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

[ilan]

Black Hole Facts
Space-facts . com

Black holes are among the strangest things in the universe. They are massive objects – collections of mass – with gravity so strong that nothing can escape, not even light. The most common types of black holes are the stellar-mass and supermassive black holes. Stellar-mass black holes are created when massive stars explode, leaving behind a black hole with the mass of just a few suns. Supermassive black holes exist in the hearts of galaxies and usually contain the mass equivalent of millions of suns.

Famous Black Holes

Cygnus X-1: a stellar-mass black hole and x-ray source that lies some 6,500 light-years away. It is a binary system that contains a blue supergiant variable star and the x-ray source thought to be the black hole.

Sagittarius A*: the supermassive black hole at the heart of the Milky Way Galaxy. It lies in the direction of the constellation Sagittarius. This black hole contains the mass of about 4 million suns.

M87: this elliptical galaxy has a 3.5 billion solar-mass black hole at its heart. The black hole is surrounded by a disk of superheated material and has a jet of superheated material streaming away from the black hole that extends across 5,000 light-years from the galaxy’s core.

Centaurus A: this galaxy, which lies in the direction of the constellation Centaurus, is a giant spiral galaxy with an incredibly active nucleus. It contains a 55 million solar-mass black hole at its heart, with two jets of material that stream away from the galaxy at about half the speed of light across a million light-years of space.

Facts About Black Holes

• The massive gravitational influence of a black hole distorts space and time in the near neighbourhood. The closer you get to a black hole, the slower time runs. Material that gets too close to a black hole gets sucked in and can never escape.
• Material spirals in to a black hole through an accretion disk — a disk of gas, dust, stars and planets that fall into orbit the black hole.
• The “point of no return” around a black hole is called the “event horizon”. This is the region where the gravity of the black hole overcomes the momentum of material spinning around it in the accretion disk. Once something crosses the event horizon, it is lost to the pull of the black hole.
• Black holes were first proposed to exist in the 18th century, but remained a mathematical curiosity until the first candidate black hole was found in 1964. It was called Cygnus X-1, an x-ray source in the constellation Cygnus.
• Black holes do not emit radiation on their own. They are detected by the radiation given off as material is heated in the accretion disk, and also by the black hole’s gravitational effect on other nearby objects (or light passing by).

[ilan]

Astronomers hoping to directly capture image of a black hole
Phys.org | April 3, 2017

Gravitational monster: This artistic impression shows the event horizon around the black hole at the centre of our galaxy. Credit: M. Moscibrodzka, T. Bronzwaar and H. Falcke, Radboud University

Astronomers want to record an image of the heart of our galaxy for the first time: a global collaboration of radio dishes is to take a detailed look at the black hole which is assumed to be located there. This Event Horizon Telescope links observatories all over the world to form a huge telescope, from Europe via Chile and Hawaii right down to the South Pole. IRAM's 30-metre telescope, an installation co-financed by the Max Planck Society, is the only station in Europe to be participating in the observation campaign. The Max Planck Institute for Radio Astronomy is also involved with the measurements, which are to run from 4 to 14 April initially.

At the end of the 18th century, the naturalists John Mitchell and Pierre Simon de Laplace were already speculating about "dark stars" whose gravity is so strong that light cannot escape from them. The ideas of the two researchers still lay within the bounds of Newtonian gravitational theory and the corpuscular theory of light. At the beginning of the 20th century, Albert Einstein revolutionized our understanding of gravitation - and thus of matter, space and time - with his General Theory of Relativity. And Einstein also described the concept of black holes.

These objects have such a large, extremely compacted mass that even light cannot escape from them. They therefore remain black – and it is impossible to observe them directly. Researchers have nevertheless proven the existence of these gravitational traps indirectly: by measuring gravitational waves from colliding black holes or by detecting the strong gravitational force they exert on their cosmic neighbourhood, for example. This force is the reason why stars moving at great speed orbit an invisible gravitational centre, as happens at the heart of our galaxy, for example.

