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There’s No Chemical Difference Between Stars With or Without Planets – Universe Today

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Strange New Worlds

Imagine if a star could tell you it had planets. That would be really helpful because finding planets orbiting distant stars – exoplanets – is hard. We found Neptune, the most distant planet in our own solar system, in 1846. But we didn’t have direct evidence of a planet around ANOTHER star until….1995.…149 years later. Think about that. Any science fiction you watched or read that was written before 1995 which depicted travel to exoplanets assumed that other planets even existed. Star Trek: The Next Generation aired its last season in 1994. We didn’t even know if Vulcan was out there. (Now we do!…sortof)

Jupiter (right bright point) and Saturn (left bright point) seen here against the Milky Way were the most distant planets we could see before inventing telescopes – C. Matthew Cimone

Since 1995, with the advent of planet hunting telescopes like Kepler and TESS, we’ve found THOUSANDS of planets orbiting other stars. These missions find exoplanets literally by looking for their shadows. Sometimes an exoplanet’s orbit crosses our view of a distant star blocking out some of the star’s light. This “transit” of the planet creates a shadow in the observed light from the star which we can then use to determine the size of the planet, whether it’s a rocky  planet like Earth or a gas giant like Jupiter, and the length of the planet’s year around its parent star.

Transit of Venus across our own Sun imaged at different stages of the transit. Planet hunting telescopes are looking for these events to discover exoplanets orbiting other stars. c NASA

But planets are very small compared to their host stars. The amount of light they block is a fraction of the star’s overall light, so our equipment needs to be very sensitive. And if the planets are not orbiting in such a way that they cross our view of the star, say if we are looking at the distant solar system from the top down, we may have a harder time detecting their presence. So, scientists are looking for alternative means of discovering planets and one might be to study the parent stars themselves. Stars are big and bright and easy to spot. If stars that give birth to a solar system are somehow unique to stars that don’t, we might have a powerful new way of planet hunting. Specifically, astronomers are paying close attention to a star’s chemical composition – the right star stuff.

Building a Solar System

Planets and stars share the same stuff. Our solar system formed from one enormous rotating cloud of dust and gas called a protoplanetary disk. 99.8% of the stuff was concentrated in the centre  drawn together by gravity to form the Sun.

An actual phot of of a protoplanetary disk of young star HL Tauri about 450 light years away imaged by the ALMA telescope C. ESO/ALMA

The remaining 0.2% of whatever didn’t end up within the Sun itself flattens out to form the disk – imagine like how a ball of dough flattens into a pizza as it is spun. This flattening is why all the planets orbit the Sun along a similar plane called the Plane of the Ecliptic. Within the spinning disk, material begins to accrete forming planetesimals which become the seeds of future planets. But what is this stuff? It’s important! It’s what the planets and you and I are made of. Astronomers refer to it as “metals.” In astronomy, “metals” are considered anything on the periodic table above atomic number 2 – so anything heavier than hydrogen and helium like the calcium in your bones or the iron in your blood. In fact, at the birth of the Universe, there was ONLY hydrogen, helium, and small amounts of lithium. None of the other elements existed. Those elements are themselves created by the stars, deep in their interior, as they convert hydrogen fuel through nuclear fusion into heavier and heaver elements – the metals. Once these stars explode at the end of their lives as supernova, they spill their guts into the interstellar void seeding it with the stuff that makes other stars as well as PLANETS. Likely the first generation of stars in the early universe had no planets at all. There wasn’t yet the raw material to build them. We call those Population III stars.

The next generation of stars, Population II, were the first to form in a universe that was enriched with heavier elements. We’re not entirely sure if this group of stars formed with enough metals to make planets. We want to pinpoint when exactly the first planets formed in the Universe to estimate how early life could have existed. But if planets did form around Population II stars, likely they were quite small and orbited very closely to their parent stars – far closer than Mercury does in our own solar system. Probably not ideal for life at a sweltering 1600K surface temperature. Even if life did form around these stars, it is likely extinct by now as these stars lived shorter lives than our Sun and have already burned out. (Unless of course that life left its solar system to explore the Universe and still exists somewhere as an ancient space-faring civilization from a long-dead star…one can imagine.)

