Astrophysicists announce discovery that could rewrite story of how galaxies die

(THIS ARTICLE IS COURTESY OF PHYSICS.ORG)

 

Astrophysicists announce discovery that could rewrite story of how galaxies die

Astrophysicist announces her discovery that could rewrite story of how galaxies die
This artist conception depicts an energetic quasar which has cleared the center of the galaxy of gas and dust, and these winds are now propagating to the outskirts. Soon, there will be no gas and dust left, and only a luminous blue quasar will remain. Credit: Michelle Vigeant

At the annual meeting of the American Astronomical Society in St. Louis, Missouri, Allison Kirkpatrick, assistant professor of physics and astronomy at the University of Kansas, will announce her discovery of “cold quasars”—galaxies featuring an abundance of cold gas that still can produce new stars despite having a quasar at the center—a breakthrough finding that overturns assumptions about the maturation of galaxies and may represent a phase of every galaxy’s lifecycle that was unknown until now.

Her news briefing, entitled “A New Population of Cold Quasars,” takes place Wednesday, June 12, on the 2nd floor of the St. Louis Union Station Hotel.

A quasar, or “quasi-stellar radio source,” is essentially a  on steroids. Gas falling toward a quasar at the center of a galaxy forms an “accretion disk” which can cast off a mind-boggling amount of electromagnetic energy, often featuring luminosity hundreds of times greater than a typical galaxy. Typically, formation of a quasar is akin to galactic retirement, and it’s long been thought to signal an end to a galaxy’s ability to produce .

“All the gas that is accreting on the black hole is being heated and giving off X-rays,” Kirkpatrick said. “The wavelength of light that you give off directly corresponds to how hot you are. For example, you and I give off infrared light. But something that’s giving off X-rays is one of the hottest things in the universe. This gas starts accreting onto the black hole and starts moving at relativistic speeds; you also have a magnetic field around this gas, and it can get twisted up. In the same way that you get solar flares, you can have jets of material go up through these magnetic field lines and be shot away from the black hole. These jets essentially choke off the gas supply of the galaxy, so no more gas can fall on to the galaxy and form new stars. After a galaxy has stopped forming stars, we say it’s a passive dead galaxy.”

But in Kirkpatrick’s survey, about 10 percent of  hosting accreting supermassive  had a supply of cold gas remaining after entering this phase, and still made new .

Astrophysicist announces her discovery that could rewrite story of how galaxies die
An optical blue quasar at a lookback time of 7 billion years (this is not a nearby galaxy). Normally, something like this would not have infrared emission. Credit: Dark Energy Camera Legacy Survey DR7/NOAO

“That in itself is surprising,” she said. “This whole population is a whole bunch of different objects. Some of the galaxies have very obvious merger signatures; some of them look a lot like the Milky Way and have very obvious spiral arms. Some of them are very compact. From this diverse population, we then have a further 10 percent that is really unique and unexpected. These are very compact, blue, luminous sources. They look exactly like you would expect a supermassive black hole to look in the end stages after it has quenched all of the star formation in a galaxy. This is evolving into a passive elliptical galaxy, yet we have found a lot of cold gas in these as well. These are the population that I’m calling ‘cold quasars.'”

The KU astrophysicist suspected the “cold quasars” in her survey represented a brief period yet to be recognized in the end-phases of a galaxy’s lifespan—in terms of a human life, the fleeting “cold quasar” phase may something akin to a galaxy’s retirement party.

“These galaxies are rare because they’re in a transition phase—we’ve caught them right before star formation in the galaxy is quenched and this transition period should be very short,” she said.

Kirkpatrick first identified the objects of interest in an area of the Sloan Digital Sky Survey, the most detailed digital map of the universe available. In an area dubbed “Stripe 82,” Kirkpatrick and her colleagues were able to visually identify quasars.

“Then we went over this area with the XMM Newton telescope and surveyed it in the X-ray,” she said. “X-rays are the key signature of growing black holes. From there, we surveyed it with the Herschel Space Telescope, a far infrared telescope, which can detect dust and gas in the host galaxy. We selected the galaxies that we could find in both the X-ray and in the infrared.”

Astrophysicist announces her discovery that could rewrite story of how galaxies die
The dust emission of the same blue-quasar galaxy. It is surprisingly bright — in fact, it’s one of the brightest objects in the field, indicating a lot of dust. Due to the resolution of the telescope, we cannot see what that dust actually looks like. Credit: Herschel/ESA

The KU researcher said her findings give scientists new understanding and detail of how the quenching of star formation in galaxies proceeds, and overturns presumptions about quasars.

“We already knew quasars go through a dust-obscured phase,” Kirkpatrick said. “We knew they go through a heavily shrouded phase where dust is surrounding the supermassive black hole. We call that the red quasar phase. But now, we’ve found this unique transition regime that we didn’t know before. Before, if you told someone you had found a luminous quasar that had a blue optical color—but it still had a lot of dust and gas in it, and a lot of star formation—people would say, ‘No, that’s not the way these things should look.'”

Next, Kirkpatrick hopes to determine if the “cold quasar” phase happens to a specific class of galaxies or every galaxy.

