Space News/UFO's Etc...(Discussion/Pics/Vids)

[Kimbo]

interstellar sexting, or tinder for aliens. LOL

[ilan]

When galaxies collide, black holes eat
Deborah Byrd in Space | March 12, 2017

When our Milky Way galaxy and neighboring Andromeda galaxy collide, supermassive black holes will have a feast!

Artist’s concept of a Tidal Disruption Event, in which a black hole eats a star, in the distant galaxy F01004-2237. As the black hole swallows the star, there’s a release of gravitational energy from the star’s debris. The result is a visible flare. Image via Mark Garlick.

What’ll our sky look like 5 billion years from now, when our Milky Way galaxy merges with the nearby Andromeda galaxy? If there are any people left to look then, they’ll be able to see flares about every 10 to 100 years, each time our Milky Way’s central supermassive black hole swallows a star. The flares will be visible to the unaided eye. They’ll appear much brighter than any other star or planet in the night sky. That’s according to astronomers at the University of Sheffield in England, who say that central, supermassive black holes in colliding galaxies swallow stars some 100 times more often than previously thought.

Their study was published March 1, 2017 in the peer-reviewed journal Nature Astronomy.

The study is based on a survey of just 15 galaxies, a very small sample size by astronomical standards. However, in that small sample, the astronomers were surprised to see a black hole swallow a star. Astronomers call this sort of event a tidal distruption event, or TDE. They’d been only been only seen before in surveys of many thousands of galaxies, leading astronomers to believe they were exceptionally rare: only one event every 10,000 to 100,000 years per galaxy.

Artist’s concept of Earth’s night sky in 3.75 billion years. The Andromeda galaxy (left) will fill our field of view then, astronomers say, as it heads toward a collision, or merger, with our Milky way galaxy. Image via NASA; ESA; Z. Levay and R. van der Marel, STScI; T. Hallas; and A. Mellinger. Read more about the eventual merger of the Milky Way and Andromeda galaxies.

The 15 galaxies of the University of Sheffield study are doing something those other thousands of galaxies weren’t doing. They’re undergoing collisions with neighboring galaxies. Study co-author James Mullaney said in a statement:

Our surprising findings show that the rate of TDEs dramatically increases when galaxies collide. This is likely due to the fact that the collisions lead to large numbers of stars being formed close to the central supermassive black holes in the two galaxies as they merge together.

Another study co-author, Rob Spence, said:

Our team first observed the 15 colliding galaxies in the sample in 2005, during a previous project.

However, when we observed the sample again in 2015, we noticed that one galaxy – F01004-2237 – appeared strikingly different. This led us to look at data from the Catalina Sky Survey, which monitors the brightness of objects in the sky over time. We found that in 2010, the brightness of F01004-2237 flared dramatically.

Galaxy F01004-2237 – which is 1.7 billion light years from Earth – had flared in a way characteristic of TDEs. These events are known to cause flaring due to energy release, as a star edges toward a galaxy’s central, supermassive black hole.

NGC 2207 and IC 2163 are two spiral galaxies in the process of merging, or colliding. If the new study from University of Sheffield is correct, there is a much greater chance for stars to be eaten in these galaxies by their central, supermassive black holes. Read more about this colliding galaxy pair from Chandra.

Bottom line: A study from the University of Sheffield shows that collisions – like that predicted for our Milky Way galaxy and neighboring Andromeda galaxy – cause black holes to eat stars some 100 times faster than previously thought.

[ilan]

There’s a supernova occurring right now in NGC 5643
Alison Klesman, Astronomy.com | Published: Wednesday, March 15, 2017

Meet “Bob,” the second Type Ia supernova in the galaxy since 2013

When most people hear the word supernova, they envision a massive star reaching the end of its life and exploding outwards to leave a ghostly remnant in its place. This is called a Type II supernova — the spectacular Supernova 1987A, which recently celebrated its 30th anniversary, was a Type II. Alternatively, a Type Ia supernova occurs when a white dwarf, the remnant of a Sun-like star, grows too massive after stripping a binary companion star of its outer layers. When the white dwarf reaches a critical mass, a runaway fusion reaction occurs in its core and the star explodes in a Type Ia supernova. Such a supernova has just been spotted occurring in a galaxy about 55 million light-years away.

