Never-Before-Seen Features Found Around A Neutron Star

An unusual infrared light emission from a nearby neutron star detected by NASA’s Hubble Space Telescope could indicate new features never before seen. One possibility is that there is a dusty disk surrounding the neutron star; another is that there is an energetic wind coming off the object and slamming into gas in interstellar space the neutron star is plowing through.

Although neutron stars are generally studied in radio and high-energy emissions, such as X-rays, this study demonstrates that new and interesting information about neutron stars can also be gained by studying them in infrared light, say researchers.

The observation, by a team of researchers at Pennsylvania State University, University Park, Pennsylvania; Sabanci University, Istanbul, Turkey; and the University of Arizona, Tucson, Arizona, could help astronomers better understand the evolution of neutron stars — the incredibly dense remnants after a massive star explodes as a supernova. Neutron stars are also called pulsars because their very fast rotation (typically fractions of a second, in this case 11 seconds) causes time-variable emission from light-emitting regions.

A paper describing the research and two possible explanations for the unusual finding appears Sept. 17, 2018, in the Astrophysical Journal.

“This particular neutron star belongs to a group of seven nearby X-ray pulsars — nicknamed ‘the Magnificent Seven’ — that are hotter than they ought to be considering their ages and available energy reservoir provided by the loss of rotation energy,” said Bettina Posselt, associate research professor of astronomy and astrophysics at Pennsylvania State and the lead author of the paper. “We observed an extended area of infrared emissions around this neutron star — named RX J0806.4-4123 — the total size of which translates into about 200 astronomical units (approximately 18 billion miles) at the assumed distance of the pulsar.”

This is the first neutron star in which an extended signal has been seen only in infrared light. The researchers suggest two possibilities that could explain the extended infrared signal seen by Hubble. The first is that there is a disk of material — possibly mostly dust — surrounding the pulsar.

“One theory is that there could be what is known as a ‘fallback disk’ of material that coalesced around the neutron star after the supernova,” said Posselt. “Such a disk would be composed of matter from the progenitor massive star. Its subsequent interaction with the neutron star could have heated the pulsar and slowed its rotation. If confirmed as a supernova fallback disk, this result could change our general understanding of neutron star evolution.”

The second possible explanation for the extended infrared emission from this neutron star is a “pulsar wind nebula.”

“A pulsar wind nebula would require that the neutron star exhibits a pulsar wind,” said Posselt. “A pulsar wind can be produced when particles are accelerated in the electrical field that is produced by the fast rotation of a neutron star with a strong magnetic field. As the neutron star travels through the interstellar medium at greater than the speed of sound, a shock can form where the interstellar medium and the pulsar wind interact. The shocked particles would then emit synchrotron radiation, causing the extended infrared signal that we see. Typically, pulsar wind nebulae are seen in X-rays and an infrared-only pulsar wind nebula would be very unusual and exciting.”

Using NASA’s upcoming James Webb Space Telescope, astronomers will be able to further explore this newly opened discovery space in the infrared to better understand neutron star evolution.

Volcano Under Glacier Offers Clues To Thicker Antarctic Ice

A region of West Antarctica is behaving differently from most of the rest of the continent: A large patch of ice there is thickening, unlike other parts of West Antarctica that are losing ice. Whether this thickening trend will continue affects the overall amount that melting or collapsing glaciers could raise the level of the world’s oceans.

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The track hidden in the middle of the ice sheet suggests that the current thickening is just a short-term feature that may not affect the glacier over the long term, the new study indicates. It also suggests that similar clues to the past may be hiding deep inside the ice sheet itself.

SHUTTING IT DOWN
“What’s exciting about this study is that we show how the structure of the ice sheet acts as a powerful record of what has happened in the past,” says first author Nicholas Holschuh, a postdoctoral researcher in Earth and space sciences at the University of Washington.