“We thought the way these things proceed was you have a growing black hole, it’s enshrouded by dust and gas, it begins to blow that material out,” she said. “Then it becomes a luminous blue object. We assumed when it blew out its own gas, it would blow out its host gas as well. But it seems with these objects, that’s not the case. These have blown out their own dust—so we see it as a blue object—but they haven’t yet blown out all of the dust and gas in the host galaxies. This is a transition phase, let’s say of 10 million years. In universal timescales, that’s really short—and it’s hard to catch this thing. We’re doing what we call a blind survey to find objects we weren’t looking for. And by finding these objects, yes, it could imply that this happens to every galaxy.”

An Asteroid Impact With the Earth in September Is Not Entirely Impossible 

(THIS ARTICLE IS COURTESY OF INVERSE NEWS)

 

An Asteroid Impact With the Earth in September Is Not Entirely Impossible

It is extremely unlikely, but the probability is actually higher than zero.

Dinosaur asteroid impact

Filed Under AsteroidsESA & NASA

Keep September free … because a massive, football field-sized asteroid has a one in 7,300 chance of smashing into the Earth on the morning of September 9, 2019, according to the European Space Agency.

But it most likely won’t hit us.

Known as asteroid 2006 QV89, it has a diameter of 164 feet — that’s double the width of the meteor that exploded in the atmosphere over Chelyabinsk in Russia in 2013. That meteor came from behind the shadow of the sun and wasn’t seen by astronomers until it was already entering our atmosphere.

Current modeling of the asteroid’s orbit shows it more likely passing by Earth at a distance of over 4.2 million miles this September, but ESA says there’s roughly a one hundredth of a 1 percent chance the model is wrong and it hits our planet instead.

Only last month, US scientists took part in an exercise simulating an imminent asteroid impact with the Earth, and NASA administrator Jim Bridenstine warned that we need to take the real-world threat seriously during his keynote speech at the International Academy of Astronautics Planetary Defense Conference in College Park, Maryland.

But it most likely won’t hit us.

New York gets hit by a meteor shower in the 1998 movie 'Armageddon'
New York gets hit by a meteor shower in the 1998 movie ‘Armageddon’. 

Bridenstine also said that detecting, tracking, and studying asteroids and other near-Earth objects (NEOs) should be taken more seriously following the Chelyabinsk event. The resulting shock wave from that 65-foot-wide asteroid damaged thousands of buildings, and debris and flying glass injured over 1,500 people.

Last June, NASA produced a 20-page plan that details the steps the US should take to be better prepared for NEOs that come within 30 million miles of Earth.

Lindley Johnson, the space agency’s planetary defense officer, said that the country “already has significant scientific, technical, and operational capabilities” to help with NEOs, but implementing the new plan would “greatly increase our nation’s readiness and work with international partners to effectively respond should a new potential asteroid impact be detected.”

According to a 2018 report put together by Planetary.org, there are more than 18,000 NEOs.

Hollywood enjoyed a brief spell of asteroid impact-themed disaster movies during the summer of 1998. In the movie Deep Impact, a comet 1½ miles long slammed into the Atlantic ocean off the coast of Cape Hatteras, creating, at first, a tsunami 100 feet high traveling at 1,100 mph (that’s faster than the speed of sound). Then, when it reached shallow water, it slowed but increased in height to 3,500 feet. The wave washed away farmland and cities and eventually reached as far inland as the Ohio and Tennessee valleys (over 600 miles).

But it most likely won’t hit us.

750 FT asteroid barreling towards an Earth APPROACH at 18,800MPH

(THIS ARTICLE IS COURTESY OF THE UK EXPRESS NEWS)

 

NASA asteroid tracker: A 750 FT asteroid barreling towards an Earth APPROACH at 18,800MPH

AN ASTEROID nearly twice as tall as the Great Pyramid of Giza is hurtling in Earth’s direction at more than 18,800mph, NASA’s asteroid trackers have revealed.

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The -tracked asteroid, dubbed Asteroid 2011 HP, is flying towards our planet on a so-called Earth Close Approach trajectory. NASA predicts the imposing space rock will shoot past Earth on the morning of Thursday, May 30. According to NASA’ Jet Propulsion Laboratory (JPL), the asteroid will approach the planet around 11.48am BST or 6.48am Eastern Time. When this happens, NASA said the asteroid will break speeds of around 8.43km per second or 18,857.4mph (30,348kmh).

Asteroid HP is an Apollo-type Near-Earth  (NEA) or Near-Earth Object (NEO).

NASA’s JPL estimates the space rock measures somewhere in the range of 328ft to 754.6ft (100m to 230m) in diameter.

At the upper end of that scale, the asteroid is as tall as the Golden Gate Bridge in San Francisco, US, and the Space Needle in Seattle.

However, even at the lower end of the estimate, the space rock is still almost as tall as Big Ben’s clock tower in London, UK.

READ MORE: 

NASA asteroid tracker: Giant space rock over Earth

NASA asteroid tracker: A colossal space rock will zip past the Earth on Thursday, May 30 (Image: GETTY)

The space rock orbits the inner circles of the solar system on a trajectory similar to that of asteroid 1862 Apollo.

The asteroid’s trajectory takes it beyond the orbit of Mars but it does not fly past the Asteroid Belt in-between Mars and the gas giant Jupiter.