It is also possible to observe a black hole directly, however. Scientists call the boundary around this exotic object, beyond which light and matter are inescapably sucked in, the event horizon. At the very moment when the matter passes this boundary, the theory states it emits intense radiation, a kind of "death cry" and thus a last record of its existence. This radiation can be registered as radio waves in the millimetre range, among others. Consequently, it should be possible to image the event horizon of a black hole.

The Event Horizon Telescope (EHT) is aiming to do precisely this. One main goal of the project is the black hole at the centre of our Milky Way, which is around 26,000 light years away from Earth and has a mass roughly equivalent to 4.5 million solar masses. Since it is so far away, the object appears at an extremely small angle.

One solution to this problem is offered by interferometry. The principle behind this technique is as follows: instead of using one huge telescope, several observatories are combined together as if they were small components of a single gigantic antenna. In this way scientists can simulate a telescope which corresponds to the circumference of our Earth. They want to do this because the larger the telescope, the finer the details which can be observed; the so-called angular resolution increases.

[ilan]

Merging galaxies behaving strangely
Deborah Byrd, Space | April 1, 2017

When large and small galaxies merge, the large galaxy’s central black hole typically gorges on gas and dust. But in a merging galaxy system called Was 49, the small galaxy has the feeding black hole.

This optical image shows the Was 49 system, which consists of a large galaxy merging with a much smaller galaxy. The dwarf galaxy rotates within the larger galaxy’s disk, about 26,000 light-years from its center. The pink-colored region indicates a feeding supermassive black hole; the green color indicates normal starlight. Image via NASA/ DCT/ NRL.

One of the fascinating discoveries of modern astronomy has been that galaxies – entire islands of stars – sometimes merge with other galaxies. Another discovery has been that many galaxies like our Milky Way are known to contain supermassive black holes at their cores. Now a supermassive black hole inside one tiny galaxy is challenging what scientists have come to believe about galaxy mergers. The merging system is known as Was 49, and it consists of a large disk galaxy (Was 49a), merging with a much smaller dwarf galaxy (Was 49b).

Both of these galaxies have central supermassive black holes. Astronomers would have expected that, as the big and little galaxies merge, their gravitational interactions would create a twisting force – a torque – that would funnel gas into the larger galaxy’s black hole. As the black hole of the larger galaxy gobbled up gas and dust, they would have expected to see it spewing out high-energy X-rays (as matter is converted to energy).

But that’s not what they see in this system.

Instead, the smaller galaxy’s central black hole is the more active one, while the larger galaxy’s black hole is relatively quiet. Nathan Secrest, lead author of the study and postdoctoral fellow at the U.S. Naval Research Laboratory in Washington, said in a statement:

This is a completely unique system and runs contrary to what we understand of galaxy mergers.

Also, the black hole of the smaller galaxy is mysterious in and of itself. Its mass – the amount of matter it contains in its hidden interior – is huge, compared to similarly sized galaxies. Data on the smaller galaxy’s x-ray emissions came from NASA’s Nuclear Spectroscopic Telescope Array (NuSTAR) mission. Data from NuSTAR and the Sloan Digital Sky Survey suggest the black hole contains more than 2 percent of the galaxy’s own mass. Secrest said:

We didn’t think that dwarf galaxies hosted supermassive black holes this big. This black hole could be hundreds of times more massive than what we would expect for a galaxy of this size, depending on how the galaxy evolved in relation to other galaxies.

Scientists are trying to figure out why the supermassive black hole of dwarf galaxy Was 49b is so big. It may have already been large before the merger began, or it may have grown during the very early phase of the merger, they said. Secrest commented:

This study is important because it may give new insight into how supermassive black holes form and grow in such systems. By examining systems like this, we may find clues as to how our own galaxy’s supermassive black hole formed.

These astronomers also said that, in several hundred million years, the black holes of the large and small galaxies will merge into one.

Bottom line: When a large and small galaxy merge, astronomers expect the supermassive black hole at the center of the larger galaxy to be the one to feed on gas and dust and shine in high-energy x-rays. But in the merging galaxy system known as Was 49, the smaller galaxy – confoundingly – contains the feeding black hole.