The data come from the ice above Mount Resnik, a 1.6-kilometer (mile-high) inactive volcano that currently sits under 300 meters (0.19 miles) of ice. The volcano lies just upstream of the thickening Kamb Ice Stream, part of a dynamic coastal region of ice that drains into Antarctica’s Ross Sea.

Studies show Kamb Ice Stream has flowed quickly in the past but stalled more than a century ago, leaving the region’s ice to drain via the four other major ice streams, a switch that glaciologists think happens every few hundred years. Meanwhile, the ice inland of Kamb Ice Stream is beginning to bulge, and it is unclear what will happen next.

“The shutdown of Kamb Ice Stream started long before the satellite era,” Holschuh says. “We need some longer-term indicators for its behavior to understand how important this shutdown is for the future of the region’s ice.”

BENEATH THE ICE

The paper analyzes two radar surveys of the area’s ice. Coauthors Robert Jacobel and Brian Welch collected one using the ice-penetrating radar system at St. Olaf College in Minnesota in 2002. Coauthor Howard Conway, a research professor of Earth and space sciences, collected the other in 2004. Conway noticed the missing layers and asked his colleagues to investigate.

“It wasn’t until we had spent probably six months with this data set that we started to piece together the fact that this thing that we could see within the ice sheet was forming in response to the subglacial volcano,” Holschuh says.

The study shows that the mysterious feature originates at the ice covering Mount Resnik. The authors believe that the volcano’s height pushes the relatively thin ice sheet up so much that it changes the local wind fields, and affects depositing of snow. So as the ice sheet passes over the volcano a section missed out on a few annual layers of snow.

“These missing layers are common in East Antarctica, where there is less precipitation and strong winds can strip away the surface snow,” Holschuh says. “But this is really one of the first times we’ve seen these missing layers in West Antarctica. It’s also the first time an unconformity has been used to reconstruct ice sheet motion of the past.”

CHECKING THE RECORD

Over time, the glacial record shows that this feature followed a straight path toward the sea. During the 5,700-year record, the five major coastal ice streams are thought to have sped up and slowed down several times, as water on the base lubricates the glacier’s flow and then periodically gets diverted, stalling one of the ice streams.

“Despite the fact that there are all these dramatic changes at the coast, the ice flowing in the interior was not really affected,” Holschuh says.

What the feature does show is that a change occurred a few thousand years ago. Previous UW research shows rapid retreat at the edge of the ice sheet until about 3,400 years ago, part of the recovery from the most recent ice age. The volcano track also shows a thinning of the ice at about this time.

“It means that the interior of the ice sheet is responding to the large-scale climate forcing from the last glacial maximum to today,” Holschuh says. “So the long-timescale climatic forcing is very consistent between the interior and the coast, but the shorter-timescale processes are really apparent in the coastal record but aren’t visible in the interior.”

Holschuh cautions that this is only a single data point and needs confirmation from other observations. He is part of an international team of Antarctic scientists looking at combining the hundreds of radar scans of Antarctic and Greenland glaciers that researchers originally did to measure ice thickness. Those data may also contain unique details of the glacier’s internal structure that researchers can use to recreate the history of the ice sheet’s motion.

“These persistent tracers of historic ice flow are probably all over the place,” Holschuh says. “The more we can tease apart the stories of past motion told by the structure of the ice sheet, the more realistic we can be in our predictions of how it will respond to future climate change.”

UPDATE : Florence Flooding Spreads As Storm Moves NE; 18 Dead

WILMINGTON, N.C. — Emergency workers delivered truckloads of food and water to Wilmington, a city of 120,000 people mostly cut off from the rest of North Carolina by Florence’s still-rising floodwaters, as helicopters and boat pulled people from homes swamped by swollen rivers.

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The deadly storm still had abundant rain and top winds around 30 mph early Monday, and forecasters said it was expected to gradually pick up forward speed and complete a big turn toward the Northeast, which is in for as much as 6 inches of rain.

