Connect with us

Science

Why astronomers are wondering whether Orion's shoulder will soon explode – CBC.ca

Published

 on


The dramatic dimming of a giant star has astronomers wondering whether it’s getting ready to explode. 

Betelgeuse — the red shoulder on the left side in the constellation Orion — has dimmed by a factor of about two since October, a change that has never been documented before.

“We know that it’s the dimmest it’s been observed ever, based on the data we have,” said Stella Kafka, chief executive officer of the American Association of Variable Star Observers

What makes this development particularly intriguing to astronomers is that the star is slated to explode in spectacular fashion: a supernova. Astronomers estimate this will happen relatively soon — in astronomical terms anyway. It could be today, tomorrow or 100,000 years from now.

And when Betelgeuse goes supernova, astronomers estimate it will be as bright as the full moon and visible even during the day.

The tricky thing is that, because Betelgeuse is a red supergiant cloaked in a cloud of dust and gas, it’s difficult to accurately describe it.

It’s believed to be anywhere between 425 to 650 light years away, with a mass roughly 10 times that of the sun. It is also huge — likely 1,400 times larger than the sun. If it sat where the sun does, it would swallow all the inner planets, including Earth, Mars and even Jupiter. It’s also about 14,000 times more luminous than our comparatively small star.

But Betelgeuse is also a variable star, meaning its brightness rises and falls periodically. But we’ve never seen it like this.

“Maybe 300 years ago, Betelgeuse was dimmer than what we’re observing now, but we don’t have data,” Kafka said. 

This image, made with the European Southern Observatory’s Atacama Large Millimeter/submillimeter Array (ALMA) telescope, shows the red supergiant Betelgeuse — one of the largest known stars. If it were at the centre of our solar system, Betelgeuse would engulf Mercury, Venus, Earth, Mars and even Jupiter. (ALMA (ESO/NAOJ/NRAO)/E. O’Gorm)

 

So, does this dimming portend a potentially historic and magnificent explosion?

Maybe. Maybe not.

It’s not quite clear why exactly Betelgeuse dims periodically, but one of the possibilities is that, like the sun, it has cooler and hotter parts. If one of those cooler parts swung into our line of sight, that could make it seem like the star had dimmed.

In 2018, Betelgeuse had a couple of dips in its brightness, Kafka said. What we’re seeing now could be that same spot, or possibly another.

Plus, dimming isn’t necessarily indicative of an impending explosion.

There’s no telling what will happen next.

“I don’t even know if that’s the dimmest it’s going to get. This is an event that has been evolving,” Kafka said. “We’re still in the middle of it. Well, we’re still actually at the beginning of it. These kinds of massive stars move slowly. They take their sweet time.”

A history of supernovas

Astronomers spot supernovas somewhat regularly, though in other galaxies.

The last one in our galaxy that may have been observed from Earth was Cassiopeia A in 1680. 

Astronomers estimate that supernovas occur in galaxies like ours once every 100 years or so, though that doesn’t mean we will witness them all; they could be on the other side of the galaxy, for example, or hidden from view.

The supernova remnant Cassiopeia A as seen by the Chandra X-Ray Observatory. The blue dot in the centre of the image is identified as a young neutron star. (NASA/CXC/SAO; Optical: NASA/STScI; Infrared: NASA/JPL-Caltech/O. Krause)

A perfect example is a study published in 2008 that detected the remnant of a supernova in the Milky Way that was traced back roughly 140 years. It wasn’t visible to the naked eye, as it lay close to the centre of the galaxy and was obscured by dust and gas.

So we may be due for one soon.

No mutants

Kafka said there’s no need to panic: even if Betelgeuse were to explode, it wouldn’t obliterate life on Earth or turn us into mutants, though we would notice the blow of radiation it would deliver.

“What I will tell you is that it will be super interesting,” Kafka said.

“It will be an excellent opportunity to study a supernova in the making.”

The star could explode in two ways, she said. Either in two beams from its poles, or with a spherical, symmetrical explosion in all directions. If we were in the way of the beam-type explosion — which we’re not — or if Betelgeuse was a lot closer, we’d be in trouble.

But for now, you can carry on enjoying the holidays, if that’s what you were planning.

“We’re not going to die,” Kafka said. “But if you’re looking for an excuse to eat more this Christmas, go for it.”

Let’s block ads! (Why?)



Source link

Continue Reading

Science

NASA’s Hubble Space Telescope captured two festive-looking nebulas – Tech Explorist

Published

 on


The image shows NGC 248, about 60 light-years long and 20 light-years wide. They are two nebulas, situated to appear as one. The nebulas, together, are called NGC 248.

Initially discovered in 1834 by the astronomer Sir John Herschel, NGC 248 resides in the Small Magellanic Cloud, located approximately 200,000 light-years away in the southern constellation Tucana.

Small Magellanic Cloud is a dwarf galaxy that is a satellite of our Milky Way galaxy. The image is part of a study called Small Magellanic Cloud Investigation of Dust and Gas Evolution (SMIDGE).

