First X-Rays Detected From Mystery Supernovas

Exploding stars lit the way for our understanding of the universe, but researchers are still in the dark about many of their features.

A team of scientists, including scholars from the University of Chicago, appear to have found the first X-rays coming from type Ia supernovae. Their findings are published online Aug. 23 in the Monthly Notices of the Royal Astronomical Society.

Astronomers are fond of type Ia supernovas, created when a white dwarf star in a two-star system undergoes a thermonuclear explosion, because they burn at a specific brightness. This allows scientists to calculate how far away they are from Earth, and thus to map distances in the universe. But a few years ago, scientists began to find type Ia supernovas with a strange optical signature that suggested they carried a very dense cloak of circumstellar material surrounding them.

Such dense material is normally only seen from a different type of supernova called type II, and is created when massive stars start to lose mass. The ejected mass collects around the star; then, when the star collapses, the explosion sends a shockwave hurtling at supersonic speeds into this dense material, producing a shower of X-rays. Thus we regularly see X-rays from type II supernovas, but they have never been seen from type Ia supernovas.

When the UChicago-led team studied the supernova 2012ca, recorded by the Chandra X-ray Observatory, however, they detected X-ray photons coming from the scene.

“Although other type Ia’s with circumstellar material were thought to have similarly high densities based on their optical spectra, we have never before detected them with X-rays,” said study co-author Vikram Dwarkadas, research associate professor in the Department of Astronomy and Astrophysics.

The amounts of X-rays they found were small — they counted 33 photons in the first observation a year and a half after the supernova exploded, and ten in another about 200 days later — but present.

“This certainly appears to be a Ia supernova with substantial circumstellar material, and it looks as though it’s very dense,” he said. “What we saw suggests a density about a million times higher what we thought was the maximum around Ia’s.”

It’s thought that white dwarfs don’t lose mass before they explode. The usual explanation for the circumstellar material is that it would have come from a companion star in the system, but the amount of mass suggested by this measurement was very large, Dwarkadas said — far larger than one could expect from most companion stars. “Even the most massive stars do not have such high mass-loss rates on a regular basis,” he said. “This once again raises the question of how exactly these strange supernovas form.”

“If it’s truly a Ia, that’s a very interesting development because we have no idea why it would have so much circumstellar material around it,” he said.

“It is surprising what you can learn from so few photons,” said lead author and Caltech graduate student Chris Bochenek; his work on the study formed his undergraduate thesis at UChicago. “With only tens of them, we were able to infer that the dense gas around the supernova is likely clumpy or in a disk.”

More studies to look for X-rays, and even radio waves coming off these anomalies, could open a new window to understanding such supernovas and how they form, the authors said.

Remnants of Hurricane Gert Made It All the Way to Ireland, United Kingdom

Hurricane Gert made a long journey across the Atlantic, and its remnants clobbered portions of Ireland and the United Kingdom.

Gert first formed as a tropical depression late Aug. 12 between Bermuda and the Bahamas. It then strengthened into a tropical storm a day later.

Gert became the second hurricane of the season on Aug. 14 and reached Category 2 status. Its peak winds reached 105 mph late on Aug. 16 while it raced east-northeast over the northern Atlantic Ocean, about 400 miles southeast of Halifax, Nova Scotia.

Gert became a post-tropical cyclone on the evening of Aug. 17 as it moved quickly east-northeastward. During this time, the only impact to land was increased surf and rip currents along the East Coast of the U.S. and Atlantic Canada. One man drowned in heavy surf created by Gert in Nantucket, Massachusetts.

The story, however, did not end when Gert was no longer a tropical system. The remnants of Gert continued to weaken as it moved east-northeastward and then merged with an area of low pressure to its northwest as both systems tracked across the Atlantic.

The remnants of Gert helped add energy and moisture to this low-pressure system, enhancing rainfall in parts of Ireland and the northern U.K.

The heavy rainfall brought flooding to areas of Northern Ireland Tuesday, with more than 100 people rescued after being trapped by flooding caused by locally heavy rainfall, BBC News reported. Numerous roads remained closed as of Wednesday.

The Irish weather service, Met Eireann, and the Met Office issued warnings for the possibility of heavy rainfall over northern Island on Tuesday.