The supernova which was officially announced via Astronomer's Telegram after an excited tweet by Rachael Beaton at the the Observatories of the Carnegie Institution for Science in Pasadena, CA, and known as 2017cbv (though Beaton has nicknamed it Bob), the explosion was spotted in NGC 5643, a spiral galaxy in the constellation Lupus. The area of the sky it inhabits is also part of the area covered by the Carnegie-Irvine Galaxy Survey, a project aimed at gathering optical and near-infrared images of bright Southern Hemisphere galaxies. NGC 5643 was also the home galaxy of SN 2013aa, which occurred in early 2013.

Type Ia supernovae play an extremely important role as rungs on the astronomical distance ladder that allows astronomers to measure the distance to faraway galaxies. They’ve also played a critical role in measuring the accelerating expansion of the universe. Because they occur in white dwarfs of exactly the same mass every time (that critical mass mentioned earlier: about 1.4 times the mass of the Sun), Type Ia supernovae are always the same brightness, which means astronomers can use them as standard candles. Knowing how bright the explosion is in terms of absolute luminosity allows astronomers to then work backwards to calculate the distance to the object based on how bright it appears.

But the word “exactly” is perhaps a bit misleading. Not every star system in which a Type Ia supernova occurs can be exactly the same. Moreover, events in the real world do not always reflect the precise nature of theoretical calculations — as in, some white dwarfs might explode at a mass slightly under 1.4 solar masses, while others might grow a little heavier than this limit before exploding. The fact that 2017cbv is the second recorded Type Ia supernova to occur in NGC 5643 is thus extremely valuable. By comparing the distance to the galaxy as calculated from each supernova, astronomers can better characterize the real-world variance in supernova Type Ia magnitudes that occur, which in turn will improve the accuracy of using these events to measure distance.

[ilan]

Astronomers observe a dying red giant star's final act
From Phys.org | 17 March 2017


Molecular gas forms a spiral pattern around the red giant star LL Pegasi. Credit: ALMA, Hyosun Kim

An international team of astronomers has observed a striking spiral pattern in the gas surrounding a red giant star named LL Pegasi and its companion star 3,400 light-years from Earth, using a powerful telescope in northern Chile called Atacama Large Millimeter/submillimeter Array, or ALMA.

"What we are seeing in splendid detail with these observations is the final act of a dying red giant star, as it sheds most of its gaseous bulk in a strong, outflowing wind," said study co-author Mark Morris, UCLA professor of physics and astronomy.

After comparing their telescopic observations with computer simulations, the astronomers concluded that a highly elliptical orbit is responsible for the shape of the gaseous emissions surrounding this system.

The research appears in the journal Nature Astronomy and is the cover story of the March issue.

"Because of the orbital motion of the mass-losing red giant, the cold molecular gas constituting the wind from that star is being spun out like the sprays of water from a rotating garden sprinkler, forming the outflowing pattern of spiral shells," Morris said.

ALMA, a powerful international facility operated cooperatively by many countries around the world including the United States, measures extremely short wavelength radio emission. Using this unique instrument, the scientists were able to create a three-dimensional image of the emission from molecules ejected from LL Pegasi and which then form a spiral pattern caused by the presence of the orbiting companion star.

See Video:

https://www.youtube.com/watch?time_continue=1&v=0Sr77kSI3nA

The images, which show many complete revolutions of the spiral pattern, offer clues about the dynamics of the binary system over a period of 5,000 years.

"This unusually ordered system opens the door to understanding how the orbits of such systems evolve with time as one of the stars loses most of its mass," Morris said.

[ilan]

Stephen Hawking: 'I may not be welcome' in Trump's America
By Judith Vonberg, CNN | March 20, 2017


Theoretical physicist Stephen Hawking says he likes and admires the US but fears he may not be welcome there.

(CNN) British scientist Stephen Hawking fears he "may not be welcome" in the United States now that Donald Trump is President.

In an interview with ITV's Good Morning Britain on Monday, Hawking described President Trump's election as "a definite swing to a right-wing" and a "more authoritarian approach."

He was especially critical of the appointment of Scott Pruitt, "a man who does not believe that carbon dioxide causes climate change," as head of the Environmental Protection Agency.

"He should replace Scott Pruitt at the Environment Protection Agency," Hawking told ITV.

"Climate change is one of the great dangers we face, and it's one we can prevent," he said.

"It affects America badly, so tackling it should win votes for [Trump's] second term, God forbid."

He suggested that the appointment of Pruitt, as well as the promise of a border wall and the sanctioning of two oil pipelines, are designed to "satisfy [Trump's] electorate, who are neither liberal nor that well-informed."

"I have many friends and colleagues [in the US] and it is still a place I like and admire in many ways," he said, "but I fear that I may not be welcome."

