The Whirlpool Galaxy, some 28 million light-years from Earth, looks to our telescopes like a cosmic hurricane littered with sparkling gemstones. Huge, lean arms spiral out from the center of Whirlpool, also known as M51. Cradled within them are young stars flaring to life and old stars expanding, expiring and exploding.
In 2012, NASA’s Chandra Observatory, which sees the sky in X-rays, spotted a curious flicker coming from the galaxy. An X-ray source in one of Whirlpool’s arms switched off for about two hours before suddenly flaring back to life. This isn’t particularly unusual for X-ray sources in the cosmos. Some flare, others periodically dim.
This particular source emanated from an “X-ray binary,” known as M51-ULS-1, which is actually two objects: Cosmic dance partners that have been two-stepping around each other for potentially billions of years. One of these objects is either a black hole or a neutron star, and the other may be a large, very bright type of star known as a “blue supergiant.”
As astronomers looked a little more closely at the X-ray signal from the pair, they began to suspect the cause for the dimming may have been something we’ve never seen before: A world outside of the Milky Way, had briefly prevented X-rays from reaching our telescopes. The team dubbed it an “extroplanet.”
A research team led by astronomer Rosanne Di Stefano, of the Harvard-Smithsonian Center for Astrophysics, published details of their hypothesis in the journal Nature Astronomy on Oct. 25. Their study lays out evidence that the X-ray wink detected by Chandra was potentially caused by a planet, about the size of Saturn, passing in front of M51-ULS-1.
The extroplanet candidate goes by the name “M51-1” and is believed to orbit its host binary at about the same distance Uranus orbits our sun.
While many news sources have championed the detection as the “first planet discovered outside of the Milky Way,” there’s no way of confirming the find. At least, not for another few decades, when the proposed planet is supposed to make another transit of the binary. Di Stefano says the team modeled other objects that could potentially produce the dip in X-rays but came up short. Still, she stresses this is not a confirmed detection.
“We cannot claim that this is definitely a planet,” says Di Stefano, “but we do claim that the only model that fits all of the data … is the planet candidate model.”
While other astronomers are excited by the use of X-rays as a way of discovering distant worlds, they aren’t as convinced Di Stefano’s team has been able to rule out other objects such as large, failed stars known as brown dwarfs or smaller, cooler M stars.
“Either this is a completely unexpected exoplanet discovered almost immediately in a small amount of data, or it’s something quite common or garden variety,” says Benjamin Pope, an astrophysicist studying exoplanets at the University of Queensland in Australia.
Prior to these first detections, humans had mostly imagined planets very similar to those we become familiar with in preschool. Rocky planets like the Earth and Mars, gas giants like Jupiter and smaller worlds, like Pluto, far from the sun. Since 1992, our ideas have proven to be extremely unimaginative.
But all of these worlds have, so far, been located within the Milky Way.
The Whirlpool Galaxy, M51, in X-ray and optical light.
NASA/CXC/SAO/R. DiStefano, et al.
It’s very likely (in fact, it’s practically certain) that planets exist outside of our galaxy — we just haven’t been able to detect them yet. Our closest galactic neighbor, Andromeda, is approximately 2.5 million light-years away. The farthest exoplanet we’ve found resides at just 28,000 light-years from Earth, according to the NASA Exoplanet Catalog.
Finding planets outside the solar system is not easy because less and less light makes its way across the universe to our telescopes. Astronomers rarely “see” an exoplanet directly. This is because the bright light from a star in nearby planetary systems usually obscures any planets that might orbit around it.
To “see” them, astronomers have to block out a star’s rays. Less than 2% of the exoplanets in NASA’s 4,538-strong catalog have been found by this method, known as “direct imaging.”
But one highly successful method, accounting for over 3,000 exoplanet detections, is known as the “transit” method. Astronomers point their telescopes at stars and then wait for periodic dips in their brightness. If these dips come with a regular cadence, they can represent a planet, moving around the star and, from our view on Earth, periodically eclipsing its fiery host. It’s the same idea as a solar eclipse, when the moon passes directly in front of our sun and darkness descends over the Earth.