Flooding worries increased in West Virginia and Virginia, where roads were closed and power outages were on the rise. About 500,000 homes and businesses were in the dark.

In some places, the rain stopped after Florence moved on, and the sun peeked through, but North Carolina Gov. Roy Cooper urged residents who were evacuated from the hardest-hit areas to stay away because of closed roads and flooding.

“There’s too much going on,” he told a news conference.

The death toll climbed to 18 as authorities found the body of a 1-year-old boy who was swept away after his mother drove into floodwaters and lost her grip on him while trying to get back to dry land.

Florence was still massive, despite being downgraded to a tropical depression from a once-fearsome Category 4 hurricane. Radar showed parts of the sprawling storm over six states, with North and South Carolina in the bull’s-eye.

North Carolina emergency response officials tweeted that 23 truckloads of military meals and bottled water were delivered overnight to Wilmington, the state’s eighth-largest city.

One route into the city was reopened by midday Monday, officials said, but it wasn’t clear which road was open and whether it available to the general public.

Signs on a flooded highway leading out of town said “ROAD CLOSED,” and many streets that weren’t flooded were blocked by fallen timber. The smell of cracked pine trees wafted through hard-hit neighborhoods.

Residents waited for hours outside stores and restaurants for water and other basic necessities. Police guarded the door of one store, and only 10 people were allowed inside at a time.

Desperate for gas to run a generator at home, Nick Monroe waited in a half-mile-long line at a Speedway station even though the pumps were wrapped in plastic. His power went off Thursday before Florence hit the coast, but he couldn’t recall exactly when.

“It’s all kind of a blur,” Monroe said.

County commission Chairman Woody White said officials were planning for food and water to be flown into the coastal city, located on a peninsula with the rising Cape Fear River to the west and more water to the east.

To the north in Pollocksville, Coast Guard members used a basket suspended from a helicopter to rescue a man from the roof of a flooded home.

About 70 miles away from the coast, residents near the Lumber River stepped from their homes directly into boats floating in their front yards. River forecasts showed that the scene could be repeated in towns as far as 250 miles inland as waters rise for days.

Fears of what could be the worst flooding in the state’s history led officials to order tens of thousands to evacuate, though it wasn’t clear how many had fled or even could.

Victor Merlos was overjoyed to find a store open for business in Wilmington since he had about 20 relatives staying at his apartment, which still had power. He spent more than $500 on cereal, eggs, soft drinks and other necessities, plus beer.

“I have everything I need for my whole family,” Merlos said. Nearby, a Waffle House restaurant limited breakfast customers to one biscuit and one drink, all takeout, with the price of $2 per item.

Julie Lamb, with her 15-month-old twins, stepped off a Coast Guard boat after being rescued from her parents’ house, where the yard was submerged and water was still rising at Lumberton. Another boat was going back to get her husband, 4-year-old daughter and their pug dog.

“We decided to stay with mom and dad here. During (Hurricane) Matthew the water never reached their house,” she said. “But the water keeps coming up in their yard.”

As rivers swelled, state regulators and environmental groups monitored the threat from gigantic hog and poultry farms in low-lying, flood-prone areas.

The industrial-scale farms contain vast pits of animal feces and urine that can pose a significant pollution threat if they are breached or inundated by floodwaters. In past hurricanes, flooding at dozens of farms also left hundreds of thousands of dead hogs, chickens and other decomposing livestock bobbing in floodwaters.

Some stream gauges used to monitor river levels failed when they became submerged, but others showed water levels rising steadily, with forecasts calling for rivers to crest at or near record levels. The Defense Department said about 13,500 military personnel were assigned to help relief efforts.

Thousands of people were ordered to evacuate homes along rivers. The evacuation zone included part of the city of Fayetteville, population 200,000.

