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The Sun Is a Bit Boring, Which May Make It Special – The New York Times

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The sun, like all stars, is a blazing ball of fusion-powered plasma. From its surface emerge magnetic field lines that can cause dark patches known as sunspots. Turn up the activity of these magnetic whorls, and you get more solar storms flinging deadly charged particles and radiation throughout our solar system. If enough of these punishing waves hit a rocky planet, that planet might end up microwaved into a dreary condition where nothing could live.

So how is it that we’re alive? A study released Thursday in the journal Science suggests that our sun is rather tame compared with its stellar siblings, and that hundreds of other sun-like stars in our galaxy have on average five times more magnetic activity than our parent star. In other words, the sun is a bit humdrum, which might be good for life here on Earth.

Astronomers have been tracking the appearance of sunspots since the time of Galileo, providing a proxy for solar activity stretching back four centuries. Some previous studies also implied that the sun was quieter than other similar stars. But competing evidence has also found the sun’s activity level is normal for stars of its size.

“This triggered the question: ‘Is the sun a real sun-like star?’” said Timo Reinhold, an astrophysicist at the Max Planck Institute for Solar System Research in Göttingen, Germany, and co-author of the paper.

Dr. Reinhold and colleagues looked at data collected by NASA’s retired Kepler space telescope, which continuously monitored approximately 150,000 stars in the Milky Way for four years to find exoplanets, and was capable of observing brightness variations from activity such as the appearance and disappearance of starspots.

The researchers selected stars with masses, temperatures, ages, chemical compositions and rotation periods comparable to our sun’s. They eventually found 369 stars for comparison, the largest such sample to date.

Stars like the sun go through regular cycles during which spots cross their surfaces with greater or less frequency. During times of peak magnetic activity, when spots pop out all over the surface, a star will dim. Our sun’s cycle lasts about 11 Earth years.

For the sun, this dimming is negligible. Data from the past 140 years indicates that its brightness changes by less than a tenth of a percent over the course of its cycle. But for the stars studied by Kepler, the variability could be up to 12 times that amount.

The team has come up with two rather different potential explanations for what this means.

The first is that the sun is in a period of unusual torpor, and will one day wake up and become more like its kin. Evidence for this idea comes from significant swings in the sun’s activity levels during recorded history. Between 1645 and 1715, an era known as the Maunder Minimum, astronomers observed few to no sunspots. More than a century later, in 1859, the sun released one of the largest electromagnetic storms ever recorded, the Carrington Event, which knocked out telegraph lines and generated auroras as far south as the Caribbean.

But Natalie Krivova, a co-author and also an astrophysicist at Max Planck said that data from ice cores, which contain chemical indicators of solar activity stretching back 9,000 years, don’t suggest that the sun was any more raucous in the geologically recent past. Then again, nine millenniums is a blip compared to the sun’s 4-billion-year life span.

The second idea, Dr. Krivova said, is that the magnetic dynamo inside the sun, which power’s its colossal magnetic field, is reaching the end of its high-powered stage, and is currently transitioning into a period of reduced activity. Stars older than the sun show marked decreases in magnetic activity, and the sun is just about getting to the age when this shift should occur.

Some stellar scientists believe that the sun’s magnetic dynamo might be “reaching its end state, or almost its death,” said Ricky Egeland, a solar physicist at the National Center for Atmospheric Research in Boulder, Colo.

The 369 sun-like stars observed by Kepler might simply be in an earlier stage of evolution than the sun, these scientists say. Or perhaps something particular about the sun is causing an early transition. Dr. Reinhold’s team doesn’t favor one explanation over the other.

In either case, a quiet sun has benefited our species. When the sun flares up, its energetic emissions do harm to astronauts and satellites in orbit, and especially powerful outbursts can affect power grids down on the ground. Radiation from such events is not particularly conducive to the existence of living organisms.

Models indicate that when the sun was younger, perhaps half a billion or a billion years old, it had greater magnetic activity than today, Dr. Egeland said.

“I always wonder what effect this variability had on the development of life,” he said. “It may be no coincidence that we live around a very inactive star.”

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Astronomers Detect a Suspiciously Shaped Galaxy Lurking in The Very Early Universe

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Astronomers Detect a Suspiciously Shaped Galaxy Lurking in The Very Early Universe_5ec5b2be6848e.jpeg

Around 13.8 billion years ago, somehow the Universe popped into existence. But it didn’t come fully equipped. At some point, the first stars formed, and the first galaxies. How and when this happened is still a mystery astronomers are trying to solve… but one galaxy could have a vitally important key.

 

It’s called DLA0817g – nicknamed the Wolfe Disk – a cool, rotating, gas-rich disc galaxy with a mass of about 72 billion times that of our Sun. And the Atacama Large Millimeter/submillimeter Array has snapped it a massive 12.5 billion light-years away – when the Universe was just 10 percent of its current age.

It’s the earliest rotating disc galaxy astronomers have found yet, and its very existence changes our understanding of galaxy formation in the early Universe.