The dwarf satellite galaxy contains several brilliant hydrogen nebulas, including NGC 248. Intense radiation from the brilliant central stars is heating hydrogen in each nebula, causing them to glow red.

The study’s principal investigator, Dr. Karin Sandstrom of the University of California, San Diego, said“The Small Magellanic Cloud has between a fifth and a tenth of the amount of heavy elements that the Milky Way does. Because it is so close, astronomers can study its dust in great detail and learn about what dust was like earlier in the history of the universe.”

“It is important for understanding the history of our galaxy, too. Most of the star formation happened earlier in the universe, at a time when there was a much lower percentage of heavy elements than there is now. Dust is a critical part of how a galaxy works, how it forms stars.”

The image is part of a study called Small Magellanic Cloud Investigation of Dust and Gas Evolution (SMIDGE). The data used in this image were taken with Hubble’s Advanced Camera for Surveys in September 2015.

Adblock test (Why?)



Source link

Continue Reading

Science

When To See An ‘Earth-Grazer’ This Weekend: Don’t Write-Off The Perseid Meteor Shower, Says Expert – Forbes

Published

 on


If you’ve ever laid down a blanket or set up a lawn chair to watch a meteor shower there’s a good chance it was to watch the Perseids.

Due to peak at 01:00 UT on Saturday, August 13, 2022, normal advice would be to be outside at that time (in Europe) or just as soon as its gets dark on Friday, August 12 (North America).

As I’ve already reported, this year the Perseids coincides with a full Moon, so all but the brightest meteors and “fireballs” (larger, brighter meteors) will be visible. So from the 50-75-or-so “shooting stars” you might normally see during the peak of the Perseids only a few—albeit bright—meteors will be visible.

It’s almost not worth the bother, I said, advising you to go watch this instead next weekend.

However, there is another opinion. In an article published on the American Meteor Society’s website, fireball coordinator Robert Lunsford says that despite the bright full Moon visible meteor rates during the peak of the Perseid meteor shower will be better than 95% of all other nights this year.

When to see the Perseid meteor shower

“Most of the Perseid meteors are faint and bright moonlight will make it difficult to view,” he writes. “Despite the glare of moonlight, the Perseids produce many bright meteors that can still be easily seen despite the bright moonlight.”

He also advises two great times to watch for shooting stars—just after sunset on Friday, August 12 and just before dawn on Saturday, August 13.

Perseids: ‘Earth-grazers’ just after sunset

You’ll need patience, but to see an “Earth-grazer” is unforgettable.

Just after sunset is actually thee worst time in terms of numbers of shooting stars you might see, but the few that do come your way this time of night are special.” The reason is that they just skim the upper regions of the atmosphere and will last much longer than Perseids seen during the morning hours,” writes Lunsford. “Most of these “earth-grazing” Perseids will be seen low in the east or west, traveling north to south.”

Perseids: ‘shooting stars’ before dawn

The activity from the Perseid meteor shower will peak where you are as the radiant—the constellation of Perseus—rises higher into the night sky. “Theoretically, the best time to watch the Perseids is just before the break of dawn when the radiant lies highest in a dark sky,” writes Lunsford. That’s about 04:00 local time, though he also reveals that experienced observers often say the hour between 03:00 and 04:00 is usually the best.

Perseids: ‘shooting stars’ in a moonless sky

If you want to look for Perseids in a dark, moonless sky then you’re mostly out of luck this year. By the time the full Moon is rising long after midnight the meteor rates will have vastly reduced, though it may be worth shooting star-gazing after August 19, 2022.

When is the Perseid meteor shower in 2023?

The Perseid meteor shower will next year peak—in thankfully moonless skies—at around 07:00 UT on August 13, 2023 (so 03:00 EST and midnight PST), which will be ideal for North America.

Wishing you clear skies and wide eyes.

Adblock test (Why?)



Source link

Continue Reading

Science

Meet Qikiqtania, a fossil fish who stayed in the water while others ventured onto land – Big Think

Published

 on


Approximately 365 million years ago, one group of fishes left the water to live on land. These animals were early tetrapods, a lineage that would radiate to include many thousands of species including amphibians, birds, lizards and mammals. Human beings are descendants of those early tetrapods, and we share the legacy of their water-to-land transition.

But what if, instead of venturing onto the shores, they had turned back? What if these animals, just at the cusp of leaving the water, had receded to live again in more open waters?

A new fossil suggests that one fish, in fact, did just that. In contrast to other closely related animals, which were using their fins to prop their bodies up on the bottom of the water and perhaps occasionally venturing out onto land, this newly discovered creature had fins that were built for swimming.

Tom Stewart holds the Qikiqtania fossil. (Stephanie Sang / CC BY-ND)

In March 2020, I was at The University of Chicago and a member of biologist Neil Shubin’s lab. I was working with Justin Lemberg, another researcher in our group, to process a fossil that was collected back in 2004 during an expedition to the Canadian Arctic.

