old or less. These included the Hale Telescope at Palomar, the W.M. Keck Observatory‘s Keck I telescope, the European Gaia space observatory, the University of Hawaii’s Pan-STARRS (Panoramic Survey Telescope and Rapid Response System) and NASA’s Neil Gehrels Swift Observatory.

The scientists found the white dwarf was about 2,670 miles (4,300 kilometers) wide, making it a bit larger than the moon, which is about 2,158 miles (3,474 km) in diameter. ZTF J1901+1458’s tiny size makes it the smallest known white dwarf, edging out previous record holders, RE J0317-853 and WD 1832+089, which each have diameters of about 3,100 miles (5,000 km).

At the same time, the newfound white dwarf is about 1.35 times the mass of our sun, which may make it the most massive white dwarf discovered yet.

Related: What makes this low-mass white dwarf so ‘impossible’ to behold?

“It might be a bit counter-intuitive that the most massive white dwarf known is also the smallest white dwarf found,” Caiazzo said. This is because gravity and other factors lead white dwarfs to be smaller the more massive they are, she added.

This white dwarf is barely under the mass at which one would expect a white dwarf to detonate. “This one is really at the limit,” Caiazzo said. “If it was slightly more massive, it would have exploded.”

The white dwarf spins very rapidly, completing one revolution every seven minutes. When its progenitor stars spiraled together to merge, ZTF J1901+1458 inherited their combined spin, the researchers said. (The fastest-whirling white dwarf known, called EPIC 228939929, rotates every 5.3 minutes).

The white dwarf’s quick rate of spin also helps give it a very powerful magnetic field, more than one billion times stronger than Earth’s. “All of these characteristics — its mass and spin and high magnetic field — all suggest this white dwarf was not born the same as normal white dwarfs,” Caiazzo said.

Since this white dwarf is so massive, it may be possible that it might collapse further, as the incredible pressure within its core forces electrons to fuse with protons in atomic nuclei to form neutrons. “It could get even smaller than the moon,” Caiazzo said, perhaps shrinking as small as about 1,240 to 1,865 miles (2000 to 3000 km) wide.

If this shrinking does occur, at some point maybe 100 million to 200 million years from now, the white dwarf might become unstable and detonate as a thermonuclear type Ia supernova, Caiazzo said. Another possibility is that if a large enough number of electrons get captured, the white dwarf might potentially collapse to form a neutron-rich dead star known as a neutron star.

“A neutron star is an extremely dense object the mass of the sun but just the size of a city, so even more extreme than this white dwarf,” Caiazzo said.

If a white dwarf does collapse to form a neutron star, atoms fusing together within its core would release a huge amount of heat, potentially in just hours or days. “The entire white dwarf would very quickly burn,” Caiazzo said.

Neutron stars are thought to normally form when stars much more massive than our sun explode as supernovas, Caiazzo explained. If giant white dwarfs can also collapse to become neutron stars, a significant number of neutron stars may arise this way. However, if a white dwarf’s core freezes to become a crystalline solid faster than it shrinks, this collapse will likely not happen.

“We don’t know if such a collapse may happen, and if it does, which outcomes might occur,” Caiazzo said. “But if white dwarfs can create neutron stars, this could be a quite common way to form neutron stars.”

In the future, the scientists hope to use the Zwicky Transient Facility to find more white dwarfs like this one and to analyze white dwarfs as a whole. 

“There are so many questions to address, such as what is the rate of white dwarf mergers in the galaxy, and is it enough to explain the number of type Ia supernovae?” Caiazzo said in a statement. “How is a magnetic field generated in these powerful events, and why is there such diversity in magnetic field strengths among white dwarfs? Finding a large population of white dwarfs born from mergers will help us answer all these questions and more.”

The scientists detailed their findings online June 30 in the journal Nature.

Follow us on Twitter @Spacedotcom and on Facebook. 

Adblock test (Why?)



Source link

Continue Reading

News

Here’s how Helene and other storms dumped a whopping 40 trillion gallons of rain on the South

Published

 on

 

More than 40 trillion gallons of rain drenched the Southeast United States in the last week from Hurricane Helene and a run-of-the-mill rainstorm that sloshed in ahead of it — an unheard of amount of water that has stunned experts.

That’s enough to fill the Dallas Cowboys’ stadium 51,000 times, or Lake Tahoe just once. If it was concentrated just on the state of North Carolina that much water would be 3.5 feet deep (more than 1 meter). It’s enough to fill more than 60 million Olympic-size swimming pools.

