RSSArchive for February, 2014

Asteroids are pounding a pulsar

SCIENTISTS USING CSIRO’s Parkes telescope and another telescope in South Africa have found evidence that a tiny star called PSR J0738-4042 is being pounded by asteroids – large lumps of rock in space.

“One of these rocks seems to have had a mass of about a billion tons,” CSIRO astronomer and member of the research team Dr Ryan Shannon said.

PSR J0738-4042 lies 37,000 light-years from Earth in the constellation of Puppis. The environment around the star is especially harsh, full of radiation and violent winds of particles.

“If a large rocky object can form here, planets could form around any star. That’s exciting,” Dr Shannon said.

The star is a special one, a ‘pulsar’ that emits a beam of radio waves. As it spins, its radio beam flashes over Earth again and again with the regularity of a clock.

An artist's impression of an asteroid breaking up

An artist’s impression of an asteroid breaking up. Credit: NASA/JPL-Caltech

Formed from shattered remains

In 2008 Dr Shannon and a colleague predicted how an infalling asteroid would affect a pulsar. It would, they said, alter the slowing of the pulsar’s spin rate and the shape of the radio pulse that we see on Earth.

“That is exactly what we see in this case,” Dr Shannon said. “We think the pulsar’s radio beam zaps the asteroid, vaporising it. But the vaporised particles are electrically charged and they slightly alter the process that creates the pulsar’s beam.”

Asteroids circling a pulsar could have been formed by the remains of the exploding star that produced the pulsar itself, the scientists say. The material blasted out from the explosion could fall back towards the pulsar, developing into a swirling cloud of dusty debris that circles it. Astronomers call it a ‘disc’.

Not the only one

Astronomers have found a dust disc around another pulsar called J0146+61.

Parkes radio telescope

The CSIRO’s Parkes radio telescope. Photo courtesy Shaun Amy.

“This sort of dust disc could provide the ‘seeds’ that grow into larger asteroids,” said Paul Brook, a PhD student co-supervised by the University of Oxford and CSIRO who led the study of PSR J0738-4042.

In 1992 two planet-sized objects were found around a pulsar called PSR 1257+12. But these were probably formed by a different mechanism, the astronomers say.

The new study has been published in The Astrophysical Journal Letters, a leading journal of astronomical research.

Adapted from information issued by CSIRO.

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Deep freeze telescope reveals galactic carbon trail

USING A TELESCOPE INSTALLED at the driest place on earth – Ridge A in Antarctica – a UNSW-led team of researchers has identified a giant gas cloud that appears to be in an early stage of formation. Giant clouds of molecular gas – the most massive bodies in our galaxy – are the birthplaces of stars.

“This newly discovered gas cloud is shaped like a very long filament, about 200 light years in extent and ten light years across, with a mass about 50,000 times that of our Sun,” says team leader, Professor Michael Burton, an astronomer at UNSW Australia. “The evidence suggests it is in the early stages of formation, before any stars have turned on.”

Stunning new way of doing science

The team is using the High Elevation Antarctic Terahertz telescope, or HEAT, at Ridge A, along with the Mopra telescope at Coonabarabran in NSW, to map the location of gas clouds in our galaxy from the carbon they contain.

At 4,000 metres elevation, Ridge A is one of the coldest places on the planet, and the driest. The lack of water vapour in the atmosphere there allows terahertz radiation from space to reach the ground and be detected.

PLATO-R in Antarctica

The PLATO-R observatory at Ridge A. The HEAT telescope is the black object on stilts at left, the instrument module is the yellow box and the solar panel array is on the right. Image Credit: Geoff Sims.

The PLATO-R robotic observatory with the HEAT telescope was installed in 2012 by a team led by UNSW physicist, Professor Michael Ashley, and Dr Craig Kulesa of the University of Arizona.

“We now have an autonomous telescope observing our galaxy from the middle of Antarctica and getting data, which is a stunning new way of doing science. Ridge A is more than 900 kilometres from the nearest people, who are at the South Pole, and is completely unattended for most of the year,” says Professor Burton.

Following the galactic carbon trail

The HEAT telescope detects atomic carbon and the Mopra telescope detects carbon monoxide. “I call it following the galactic carbon trail,” says Professor Burton.

Mopra telescope

The Mopra telescope, near Coonabarabran in NSW.

The discovery of the new galactic cloud, which is about 15,000 light years from earth, will help determine how these mysterious objects develop in the interstellar medium.

One idea is that they are formed from the gravitational collapse of an ensemble of small clouds into a larger one. Another involves the random collision of small clouds that then agglomerate. Or it may be that the molecular gas filament is condensing out of a very large, surrounding cloud of atomic gas.

About one star per year, on average, is formed in the Milky Way. Stars that explode and die then replenish the gas clouds as well as moving the gas about and mixing it up.

The team includes researchers from Australia, Germany and the US. The results have been published in The Astrophysical Journal.

Adapted from information issued by UNSW. Image Credit: Geoff Sims.