Western areas of Northern Ireland were particularly hard-hit, according to the Guardian. A spokesman for a Northern Ireland Fire and Rescue Service noted late Tuesday night that they were dealing with “a large number of flood-related incidents across the province as a result of localized heavy rainfall.”

Malin Head, Ireland, located in northern County Donegal, recorded more than 3 inches of rainfall late Tuesday afternoon through the evening.

This strong system also influenced the jet stream, which allowed warm and humid conditions to surge northward into portions of the U.K.

The humid conditions will not last long, as drier air will return to southern parts of the U.K. by Wednesday night.

Ancient Earth’s Hot Interior Created ‘Graveyard’ Of Continental Slabs

Plate tectonics has shaped the Earth’s surface for billions of years: Continents and oceanic crust have pushed and pulled on each other, continually rearranging the planet’s façade. As two massive plates collide, one can give way and slide under the other in a process called subduction. The subducted slab then slips down through the Earth’s viscous mantle, like a flat stone through a pool of honey.

For the most part, today’s subducting slabs can only sink so far, to about 670 kilometers below the surface, before the mantle’s makeup turns from a honey-like consistency, to that of paste — too dense for most slabs to penetrate further. Scientists have suspected that this density filter existed in the mantle for most of Earth’s history.

Now, however, geologists at MIT have found that this density boundary was much less pronounced in the ancient Earth’s mantle, 3 billion years ago. In a paper published in Earth and Planetary Science Letters, the researchers note that the ancient Earth harbored a mantle that was as much as 200 degrees Celsius hotter than it is today — temperatures that may have brewed up more uniform, less dense material throughout the entire mantle layer.

The researchers also found that, compared with today’s rocky material, the ancient crust was composed of much denser stuff, enriched in iron and magnesium. The combination of a hotter mantle and denser rocks likely caused subducting plates to sink all the way to the bottom of the mantle, 2,800 kilometers below the surface, forming a “graveyard” of slabs atop the Earth’s core.

Their results paint a very different picture of subduction than what occurs today, and suggests that the Earth’s ancient mantle was much more efficient in drawing down pieces of the planet’s crust.

“We find that around 3 billion years ago, subducted slabs would have remained more dense than the surrounding mantle, even in the transition zone, and there’s no reason from a buoyancy standpoint why slabs should get stuck there. Instead, they should always sink through, which is a much less common case today,” says lead author Benjamin Klein, a graduate student in MIT’s Department of Earth, Atmospheric and Planetary Sciences (EAPS). “This seems to suggest there was a big change going back in Earth’s history in terms of how mantle convection and plate tectonic processes would have happened.”

Klein’s co-authors are Oliver Jagoutz, associate professor in EAPS, and Mark Behn of the Woods Hole Oceanographic Institution.

Temperature difference

“There’s this open question as to when plate tectonics really started in Earth’s history,” Klein says. “There’s general consensus that it was probably going on back at least 3 billion years ago. This is also when most models suggest the Earth was at its hottest.”

Around 3 billion years ago, the mantle was probably about 150-200 C warmer than it is today. Klein, Jagoutz, and Behn investigated whether hotter temperatures in the Earth’s interior made a difference in how tectonic plates, once subducted, were transported through the mantle.

“Our work started as this thought experiment to say, if we know temperatures were much hotter, how might that have modulated what the tectonics looked like, without changing it wholesale?” Klein says. “Because the debate before was this binary argument: Either there was plate tectonics, or there wasn’t, and we’re suggesting there’s more room in between.”

A “density flip”

The team carried out its analysis, making the assumption that plate tectonics was indeed shaping the Earth’s surface 3 billion years ago. They looked to compare the density of subducting slabs at that time with the density of the surrounding mantle, the difference of which would determine how far slabs would have sunk.

To estimate the density of ancient slabs, Klein compiled a large dataset of more than 1,400 previously analyzed samples of both modern rocks and komatiites — classic rock types that were around 3 billion years ago but are no longer produced today. These rocks contain a higher amount of dense iron and magnesium compared to today’s oceanic crust. Klein used the composition of each rock sample to calculate the density of a typical subducting slab, for both the modern day and 3 billion years ago.