All NEOs are comets and asteroids on paths, which orbit the Sun from distances smaller than 1.3 astronomical units or 120.8 million miles (194.5 million km).

One astronomical unit measures approximately 93 million miles (149.6 million km) – the distance from the Earth to the Sun.

READ MORE: 

Next week, Asteroid HP will significantly cut this distance down to around 0.03149 astronomical units.

Near-Earth Objects can occasionally approach close to Earth

NASA

This means the asteroid will near-miss the Earth from a distance of just 2.92 million miles (4.7 million km).

In other words, the  rock will approach our home-world 12.26 times as far as the Moon is.

NASA said: “As they orbit the Sun, Near-Earth Objects can occasionally approach close to Earth.

READ MORE: 

NASA asteroid tracker: Giant space rock over Earth

NASA asteroid tracker: The asteroid was discovered on April 13, 2011 (Image: GETTY)

NASA asteroid tracker: Giant space rock over Earth

NASA asteroid tracker: Thankfully, the space rock will not hit the Earth and pass safely (Image: GETTY)

“Note that a ‘close’ passage astronomically can be very far away in human terms: millions or even tens of millions of kilometres.”

After the asteroid ups past the Earth next week, NASA predicts HP will visit us again on May 17, 2027.

Then, the space rock will make many more approaches every few years until September 2, 2184.

NASA asteroid trackers first observed the asteroid on April 13, 2011.

Pluto Has a Buried Ocean — And So Might Many Other Worlds

(THIS ARTICLE IS COURTESY OF SPACE.COM)

 

Pluto Has a Buried Ocean — And So Might Many Other Worlds

This view of Pluto's Sputnik Planitia nitrogen-ice plain was captured by NASA's New Horizons spacecraft during its flyby of the dwarf planet in July 2015.

This view of Pluto’s Sputnik Planitia nitrogen-ice plain was captured by NASA’s New Horizons spacecraft during its flyby of the dwarf planet in July 2015.
(Image: © NASA/JHUAPL/SwRI)

Buried oceans like the one thought to slosh beneath the icy surface of the dwarf planet Pluto may be incredibly common across the cosmos.

A gassy insulating layer probably keeps Pluto’s liquid-water ocean from freezing solid, a new study reports. And something similar could be happening under the surfaces of frigid worlds in other solar systems as well, study team members said.

“This could mean there are more oceans in the universe than previously thought, making the existence of extraterrestrial life more plausible,”  lead author Shunichi Kamata, of Hokkaido University in Japan, said in a statement.

Related: Photos of Pluto and Its Moons

Image 1 of 2

The bright “heart” on Pluto is located near the equator. Its left half is a big basin dubbed Sputnik Planitia.

The bright “heart” on Pluto is located near the equator. Its left half is a big basin dubbed Sputnik Planitia.
(Image: © Figures created using images by NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute.)

Pluto’s “Heart” Hints at Buried Ocean

The proposed interior structure of Pluto. A thin clathrate (gas) hydrate layer works as a thermal insulator between the subsurface ocean and the ice shell, keeping the ocean from freezing.

The proposed interior structure of Pluto. A thin clathrate (gas) hydrate layer works as a thermal insulator between the subsurface ocean and the ice shell, keeping the ocean from freezing.
(Image: © Kamata S. et al., Pluto’s ocean is capped and insulated by gas hydrates. Nature Geosciences, May 20, 2019.)

The bright “heart” on Pluto is located near the equator. Its left half is a big basin dubbed Sputnik Planitia.

The bright “heart” on Pluto is located near the equator. Its left half is a big basin dubbed Sputnik Planitia.
(Image: © Figures created using images by NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute.)

Pluto’s “Heart” Hints at Buried Ocean

The proposed interior structure of Pluto. A thin clathrate (gas) hydrate layer works as a thermal insulator between the subsurface ocean and the ice shell, keeping the ocean from freezing.

The proposed interior structure of Pluto. A thin clathrate (gas) hydrate layer works as a thermal insulator between the subsurface ocean and the ice shell, keeping the ocean from freezing.
(Image: © Kamata S. et al., Pluto’s ocean is capped and insulated by gas hydrates. Nature Geosciences, May 20, 2019.)

The case for a subsurface ocean on Pluto is bolstered by the location of Sputnik Planitia, a 600-mile-wide (1,000 kilometers) plain of nitrogen ice that forms the left lobe of the dwarf planet’s famous “heart.”

Observations by NASA’s New Horizons probe showed that Sputnik Planitia is aligned with Pluto’s tidal axis — the line along which the gravitational pull from the dwarf planet’s biggest moon, Charon, is most powerful. Scientists think that Pluto rolled into this orientation because of extra mass concentrated at and near the surface in the Sputnik Planitia region.

That extra mass likely comes from the nitrogen ice that’s built up on the plain, as well as water from the buried ocean, which was freed to rise from deep underground after the comet impact that formed Sputnik Planitia shattered the crust in that locale, previous research suggests.

Below Pluto’s ‘Heart’ A Slushy Ocean May Churn | Video
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But how could a buried ocean stay unfrozen on Pluto over the 4.6-billion-year history of the solar system? After all, the dwarf planet doesn’t circle a gas giant, so its innards aren’t roiled and heated by tidal forces nearly as dramatically as are the insides of Jupiter’s moon Europa and the Saturn satellite Enceladus, both of which also harbor subsurface oceans.