“That’s an astronomical amount of precipitation,” said Ed Clark, head of the National Oceanic and Atmospheric Administration’s National Water Center in Tuscaloosa, Alabama. “I have not seen something in my 25 years of working at the weather service that is this geographically large of an extent and the sheer volume of water that fell from the sky.”

The flood damage from the rain is apocalyptic, meteorologists said. More than 100 people are dead, according to officials.

Private meteorologist Ryan Maue, a former NOAA chief scientist, calculated the amount of rain, using precipitation measurements made in 2.5-mile-by-2.5 mile grids as measured by satellites and ground observations. He came up with 40 trillion gallons through Sunday for the eastern United States, with 20 trillion gallons of that hitting just Georgia, Tennessee, the Carolinas and Florida from Hurricane Helene.

Clark did the calculations independently and said the 40 trillion gallon figure (151 trillion liters) is about right and, if anything, conservative. Maue said maybe 1 to 2 trillion more gallons of rain had fallen, much if it in Virginia, since his calculations.

Clark, who spends much of his work on issues of shrinking western water supplies, said to put the amount of rain in perspective, it’s more than twice the combined amount of water stored by two key Colorado River basin reservoirs: Lake Powell and Lake Mead.

Several meteorologists said this was a combination of two, maybe three storm systems. Before Helene struck, rain had fallen heavily for days because a low pressure system had “cut off” from the jet stream — which moves weather systems along west to east — and stalled over the Southeast. That funneled plenty of warm water from the Gulf of Mexico. And a storm that fell just short of named status parked along North Carolina’s Atlantic coast, dumping as much as 20 inches of rain, said North Carolina state climatologist Kathie Dello.

Then add Helene, one of the largest storms in the last couple decades and one that held plenty of rain because it was young and moved fast before it hit the Appalachians, said University of Albany hurricane expert Kristen Corbosiero.

“It was not just a perfect storm, but it was a combination of multiple storms that that led to the enormous amount of rain,” Maue said. “That collected at high elevation, we’re talking 3,000 to 6000 feet. And when you drop trillions of gallons on a mountain, that has to go down.”

The fact that these storms hit the mountains made everything worse, and not just because of runoff. The interaction between the mountains and the storm systems wrings more moisture out of the air, Clark, Maue and Corbosiero said.

North Carolina weather officials said their top measurement total was 31.33 inches in the tiny town of Busick. Mount Mitchell also got more than 2 feet of rainfall.

Before 2017’s Hurricane Harvey, “I said to our colleagues, you know, I never thought in my career that we would measure rainfall in feet,” Clark said. “And after Harvey, Florence, the more isolated events in eastern Kentucky, portions of South Dakota. We’re seeing events year in and year out where we are measuring rainfall in feet.”

Storms are getting wetter as the climate change s, said Corbosiero and Dello. A basic law of physics says the air holds nearly 4% more moisture for every degree Fahrenheit warmer (7% for every degree Celsius) and the world has warmed more than 2 degrees (1.2 degrees Celsius) since pre-industrial times.

Corbosiero said meteorologists are vigorously debating how much of Helene is due to worsening climate change and how much is random.

For Dello, the “fingerprints of climate change” were clear.

“We’ve seen tropical storm impacts in western North Carolina. But these storms are wetter and these storms are warmer. And there would have been a time when a tropical storm would have been heading toward North Carolina and would have caused some rain and some damage, but not apocalyptic destruction. ”

___

Follow AP’s climate coverage at https://apnews.com/hub/climate

___

Follow Seth Borenstein on Twitter at @borenbears

___

Associated Press climate and environmental coverage receives support from several private foundations. See more about AP’s climate initiative here. The AP is solely responsible for all content.

Source link

Continue Reading

Science

‘Big Sam’: Paleontologists unearth giant skull of Pachyrhinosaurus in Alberta

Published

 on

 

It’s a dinosaur that roamed Alberta’s badlands more than 70 million years ago, sporting a big, bumpy, bony head the size of a baby elephant.

On Wednesday, paleontologists near Grande Prairie pulled its 272-kilogram skull from the ground.

They call it “Big Sam.”

The adult Pachyrhinosaurus is the second plant-eating dinosaur to be unearthed from a dense bonebed belonging to a herd that died together on the edge of a valley that now sits 450 kilometres northwest of Edmonton.