He then estimated the average temperature of a modern versus an ancient subducting slab, relative to the temperature of the surrounding mantle. He reasoned that the distance a slab sinks depends on not only its density but also its temperature relative to the mantle: The colder an object is relative to its surroundings, the faster and further it should sink.

The team used a thermodynamic model to determine the density profile of each subducting slab, or how its density changes as it sinks through the mantle, given the mantle’s temperature, which they took from others’ estimates and a model of the slab’s temperature. From these calculations, they determined the depth at which each slab would become less dense than the surrounding mantle.

At this point, they hypothesized that a “density flip” should occur, such that a slab should not be able to sink past this boundary.

“There seems to be this critical filter and control on the movement of slabs and therefore convection of the mantle,” Klein says.

A final resting place

The team found that their estimates for where this boundary occurs in the modern mantle — about 670 kilometers below the surface — agreed with actual measurements taken of this transition zone today, confirming that their method may also accurately estimate the ancient Earth.

“Today, when slabs enter the mantle, they are denser than the ambient mantle in the upper and lower mantle, but in this transition zone, the densities flip,” Klein says. “So within this small layer, the slabs are less dense than the mantle, and are happy to stay there, almost floating and stagnant.”

For the ancient Earth, 3 billion years ago, the researchers found that, because the ancient mantle was so much hotter than today, and the slabs much denser, a density flip would not have occurred. Instead, subducting slabs would have sunk straight to the bottom of the mantle, establishing their final resting place just above the Earth’s core.

Jagoutz says the results suggest that sometime between 3 billion years ago and today, as the Earth’s interior cooled, the mantle switched from a one-layer convection system, in which slabs flowed freely from upper to lower layers of the mantle, to a two-layer configuration, where slabs had a harder time penetrating through to the lower mantle.

“This shows that when a planet starts to cool down, this boundary, even though it’s always there, becomes a significantly more profound density filter,” Jagoutz says. “We don’t know what will happen in the future, but in theory, it’s possible the Earth goes from one dominant regime of one-layer convection, to two. And that’s part of the evolution of the entire Earth.”

This research was funded, in part, by the National Science Foundation.

Hidden River Once Flowed Beneath Antarctic Ice

Antarctic researchers from Rice University have discovered one of nature’s supreme ironies: On Earth’s driest, coldest continent, where surface water rarely exists, flowing liquid water below the ice appears to play a pivotal role in determining the fate of Antarctic ice streams.

The finding, which appears online this week in Nature Geoscience, follows a two-year analysis of sediment cores and precise seafloor maps covering 2,700 square miles of the western Ross Sea. As recently as 15,000 years ago, the area was covered by thick ice that later retreated hundreds of miles inland to its current location. The maps, which were created from state-of-the-art sonar data collected by the National Science Foundation research vessel Nathaniel B. Palmer, revealed how the ice retreated during a period of global warming after Earth’s last ice age. In several places, the maps show ancient water courses — not just a river system, but also the subglacial lakes that fed it.

Today, Antarctica is covered by ice that is in some places more than 2 miles thick. Though deep, the ice is not static. Gravity compresses the ice, and it moves under its own weight, creating rivers of ice that flow to the sea. Even with the best modern instruments, the undersides of these massive ice streams are rarely accessible to direct observation.

“One thing we know from surface observations is that some of these ice streams move at velocities of hundreds of meters per year,” said Rice postdoctoral researcher Lauren Simkins, lead author of the new study. “We also know that ice, by itself, is only capable of flowing at velocities of no more than tens of meters per year. That means the ice is being helped along. It’s sliding on water or mud or both.”

Because of the paucity of information about how water presently flows beneath Antarctic ice, Simkins said the fossilized river system offers a unique picture of how Antarctic water drains from subglacial lakes via rivers to the point where ice meets sea.

“The contemporary observations we have of Antarctic hydrology are recent, spanning maybe a couple decades at best,” Simkins said. “This is the first observation of an extensive, uncovered, water-carved channel that is connected to both subglacial lakes on the upstream end and the ice margin on the downstream end. This gives a novel perspective on channelized drainage beneath Antarctic ice. We can track the drainage system all the way back to its source, these subglacial lakes, and then to its ultimate fate at the grounding line, where freshwater mixed with ocean water.”