[ilan]

New Hubble image of Jupiter
Deborah Byrd, Today's Image | April 7, 2017

Jupiter is the largest planet in our solar system – some 88,789 miles (142,984 km) at its equator. We pass between Jupiter and the sun this week, and Hubble Space Telescope looked its way.

When the Hubble Space Telescope aimed toward Jupiter on April 3, Jupiter was 4.45 Astronomical Units from Earth (415 million miles or 668 million km). Image via NASA/ ESA/ A. Simon (GSFC).

Earth goes between the sun and Jupiter this week, on April 7, 2017. And Jupiter is closer to Earth for this year on April 8. So it was an opportune time, a few days ago, for the Hubble Space Telescope to aim toward Jupiter and capture this beautiful new image. NASA said:

Hubble reveals the intricate, detailed beauty of Jupiter’s clouds as arranged into bands of different latitudes, known as tropical regions. These bands are produced by air flowing in different directions at various latitudes. Lighter colored areas, called zones, are high-pressure where the atmosphere rises. Darker low-pressure regions where air falls are called belts. The planet’s trademark, the Great Red Spot, is a long-lived storm roughly the diameter of Earth. Much smaller storms appear as white or brown-colored ovals. Such storms can last as little as a few hours or stretch on for centuries.

It’s easy to see Jupiter now! The planet is the brightest “star” in the evening sky, brightest thing up all night (with the exception of the moon) until Venus rises shortly before dawn. You can’t miss Jupiter. But in case you feel uncertain, you can also follow the arc in the Big Dipper’s handle and speed on to Spica, the bright star near Jupiter now on the sky’s dome.

In any year, you can extend the arc of the Big Dipper handle to bright stars Arcturus and Spica. But this year, 2017, is special because the dazzling planet Jupiter beams close to Spica all year long.

[ilan]

Big asteroid to whiz (safely) by Earth this month
Faith Karimi and Amanda Barnett, CNN | Updated 12:11 PM ET, Sat April 8, 2017


NASA scientists used Earth-based radar to produce these sharp views of the asteroid designated "2014 HQ124" on June 8, 2014. NASA called the images "most detailed radar images of a near-Earth asteroid ever obtained."

(CNN) A large asteroid is hurtling toward Earth -- but there's no need to duck and cover.

The space rock, known by the very dull name of 2014 JO25 will safely fly by Earth on April 19, according to NASA. The chances of it pounding our planet and leaving us for the dead? Zero, experts say.

"Although there is no possibility for the asteroid to collide with our planet, this will be a very close approach for an asteroid of this size," NASA said in a statement.

What size are we talking about? Measurements taken by NASA's NEOWISE space probe indicate the asteroid is about 2,000 feet (650 meters) in size. That's about 670 yards (613 meters), or about the length of six NFL football fields.

And how close is "very close"? NASA says this rock will come about 1.1 million miles (1.8 million kilometers) from Earth. That's about 4.6 times the distance from Earth to the moon. The moon, by the way, is about 239,000 miles (384,400 kilometers) from Earth.

While several small asteroids pass within this distance of Earth a few times a week, this is the closest by any known asteroid of this size or bigger in 13 years -- since asteroid Toutatis in 2004, according to the space agency.

Can you see asteroid 2014 JO25? Well, maybe. This asteroid has a reflective surface and you might be able to see it with a telescope.

"The asteroid will approach Earth from the direction of the sun and will become visible in the night sky after April 19," NASA said.

If you don't have your own telescope, you can watch the asteroid online.

Astronomers discovered 2014 J025 three years ago (you guessed it in 2014). This will be its closest encounter with Earth for the last 400 years. NASA said telescopes around the world will be trained on it during the flyby to try to learn more about it.

"Radar observations are planned at NASA's Goldstone Solar System Radar in California and the National Science Foundation's Arecibo Observatory in Puerto Rico, and the resulting radar images could reveal surface details as small as a few meters," NASA said.

