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Weekly space gallery for January 28, 2014

WELCOME TO OUR WEEKLY COLLECTION of the best astronomy and space exploration images taken by observatories around the world and in space. Each week we’ll bring you a selection of our favourite recent images – if you like them (and we hope you do), please share them with your friends. And don’t forget you can elect to have this and other stories emailed direct to your inbox, just by signing up to our free email service – see the Subscribe box in the column at right.

So, let’s get started on this week’s images.

1. Disruptive black hole

A black hole lives at the heart of the white galaxy in the middle of this image. Extensive clouds of hot gas, detected by NASA’s Chandra X-ray Observatory satellite and coloured purple, should be the raw material from which countless new stars would be born. But jets of energy emanating from the vicinity of the black hole have disrupted the gas, forming two cavities on either side of the centre and sending out shock waves that prevent the gas from clumping and forming stars. The galaxy in question is called RX J1532+3201, and it is 3.9 billion light years from Earth. Image credit: X-ray: NASA / CXC / Stanford / J.Hlavacek-Larrondo et al, Optical: NASA / ESA / STScI / M.Postman & CLASH team.

Gas surrounding galaxy RX J1532+3201

Hot gas surrounds galaxy RX J1532+3201.

 

2. Titan, top and bottom

This black and white image of Titan, Saturn’s largest moon, was taken through a special infrared filter to bring out detail in its atmosphere. Visible at the far north (top) is a haze that stands up above the bulk of atmosphere, while near the south pole is the South Polar Vortex – thought to be an uplifted mass of air caused by a change in the seasons. This image was taken by NASA’s Cassini spacecraft from a distance of 2.5 million kilometres. Cassini has been orbiting Saturn since 2004. Courtesy NASA / JPL-Caltech / Space Science Institute.

Titan

Haze is visible in Titan’s north, while a polar vortex is in the south.

 

3. Brown dwarf revealed

Astronomers have used special techniques to block out the light of a star (leaving a speckled appearance) to reveal a dim brown dwarf that is in orbit around it. Brown dwarfs are bodies at are two big to be planets, but two small to be proper stars. They give off a relatively small amount of heat. The astronomers are particularly interested in studying the brown dwarf’s atmosphere, by analysing the light that reflects from it. “This object is old and cold and will ultimately garner much attention as one of the most well-studied and scrutinised brown dwarfs detected to date,” says Justin R. Crepp of the University of Notre Dame. “With continued follow-up observations, we can use it as a laboratory to test theoretical atmospheric models. Eventually we want to directly image and acquire the spectrum of Earth-like planets. Then, from the spectrum, we should be able to tell what the planet is made out of, what its mass is, radius, age, etc., basically all relevant physical properties.” Courtesy Crepp et al. 2014, ApJ.

Brown dwarf image

By blocking most of the light of its parent star, a faint brown dwarf is revealed.

 

4. A gallery of galaxies

The Hubble Space Telescope was used to make this long-exposure image of the galaxy cluster Abell 2744, which comprises the bright galaxies in the foreground. Fainter background galaxies appear to have become distorted as their light is bent by Abell 2744’s gravity. Astronomers have counted up to 3,000 of these background galaxies in the full-size version of this image alone. Courtesy NASA / ESA.

Galaxy cluster Abell 2744

A long Hubble exposure of galaxy cluster Abell 2744 also reveals other galaxies in the far background.

 

5. We have lift-off

NASA’s newest Tracking and Data Relay System Satellite (TDRSS) was launched on January 23 from the Kennedy Space Centre in Florida. There are several TDRSS satellites circling Earth, through which NASA can communicate with spacecraft in Earth orbit. They are not directly involved in communicating with deep space missions. Courtesy NASA / Tony Grey.

Time exposure of TDRSS launch

Lift off of NASA’s latest TDRSS satellite.

 

6. A supernova surprise

A supernova was spotted in galaxy M82 on January 21, causing great excitement amongst astronomers. M82 is only 12 million light years from Earth, making the supernova (called SN 2014J) one of the closest in many years. Many observatories broke into their normal scheduled operations to make observations of the supernova, including NASA’s Swift orbiting observatory. This picture, sensitive to ultraviolet light, shows the supernova standing out brightly against the amorphous background of the rest of M82. Courtesy NASA / Swift / P. Brown, TAMU.

Swift image of galaxy M82 and its supernova

A Swift image of galaxy M82 and its supernova.