Simkins said meltwater builds up in subglacial lakes. First, intense pressures from the weight of ice causes some melting. In addition, Antarctica is home to dozens of volcanoes, which can heat ice from below. Simkins found at least 20 lakes in the fossil river system, along with evidence that water built up and drained from the lakes in episodic bursts rather than a steady stream. She worked with Rice co-author and volcanologist Helge Gonnermann to confirm that nearby volcanoes could have provided the necessary heat to feed the lakes.

Study co-author John Anderson, a Rice oceanographer and veteran of nearly 30 Antarctic research expeditions, said the size and scope of the fossilized river system could be an eye-opener for ice-sheet modelers who seek to simulate Antarctic water flow. For example, the maps show exactly how ice retreated across the channel-lake system. The retreating ice stream in the western Ross Sea made a U-turn to follow the course of an under-ice river. Simkins said that’s notable because “it’s the only documented example on the Antarctic seafloor where a single ice stream completely reversed retreat direction, in this case to the south and then to the west and finally to the north, to follow a subglacial hydrological system.”

Simkins and Anderson said the study may ultimately help hydrologists and modelers better predict how today’s ice streams will behave and how much they’ll contribute to rising sea levels.

“It’s clear from the fossil record that these drainage systems can be large and long-lived,” Anderson said. “They play a very important role in the behavior of the ice sheet, and most numerical models today are not at a state where they can deal with that kind of complexity.”

He said another key finding is that drainage through the river system took place on a time scale measured in tens to several hundreds of years.

“We’re kind of in this complacent mode of thinking right now,” Anderson said. “Some people say, ‘Well, the ice margin seems to be stable.’ Some people may take comfort in that, but I don’t because what this new research is telling us is that there are processes that operate on decadal time scales that influence ice behavior. The probability of us having observed a truly stable condition in the contemporary system, given our limited observation time, is pretty low.”

Naples Earthquake: 2 Dead, 39 Injured, 7 Missing As Ischia Rocked By Quake On VOLCANO Edge

The 4.3 magnitude quake hit the tourist hotspot at 8:57pm local time (7:57pm UK time), destroying several buildings across the island.

Two women died and 39 people have been injured – at least one of them seriously – after the earthquake struck.

Seven are still missing as officials rush to find them in the rubble.

One woman died after the island’s historic church collapsed, while the other woman died after she was buried under the rubble of her home.

Aftershocks were felt as rescue teams worked through the night, pulling alive a seven-month-old baby boy, Pasquale, from a collapsed home in Casamicciola.

Rescuers this morning pulled his older brother Ciro, aged five, and his three-year-old brother Mattias from the rubble.

Their pregnant mother, and father were rescued yesterday.

All doctors and patients were evacuated from the Rizzoli Hospital during the disaster, local media outlets have reported.

Italy lies on the edge of the Eurasian and African tectonic plates, making it vulnerable to seismic activity.

Locals and tourists ran out onto the street as the earthquake triggered a short electrical blackout across the island.

Italian news agency ANSA added: “A shock magnitude 3.6 earthquake was recorded at 20:57pm in front of Ischia Island.

“People poured into the street while an electric blackout was in the centre of Ischia port. There is no damage to person or things.

“Ischia firefighters sent the rescue team to Casamicciola for a critical situation that was reported after the shock.”

National newspaper Il Messaggero reported: “An inhabited building collapsed in Maio Square due to the effects of the earthquake.

“The Church of Purgatory has been destroyed, many hotels are isolated. There are several injured and some are missing.

“Police and firefighters are operating, as well as medical rescue units.”

Local politician Francesco Emilio Borrelli said: “These are the days of a large tourist turnout for the island, there are thousands of visitors.

“The tension is very high. People are scared, while rescuers are working barefoot to save lives under rubble.

“Collapses have occurred mostly in Casamicciola and a woman died in the rubble of the collapse of a church.

“Assistance is difficult, as the only hospital in the island has been evacuated.”