If you head out to try to spot the asteroid, you might also want to check out comet PanSTARRS (C/2015 ER61). It also is making its closest approach to Earth -- coming about 109 million miles (175 million kilometers) from the planet. NASA said it's visible in the dawn sky with binoculars or a small telescope.

[ilan]

First 'image' of a dark matter web that connects galaxies
Royal Astronomical Society (RAS) | April 12, 2017

Researchers have been able to capture the first composite image of a dark matter bridge that connects galaxies together.

Dark matter filaments bridge the space between galaxies in this false colour map. The locations of bright galaxies are shown by the white regions and the presence of a dark matter filament bridging the galaxies is shown in red. Credit: S. Epps & M. Hudson / University of Waterloo

Researchers at the University of Waterloo have been able to capture the first composite image of a dark matter bridge that connects galaxies together. The scientists publish their work in a new paper in Monthly Notices of the Royal Astronomical Society.

The composite image, which combines a number of individual images, confirms predictions that galaxies across the universe are tied together through a cosmic web connected by dark matter that has until now remained unobservable.

Dark matter, a mysterious substance that comprises around 25 per cent of the universe, doesn't shine, absorb or reflect light, which has traditionally made it largely undetectable, except through gravity.

"For decades, researchers have been predicting the existence of dark-matter filaments between galaxies that act like a web-like superstructure connecting galaxies together," said Mike Hudson, a professor of astronomy at the University of Waterloo. "This image moves us beyond predictions to something we can see and measure."

As part of their research, Hudson and co-author Seth Epps, a master's student at the University of Waterloo at the time, used a technique called weak gravitational lensing, an effect that causes the images of distant galaxies to warp slightly under the influence of an unseen mass such as a planet, a black hole, or in this case, dark matter. The effect was measured in images from a multi-year sky survey at the Canada-France-Hawaii Telescope.

They combined lensing images from more than 23,000 galaxy pairs located 4.5 billion light-years away to create a composite image or map that shows the presence of dark matter between the two galaxies. Results show the dark matter filament bridge is strongest between systems less than 40 million light years apart.

"By using this technique, we're not only able to see that these dark matter filaments in the universe exist, we're able to see the extent to which these filaments connect galaxies together," said Epps.

[ilan]

First 'image' of a dark matter web that connects galaxies
Royal Astronomical Society (RAS) | April 12, 2017

Researchers have been able to capture the first composite image of a dark matter bridge that connects galaxies together.

Dark matter filaments bridge the space between galaxies in this false colour map. The locations of bright galaxies are shown by the white regions and the presence of a dark matter filament bridging the galaxies is shown in red. Credit: S. Epps & M. Hudson / University of Waterloo

Researchers at the University of Waterloo have been able to capture the first composite image of a dark matter bridge that connects galaxies together. The scientists publish their work in a new paper in Monthly Notices of the Royal Astronomical Society.

The composite image, which combines a number of individual images, confirms predictions that galaxies across the universe are tied together through a cosmic web connected by dark matter that has until now remained unobservable.

Dark matter, a mysterious substance that comprises around 25 per cent of the universe, doesn't shine, absorb or reflect light, which has traditionally made it largely undetectable, except through gravity.

"For decades, researchers have been predicting the existence of dark-matter filaments between galaxies that act like a web-like superstructure connecting galaxies together," said Mike Hudson, a professor of astronomy at the University of Waterloo. "This image moves us beyond predictions to something we can see and measure."

As part of their research, Hudson and co-author Seth Epps, a master's student at the University of Waterloo at the time, used a technique called weak gravitational lensing, an effect that causes the images of distant galaxies to warp slightly under the influence of an unseen mass such as a planet, a black hole, or in this case, dark matter. The effect was measured in images from a multi-year sky survey at the Canada-France-Hawaii Telescope.

They combined lensing images from more than 23,000 galaxy pairs located 4.5 billion light-years away to create a composite image or map that shows the presence of dark matter between the two galaxies. Results show the dark matter filament bridge is strongest between systems less than 40 million light years apart.