The new study offers a possible explanation. Kamata and his colleagues hypothesized that an insulating layer of “gas hydrates” — ice-like solids composed of gases trapped within “cages” of molecular water — beneath Pluto’s ice shell might be responsible, then performed computer simulations to test the idea.

In simulations run without the gas hydrates, Pluto’s ocean froze solid hundreds of millions of years ago. But with the insulating layer, the ocean persists to this day, the researchers found. The gas hydrates also act as an insulator in the other direction, helping to keep Pluto’s surface cold enough to support observed variations in ice-shell thickness, the researchers said.

It’s unclear what the gas inside the water cages might be (if such a layer does indeed exist). But the study team thinks methane is a good candidate, partly because Pluto’s wispy atmosphere is notably lacking the stuff.

The new study was published online today (May 20) in the journal Nature Geoscience.

Mike Wall’s book about the search for alien life, “Out There” (Grand Central Publishing, 2018; illustrated by Karl Tate), is out now. Follow him on Twitter @michaeldwall. Follow us on Twitter @Spacedotcom or Facebook

Have a news tip, correction or comment? Let us know at [email protected]

“Enormous Ghost Galaxy” –Hidden In the Milky Way’s ‘Zone of Avoidance’

(THIS ARTICLE IS COURTESY OF THE DAILY GALAXY)

 

“Enormous Ghost Galaxy” –Hidden In the Milky Way’s ‘Zone of Avoidance’ (Weekend Feature)

Milky Way Galactic Center

 

An enormous ‘ghost’ galaxy, believed to be one of the oldest in the universe, was detected lurking on the outskirts of the Milky Way in November of 2018 by a team of astronomers who discovered the massive object when trawling through new data from the European Space Agency’s Gaia satellite. The object, named Antlia 2, avoided detection thanks to its extremely low density as well as a perfect hiding place in the Zone of Avoidance, behind the shroud of the Milky Way’s disc–a region full of dust and an overabundance of bright stars near the galactic center.

“This is a ghost of a galaxy,” said Gabriel Torrealba, an astrophysicist at Taiwan’s Academia Sinica Institute of Astronomy and Astrophysics (ASIAA) and the paper’s lead author. “Objects as diffuse as Ant 2 have simply not been seen before. Our discovery was only possible thanks to the quality of the Gaia data.” Gaia is able to dig into the Zone of Avoidance, he says, because it provides high-quality proper motions of stars behind the central disk of our Milky Way galaxy. That is, it is able to track stars as they move across the celestial sphere.

Optically, the Zone of Avoidance is like “trying to look through a velvet cloth—black as black can be,” says Thomas Dame, Director of the Radio Telescope Data Center at the Harvard-Smithsonian Center for Astrophysics and Senior Radio Astronomer at the Smithsonian Astrophysical Observatory. “In terms of tracing and understanding the spiral structure, essentially half of the Milky Way is terra incognito.”

“It’s the most Important thing in astrophysics”–the ‘Holy Grail’ of astronomy is to provide a clear perspective of our relationship to the physical universe. The map of our Milky Way galaxy is a part of that, a map that is still incomplete. Our solar system drifts between two spiral arms at its outer edges, some 27,000 light-years from its center. Beyond that, like the ancient sea-faring mariners, no space craft has ever traveled beyond the opaque central disk to turn back and take its picture.

“Monsters & Dragons?” –Mapping the Terra Incognito of Milky Way’s Unseen Far Side

“The zone of avoidance is basically the part of the sky obscured by the Milky Way’s disk as seen from the Earth,” said Torrealba. “The disk of the Milky Way has a lot of gas and stars, making it extremely crowded and complex.” But the team was able to use about a hundred old and metal-poor pulsating, so-called ‘RR Lyrae’ stars to probe inside and ultimately identify Antlia 2.

Optically, penetrating the Zone of Avoidance is like “trying to look through a velvet cloth—black as black can be,” says Thomas Dame, Director of the Radio Telescope Data Center at the Harvard-Smithsonian Center for Astrophysics and Senior Radio Astronomer at the Smithsonian Astrophysical Observatory. “In terms of tracing and understanding the spiral structure, essentially half of the Milky Way is terra incognito.”

“It’s the most Important thing in astrophysics”–the ‘Holy Grail’ of astronomy is to provide a clear perspective of our relationship to the physical universe. The map of our Milky Way galaxy is a part of that, a map that is still incomplete. Our solar system drifts between two spiral arms at its outer edges, some 27,000 light-years from its center. Beyond that, like the ancient sea-faring mariners, no space craft has ever traveled beyond the opaque central disk to turn back and take its picture.

Swarm of Faint Dwarf Galaxies Orbit the Milky Way –“Many More Hidden, Yet to Be Discovered”

“Compared to the rest of the 60 or so Milky Way satellites, Ant 2 is an oddball,” said co-author Matthew Walker, also from Carnegie Mellon University. “We are wondering whether this galaxy is just the tip of an iceberg, and the Milky Way is surrounded by a large population of nearly invisible dwarfs similar to this one.”

