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"Farthest galaxy ever" HD1 is probably not what it seems

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An exciting potential discovery has recently rocked the world of astrophysics.

Artist’s logarithmic scale conception of the observable universe. The Solar System gives way to the Milky Way, which gives way to nearby galaxies which then give way to the large-scale structure and the hot, dense plasma of the Big Bang at the outskirts. Each line-of-sight that we can observe contains all of these epochs, but the quest for the most distant observed object will not be complete until we’ve mapped out the entire Universe.

(Credit: Pablo Carlos Budassi; Unmismoobjetivo/Wikimedia Commons)

This galaxy, HD1, was just announced as the youngest, most distant galaxy ever seen.

farthest galaxy

Shown here with purple arrows, this tiny red object, barely able to be seen without pointers to it, may represent the most distant object presently known in the Universe: HD1. However, its distance has yet to be definitively determined.

(Credit: Harikane et al.)

Possessing an age of 330 million years, it’s presently 33 billion light-years away: the farthest ever seen.

unreachable

The light from any galaxy that was emitted after the start of the hot Big Bang, 13.8 billion years ago, would have reached us by today so long as it’s within about 46.1 billion light-years at present. But the light from the earliest, most distant galaxies will be blocked by intervening matter and redshifted by the expanding Universe. Both represent severe challenges to detection, and pose cautionary tales against us drawing definitive conclusions about their distance without the proper, necessary data.

(Credit: F. Summers, A. Pagan, L. Hustak, G. Bacon, Z. Levay, and L. Frattere (STScI))

This could break the old record of GN-z11: 407 million years old and 32 billion light-years distant.

most distant

A section of the GOODS-N field, which contains the galaxy GN-z11, the most distant galaxy ever observed. At a redshift of 11.1, a distance of 32.1 billion light-years, and an inferred age of the Universe of 407 million light-years at the time this light was emitted, this is the farthest back we’ve ever seen a luminous object in the Universe. Hubble’s spectroscopic confirmation was key; without it, we should have remained skeptical.

(Credit: NASA, ESA, G. Bacon (STScI), A. Feild (STScI), P. Oesch (Yale))

If so, it’s a fascinating find: bright, luminous, and possibly home to the first truly pristine stars.

The very first stars and galaxies that form should be home to Population III stars: stars made out of only the elements that first formed during the hot Big Bang, which is 99.999999% hydrogen and helium exclusively. Such a population has never been seen or confirmed, but some are hopeful that HD1 will contain them.

(Credit: Pablo Carlos Budassi/Wikimedia Commons)

But there’s an excellent chance that HD1 is not the record-breaker it’s widely reported to be.

Although there are magnified, ultra-distant, very red and even infrared galaxies like the ones identified here in the Hubble eXtreme Deep Field, many of these candidate galaxies have turned out to be either intrinsically red and/or closer interlopers, not the ultra-distant objects we hoped they were. Without spectroscopic confirmation, fooling ourselves as to an object’s cosmic distance is an unfortunate, but commonplace occurrence.

(Credit: NASA, ESA, R. Bouwens and G. Illingsworth (UC, Santa Cruz))

Yes, it’s extremely red in color, missing all of its short-wavelength light.

farthest galaxy

This figure shows various photometric filters (top) and the images of HD1 that they do or do not reveal, as well as two different fits to the photometric data. Note that even though the high-redshift fit is superior, there is no spectroscopic confirmation of the galaxy HD1’s distance at all.

(Credit: Y. Harikane et al., ApJ, 2022)

Only the longest-wavelength photometric filters reveal the object at all.

farthest galaxy

Before a sufficient number of stars form, neutral atoms persist in the intergalactic medium of the Universe, where they are remarkably efficient at blocking ultraviolet and visible light starlight. Without spectroscopic confirmation, like we have for GN-z11 but not HD1, caution should be warranted.

(Credit: Harikane et al., NASA, EST and P. Oesch/Yale)

This is consistent with an object behind the “wall of neutral atoms” prior to reionization.

reionization

Schematic diagram of the Universe’s history, highlighting reionization. Before stars or galaxies formed, the Universe was full of light-blocking, neutral atoms. Most of the Universe doesn’t become reionized until 550 million years afterwards, with some regions achieving full reionization earlier and others later. The first major waves of reionization begin happening at around 250 million years of age, while a few fortunate stars may form just 50-to-100 million years after the Big Bang. With the right tools, like the James Webb Space Telescope, we may begin to reveal the earliest galaxies.

(Credit: S. G. Djorgovski et al., Caltech; Caltech Digital Media Center)

But only spectroscopy can determine a galaxy’s redshift with absolute certainty.

Only by breaking the light from a distant object up into its component wavelengths and by identifying the signature of atomic or ionic electron transitions that can be linked to a redshift, and hence, the expanding Universe, can a confident redshift (and hence, distance) be arrived at. That evidence is lacking for HD1 and HD2 today.

(Credit: Vesto Slipher, 1917, Proc. Amer. Phil. Soc.)

Multiple spectral lines, linked to quantum transitions, reveal how severely emitted light is redshifted by the expanding Universe.

expanding universe

This simplified animation shows how light redshifts and how distances between unbound objects change over time in the expanding Universe. Only by linking the wavelength of the emitted light to the observed light can the redshift truly be measured with confidence.

(Credit: Rob Knop)

For HD1, only one candidate line exists, and its detection significance is below the 5-σ threshold.

In the entirety of the spectra taken by our most powerful observatories, including ALMA, of galaxy HD1, only one tentative signature for a line emerges: for a doubly-ionized oxygen line. Its confidence does not rise to the “gold standard” required to announce a discovery.

(Credit: Y. Harikane et al., ApJ, 2022)

The “other” distant candidate, HD2, possesses no spectral lines at all.

The exposures in different photometric bands (top) of candidate galaxy HD2, along with two possible spectral fits (curves) to the data points (red). Note how although a high redshift (z = 12) solution is favored over a low redshift (z = 3.5) interpretation, both are possible, and the unambiguous signature from spectroscopy is not available.

(Credit: Y. Harikane et al., ApJ, 2022)

Until spectroscopic confirmation arrives, caution is mandated, as no distances can be decisively determined.

The full published spectrum of candidate galaxy HD1 shows no definitive spectral line detections at all. The red arrow corresponds to the candidate signal of a doubly ionized oxygen line. Without decisive data, we cannot responsibly conclude that this is, in fact, the farthest galaxy we’ve ever seen. It might not be anything like that at all.

(Credit: Y. Harikane et al., ApJ, 2022)

Mostly Mute Monday tells an astronomical story in images, visuals, and no more than 200 words. Talk less; smile more.

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

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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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Follow Seth Borenstein on Twitter at @borenbears

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

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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.

The Canadian Press. All rights reserved.

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

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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.

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