It’s this method that was critical to the discovery of M51-1. However, instead of detecting dips in visible light (a form of electromagnetic radiation), the team saw a dip in the X-rays (a different form of electromagnetic radiation). Because those X-rays were emanating from a relatively small region, Di Stefano says, a passing planet seems like it could block most or all of them.
M51-1
If M51-1 is a planet, Di Stefano’s team believe it may have had a tumultuous life.
It’s gravitationally bound to the X-ray binary M51-ULS-1, which Di Stefano’s team posits consists of a black hole or neutron star orbiting a supergiant star. In the eons-old dance between the pair, the black hole or neutron star has been siphoning off mass from the supergiant. This mass, made of hot dust and gas, is constantly in motion around the black hole/neutron star in what’s known as an accretion disk. This hot disk gives off the X-rays detected by Chandra.
Regions of space around X-ray binaries are violent places, and this disk doesn’t give off X-rays in a stable manner. Sometimes, the X-rays seem to switch off for hours, but pinning down the reason is hard. “Within the very wide range of kinds of behaviors of these dynamic systems, it’s possible that some variation in the accretion rate or something like that could give rise to events like this,” says Duncan Galloway, an astrophysicist at Monash University studying neutron star binaries.
The dip in X-ray brightness is apparent on this graph, just prior to 45 hours — but was it caused by a planet?
NASA/CXC/SAO/R. DiStefano, et al.
One belief is that the dimming could result from some of the hot gas and dust in the system obscuring the signal. Di Stefano says this is not the case, because gas and dust would provide a different signal. “As they pass in front of the X-ray source, some of the light from the source begins to interact with the outer regions of the cloud and this gives a distinctive spectral signature,” she notes.
Another possibility is that the X-ray dimming was caused by different types of stars obscuring our view. One type, known as a brown dwarf, arises when a star fails to properly ignite. Another, an M dwarf, is a common type of star sometimes dubbed a “red dwarf.” But due to the age of the M51-ULS-1 system, Di Stefano’s team believe these objects would be much larger than the object they’ve detected.
Di Stefano’s team ran a load of models exploring various scenarios for why the X-ray source switched off. In the end, she says, it was a Saturn-sized planet that seemed to fit what they were seeing best.
“The planet candidate model was the last one standing, so to speak,” says Di Stefano.
Pope is less convinced. “Personally, I wouldn’t bet that this is a planet,” he says. “In my view this is probably a stellar companion or something exotic happening in the disk.”
Trust the process
This isn’t the first time NASA’s Chandra observatory has been swept up in a potential “extroplanet” find. Studying how radiation from distant stars is “bent” by gravity, a technique known as microlensing, astronomers at the University of Oklahoma believed they detected thousands of extragalactic planets back in 2018. Earlier studies have claimed to find evidence of extragalactic planets in the Andromeda galaxy.
Other astronomers were skeptical about these detections, too. The same skepticism has played out in the case of M51-1. And, importantly, that’s perfectly normal.
This is the scientific process in action. Di Stefano’s team have argued their case: M51-1 is an extragalactic planet. Now there’s more work to do. Confirmation that M51-1 is planetary won’t be possible until it makes another transit of the X-ray binary in many decades’ time, but there are other ways for astronomers to vet their results.
Pope notes that if we found analogous systems in the Milky Way, we’d be able to follow up with optical telescopes and get a better understanding of what might be happening at these types of systems.
We know there must be planets outside of the Milky Way, and so, eventually, humans will discover them. For Galloway, the study is exciting not because of what caused the X-ray binary to dip in brightness, but what happens next.
“The really exciting thing is there might be additional events in other data, so now we have a motivation where we can go and look for them,” he says.
Di Stefano feels the same way, hoping the publication will bring others into this type of research. She says the team is working hard, studying the skies for other X-ray binaries that may exhibit similar dimming.
“Ultimately,” she notes, “the best verification will be the discovery of more planets.”
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. ”
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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.
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.”