Which brings us to Population I, the group of stars our Sun belongs to. Our Sun formed in a Universe where billions of years of star births and deaths had already occurred. The Universe had been fertilized with more metals. Not only do the metals in a protoplanetary disk create the raw material for planet formation, but also protect the disk itself from being blown away by the parent star’s radiation. More metals mean more time available for the planets to form before the star’s energy eventually evaporates the remaining material that hasn’t yet formed planets

Comets like NEOWISE, which recently visited our skies, is literally just some of the leftover stuff from the protoplanetary disk that formed the solar system c. Matthew Cimone

“Where to Look”

Understanding how planets form give us our first clue as to where to look for them – stars with metals. Remember, the host star and their planets form from the same cloud of stuff, so some of those metals are mixed into the star. By looking at the light from a star using spectroscopy, we can tell how highly enriched it is with metals – the star’s “metallicity.” Studying these metal-rich stars, we know terrestrial rocky planets like Earth are 1.72 times more likely to form around them. Even gas giants are more likely to form around metal-rich stars. Although made from gases rather than metals, gas giants like Jupiter are theorized to form around an initial rocky seed or from the disruptions in the flows of hydrogen gas orbiting in the disk caused by the introduction of metals.

NASA’s Transiting Exoplanet Survey Satellite being prepped for launch C NASA

But while a star’s chemistry can tell us the likelihood that planets are there – can the chemistry tell us exoplanets ARE there!? Is there a key chemical fingerprint for a star to tell us in a booming stellar voice “Yes indeed, I host planets! Behold my children!”

The research so far SAAAYYYYYSS……no. I know. Kind of anticlimactic.

BUT there is still hope. Last week, the Monthly Notices of the Royal Astronomical Society posted a study by the National Centre of Competence in Research PlanetS. NCCR PlanetS researched 84 stars observed by the 10M Keck Telescope in Hawaii. The team of researchers were trying to determine if planet formation leaves a unique chemical tell on a star – a beacon for us to know that indeed the star had given rise to planets – but a unique indicator couldn’t be found. Comparing 16 stars with planets and 68 without, the team found that planets orbit chemically diverse stars. But the findings are still useful. The team issued a warning that given the preponderance of planet discoveries, most of the stars in the study “probably have planets” (pg 8/3698 of the study) that just haven’t been found yet. So, the study might not be entirely accurate. However, this research could yield future discoveries of what KIND of planets, in terms of size or composition, form around a star with a certain chemical signature especially if/when planets are discovered around more stars used in the study. So, while we may not be able to know IF planets exist because of a star’s chemistry, in the future we may be able to infer with more accuracy what types of exoplanets orbit a star given a certain metallicity. For example, we know that metal-rich stars on average give rise to more planets – perhaps the types and quantities of each metal result in a certain arrangement of the solar system, or the quantities of terrestrial vs gas giants, or whether the planets are habitable. More research is needed.

In the meantime, we continue searching for planets using transits. TESS completed its primary mission, imaging 75% of the sky in a two-year survey, just this past August 20th. We don’t yet know what discoveries will be found in the data including perhaps new ways to understand the relationships between a host star and its planets. Whatever we find will certainly inform both future planet hunting missions as well as provide inspiration to the fictional stories boldly going to the strange new worlds our research has discovered. Engage!

Further Reading:

NCCR PlanetS Report http://nccr-planets.ch/blog/2020/08/17/stars-with-planets-show-no-special-fingerprint

“Revealing a Universal Planet-Metallicity Correlation for Planets of Different Sizes Around Solar-Type Star (Astronomical Journal) https://iopscience.iop.org/article/10.1088/0004-6256/149/1/14

“The First Planets: The Critical Metallicity for Planet Formation” – Johnson and Li (2012) https://arxiv.org/abs/1203.4817

“When Stellar Metallicity Sparks Planet Formation” – Astrobiology Magazine

“Do Metal-Rich Stars Make Metal-Rich Planets?” New Insights on Giant Planet Formation from Host Star Abundances – Johanna K. Teske, Daniel Thorngren, Jonathan J. Fortney, Natalie Hinkel, John M. Brewer 2019 https://arxiv.org/abs/1912.00255

Metallicity and Planet Formation: Models” – Boss

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

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Follow Seth Borenstein on Twitter at @borenbears

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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.

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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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