Most of the galaxies in the early Universe are a hot mess, literally. They’re all blobby, with stars flying every which way, and rather high temperatures. Astronomers have interpreted this to mean that they grew large by colliding and merging with other galaxies – a hot, messy process.

“Most galaxies that we find early in the Universe look like train wrecks because they underwent consistent and often ‘violent’ merging,” explained astronomer Marcel Neeleman of the Max Planck Institute for Astronomy in Germany.

“These hot mergers make it difficult to form well-ordered, cold rotating disks like we observe in our present Universe.”

 

Under this scenario, it takes a long time for the galaxies to cool down and smooth out into the more orderly rotating disc galaxies like the Milky Way. We don’t generally start seeing them until about 4 to 6 billion years after the Big Bang.

This is the “hot” mode of galaxy formation. But astronomers had also predicted and simulated another way – the “cold” mode. 

First, you need to start with the primordial soup, an ionised quark-gluon plasma that filled the Universe before the formation of matter. To go from this homogeneous plasma to a Universe filled with stuff, astrophysicists have run simulations that suggest dark matter is responsible.

We don’t know what dark matter is. We can’t detect it directly, but it interacts gravitationally with normal matter. It helps to hold galaxies together, and we believe that it could be crucial to galaxy formation, clumps of it pulling together gas and stars into galaxies.

Supercomputer simulations have shown that a massive network of dark matter in the early Universe could have facilitated the formation of cool galaxies. If the gas was cool to start with, it could have been fed along filaments of the network into the dark matter clumps, accreting into large, cool, orderly disc galaxies.

 

But the only way to confirm this model is through observational evidence, so the researchers went looking, using the light of even more distant galaxies, called quasars, to illuminate the way.

Distant galaxies are very hard to see, but quasars are among the most luminous objects in the Universe – galaxies lit by an active supermassive black hole, the space around it blasting out radiation as it feeds. The team turned ALMA’s powerful capabilities to these distant quasars, looking for signatures in their light that showed that it had passed through a gas-filled galaxy on the way.

They found it. The light from one of the quasars they imaged had passed through a region rich with hydrogen – the signature of the Wolfe Disk.

And there was something else. The light on one side of the disc was compressed, or blueshifted. We see this when something is moving towards us. And the light from the other side was stretched, or redshifted – moving away from us. The object was rotating.

Those Doppler shifts, as they are known, then allowed the researchers to calculate the velocity of the galaxy’s rotation: around 272 kilometres per second.

What’s even more wild is that the team believes the Wolfe Disk isn’t one of a kind. 

“The fact that we found the Wolfe Disk using this method, tells us that it belongs to the normal population of galaxies present at early times,” Neeleman said.

“When our newest observations with ALMA surprisingly showed that it is rotating, we realised that early rotating disk galaxies are not as rare as we thought and that there should be a lot more of them out there.”

The team will continue their search for these galaxies to find out just how common cold accretion was in the early Universe.

The research has been published in Nature.

 

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NASA’s head of human spaceflight abruptly resigns, citing ‘mistake’ – CNN

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His departure was effective on Monday.

The incident in question was related to the Artemis Program, a source familiar with the matter told CNN Business.
The Artemis Program seeks to return astronauts to the moon by 2024, which was announced by the Trump administration last year and has been criticized as unrealistic. The source familiar with the reason for Loverro’s departure said the issue centered on contracts that were awarded earlier this year for development of lunar landers, or vehicles that can carry astronauts to the moon’s surface.

When reached by phone Tuesday evening, Loverro declined to comment on the reason for his departure.

Loverro began serving in his role as the head of NASA’s human spaceflight programs in December, replacing William Gerstenmaier, who served in the role for more than a decade. In his nearly 700-word note, Loverro told NASA workers only that leaders are “called on to take risks” and added that, “I took such a risk earlier in the year because I judged it necessary to fulfill our mission.”

“Now, over the balance of time, it is clear that I made a mistake in that choice for which I alone must bear the consequences,” Loverro wrote. “And therefore, it is with a very, very heavy heart that I write to you today to let you know that I have resigned from NASA effective May 18th, 2020.”

NASA’s Office of the Inspector General announced an audit of the agency’s acquisition strategy for the Artemis program in March, though it’s unclear if that review was related to Loverro’s departure. It’s also unclear exactly what role Loverro played in the selection process.
The source familiar with the matter, who asked to remain anonymous because the space agency has not yet publicized details, told CNN Business that the incident in question was unrelated to NASA’s historic milestone next week when SpaceX, NASA’s partner in the Commercial Crew Program, launches two astronauts to the International Space Station. That mission will mark the first time since 2011 that humans have launched into orbit from US soil, and Loverro was slated to preside over a final technical review meeting on Thursday, ahead of launch on May 27. Steve Jurczyk, NASA’s associate administrator, will take over Loverro’s role at that meeting, according to NASA.

Ken Bowersox, NASA’s acting deputy associate administrator for human exploration and operations, will become NASA’s interim head of human spaceflight.