 

Antlia2 Dwarf Galaxy

 

Torrealba says that Antlia 2 is likeliest one of the oldest dwarf galaxies in the universe, but he and colleagues are still puzzled as to how it became so diffuse. “One possibility is that Antlia 2 was much more massive in the past, and as it fell into the Milky Way, it lost its mass to become more diffuse,” said Torrealba. One problem with this idea says Torrealba is that rather than grow, galaxies tend to shrink at the same time they lose stars.

Extreme Disk Galaxy Discovered –“Seven Times the Width of the Milky Way”

The object’s giant size, says astronomer Sergey Koposov at Carnegie Mellon University presents a puzzle, agreeing with Torrealba. “Normally, as galaxies lose mass to the Milky Way’s tides, they shrink, not grow.”

“Another possible explanation of the extraordinary appearance of Antlia 2,” Koposov wrote in an email to dailygalaxy.com, “is that there is something wrong with currently favored Cold Dark Matter theory that predicts that dark matter should be tightly packed in centers of galaxies. If dark matter distribution however is more fluffy, that can make it easier to form galaxies like Antlia 2,” he added.

Ant 2 is known as a dwarf galaxy. As structures emerged in the early Universe, dwarfs were the first galaxies to form, and so most of their stars are old, low-mass and metal-poor. But compared to the other known dwarf satellites of our Galaxy, Ant 2 is immense: it is as big as the Large Magellanic Cloud (LMC), and a third the size of the Milky Way itself.

What makes Ant 2 even more unusual is how little light it gives out. Compared to the LMC, another satellite of the Milky Way, Ant 2 is 10,000 times fainter. In other words, it is either far too large for its luminosity or far too dim for its size.

The ESA’s Gaia mission has produced the richest star catalog to date, including high-precision measurements of nearly 1.7 billion stars and revealing previously unseen details of our home Galaxy. Earlier in 2018, Gaia’s second data release made new details of stars in the Milky Way available to scientists worldwide.

The researchers behind the current study – from Taiwan, the UK, the US, Australia and Germany – searched the new Gaia data for Milky Way satellites by using RR Lyrae stars. These stars are old and metal-poor, typical of those found in a dwarf galaxy. RR Lyrae change their brightness with a period of half a day and can be located thanks to these well-defined pulses.

“RR Lyrae had been found in every known dwarf satellite, so when we found a group of them sitting above the Galactic disc, we weren’t totally surprised,” said co-author Vasily Belokurov from Cambridge’s Institute of Astronomy. “But when we looked closer at their location on the sky it turned out we found something new, as no previously identified object came up in any of the databases we searched through.”

The team contacted colleagues at the Anglo-Australian Telescope (AAT) in Australia, but when they checked the coordinates for Ant 2, they realized they had a limited window of opportunity to get follow-up data. They were able to measure the spectra of more than 100 red giant stars just before the Earth’s motion around the Sun rendered Ant 2 unobservable for months.

The spectra enabled the team to confirm that the ghostly object they spotted was real: all the stars were moving together. Ant 2 never comes too close to the Milky Way, always staying at least 40 kiloparsecs (about 130,000 light-years) away. The researchers were also able to obtain the galaxy’s mass, which was much lower than expected for an object of its size.

If it is impossible to puff the dwarf up by removing matter from it, then Ant 2 had to have been born huge. The team has yet to figure out the exact process that made Ant 2 so extended. While objects of this size and luminosity have not been predicted by current models of galaxy formation, recently it has been speculated that some dwarfs could be inflated by vigorous star formation. Stellar winds and supernova explosions would push away the unused gas, weakening the gravity that binds the galaxy and allowing the dark matter to drift outward as well.

“Even if star formation could re-shape the dark matter distribution in Ant 2 as it was put together, it must have acted with unprecedented efficiency,” said co-author Jason Sanders, also from Cambridge.

Alternatively, Ant 2’s low density could mean that a modification to the dark matter properties is needed. The currently favored theory predicts dark matter to pack tightly in the centers of galaxies. Given how fluffy the new dwarf appears to be, a dark matter particle which is less keen to cluster may be required.

The gap between Ant 2 and the rest of the Galactic dwarfs is so wide that this may well be an indication that some important physics is missing in the models of dwarf galaxy formation. Solving the Ant 2 puzzle may help researchers understand how the first structures in the early universe emerged.

The Daily Galaxy via Imperial College London

“One Trillion Times Age Of The Cosmos”–Rarest Thing Ever Detected

(THIS ARTICLE IS COURTESY OF THE ‘DAILY GALAXY’)

 

“One Trillion Times Age of the Cosmos” –Rarest Thing Ever Detected

 

Cluster Abell 3827

 

“We actually saw this decay happen. It’s the longest, slowest process that has ever been directly observed, and our dark matter detector was sensitive enough to measure it,” said Ethan Brown, an assistant professor of physics at Rensselaer Polytechnic Institute. “It’s an amazing to have witnessed this process, and it says that our detector can measure the rarest thing ever recorded.”

How do you observe a process that takes more than one trillion times longer than the age of the universe? The XENON Collaboration research team did it with an instrument built to find the most elusive particle in the universe—dark matter. In a paper to be published tomorrow in the journal Nature, researchers announce that they have observed the radioactive decay of xenon-124, which has a half-life of 1.8 X 1022 years.