His comments about the US President echo those he made in May last year, before Trump became the Republican nominee. At the time, Hawking described Trump as "a demagogue, who seems to appeal to the lowest common denominator."

Brexit will leave UK 'isolated'

In Monday's wide ranging interview, Hawking also had harsh words for Britons who voted to leave the European Union in last year's Brexit referendum.

"A main worry for the British people was the feeling that Eastern Europe migration would take their jobs and undercut their wages," he said. "The majority voted accordingly and I see this as short-sighted."

A "hard Brexit" would "leave us isolated and inward looking," he said.

"A few people will get mega rich as is often the case but the majority will be poorer."

Trip to space on the horizon

Turning to lighter matters, Hawking also spoke about the prospect of going into space.

"I have already completed a zero gravity flight which allowed me to float weightless, but my ultimate ambition is to fly into space. I thought no one would take me but Richard Branson has offered me a seat on Virgin Galactic and I said yes immediately."

Asked if he believed he was the most intelligent person in the world, he gave a sharp response: "I would never claim this. People who boast about their IQ are losers."

[ilan]

A new definition would add 102 planets to our solar system — including Pluto
Sarah Kaplan, Washington Post | March 20 at 2:59 PM


An image of Pluto captured by the New Horizons spacecraft. (NASA)

Is Pluto a planet?

It's not a question scientists ask in polite company.

“It's like religion and politics,” said Kirby Runyon, a planetary scientist at Johns Hopkins University. “People get worked up over it. I've gotten worked up over it.”

For years, astronomers, planetary scientists and other space researchers have fought about what to call the small, icy world at the edge of our solar system. Is it a planet, as scientists believed for nearly seven decades? Or must a planet be something bigger, something more dominant, as was decided by vote at the International Astronomical Union (IAU) in 2006?

The issue can bring conversations to a screeching halt, or turn them into shouting matches. “Sometimes,” Runyon said, “it's just easier not to bring it up.”

But Runyon will ignore his own advice this week when he attends the annual Lunar and Planetary Science Conference in Houston. In a giant exhibit hall crowded with his colleagues, he's attempting to reignite the debate about Pluto's status with an audacious new definition for planet — one that includes not just Pluto, but several of its neighbors, objects in the asteroid belt, and a number of moons. By his count, 102 new planets could be added to our solar system under the new criteria.

“It's a scientifically useful bit of nomenclature and, I think, given the psychological power behind the word planet, it’s also more consumable by the general public,” Runyon said.

“A classification has to be useful, or else it’s just lipstick on a pig,” countered planetary scientist Carolyn Porco. Runyon's definition “is not useful at all.”

The debate rages on.

An artist's impression of the solar system. (NASA)

If aliens arrived at our solar system tomorrow, they would not see planets laid out in the orderly parade depicted in textbooks. Instead, they'd encounter hundreds of constantly moving bodies engaged in a complex dance around a brightly burning star.

It's hard to know what would immediately catch their attention. Probably Jupiter, the largest body in our solar system. Next they'd spot Saturn, Neptune and Uranus — other giant worlds — and the two belts of debris that orbit the sun inside Jupiter's orbit (the asteroid belt) and beyond Neptune (the Kuiper belt).

If they peered a bit closer, they'd spot the small, rocky spheres of the inner solar system: Mercury, Venus, Earth and Mars. They might see the dozens of worlds that circle the larger bodies or Ceres in the asteroid belt. And finally, if they searched near the Kuiper belt, they'd discern Pluto, tinier than Earth's moon but undeniably captivating, with water ice mountains and a heart-shaped plain.

Which of these would they consider a “planet” — or whatever the alien term for “planet” might be?

When the IAU voted in 2006, scientists came to the conclusion that gravitational dominance is what distinguishes the eight planets from the solar system’s other spheres. From giant Jupiter to tiny Mercury, each is massive enough to make them the bullies of their orbits, absorbing, ejecting or otherwise controlling the motion of every other object that gets too close. According to the definition, planets must also orbit the sun.

Pluto, which shares its zone of the solar system with a host of other objects, was reclassified as a “dwarf planet” — a body that resembles a planet but fails to “clear its neighborhood,” in the IAU's parlance.

“If you look at the solar system with fresh eyes, it is really hard to not realize that there are eight big things dominating the solar system and millions of tiny things flitting around,” said Caltech astronomer Mike Brown, whose discovery of the dwarf planet Eris, announced in 2005, precipitated the IAU vote a year later.