From the surface of the rock it was embedded in, we could see fragments of the jaws, about 2 inches long (5 cm) and with pointed teeth. There were also patches of white scales with bumpy texture. The anatomy gave us subtle hints that the fossil was an early tetrapod. But we wanted to see inside the rock.

Smarter faster: the Big Think newsletter

Subscribe for counterintuitive, surprising, and impactful stories delivered to your inbox every Thursday

Notice: JavaScript is required for this content.

So we used a technology called CT scanning, which shoots X-rays through the specimen, to look for anything that might be hidden within, out of view. On March 13, we scanned an unassuming piece of rock that had a few scales on top and discovered it contained a complete fin buried inside. Our jaws dropped. A few days later, the lab and campus shut down, and COVID-19 sent us into lockdown.

The fin revealed

A fin like this is extremely precious. It can give scientists clues into how early tetrapods were evolving and how they were living hundreds of millions of years ago. For example, based on the shape of certain bones in the skeleton, we can make predictions about whether an animal was swimming or walking.

Although that first scan of the fin was promising, we needed to see the skeleton in high resolution. As soon as we were allowed back on campus, a professor in the university’s department of the geophysical sciences helped us to trim down the block using a rock saw. This made the block more fin, less rock, allowing for a better scan and a closer view of the fin.

[embedded content]

When the dust had cleared and we’d finished analyzing data on the jaws, scales and fin, we realized that this animal was a new species. Not only that, it turns out that this is one of the closest known relatives to limbed vertebrates – those creatures with fingers and toes.

We named it Qikiqtania wakei. Its genus name, pronounced “kick-kiq-tani-ahh,” refers to the Inuktitut words Qikiqtaaluk or Qikiqtani, the traditional name for the region where the fossil was found. When this fish was alive, many hundreds of millions of years ago, this was a warm environment with rivers and streams. Its species name honors the late David Wake, a scientist and mentor who inspired so many of us in the field of evolutionary and developmental biology.

[embedded content]

Skeletons tell how an animal lived

Qikiqtania reveals a lot about a critical period in our lineage’s history. Its scales tell researchers unambiguously that it was living underwater. They show sensory canals that would have allowed the animal to detect the flow of water around its body. Its jaws tell us that it was foraging as a predator, biting and holding onto prey with a series of fangs and drawing food into its mouth by suction.

But it is Qikiqtania’s pectoral fin that is most surprising. It has a humerus bone, just as our upper arm does. But Qikiqtania’s has a very peculiar shape.

Early tetrapods, like Tiktaalik, have humeri that possess a prominent ridge on the underside and a characteristic set of bumps, where muscles attach. These bony bumps tell us that early tetrapods were living on the bottom of lakes and streams, using their fins or arms to prop themselves up, first on the ground underwater and later on land.

Qikiqtania’s humerus is different. It lacks those trademark ridges and processes. Instead, its humerus is thin and boomerang-shaped, and the rest of the fin is large and paddle-like. This fin was built for swimming.

Whereas other early tetrapods were playing at the water’s edge, learning what land had to offer, Qikiqtania was doing something different. Its humerus is truly unlike any others known. My colleagues and I think it shows that Qikiqtania had turned back from the water’s edge and evolved to live, once again, off the ground and in open water.

Evolution isn’t a march in one direction

Evolution isn’t a simple, linear process. Although it might seem like early tetrapods were trending inevitably toward life on land, Qikiqtania shows exactly the limitations of such a directional perspective. Evolution didn’t build a ladder towards humans. It’s a complex set of processes that together grow the tangled tree of life. New species form and they diversify. Branches can head off in any number of directions.

Neil Shubin, who found the fossil, pointing across the valley to the site where Qikiqtania was discovered on Ellesmere Island. (Neil Shubin / CC BY-ND)

This fossil is special for so many reasons. It’s not just miraculous that this fish was preserved in rock for hundreds of millions of years before being discovered by scientists in the Arctic, on Ellesmere Island. It’s not just that it’s remarkably complete, with its full anatomy revealed by serendipity at the cusp of a global pandemic. It also provides, for the first time, a glimpse of the broader diversity and range of lifestyles of fishes at the water-to-land transition. It helps researchers see more than a ladder and understand that fascinating, tangled tree.

Discoveries depend on community

Qikiqtania was found on Inuit land, and it belongs to that community. My colleagues and I were only able to conduct this research because of the generosity and support of individuals in the hamlets of Resolute Bay and Grise Fiord, the Iviq Hunters and Trappers of Grise Fiord, and the Department of Heritage and Culture, Nunavut. To them, on behalf of our entire research team, “nakurmiik.” Thank you. Paleontological expeditions onto their land have truly changed how we understand the history of life on Earth.

COVID-19 kept many paleontologists from traveling and visiting field sites across the world these last few years. We’re eager to return, to visit with old friends and to search again. Who knows what other animals lie hidden, waiting to be discovered inside blocks of unassuming stone.

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Adblock test (Why?)



Source link

Continue Reading

Trending