The XENON Collaboration runs XENON1T, a 1,300-kilogram vat of super-pure liquid xenon shielded from cosmic rays in a cryostat submerged in water deep 1,500 meters beneath the Gran Sasso mountains of Italy. The researchers search for dark matter by recording tiny flashes of light created when particles interact with xenon inside the detector. And while XENON1T was built to capture the interaction between a dark matter particle and the nucleus of a xenon atom, the detector actually picks up signals from any interactions with the xenon.

Dark Matter –“Emerged From an Eon Before the Big Bang” (Weekend Feature)

The evidence for xenon decay was produced as a proton inside the nucleus of a xenon atom converted into a neutron. In most elements subject to decay, that happens when one electron is pulled into the nucleus. But a proton in a xenon atom must absorb two electrons to convert into a neutron, an event called “double-electron capture.”

Double-electron capture only happens when two of the electrons are right next to the nucleus at just the right time, Brown said, which is “a rare thing multiplied by another rare thing, making it ultra-rare.”

When the ultra-rare happened, and a double-electron capture occurred inside the detector, instruments picked up the signal of electrons in the atom re-arranging to fill in for the two that were absorbed into the nucleus.

“Ultralight” –‘Dark Matter Exists Beyond the Standard Model’

“Electrons in double-capture are removed from the innermost shell around the nucleus, and that creates room in that shell,” said Brown. “The remaining electrons collapse to the ground state, and we saw this collapse process in our detector.”

The achievement is the first time scientists have measured the half-life of this xenon isotope based on a direct observation of its radioactive decay.

“This is a fascinating finding that advances the frontiers of knowledge about the most fundamental characteristics of matter,” said Curt Breneman, dean of the School of Science. “Dr. Brown’s work in calibrating the detector and ensuring that the xenon is scrubbed to the highest possible standard of purity was critical to making this important observation.”

Very Weird Galaxies –“The Absence of Dark Matter is Unprecedented”

The XENON Collaboration includes more than 160 scientists from Europe, the United States, and the Middle East, and, since 2002, has operated three successively more sensitive liquid xenon detectors in the Gran Sasso National Laboratory in Italy. XENON1T, the largest detector of its type ever built, acquired data from 2016 until December 2018, when it was switched off. Scientists are currently upgrading the experiment for the new XENONnT phase, which will feature an active detector mass three times larger than XENON1T. Together with a reduced background level, this will boost the detector’s sensitivity by an order of magnitude.

Three years ago researchers were excited to find that a galaxy at the heart of cluster Abell 3827 shown at the top of the page that appeared to have separated from the dark matter that surrounded it. New research suggests this is incorrect. (Nasa/ESA/Richard Massey)

The Daily Galaxy via Rensselaer Polytechnic Institute

Astronomers discover third planet in the Kepler-47 circumbinary system

(THIS ARTICLE IS COURTESY OF PHYS.ORG)

 

Astronomers discover third planet in the Kepler-47 circumbinary system

Astronomers discover third planet in the Kepler-47 circumbinary system
Artistic rendition of the Kepler-47 circumbinary planet system. The three planets with the large middle planet being the newly discovered Kepler47d. Credit: NASA/JPLCaltech/T. Pyle

Astronomers have discovered a third planet in the Kepler-47 system, securing the system’s title as the most interesting of the binary-star worlds. Using data from NASA’s Kepler space telescope, a team of researchers, led by astronomers at San Diego State University, detected the new Neptune-to-Saturn-size planet orbiting between two previously known planets.

With its three planets orbiting two suns, Kepler-47 is the only known multi-planet circumbinary system. Circumbinary planets are those that orbit two stars.

The planets in the Kepler-47 system were detected via the “transit method.” If the orbital plane of the planet is aligned edge-on as seen from Earth, the planet can pass in front of the host stars, leading to a measurable decrease in the observed brightness. The new planet, dubbed Kepler-47d, was not detected earlier due to weak transit signals.

As is common with circumbinary planets, the alignment of the orbital planes of the planets change with time. In this case, the middle planet’s orbit has become more aligned, leading to a stronger transit signal. The transit depth went from undetectable at the beginning of the Kepler Mission to the deepest of the three planets over the span of just four years.

The SDSU researchers were surprised by both the size and location of the new planet. Kepler-47d is the largest of the three planets in the Kepler-47 system.

“We saw a hint of a third planet back in 2012, but with only one transit we needed more data to be sure,” said SDSU astronomer Jerome Orosz, the paper’s lead author. “With an additional transit, the planet’s orbital period could be determined, and we were then able to uncover more transits that were hidden in the noise in the earlier data.”

William Welsh, SDSU astronomer and the study’s co-author, said he and Orosz expected any additional planets in the Kepler-47 system to be orbiting exterior to the previously known planets. “We certainly didn’t expect it to be the largest planet in the system. This was almost shocking,” said Welsh. Their research was recently published in the Astronomical Journal.

Astronomers discover third planet in the Kepler-47 circumbinary system
Artistic rendition of the Kepler-47 circumbinary planet system. An overhead view of the orbital configuration. Credit: NASA/JPLCaltech/T. Pyle

With the discovery of the new planet, a much better understanding of the system is possible. For example, researchers now know the planets in in this circumbinary system are very low density – less than that of Saturn, the Solar System planet with the lowest density.