Story by Jonathan Nally.

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Brown dwarfs – Sun has two new neighbours

Artist's impression of a brown dwarf

Artist's impression of a brown dwarf. Two new brown dwarfs have been discovered only 15 and 18 light-years from the Sun, making them very close neighbours.

THE SUN HAS TWO NEW NEIGHBOURS in the form of brown dwarf stars estimated to be only 15 and 18 light-years from the Solar System.

This puts them very close indeed. The closest known star to the Sun is Proxima Centauri, slightly more than 4 light-years away. The closest known brown dwarfs (known as Epsilon Indi Ba and Bb) are about 12 light-years away.

Brown dwarfs are halfway between big planets are fully-fledged stars. They’re often called ‘failed stars’, since during their formation they could not accumulate enough mass to ignite the natural nuclear fusion reactor in their core that is the long-living energy source of stars.

Ralf-Dieter Scholz and colleagues at the Leibniz Institute for Astrophysics Potsdam (AIP) used recently published data from the NASA satellite WISE (Wide-field Infrared Survey Explorer) for their discovery.

WISE images of brown dwarfs WISE J0254+0223 and WISE J1741+2553

False-colour images of brown dwarfs WISE J0254+0223 and WISE J1741+2553 (which show up as green at infrared wavelengths). Symbols show how the dwarfs have moved over the past 10 years.

On the move

The two new neighbours—named WISE J0254+0223 and WISE J1741+2553— attracted attention by the extreme contrast between their strong brightness at infrared wavelengths and their almost invisible appearance at optical wavelengths.

In addition, both objects have been measured to move at relatively high speed across the sky, and their current positions are noticeably different compared with earlier observations.

High speed is usually a good indication that objects are close to the observer.

Large Binocular Telescope

The Large Binocular Telescope (LBT) helped identify the brown dwarfs.

The AIP team used the Large Binocular Telescope (LBT) in Arizona, USA, to more accurately determine the spectral type and distance of the brighter of the two dwarfs.

Both objects belong to the coolest class of brown dwarfs, the T-type, which are just on the borderline of the predicted but not yet well-defined class of Y-type ultracool brown dwarfs.

No hotter than an oven

It is presumed that most brown dwarfs have cooled to around the temperature of an oven, about 230 degrees Celsius … and maybe even as cool as the temperature at the surface of the Earth.

The search for these elusive neighbours of the Sun is currently in full swing.

Scientists say it is possible that we are surrounded by ultracool brown dwarfs in similar high numbers as normal stars, and that our nearest known neighbour will soon be a brown dwarf rather than Proxima Centauri.

Adapted from information issued by the Leibniz Institute for Astrophysics Potsdam. Images: brown dwarf illustration, ESO/L. Calçada; LBT, AIP, LBT Observatory; WISE images, AIP, NASA/IPAC Infrared Science Archive.

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Really cool stars

Artist’s impression of CFBDSIR 1458+10

Artist’s impression of the pair of brown dwarfs named CFBDSIR 1458+10. Observations suggest this is the coolest pair of brown dwarfs found so far. The colder of the two (background) could have a temperature similar to that of a cup of freshly made tea.

  • Brown dwarfs are halfway between big planets and small stars
  • They don’t shine, but give off only a small amount of heat
  • Newly found brown dwarf seems to be the coldest yet discovered

ASTRONOMERS HAVE FOUND a new candidate for the coldest known star—a ‘brown dwarf’ in a binary star system that has about the same temperature as a freshly made cup of tea.

That’s hot in human terms, but extraordinarily cold for the surface of a star.

This object is cool enough to begin crossing the blurred line dividing small, cold stars from big, hot planets.

Brown dwarfs are essentially failed stars—they don’t have enough mass for gravity to trigger the nuclear reactions that make stars shine.

The newly discovered brown dwarf, identified as CFBDSIR 1458+10B, is the dimmer member of a binary brown dwarf system located just 75 light-years from Earth.

The powerful X-shooter spectrograph on the European Southern Observatory’s (ESO) Very Large Telescope (VLT) was used to show that the object was very cool by brown dwarf standards.

“We were very excited to see that this object had such a low temperature, but we couldn’t have guessed that it would turn out to be a double system and have an even more interesting, even colder [star],” said Philippe Delorme of the Institut de planétologie et d’astrophysique de Grenoble (CNRS/Université Joseph Fourier), a co-author of the paper.