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Oldest known star found by Australian astronomers

A TEAM LED BY ASTRONOMERS at The Australian National University has discovered the oldest known star in the Universe, which formed shortly after the Big Bang 13.7 billion years ago.

The discovery has allowed astronomers for the first time to study the chemistry of the first stars, giving scientists a clearer idea of what the Universe was like in its infancy.

“This is the first time that we’ve been able to unambiguously say that we’ve found the chemical fingerprint of a first star,” said lead researcher, Dr Stefan Keller of the ANU Research School of Astronomy and Astrophysics.

“This is one of the first steps in understanding what those first stars were like. What this star has enabled us to do is record the fingerprint of those first stars.”

The star was discovered using the ANU SkyMapper telescope at the Siding Spring Observatory, which is searching for ancient stars as it conducts a five-year project to produce the first digital map the southern sky.

Star SMSS J031300.36-670839.3

Astronomers have determined that star SMSS J031300.36-670839.3 is the oldest yet found.

A different star recipe

The ancient star is around 6,000 light years from Earth, relatively close in astronomical terms. It is one of the 60 million stars photographed by SkyMapper in its first year.

“The stars we are finding number one in a million,” says team member Professor Mike Bessell, who worked with Keller on the research.

“Finding such needles in a haystack is possible thanks to the ANU SkyMapper telescope that is unique in its ability to find stars with low iron from their colour.”

Dr Keller and Professor Bessell confirmed the discovery using the Magellan telescope in Chile.

The composition of the newly discovered star – known only as SMSS J031300.36-670839.3 – shows it formed in the wake of a primordial star, which had a mass 60 times that of our Sun.

“To make a star like our Sun, you take the basic ingredients of hydrogen and helium from the Big Bang and add an enormous amount of iron – the equivalent of about 1,000 times the Earth’s mass,” Dr Keller says.

Dr Stefan Keller with the SkyMapper telescope

Dr Stefan Keller with the SkyMapper telescope

“To make this ancient star, you need no more than an Australia-sized asteroid of iron and lots of carbon. It’s a very different recipe that tells us a lot about the nature of the first stars and how they died.”

No sign of iron

Dr Keller says it was previously thought that primordial stars died in extremely violent explosions that blasted their iron into huge volumes of space. But the ancient star shows signs of pollution with lighter elements such as carbon and magnesium, and no sign of pollution with iron.

“This indicates the primordial star’s supernova explosion was of surprisingly low energy. Although sufficient to disintegrate the primordial star, almost all of the heavy elements such as iron, were consumed by a black hole that formed at the heart of the explosion,” he says.

The result may resolve a long-standing discrepancy between observations and predictions of the Big Bang.

The discovery was published in the latest edition of the journal Nature.

Adapted from information issued by ANU.

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SpaceInfo gallery for 10 February 2014

1. Saturn’s turbulent clouds

This colour-enhanced view of Saturn’s clouds, made with data from NASA’s Cassini spacecraft, shows the progress of a huge, long-lived storm that began way back in December 2010. White areas signify the highest cloud tops. The storm ended up becoming so large that it covered an area the size of Europe. Saturn itself is 9.5 times wider than the Earth. Courtesy NASA / JPL-Caltech / SSI / Hampton University.

Storms in Saturn's atmosphere

Storm clouds in Saturn’s atmosphere.

 

2. Starburst galaxy

This is galaxy M82, inside which a supernova was recently spotted. Located about 12 million light-years from Earth, and seen nearly side on, M82 is classed as a ‘starburst’ galaxy since it is undergoing a wave of stellar formation. The main image at lower left is a visible-light image made with the Hubble Space Telescope. The inset shows part of the galaxy viewed at radio wavelengths with the Karl G. Jansky Very Large Array (VLA) radio telescope system – it reveals bright dots that are in some cases star-forming regions, and in other cases the remains of exploded stars. The VLA studies are helping astronomers sort out which is which. Courtesy Josh Marvil (NM Tech/NRAO), Bill Saxton (NRAO/AUI/NSF), NASA.

Views of galaxy M82

Radio wavelength (inset) observations of galaxy M82 reveal regions of both star birth and star death.

 

3. A new camera for space

A technician examines the Near Infrared Camera (NIRCam) that will form part of the suite of instruments aboard the James Webb Space Telescope (JWST), due for launch later this decade. The JWST will be much larger than the Hubble Space Telescope, which it is designed to replace. NIRCam’s ability to detect infrared light will enable it to peer back in time toward the Big Bang, since cosmological redshift has moved visible light wavelengths into the infrared part of the spectrum. Courtesy NASA GSFC.

A technician looks at NIRCam

A technician looks at NIRCam, one of the instruments that will be used by the James Webb Space Telescope.

 

4. Solar flare

NASA’s Solar Dynamics Observatory captured this image of a solar flare on 3 February 2014 – the flare is the bright section near the middle of the Sun’s disc. When flares are seen on the edge of the Sun, they stand out as huge tongues of ultra-hot gas reaching into space. In the case of this flare, it was aimed straight upwards towards the camera. Courtesy NASA.