Near the flooded-out town of New Bern, where about 455 people had to be rescued from the swirling flood waters, water completely surrounded churches, businesses and homes. In the neighboring town of Trenton, downtown streets were turned to creeks full of brown water.

The rain was unrelenting in Cheraw, a town of about 6,000 people in northeastern South Carolina. Streets were flooded, and Police Chief Keith Thomas warned people not to drive, but the local food and gas store had customers.

“As you can tell, they’re not listening to me,” he said.

Slow-Moving Storms Like Florence Produce Big Floods — And Are Becoming The Norm

Hurricane Florence continued to ravage North Carolina on Sunday, prompting weather alerts for every county in the state. The storm moved sluggishly — it made landfall at about 6 mph Friday and had slowed to 2 mph on Saturday, dumping massive amounts of rain as it went. The deluge, called a 1,000-year rain event by the state’s governor, swelled rivers and drew comparisons to last years’ Hurricane Harvey. But Florence’s slow forward movement and dangerous torrent of heavy rain aren’t unique to hurricanes. These features are also present in big storms that strike around the country. And what’s more, extreme rainfall events are hitting more often, and big, slow-moving systems are becoming more common. As the climate changes, it’s not just that we can expect to see more hurricanes like Florence, it’s also that more storms of other types will look like this, too.

Even though hurricanes are formed differently from inland storms, the basic components of a record-breaking flood can be present in both, said Andreas Prein, a scientist at the National Center for Atmospheric Research. “It takes very high rainfall rates, high precipitation. It has to cover a big area. And it has to move slow. Those are the big ingredients that produce a big flood,” he said.

You can see the added dangers of a slow-moving storm by looking at the costliest hurricanes to hit the U.S. The forward speed of Atlantic hurricanes tends to vary by latitude, but the eastern and Gulf coasts mostly fall into an area where the average forward speeds are above 17 mph. The costliness of a storm depends in part on where it strikes — hitting a large urban area drives up costs much faster than hitting a more sparsely populated rural area — but all but three of the costliest storms moved at slower-than-average pace.

Florence was traveling at about a fraction of the average speed for its latitude when it made landfall and has made it obvious how a slow, wet storm can turn a hurricane from a coastal wind disaster to a far-reaching flood risk.

And one of the calling cards of climate change is the wet storms it produces. Scientists are still studying how the shifting environment is changing weather systems, but they’re more certain than usual that it’s causing an increase in extreme precipitation events. “Just look at the U.S. records for the last 100 years. Extreme daily rainfall rates went up in all regions,” Prein said.

There’s a clear causal explanation for that, said David Gochis, a hydrometeorologist at NCAR. Warmer air means more evaporation of surface water, resulting in more water vapor in the air that’s available to fall as rain.

The forward speed of storms is not as well-studied, experts said, but there’s some evidence that the same changing climate that’s leading to more extreme rainfall is also putting the brakes on big rainstorms, which means they dump more water in one place. “There’s research out there in the atmospheric community that’s found that in certain seasons — especially fall — large-scale, mid-latitude storms are slowing down,” Gochis said. And it’s not just hurricanes. What’s happening right now in North Carolina is, in this way, pretty similar to what happened in Colorado in 2013, when a storm parked over a single area for a week, causing flooding that collapsed bridges and homes and spurred massive evacuations.

Last year, Prein was involved in a paper that tried to model the impacts of climate change on large storm systems of all kinds, including, but not limited to, hurricanes. Prein said his paper didn’t find evidence that climate change was making storms move more slowly. But, he said, you could still end up with a higher likelihood of encountering a big, slow, wet storm. “It’s not that climate change is changing the speed of movement, but you get more big, high-intensity storms, which [tend to] move slowly,” he said.

The result is a shifting norm in flood risk across the country. If you live on the coast, you can probably expect more flooding caused by hurricanes like Florence. If you live in the Midwest, you can probably expect more thunderstorm-related flooding. And in both cases, the kind of big floods that were rare in the past are becoming more common now. How big can the storms (and the floods) get? We don’t know what the limits are, Gochis said. We know what’s been normal in the past. But if storms are getting slower and wetter, “Well, then you have to do the calculation again,” he said.