Keeping its cool

CFBDSIR 1458+10 is the name of the binary system. The individual stars are known as CFBDSIR 1458+10A and CFBDSIR 1458+10B, with the latter the fainter and cooler of the two. They seem to be orbiting each other at a separation of about three times the distance between the Earth and the Sun with a period of about thirty years.

Brown dwarf binary CFBDSIR 1458+10

Actual image of the brown dwarf binary CFBDSIR 1458+10, obtained using the Laser Guide Star (LGS) Adaptive Optics system on the Keck II Telescope in Hawaii. Adaptive optics cancels out much of Earth’s atmospheric interference, improving the image sharpness by a factor of 10.

The dimmer of the two dwarfs has now been found to have a temperature of about 100 degrees Celsius — the boiling point of water, and not much different from the temperature inside a sauna.

By comparison the temperature of the surface of the Sun is about 5,500 degrees Celsius.

“At such temperatures we expect the brown dwarf to have properties that are different from previously known brown dwarfs and much closer to those of giant exoplanets—it could even have water clouds in its atmosphere,” said Michael Liu of the University of Hawaii’s Institute for Astronomy, who is lead author of the paper describing this new work.

“In fact, once we start taking images of gas-giant planets around Sun-like stars in the near future, I expect that many of them will look like CFBDSIR 1458+10B.”

Three telescopes needed

Unravelling the secrets of this unique object involved exploiting the power of three different telescopes. CFBDSIR 1458+10 was first found to be a binary using the Laser Guide Star (LGS) Adaptive Optics system on the Keck II Telescope in Hawaii.

Liu and his colleagues then employed the Canada–France–Hawaii Telescope, also in Hawaii, to determine the distance to the brown dwarf duo using an infrared camera. Finally the ESO VLT was used to study the object’s infrared spectrum and measure its temperature.

The hunt for cool objects is a very active astronomical hot topic. The Spitzer Space Telescope has recently identified two other very faint objects as other possible contenders for the coolest known brown dwarfs, although their temperatures have not been measured so precisely.

Future observations will better determine how these objects compare to CFBDSIR 1458+10B.

Liu and his colleagues are planning to observe CFBDSIR 1458+10B again to better determine its properties and to begin mapping the binary’s orbit, which, after about a decade of monitoring, should allow astronomers to determine the binary’s mass.

Adapted from information issued by ESO / Michael Liu (University of Hawaii) / L. Calçada.

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“Failed star” orbits Sun look-alike

PZ Tel A and PZ Tel B

The Sun-like star, PZ Tel A and its brown dwarf companion, PZ Tel B. The majority of light from PZ Tel A has been blocked using specialised image analysis techniques. For distance comparison, the size of Neptune's orbit is shown.

  • Brown dwarf, a “failed star”, spotted
  • 36 times the mass of Jupiter
  • Orbits a younger version of our Sun

Astronomers have made a direct image of brown dwarf in a close orbit around a young, Sun-like star. Brown dwarfs are a class of astronomical bodies that are bigger than planets but smaller than genuine stars. They’re often called “failed stars”.

The team was led by Beth Biller and Michael Liu from the University of Hawaii (UA). They used the huge 8-metre Gemini South telescope in Chile, which is operated by a consortium of countries, including Australia.

Dubbed PZ Tel B, the brown dwarf was spotted at a distance of only 18 astronomical units (AU) from its parent star, known as PZ Tel A.

An astronomical unit is a standard measurement used by astronomers, being the average distance between the Sun and the Earth. At 18 AU, PZ Tel B is at the equivalent of the orbit of Uranus in our Solar System.

The brown dwarf is not visible in an image made back in 2003, suggesting it was at that time closer to and lost in the glare of its parent star.

“Because PZ Tel A is a rare star being both close and very young, it had been imaged several times in the past” said Laird Close, a professor at UA’s Steward Observatory. “So we were quite surprised to see a new companion around what was thought to be a single star.”

The new observations confirm that the brown dwarf is currently moving outward from the main star. They also show that it is 36 times the mass of Jupiter, the largest planet in our Solar System.

“PZ Tel B travels on a particularly eccentric orbit—in the last 10 years, we have literally watched it careen through its inner solar system,” said Beth Biller, lead author of the scientific paper. “This can best be explained by a highly eccentric, or oval-shaped, orbit.”