Loverro’s exit immediately raised some eyebrows on Capitol Hill.

Meet the NASA astronauts who will fly on historic SpaceX mission

Congresswoman Eddie Bernice Johnson, a Democrat from Texas who chairs the House space and science committee, said in a statement that she was “shocked” by the news.

“I trust that NASA Administrator Bridenstine will ensure that the right decision is made as to whether or not to delay the launch attempt,” Johnson said. “Beyond that, Mr. Loverro’s resignation is another troubling indication that the Artemis Moon-Mars initiative is still not on stable footing. I look forward to clarification from NASA as to the reasons for this latest personnel action.”

Kendra Horn, a Democrat from Oklahoma who chairs a House subcommittee on space, said in a tweet Tuesday that she is “deeply concerned over this sudden resignation, especially eight days before the first scheduled launch of US astronauts on US soil in almost a decade.”

The timing of Loverro’s departure was related to when Jurczyk, the associate administrator, made a recommendation to NASA Administrator Jim Bridenstine, the source said. It was unrelated to next week’s Crew Dragon launch, the source added.

Jurczyk was the source selection officer for the Artemis lunar lander contract awards, according to public documents.

In announcing Loverro’s appointment in October, NASA chief Jim Bridenstine called Loverro “a respected strategic leader in both civilian and defense programs” who “will be of great benefit to NASA at this critical time in our final development of human spaceflight systems for both Commercial Crew and Artemis.”

An agency-wide email sent on Tuesday said Loverro “hit the ground running” after his appointment in 2019 and had made “significant progress in his time at NASA.”

“His leadership of [NASA’s Human Exploration and Operations] has moved us closer to our goal of landing the first woman and the next man on the moon in 2024,” the email said. It said his resignation was effective immediately, though it did not provide details on the reason for his exit.

A NASA spokesperson declined to comment.

Loverro told CNN Business he is “100% confident” that leadership will be able to carry out the SpaceX mission. He added that he believes NASA’s ambitious human spaceflight goals are “doable.” “But,” he added, “it will take risk takers to get us there, and I hope folks who step in my shoes will continue to take risks.”

Next week’s SpaceX launch will mark the space agency’s highest-profile mission since the Space Shuttle program ended in 2011. SpaceX, which has a multibillion-dollar contract under NASA’s Commercial Crew Program, has worked for the better part of a decade to ready its Dragon spacecraft for crewed flights to the International Space Station. Since the Shuttle retired, NASA has had to rely on Russia for rides to the ISS.

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In an orange swirl, astronomers say humanity has its first look at the birth of a planet

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In an orange swirl, astronomers say humanity has its first look at the birth of a planet_5ec5b2aa94bef.jpeg

An image of a mesmerizing cosmic spiral, twisting and swirling around a galactic maw, may be the first direct evidence of the birth of a planet ever captured by humanity.

The European Southern Observatory released a picture Wednesday of what astronomers believe shows the process of cosmic matter at a gravitational tipping point, collapsing into a new world around a nearby star.

Astronomers said the dramatic scene offers a rare glimpse into the formation of a baby planet, which could help scientists better understand how planets come to exist around stars.

“Thousands of exoplanets have been identified so far, but little is known about how they form,” the lead author of a study detailing the discovery, Anthony Boccaletti, an astronomer at the Observatoire de Paris in France, said in a statement.

Planets are thought to form out of the massive discs of gas and dust that surround young stars. As tiny specks of dust circle a star and collide with one another, some material starts to fuse, much like how rolling a snowball through more snow will eventually yield a bigger snowball. After billions of years, the clumps of material become large enough that the force of gravity shapes them into planets.

The new image peers into the disc of material around a young star known as AB Aurigae, which is 520 light-years from Earth in the constellation of Auriga. Amid the hypnotic spiral arms is a “twist,” visible in the photo as a bright yellow region in the center, that is thought to be a sign of a planet being born, said Emmanuel Di Folco, a researcher at the Astrophysics Laboratory of Bordeaux in France, who participated in the study.

When a planet forms, the clumps of material create wavelike perturbations in the gas- and dust-filled disc around a star, “somewhat like the wake of a boat on a lake,” Di Folco said.

The bright region at the center of the new image is thought to be evidence of such a disturbance, which had been predicted in models of planetary birth.

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“The twist is expected from some theoretical models of planet formation,” said Anne Dutrey, an astronomer at the Astrophysics Laboratory of Bordeaux and co-author of the study, published Wednesday in the journal Astronomy & Astrophysics. “It corresponds to the connection of two spirals — one winding inwards of the planet’s orbit, the other expanding outwards — which join at the planet location.”

The new observations of the baby planet were made in 2019 and early 2020 by the European Southern Observatory’s Very Large Telescope in the Atacama Desert in northern Chile. The research team, made up of astronomers from France, Taiwan, the U.S. and Belgium, said the images are the deepest observations of the AB Aurigae system made to date.

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