"By using this technique, we're not only able to see that these dark matter filaments in the universe exist, we're able to see the extent to which these filaments connect galaxies together," said Epps.

[ilan]

Can you imagine the sky in five million years?
Alison Klesman, Astronomy Magazine | Thursday, April 13, 2017

Now you don’t have to — Gaia has the answer.


In five million years, the sky will look a little different. The constellations will be unrecognizable,
and many of the stars we can see today will have moved significantly.

Have you ever wondered what it would be like to stare up at the sky millions of years from today? Would things look exactly the same, or would the sky be totally unrecognizable? Wonder no longer — the European Space Agency (ESA) has just released a video (see below) answering that exact question.

Since July 2014, ESA’s Gaia mission has been charting the positions of stars in the Milky Way with higher accuracy than ever before. Its goal is to create a three-dimensional map of our galaxy, which is uniquely challenging because we’re trying to make a map from inside the galaxy, rather than being able to take a step back and view it from outside.

With such precise stellar positions, however, comes something else: stellar motions. The stars seem perpetually fixed in the sky — sure, they rise and set, and change throughout the year as we go around the Sun, but they always form the same patterns. A significant percentage of the constellations most of us know are those derived, after all, by the Greeks just a little under 2,000 years ago. So, of course, it’s natural to assume that the stars just don’t move, because they’ve looked pretty much the same for thousands of years.

But thousands of years is but an eyeblink in the lifetime of a galaxy, and the notion that the stars don’t change positions is false. The stars do move, largely in bulk as they rotate around the center of the Milky Way, but sometimes they zip off in random directions dictated by the conditions of their formation or past interactions. This latter effect is exacerbated by perspective — the closer a star is to us, the more it will appear to move. This perspective effect is also essentially how Gaia measures stellar positions so accurately, using a technique called parallax that causes nearby stars to shift against the background as Earth orbits the Sun.

But largely, from our perspective, the stars are just so far away that even though they’re moving at hundreds of kilometers per second, they seem pretty fixed to the casual observer. Now, though, ESA has released a video containing 2,057,050 stars that have been measured well enough to predict where they are and where they’re going in the future. The overall motion of a star from our point of view against the background of extremely far away stars is called proper motion, and that’s the basis for the stellar motions in this video. Using the projected proper motions of the stars in the Gaia catalog, the result is a fast-forwarded trip through time that ends with the sky as it would appear from Earth in 5 million years. Each frame in the video represents the passage of 750 years.

Watch Video:

https://www.youtube.com/watch?v=Ag0qsSFJBAk

To really see the changes, click early in the video (and pause) then click toward the end of the video (and pause). You will note a vast difference. - Ilan

[ilan]

Photos of close asteroid 2014 JO25
Deborah Byrd in Space | Today's Image | April 20, 2017

Large asteroid 2014 JO25 safely passed Earth on April 19, 2017 at some 1,098,733 miles (1,768,239 km) or about 4.6 times the distance from Earth to the moon. Images from the EarthSky community here.

Video:

https://www.youtube.com/watch?v=kUseAMZPsM4

In the video, the asteroid emerges at about :08 at the bottom center and makes it way toward the center right. - Ilan

[ilan]

Record-Breaking 'Gigapixel' View of a Tiny Galaxy Reveals Secret Lives of Stars
Ian O'Neill, Space.com Contributor | May 3, 2017 10:30am ET

A telescope in Chile captured this incredible view of a nearby dwarf galaxy, which reveals millions of previously hidden stars that you can explore without stepping away from your computer.

As a part of the VISTA survey of the Magellanic Clouds (VMC) project, an international team of astronomers, led by Stefano Rubele of the University of Padova in Italy, has released this jaw-dropping "gigapixel," zoomable image of the SMC here (Link Below).

"The result is this record-breaking image — the biggest infrared image ever taken of the Small Magellanic Cloud — with the whole frame filled with millions of stars," researchers explained in a statement.

See zoomable image here:

https://www.eso.org/public/images/eso1714a/zoomable/