While a low density is not that unusual for the sizzling hot-Jupiter type exoplanets, it is rare for mild-temperature planets. Kepler-47d’s equilibrium temperature is roughly 50 degrees F (10 degrees C), while Kepler-47c is 26 degrees F ( 32 degrees C). The innermost planet, which is the smallest circumbinary planet known, is a much hotter 336 degrees F (169 degrees C).

The inner, middle, and outer planets are 3.1, 7.0, and 4.7 times the size of the Earth, and take 49, 187, and 303 days, respectively, to orbit around their suns. The stars themselves orbit each other in only 7.45 days; one star is similar to the Sun, while the other has a third of the mass of the Sun. The entire system is compact and would fit inside the orbit of the Earth. It is approximately 3340 light-years away in the direction of the constellation Cygnus.

“This work builds on one of the Kepler’s most interesting discoveries: that systems of closely-packed, low-density planets are extremely common in our galaxy,” said University of California, Santa Cruz astronomer Jonathan Fortney, who was not part of the study. “Kepler 47 shows that whatever process forms these planets – an outcome that did not happen in our solar system – is common to single-star and circumbinary planetary systems.”

Correction: A prior version of this article contained inaccuracies regarding the orbits of the Kepler-47 planets. This article has been updated to reflect the correct number of days it takes the inner, middle, and outer planets to orbit their suns: 49, 187 and 303 days respectively.


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Kepler-1647b: New planet is largest discovered that orbits two suns


More information: Jerome A. Orosz et al. Discovery of a Third Transiting Planet in the Kepler-47 Circumbinary System, The Astronomical Journal(2019). DOI: 10.3847/1538-3881/ab0ca0 , iopscience.iop.org/article/10. … 847/1538-3881/ab0ca0

Journal information: Astronomical Journal

Hubble Peers At Cosmic Blue Bauble

(THIS ARTICLE IS COURTESY OF PHYSICS.ORG AND NASA)

 

Hubble peers at cosmic blue bauble

Hubble peers at cosmic blue bauble
Messier 3: Containing an incredible half-million stars, this 8-billion-year-old cosmic bauble is one of the largest and brightest globular clusters ever discovered. Credit: ESA/Hubble & NASA, G. Piotto et al.

Globular clusters are inherently beautiful objects, but the subject of this NASA/ESA Hubble Space Telescope image, Messier 3, is commonly acknowledged to be one of the most beautiful of them all.

Containing an incredible half-million stars, this 8-billion-year-old cosmic bauble is one of the largest and brightest  ever discovered. However, what makes Messier 3 extra special is its unusually large population of variable stars—stars that fluctuate in brightness over time. New variable stars continue to be discovered in this sparkling stellar nest to this day, but so far we know of 274, the highest number found in any globular cluster by far. At least 170 of these are of a special variety called RR Lyrae variables, which pulse with a period directly related to their intrinsic brightness. If astronomers know how bright a star truly is based on its  and classification, and they know how bright it appears to be from our viewpoint here on Earth, they can thus work out its distance from us. For this reason, RR Lyrae stars are known as standard candles—objects of known luminosity whose  and position can be used to help us understand more about vast celestial distances and the scale of the cosmos.

Messier 3 also contains a relatively high number of so-called , which are shown quite clearly in this Hubble image. These are blue main sequence stars that appear to be young because they are bluer and more luminous than other stars in the . As all stars in globular clusters are believed to have formed together and thus to be roughly the same age, only a difference in mass can give these  a different color. A red, old star can appear bluer when it acquires more mass, for instance by stripping it from a nearby star. The extra mass changes it into a bluer star, which makes us think it is younger than it really is.


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Hubble spots flock of cosmic ducks


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Magnetic fields may be the key to black hole activity

(THIS ARTICLE IS COURTESY OF PHYS.ORG AND NASA)

 

Magnetic fields may be the key to black hole activity

October 17, 2018, NASA
Magnetic fields may be the key to black hole activity
Artist’s conception of the core of Cygnus A, including the dusty donut-shaped surroundings, called a torus, and jets launching from its center. Magnetic fields are illustrated trapping the dust in the torus. These magnetic fields could be …more

Collimated jets provide astronomers with some of the most powerful evidence that a supermassive black hole lurks in the heart of most galaxies. Some of these black holes appear to be active, gobbling up material from their surroundings and launching jets at ultra-high speeds, while others are quiescent, even dormant. Why are some black holes feasting and others starving? Recent observations from the Stratospheric Observatory for Infrared Astronomy, or SOFIA, are shedding light on this question.

SOFIA data indicate that magnetic fields are trapping and confining dust near the center of the active galaxy, Cygnus A, and feeding material onto the supermassive black hole at its center.

The , which attempts to explain the different properties of active galaxies, states that the core is surrounded by a donut-shaped dust cloud, called a torus. How this obscuring structure is created and sustained has never been clear, but these new results from SOFIA indicate that magnetic fields may be responsible for keeping the dust close enough to be devoured by the hungry black hole. In fact, one of the fundamental differences between active galaxies like Cygnus A and their less active cousins, like our own Milky Way, may be the presence or absence of a  around the black hole.