Storm Helene Alert For Strong Winds Widens Across Wales

A storm is set to hit Wales later but the strongest gusts are due to be weaker than first expected, the Met Office has said.

Storm Helene is due to arrive later on Monday with a yellow “be aware” warning from 21:00 BST. It is expected to last until 18:00 on Tuesday.

Winds are likely to reach 40mph to 50mph with top gusts of up to 60mph.

The Met Office has warned of delays to road, rail and air services while power loss and tree damage is “possible”.

The warning was originally for west Wales but it has since been extended to cover the whole country.

“The wind will pick up as the storm moves across us,” said Rhian Haf, BBC Wales weather presenter.

Strongest Storm Recorded This Year Leaves Path Of Destruction Across Asia

Although they are used to weathering several typhoons every year, Hong Kongers woke up shell-shocked on Monday after Super Typhoon Mangkhut, the strongest storm on the planet recorded this year, tore through the city on Sunday, injuring over 300 people but killing none. Even after such a devastating storm, most people went back to work on Monday, and the stock markets opened for trading.

Despite weakening after first hitting the Philippines and killing at least 65 people, the Hong Kong Observatory confirmed Mangkhut was the most powerful storm to hit the southern Chinese territory since records have been kept beginning in 1946.

Hong Kong avoided a direct hit and escaped without any fatalities, but Mangkhut’s ferocious winds and storm surge uprooted more than 1500 trees and broke hundreds of windows across the city.

Record-setting storm surges of more than 11 feet were measured in some parts of Hong Kong, while huge waves crashed into waterfront apartments. Low elevation and coastal neighborhoods like the beach town of Shek O and waterfront housing estate Heng Fa Chuen experienced flooding.

Windows across Hong Kong were blown out by wind gusts that were recorded at speeds of up to 120 mph. Most dramatically, dozens of windows of the One Harbourfront complex that juts out into Hong Kong’s famed Victoria Harbor were destroyed. Online video taken during the storm showed reams of paper being blown out from the building.

Hong Kong’s normally secure and bendable bamboo-scaffolding used in construction could not withstand the force of the winds, and many scaffolds were ripped off of buildings, crashing into the streets below.

The Hong Kong Government made the call to lower the storm signal early Monday morning to allow the stock market to open for trading, meaning that Hong Kongers were also expected to go to work.

Public transportation was not running at full capacity as numerous bus routes and light rail services were suspended due to debris, causing major crowding at transportation hubs across the city.

In a press conference Monday, trade union leader Lee Cheuk-yan criticized Hong Kong’s Chief Executive Carrie Lam for not giving workers a day off to recover from the typhoon.

Terence Chong, an Economics professor at Chinese University of Hong Kong told the South China Morning Post that if the entire city had not worked on Monday, the economic loss could amount to about $7.3 billion Hong Kong dollars, the equivalent of $930 million U.S. dollars.

What was left of Mangkhut went on to wreak havoc on neighboring Macau on Sunday, which suspended normal casino operations for the first time ever. The storm later made landfall in China’s Guangdong province, where it has killed at least four people.

JUST IN: Watch for Increased Geomagnetic Flux Approaching Autumn Equinox

Starting this week Earth’s magnetic field is vulnerable to enhanced charged particles making its way through Earth’s magnetic field as we approach Autumn Equinox. Since our seasons are caused by the tilt of Earth’s axis relative to its orbital plane, the equinox roughly marks the transition from longer periods of daylight to shorter ones or vice versa.

During this time an occurrence known as the Russell-McPherron effect; is a hypothesis identifying geomagnetic activity is more intense around fall equinox when the direction of the interplanetary magnetic field (IMF) is away the Sun.

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