Scientists from University College London (UCL) and the Vesuvius Observatory in Naples recently warned the volcano “may be approaching a critical stage”.

Dr Christopher Kilburn, director of the UCL Hazard Centre, warned officials that “further unrest will increase the possibility of an eruption”.

Professor Giuseppe De Natale, who also worked on the study, added: “We must adapt our preparations for another emergency, whether or not it leads to an eruption.”

BREAKING NEWS: Currently Monitoring High Volume Earthquake Zones

There are five areas I am watching most closely due to the high amount of registered earthquakes, some of which could be defined as ‘swarms’. These areas sit on historic faults or calderas.

Cascadia Subduction Zone

The Cascadia Subduction Zone is capable of producing very large earthquakes if rupture occurs along its entire length. The 1700 Cascadia earthquake occurred along the Cascadia subduction zone on January 26 with an estimated moment magnitude of 8.7 – 9.2. The megathrust earthquake involved the Juan de Fuca Plate that underlies the Pacific Ocean. The earthquake caused a tsunami that struck the coast of Japan with some reports telling of hundreds killed.

Denali Fault

Shortly after midday on November 3, 2002, a magnitude 7.9 earthquake ruptured the Denali Fault in the rugged Alaska Range, about 90 miles south of Fairbanks. Called the Denali Fault earthquake, this shock was the strongest ever recorded in the interior of Alaska. Although comparable in size and type to the quake that devastated San Francisco in 1906, the Denali Fault earthquake caused no deaths and little damage to structures because it struck a sparsely populated region of south-central Alaska.

Long Valley Caldera

In 1872, the magnitude 7.6 Owens Valley earthquake was felt throughout most of California, and a number of moderate (mag. 5 to 6) earthquakes have shaken the Long Valley area during this century. A period of ongoing geologic unrest in the Long Valley area began in 1978, and has since experienced numerous swarms of earthquakes, especially in the southern part of the caldera and the adjacent Sierra Nevada.

Puerto Rico Trench

On October 11, 1918, the island of Puerto Rico was struck by a magnitude 7.5 earthquake, centered approximately 15 kilometers off island’s northwestern coast, in the Mona Passage. In addition to causing widespread destruction across Puerto Rico, the quake generated a medium sized tsunami that produced waves as high as 20 feet along the western coast of the island. The tsunami caused an estimated 4 million dollars in property and other damages to the coastal communities of Puerto Rico. Of the 116 people killed by the earthquake, 40 of those were victims of the tsunami.

1886 Charleston, South Carolina 7.6 Quake

The fifth area I am keeping my eye onOn August 31st 1886, a 7.6 magnitude earthquake struck near Charleston, South Carolina leaving 100 people dead, hundreds of buildings destroying 2,000 buildings in the city and caused $6 million worth of damage ($133 million in modern-day USD).

COMING NEXT: Update on all earth changing events as well as more on the continuing ‘civil disturbance’ occurrences. 

ANNOUNCEMENT: Solar Eclipse ‘Live’ Streaming Sites

I have set up a ‘live stream’ site to monitor Monday’s full solar eclipse. I will list the times according to your area. I’m not sure how well the bandwidth will hold out, so I am also listing several sites which will also carry this event live.There are also links for android and iphone apps.

I am keeping a close eye on events around the world. Currently there are four areas I am watching most closely due to the current amount of registered earthquakes. These areas sit on historic faults or calderas.

Science Of Cycles ‘Live Stream’: http://www.ustream.tv/channel/W4ZGGpkUatu

Facebook Live: https://www.facebook.com/NASA/videos/10155497958441772/

Twitter/Periscope: https://www.pscp.tv/nasa

Twitch TV: https://twitch.tv/nasa

Ustream: http://www.ustream.tv/nasahdtv

YouTube: https://www.youtube.com/watch?v=wwMDvPCGeE0

TIME ZONE LINK: CLICK HERE

NASA App for iOS: http://itunes.apple.com/app/nasa-app/id334325516?mt=8

NASA App for Android: https://play.google.com/store/apps/details?id=gov.nasa

NASA App for Amazon Fire and Fire TV: http://amzn.com/B00ZVR87LQ

COMING NEXT: Current High Volume Earthquake Zones