Although celestial magnetic fields are notoriously difficult to observe, astronomers have used polarized light—optical light from scattering and radio light from accelerating electrons—to study magnetic fields in galaxies. But optical wavelengths are too short and the radio wavelengths are too long to observe the torus directly. The infrared wavelengths observed by SOFIA are just right, allowing scientists, for the first time, to target and isolate the dusty torus.

Magnetic fields may be the key to black hole activity
Two images of Cygnus A layered over each other to show the galaxy’s jets glowing with radio radiation (shown in red). Quiescent galaxies, like our own Milky Way, do not have jets like this, which may be related to magnetic fields. The …more

SOFIA’s new instrument, the High-resolution Airborne Wideband Camera-plus (HAWC+), is especially sensitive to the infrared emission from aligned dust grains. This has proven to be a powerful technique to study magnetic fields and test a fundamental prediction of the unified model: the role of the dusty torus in the active-galaxy phenomena.

“It’s always exciting to discover something completely new,” noted Enrique Lopez-Rodriguez, a scientist at the SOFIA Science Center, and the lead author on the report of this new discovery. “These observations from HAWC+ are unique. They show us how infrared polarization can contribute to the study of galaxies.”

Recent observations of the heart of Cygnus A made with HAWC+ show infrared radiation dominated by a well-aligned dusty structure. Combining these results with archival data from the Herschel Space Observatory, the Hubble Space Telescope and the Gran Telescopio Canarias, the research team found that this powerful active galaxy, with its iconic large-scale jets, is able to confine the obscuring torus that feeds the supermassive black hole using a strong .

The results of this study were published in the July 10th issue of The Astrophysical Journal Letters.

Cygnus A is in the perfect location to learn about the role magnetic fields play in confining the dusty torus and channeling material onto the supermassive black hole because it is the closest and most powerful active galaxy. More observations of different types of galaxies are necessary to get the full picture of how magnetic fields affect the evolution of the environment surrounding . If, for example, HAWC+ reveals highly polarized  from the centers of active galaxies but not from quiescent , it would support the idea that magnetic fields regulate black hole feeding and reinforce astronomers’ confidence in the unified model of .

 Explore further: Black holes play hide-and-seek in low-luminosity radio galaxies

More information: Enrique Lopez-Rodriguez et al. The Highly Polarized Dusty Emission Core of Cygnus A, The Astrophysical Journal (2018). DOI: 10.3847/2041-8213/aacff5

Read more at: https://phys.org/news/2018-10-magnetic-fields-key-black-hole.html#jCp

“Planet Nine” Might Be Invisible, Hiding Beyond Neptune

(THIS ARTICLE IS COURTESY OF THE ‘ADVOCATOR NEWS’)

 

“Planet Nine” Might Be Invisible, Hiding Beyond Neptune, Scientists Think

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Increasingly more astronomers from all around the world believe that there is the so-called “Planet Nine,” hiding beyond Neptune. On the other hand, circumstantial evidence of its existence continues to gather, while some scientists also think that the mysterious planet might be invisible to our current observatories.

“Every time we take a picture, there is this possibility that Planet Nine exists in the shot,” said Surhud More from the University of Tokyo.

On the other hand, Michael Brown from the California Institute of Technology believes that “Planet Nine” will eventually be discovered by astronomers, but, so far, our existing observatories are not capable of detecting the mysterious space object.

Also, in 2016, Michael Brown, along with his team, studied the planetoid found in 2014 and which revealed that some mini ice-worlds at the outermost border of our Solar System followed similar paths around the Sun. This discovery boosted the beliefs in the existence of the so-called “Planet Nine.”

If there’s a “Planet Nine” hiding far beyond Neptune, it is invisible for us

According to Michael Brown and Konstantin Batygin, the mysterious planet would weigh between five and 20 Earth masses, while it would follow an elliptical orbit hundreds or even 1,000 times more distant from the Sun in comparison to the Earth’s orbit.

At such a distance, space is too dark for the current observatories to spot the “Planet Nine” directly. Accordingly, this strange object would be by 160,000 times dimmer than Neptune is at 30 AU (astronomical unit – Earth-Sun distance). So, at about 1,000 AU, “Planet Nine” would be by 1 million times dimmer.

On the other hand, even if the scientists use the most potent observatory of the moment, the Subaru telescope in Hawaii which has a wide field of view permitting astronomers to access a search area of the size of 4,000 full moons, there is very challenging to observe such a distant world.

At the moment of the observation, the “Planet Nine” might hide in the light pollution of the Milky Way, could find itself in the shine of a bright star, or, even worse, it might be at a specific point of its orbit beyond the 1,000 AU-limit which would make it entirely invisible for at least a thousand years.

So, at the moment, the scientists believe there’s something beyond Neptune that causes some disturbances in the orbit of other space objects, but could that be “Planet Nine?” So far, nobody knows.

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Jasmine holds a Master’s in Journalism from Ryerson University in Toronto and writes professionally in a broad variety of genres. She has worked as a senior manager in public relations and communications for major telecommunication companies, and is the former Deputy Director for Media Relations with the Modern Coalition. Jasmine writes primarily in our LGBTTQQIAAP section.

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