Brown dwarf size compared to Jupiter, the Sun and the Earth

The size of a brown dwarf compared to Jupiter, the Sun and the Earth (to scale). Brown dwarfs are more massive than planets and less massive than stars, but have similar diameters to planets such as Jupiter.

A young version of our Sun

The host star, PZ Tel A, is similar to our Sun, but at 12 million years of age is about 400 times younger. Astronomers are keen to study it and other such stars to learn more about the formation and evolution of Sun-like stars.

PZ Tel A is expected to retain a surrounding cloud of gas and dust from which planets might form. The gravitational pull of the brown dwarf could upset the formation of any such planets.

The find was made using the Near-Infrared Coronagraphic Imager (NICI) instrument, which blocks out much of the glare of a star and enables nearby regions to be seen.

The brown dwarf is so close to its parent star that it required all the power of NICI, plus adaptive optics—which help to remove the blurring effect of the Earth’s atmosphere—plus special image enhancing techniques, to pick it out of the glare.

NICI is so powerful that it can detect objects 1 million times fainter than their host stars at very close distances.

An international team is using NICI to conduct a 300-star survey, and it will be fascinating to see what they find.

“We are just beginning to glean the many configurations of solar systems around stars like the Sun,” said NICI Campaign leader Michael Liu. “The unique capabilities of NICI provide us with a powerful tool for studying their constituents using direct imaging.”

Also involved in the PZ Tel B research were graduate students Eric Nielsen, Jared Males and Andy Skemer.

Story by Jonathan Nally, Editor, SpaceInfo.com.au

Images by Jon Lomberg / Gemini Observatory / Beth Biller / Gemini NICI Planet-Finding Campaign.

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Mystery planet grew up quickly

Artist's concept of a binary system comprising a brown dwarf  and a 5- to 10-Jupiter-mass companion

Artist's concept of a binary system comprising a 20-Jupiter-mass brown dwarf (left) surrounded by cloud of gas and dust, and a 5- to 10-Jupiter-mass companion (right). The companion probably did not form our of the brown dwarf's cloud, but from the same larger, original cloud from which the brown dwarf itself formed.

  • Planet orbiting a brown dwarf
  • 5-10 times the mass of Jupiter
  • Probably formed in an unusual way

How big does a celestial body have to be before it is called a star? Conversely, how small does one have to be before it is considered a planet? And is there any size in between?

The answer to the in between question, is yes. They’re called brown dwarfs — objects that are typically tens of times the mass of Jupiter, but too small to sustain nuclear fusion to shine as stars do. They’re often called “failed stars”.

But even so, as telescopes grow more powerful, astronomers are finding other in-between objects that defy conventional wisdom.

The latest example is the discovery of a planet-like object circling a brown dwarf. It’s the right size for a planet — estimated to be 5-10 times the mass of Jupiter — but seems to have formed in less than 1 million years, much faster than the time it takes to build planets according to some models.

The mystery object orbits the brown dwarf at a distance of approximately 3.6 billion kilometres … which, in our Solar System, would put it halfway between Saturn and Uranus.

Diagram showing three ways a large planet might form.

Three scenarios for making a very large planet.

Kamen Todorov of Penn State University and co-investigators used the keen eyesight of the Hubble Space Telescope and the Gemini Observatory to directly image the object, which was uncovered in a survey of 32 young brown dwarfs in the Taurus star-forming region.

How to make a super planet

This mystery object is within the range of masses observed for planets orbiting other stars — that is, less than 15 times the mass of Jupiter. But should it be called a planet?

The answer depends on the mechanism by which it most likely formed.

Three scenarios have been proposed.

In the first, dust in a flattened cloud surrounding a young star slowly agglomerates to form a rocky planet 10 times larger than Earth, which then accumulates a large atmosphere.

The second idea is that a volume of gas in the cloud rapidly collapses to form an object the size of a gas giant planet.

The other idea is that, rather than forming in the cloud that surrounds the star, the body forms directly from the collapse of the same vast cloud of gas and dust from which the star (or brown dwarf) itself formed.

If the last scenario is correct, then the discovery of the strange object demonstrates that planetary-mass bodies can be made the same way that stars are made.

This is the likely solution because the mystery object is too young to have formed by the first scenario, which is very slow. The second scenario occurs more rapidly, but the cloud around the central brown dwarf probably did not contain enough material to make an object with a mass of 5-10 Jupiter masses.

Adapted from information issued by Gemini Observatory / NASA / ESA / A. Feild (STScI) / AURA artwork by Lynette Cook.