Fifty years ago, a meteorite fell to Earth and landed in Australia, carrying with it a rare sample from interstellar space. A new analysis of the meteorite revealed stardust that formed between five to seven billion years ago. That makes the meteorite and its stardust the oldest solid material ever discovered on Earth.
Our sun is around 4.6 billion years old, meaning this stardust existed long before our sun or solar system were even a reality. The stardust found on the meteorite are called presolar grains because they formed before our sun.
Stars are born when gas, dust and heat combine in just the right way. They can exist for millions or even billions of years before dying and expelling their key ingredients into space. This in turn helps new stars to be born, creating a space daisy chain.
Meteorites, if they don’t knock into too many things, can act like time capsules of the materials trapped within them, like stardust. That’s why the discovery of the presolar grains is such a rarity — only 5% of meteorites found on Earth contain them. Their impossibly tiny size is difficult to fathom.
One hundred of the largest found presolar grains could fit on a period, according to a release by the Field Museum in Chicago.
A new study of presolar grains from the Murchison meteorite recovered in Australia published Monday in the Proceedings of the National Academy of Sciences journal.
“This is one of the most exciting studies I’ve worked on,” said Philipp Heck, lead study author and a curator at the Field Museum. “These are the oldest solid materials ever found, and they tell us about how stars formed in our galaxy. They’re solid samples of stars.”
The meteorite was recovered in 1969 and presolar grains were isolated from it.
“It starts with crushing fragments of the meteorite down into a powder,” said Jennika Greer, study co-author and a graduate student at the Field Museum and the University of Chicago. “Once all the pieces are segregated, it’s a kind of paste, and it has a pungent characteristic. It smells like rotten peanut butter.”
Dissolving the paste in acid reveals the presolar grains, allowing the researchers to determine their age and the type of star they once belonged to.
The researchers were able to measure the exposure of the grains to cosmic rays, highly energized particles zipping through our galaxy.
“Some of these cosmic rays interact with the matter and form new elements,” Heck said. “And the longer they get exposed, the more those elements form. I compare this with putting out a bucket in a rainstorm. Assuming the rainfall is constant, the amount of water that accumulates in the bucket tells you how long it was exposed.”
Many of the grains recovered were between 4.6 and 4.9 billion years old, while others were older than 5.5 billion years.
They also learned that seven billion years ago, more stars began forming.
“We have more young grains than we expected,” Heck said. “Our hypothesis is that the majority of those grains, which are 4.9 to 4.6 billion years old, formed in an episode of enhanced star formation. There was a time before the start of the solar system when more stars formed than normal.”
Astronomers have argued about the rate of star formation. Some believe it’s steady and unchanging, while others believe there are peaks and dips.
“Some people think that the star formation rate of the galaxy is constant,” Heck said. “But thanks to these grains, we now have direct evidence for a period of enhanced star formation in our galaxy seven billion years ago with samples from meteorites. This is one of the key findings of our study.”
They also determined that the presolar grains have a habit of clumping together in granola-like clusters, which they didn’t think possible, Heck said.
Understanding the grains has shed light not only on stars and how long their stardust can last but also more on galaxies and their timelines.
“With this study, we have directly determined the lifetimes of stardust. We hope this will be picked up and studied so that people can use this as input for models of the whole galactic life cycle,” Heck said. “It’s so exciting to look at the history of our galaxy. Stardust is the oldest material to reach Earth, and from it, we can learn about our parent stars, the origin of the carbon in our bodies [and] the origin of the oxygen we breathe. With stardust, we can trace that material back to the time before the sun.”
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SpaceX's latest batch of internet satellites includes one with a sun shield – Report Door
(Reuters) – ZoomInfo Technologies Inc on Wednesday priced its initial public offering (IPO) above its upwardly revised target range in the largest U.S. technology listing so far this year, people familiar with the matter said.
The listing is the latest in a packed week for IPOs, which have rebounded after market turmoil in March and April over the COVID-19 pandemic delayed many listings.
Earlier on Wednesday, Warner Music Group Corp’s stock popped 8% on its Nasdaq debut, after selling $1.9 billion in shares toward the higher end of its target range in the largest U.S. IPO so far this year.
ZoomInfo sold shares in the IPO at $21 each, above its upwardly revised $19-$20 target range, the sources said.
The IPO was around 20 times oversubscribed, the sources added.
The Carlyle Group-backed business intelligence platform has said it is looking to sell 44.5 million shares, which at $21 would raise $934.5 million to value the company at just over $8 billion.
ZoomInfo declined to comment.
ZoomInfo said its customers in industries most impacted by the pandemic, including retail, restaurant, hotels, airlines and oil and gas, may reduce their technology or sales and marketing spending, which could adversely impact its business.
JPMorgan and Morgan Stanley were lead bookrunners for the IPO. ZoomInfo shares are due to begin trading on Nasdaq on Thursday under the trading symbol “ZI.”
Reporting by Joshua Franklin in New York; Editing by Tom Brown and Christopher Cushing
SpaceX launches 60 more Starlink satellites and achieves a reusability record for a Falcon 9 booster – TechCrunch
SpaceX launched its second Falcon 9 rocket in the span of just four days on Wednesday at 9:25 PM EDT (6:25 PM PDT). This one was carrying 60 more satellites for its Starlink constellation, which will bring the total currently in operation on orbit to 480. The launch took off from Florida, where SpaceX launched astronauts for the first time ever on Saturday for the final demonstration mission of its Crew Dragon to fulfill the requirements of NASA’s Commercial Crew human-rating process.
Today’s launch didn’t include any human passengers, but it did fly that next big batch of Starlink broadband internet satellites, as mentioned. Those will join the other Starlink satellites in low Earth orbit, forming part of a network that will eventually serve to provide high-bandwidth, reliable internet connectivity, particularly in underserved areas where terrestrial networks either aren’t present or don’t offer high-speed connections.
This launch included a test of a new system that SpaceX designed in order to hopefully improve an issue its satellites have had with nighttime visibility from Earth. The test Starlink satellite, one of the 60, has a visor system installed that it can deploy post-launch in order to block the sun from reflecting off of its communication antenna surfaces. If it works as designed, it should greatly reduce sunlight reflected off of the satellite back to Earth, and SpaceX will then look to make it a standard part of its Starlink satellite design going forward.
Part of this launch included landing the first stage of the Falcon 9 rocket used for the launch, which has already flown previously four times and been recovered – that makes this a rocket that has now flown five missions, and today it touched down safely once again on SpaceX’s drone landing barge in the ocean so it can potentially be used again.
SpaceX will also be attempting to recover the two fairing halves that form the protective nose cone used during launch at the top of the rocket to protect the payload being carried by the Falcon 9. We’ll provide an update about how that attempt goes once SpaceX provides details.
Tomorrow, June 4, actually marks the 10-year anniversary of the first flight of a Falcon 9 rocket – between this reusability record, and the much more historic first human spaceflight mission earlier this week, that’s quite the decade.
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