It didn’t die alone.

“We have hundreds of juvenile bones in the bonebed, so we know that there are many babies and some adults among all of the big adults,” Emily Bamforth, a paleontologist with the nearby Philip J. Currie Dinosaur Museum, said in an interview on the way to the dig site.

She described the horned Pachyrhinosaurus as “the smaller, older cousin of the triceratops.”

“This species of dinosaur is endemic to the Grand Prairie area, so it’s found here and nowhere else in the world. They are … kind of about the size of an Indian elephant and a rhino,” she added.

The head alone, she said, is about the size of a baby elephant.

The discovery was a long time coming.

The bonebed was first discovered by a high school teacher out for a walk about 50 years ago. It took the teacher a decade to get anyone from southern Alberta to come to take a look.

“At the time, sort of in the ’70s and ’80s, paleontology in northern Alberta was virtually unknown,” said Bamforth.

When paleontogists eventually got to the site, Bamforth said, they learned “it’s actually one of the densest dinosaur bonebeds in North America.”

“It contains about 100 to 300 bones per square metre,” she said.

Paleontologists have been at the site sporadically ever since, combing through bones belonging to turtles, dinosaurs and lizards. Sixteen years ago, they discovered a large skull of an approximately 30-year-old Pachyrhinosaurus, which is now at the museum.

About a year ago, they found the second adult: Big Sam.

Bamforth said both dinosaurs are believed to have been the elders in the herd.

“Their distinguishing feature is that, instead of having a horn on their nose like a triceratops, they had this big, bony bump called a boss. And they have big, bony bumps over their eyes as well,” she said.

“It makes them look a little strange. It’s the one dinosaur that if you find it, it’s the only possible thing it can be.”

The genders of the two adults are unknown.

Bamforth said the extraction was difficult because Big Sam was intertwined in a cluster of about 300 other bones.

The skull was found upside down, “as if the animal was lying on its back,” but was well preserved, she said.

She said the excavation process involved putting plaster on the skull and wooden planks around if for stability. From there, it was lifted out — very carefully — with a crane, and was to be shipped on a trolley to the museum for study.

“I have extracted skulls in the past. This is probably the biggest one I’ve ever done though,” said Bamforth.

“It’s pretty exciting.”

This report by The Canadian Press was first published Sept. 25, 2024.

The Canadian Press. All rights reserved.

Source link

Continue Reading

News

The ancient jar smashed by a 4-year-old is back on display at an Israeli museum after repair

Published

 on

 

TEL AVIV, Israel (AP) — A rare Bronze-Era jar accidentally smashed by a 4-year-old visiting a museum was back on display Wednesday after restoration experts were able to carefully piece the artifact back together.

Last month, a family from northern Israel was visiting the museum when their youngest son tipped over the jar, which smashed into pieces.

Alex Geller, the boy’s father, said his son — the youngest of three — is exceptionally curious, and that the moment he heard the crash, “please let that not be my child” was the first thought that raced through his head.

The jar has been on display at the Hecht Museum in Haifa for 35 years. It was one of the only containers of its size and from that period still complete when it was discovered.

The Bronze Age jar is one of many artifacts exhibited out in the open, part of the Hecht Museum’s vision of letting visitors explore history without glass barriers, said Inbal Rivlin, the director of the museum, which is associated with Haifa University in northern Israel.

It was likely used to hold wine or oil, and dates back to between 2200 and 1500 B.C.

Rivlin and the museum decided to turn the moment, which captured international attention, into a teaching moment, inviting the Geller family back for a special visit and hands-on activity to illustrate the restoration process.

Rivlin added that the incident provided a welcome distraction from the ongoing war in Gaza. “Well, he’s just a kid. So I think that somehow it touches the heart of the people in Israel and around the world,“ said Rivlin.

Roee Shafir, a restoration expert at the museum, said the repairs would be fairly simple, as the pieces were from a single, complete jar. Archaeologists often face the more daunting task of sifting through piles of shards from multiple objects and trying to piece them together.

Experts used 3D technology, hi-resolution videos, and special glue to painstakingly reconstruct the large jar.

Less than two weeks after it broke, the jar went back on display at the museum. The gluing process left small hairline cracks, and a few pieces are missing, but the jar’s impressive size remains.

The only noticeable difference in the exhibit was a new sign reading “please don’t touch.”

The Canadian Press. All rights reserved.

Source link

Continue Reading

Trending

Exit mobile version