Brown was not at that vote, but he said that a definition based on orbital dynamics “is the most profound classification you can come up with.”

“That’s the one that asks the question we’re asking as planetary scientists,” he explained. “Why did the solar system form with these eight giant things and all these other things around them?”

But to Runyon, that distinction is less important than what dozens of solar system worlds have in common: geology.

“I’m interested in an object's intrinsic properties,” he said. “What it is on its surface and in its interior? Whether an object is in orbit around another planet or the sun doesn’t really matter for me.”

Runyon calls his a “geophysical” definition. A planet, he says, is anything massive enough that gravity pulls it into a sphere (a characteristic called “hydrostatic equilibrium"), but not so massive that it starts to undergo nuclear fusion and become a star.

“It’s only about one force and one property, the mass,” said Alan Stern, who led NASA's New Horizons mission to visit Pluto in 2015. Stern is a co-author on the paper outlining Runyon's new definition. “I think that's very elegant, as a physicist.”

Within that definition, Runyon and Stern say, scientists can divide planets into subcategories: moon planets like Europa and Titan; rocky planets like Earth and Mars; gas giant planets like Jupiter and Saturn; icy planets like Eris and Pluto.

But making “planet” more inclusive would formalize something many scientists already do: use the term when comparing geologic features. Runyon said he found dozens of examples in the scientific literature of researchers referring to “the planets Pluto, Earth and Mars” to talk about glacial processes on their surfaces, or “a planet-wide haze layer” when discussing the moon Titan's atmosphere.

“As planetary scientists we feel like the situation got really badly mangled back in 2006,” Stern said. “It was time somebody write this all down … and start a new conversation.”

A 16th century illustration of the universe, which lists the moon as a planet. (Bibliothèque Nationale, Paris via NASA)

Questions about the definition of “planet” go back much further than the debate over Pluto. The moon was considered a planet until the 17th century, when Copernicus placed it in orbit around the Earth. Galileo initially referred to the four largest moons of Jupiter as planets, but astronomers eventually adopted the term “satellite” (“attendant”) instead.

Ceres was considered a planet for several years after it was discovered circling between Mars and Jupiter in 1801. But when astronomers realized it was just the largest of thousands of objects inhabiting that stretch of sky, they renamed Ceres an “asteroid” and called its crowded home orbit “the asteroid belt.”

When Pluto was named the ninth planet in 1930, astronomers vastly overestimated its size, suggesting it could be even larger than Jupiter. It would also take more than 50 years for them to realize that Pluto had plenty of company in its far-flung orbit.

Jean-Luc Margot, a planetary scientist at the University of California at Los Angeles who voted in favor of the IAU resolution in 2006, said Pluto might have gone the way of Ceres if scientists had found other Kuiper belt objects sooner.

“An aspect of science is that we revisit our ideas,” he said. “We have to be able to acknowledge when we make a mistake.”

That moment came in 2006. When astronomers arrived at IAU meeting in Prague that year, they were surprised to hear that a group had been working in secret to devise a formal definition for planet — something that had never been done before.

“Planet,” the group proposed, was any object made round by its gravity that's in orbit around a star. Though many bodies in the solar system met this requirement, only Ceres and Eris would be made new planets; Pluto and its moon Charon would be called a binary planet system. The group also suggested a new classification, “pluton,” for bodies like Pluto whose orbits around the sun took 200 years or more.

The draft definition made almost no one happy. It was criticized as awkward and arbitrary, and the secrecy in which it was developed meant that researchers who wanted to improve the definition had little time to do so. Scientists spent the next two weeks of the conference rushing to come up with terminology they liked better.

Sara Seager, an exoplanet researcher at MIT who did not attend that year's meeting, recalled watching the chaos from afar.

“It actually was very confusing,” she said. “Everyone was asking me what was going on. … I'd be in a taxi and the taxi driver would say, 'I really want Pluto to be a planet. Will it still be a planet?' And I couldn't say.”

The vote happened on the meeting's last day. Despite the rushed circumstances, the resolution passed with a large enough majority that no one counted the votes. Pluto had lost.

Stern, who missed the 2006 meeting to help his daughter move into her college dorm, said it felt like astronomers who study black holes and stars had hijacked the most important concept in his field. He hadn't even known that a definition was being formulated — otherwise, he might have tried to attend the meeting. Now, suddenly, he was a planetary scientist whose object of study was no longer a planet.

He scoffed at Pluto's new classification, “dwarf planet” — “How can an adjective in front of a noun not describe the noun?” Stern asked. “There are dwarf stars but they're still considered stars.”

Our evolving view of Pluto (NASA)

Runyon, who was a 21-year-old college student at the time of the IAU vote, said that the result never sat well with him. In 2015, he was on the data analysis team for the New Horizons spacecraft as it flew past Pluto. That December, the stunning new images of that distant world fresh in his mind, he sat down and “in a fit of creative passion” drafted his definition.

The paper that Runyon will present this week isn't a formal proposal, like the one that was devised at the IAU. He's not putting his definition up to a vote, or even suggesting that it should replace the IAUs. If he did, it's unlikely that the IAU would adopt it.

But it's sure to spark debate. Porco, who is one of the lead scientists for NASA's Cassini mission to Saturn, pointed out that she is a planetary scientist and has no problem with the IAU's orbital dynamics-based definition.

She also noted that astronomers already have a perfectly serviceable term for the kind of body Stern and Runyon are trying to describe: “world.” In her view, the only scientists who want to make those places planets are people who study Pluto.

Nearly everyone agrees that the IAU definition is imperfect. Margot, the UCLA planetary scientist who voted for the resolution, has tried to refine it. But the debate over Pluto was so “traumatic” for the community, he said, that he doubts that the IAU would be willing to revisit the issue anytime soon.

If you talk to enough scientists on either side of this debate, you'll notice that their arguments start to echo each other. They use the same terms to criticize the definitions they don't like: “not useful,” “too emotional,” “confusing.” Both groups want the same thing: for the public to understand and embrace the science of the solar system. But each is convinced that only their definition can achieve that goal. And each accuses the other of confusing people by prolonging the debate.

But Seager, the exoplanet researcher, said the opposite might be true. In her experience, the debate over Pluto's status has given her more opportunities to talk about the solar system than ever before.

“What I love about it is it’s a teaching moment,” she said. “If someone asks about Pluto … you use that as an opening to say, look whatever you want to call it, here’s what’s going on in our system today.”

Seager has no dog in this fight. Her gaze extends far beyond the Kuiper belt, to worlds that orbit stars light-years from our own. In the years since the IAU resolution, scientists have found thousands more planets outside our solar system. Many are like nothing astronomers have ever seen before — giant “hot Jupiters” that orbit tightly around their stars; “rogue planets” that rocket through the galaxy independent of any sun. For scientists like Seager, the age of planet discovery is just beginning.

“What else is out there? What’s beyond Pluto?” she asked. “There’s so much we still don’t know.

[ilan]

I'd like to see Pluto back on the team, although I wouldn't be excited to see the other 101 added to the roster.

[ilan]

Astronomers spot a runaway quasar
Alison Klesman, Astronomy Magazine | Friday, March 24, 2017

This rogue black hole may have been ousted from the center of its galaxy by gravitational waves.

The quasar 3C 186 is clearly offset from the center of its host galaxy, encircled by the dashed line. 3C 186 is the bright star-like object to the lower right of the dimmer, blob-like galaxy. NASA, ESA, and M. Chiaberge (STScI and JHU)

Supermassive black holes reside at the centers of most galaxies — or do they? A new detection by the Hubble Space Telescope (HST) points to an active supermassive black hole in the process of fleeing its galaxy. The astronomers who spotted it say the data present a strong case for a gravitational wave event that knocked the black hole for a loop and sent it rocketing away in one direction.

While this isn’t the first such suspected “rogue black hole,” it’s currently the most compelling evidence for one. Astronomers have now assembled data from not only HST, but the Chandra X-ray Observatory and the Sloan Digital Sky Survey as well. “The amount of data we collected, from X-rays to ultraviolet to near-infrared light, is definitely larger than for any of the other candidate rogue black holes,” said Marco Chiaberge of the Space Telescope Science Institute (STScI) and Johns Hopkins University in a press release. Chiaberge is the lead author of a paper detailing the observations, which will be published in Astronomy & Astrophysics on March 30.

A quasar is really the disk of dust, gas, and other matter that surrounds a supermassive black hole. As this material clumps and rubs together on its way into the black hole itself, it heats up and shines brightly, allowing astronomers to spot it. (This is because the material is located outside the black hole’s event horizon, inside of which even light cannot escape.) This quasar, named 3C 186, is associated with a distant galaxy that sits about 8 billion light-years away.

[Kimbo]

Black holes are awesome!!!

[ilan]

Indeed!! Unfathomable power from these critters -- and we can't even see 'em. What a phenomenon!