Full view of the Sun with a solar flare

The white region in the middle of this image of the Sun, is a solar flare.

 

5. Deluge after the impact

Flood channels lead away from a 20-kilometre-wide crater on the surface of Mars. When the small asteroid or comet that formed the crater hit, it would have melted the rock, dust and below-ground ice, leading to a runaway flood that flowed downhill across the surface. In this false-colour image produced from data collected by the European Space Agency’s Mars Express spacecraft, green and yellow colouring represent shallow areas; blue and purple show deeper areas down to about four kilometres depth. Courtesy ESA / DLR / FU Berlin (G. Neukum).

Flood channels on Mars

Ancient flood channels snake away from a crater on Mars.

 

6. A galactic giant

Twelve million light-years from Earth lies the giant galaxy NGC 5128. In its core lies a huge black hole, responsible for accelerating material near it into an intense jet of gas shooting through the galaxy. The jet and its after-effects can be seen at X-ray wavelengths. This image, from NASA’s Chandra X-ray Observatory satellite, shows X-ray emission at several wavelengths, colour-coded in blue, red and green. Courtesy NASA / CXC / U.Birmingham / M.Burke et al.

X-ray view of NGC 5128

The galaxy NGC 5128 viewed at infrared wavelengths. Revealed is a huge jet of material being shot from the vicinity of a black hole in the galaxy’s core.

 

7. Fire drill

Fire inside a spacecraft is the one thing astronauts dread the most, even more than a slow loss of atmosphere. That’s why regular fire drills are so important. Here, European Space Agency astronaut Alexander Gerst (in the white shirt) and NASA astronaut Reid Wiseman (blue) are practicing a fire drill in NASA’s Space Station mock-up in Houston, USA. Courtesy NASA.

Astronauts conduct a fire drill

Astronauts conduct a fire drill inside an International Space Station mock-up.

 

8. Herbig-Haro object

Hidden deep inside this hourglass-shaped cloud is a newly formed star that is spitting out streams of gas from its poles – standard behaviour for such stellar youngsters. The gas collides with other gas in star’s vicinity, forming a glowing cloud. Such a cloud, or nebula, is called a Herbig-Haro object (named for two astronomers who studied them). This one, known as HH 909A, is located in the Chamaeleon I molecular cloud 500 light-years from Earth. Courtesy ESA / NASA.

Herbig-Haro object HH 909A

This hourglass-shaped cloud is called a Herbig-Haro object. Hidden inside is a newly formed star.

 

9. Heavy lift-off

Flight VA217 launched from Europe’s spaceport in French Guiana on 6 February to place two communications satellites (ABS-2 and Athena–Fidus) into orbit. The rocket was an Ariane 5 ECA ‘heavy-class’ rocket belonging to the Arianespace company. This was the 216th launch of an Ariane family rocket. Courtesy ESA / CNES / Arianespace / Optique video du CSG – S. Martin.

Launch of Ariane flight VA217

An Ariane 5 ECA rocket lifts off from Europe’s launch site in French Guiana.

Story by Jonathan Nally.

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What’s up? Night sky for February 2014

WHEN STARTING OUT IN STARGAZING, most people are particularly keen to spot the planets. The problem is, that, to the novice, planets and stars look pretty much alike. The best way to identify planets is to determine their locations in relation to nearby bright stars or the Moon, and then see how watch as they change their positions slightly as each night passes. The information below will help you spot planets using this method.

Except where indicated, all of the phenomena described here can be seen with the unaided eye. Dates and times are for the Australian Eastern Summer Time zone, and sky directions are from the point of view of an observer at mid latitudes in the Southern Hemisphere.

7 Feb

It is First Quarter Moon today at 6:22am Sydney time. First Quarter is a good time to look at the Moon through a telescope, as the sunlight angle means the craters and mountains are throwing nice shadows, making it easier to get that 3D effect.

8 Feb

The just-past-half Moon is the north-western sky this evening, and just above it is a group of stars called the Hyades. See if you can spot them – they’re in a triangular formation. The Hyades is an ‘open star cluster’ about 153 light years from Earth, making it the closest such cluster to our Solar System. Although you’ll probably only be able to see a handful of stars with the naked eye (assuming, of course, that you’re not standing under a streetlight), a pair of binoculars will show many more – and long-exposure photographs reveal hundreds.

Just above and to the right of the Moon is a bright orange-coloured star called Aldebaran, although astronomers classify it as a red giant. It is roughly 44 times as big as the Sun and located about 65 light-years from Earth. Think about that – if Aldebaran were at the same distance from us as the Sun, it would appear 44 times as big in the sky. Just as well it’s a long way away!

View showing where the Moon is on the night of 8 February 2014

The Moon (shown bigger than it really is) will be near the star Aldebaran and the star cluster the Hyades on the evening of 8 February. Another star cluster, the Pleiades, is lower in the sky.

11 Feb

By tonight, you’ll see that Moon has moved a fair distance to the right (or east) of the Hyades, as a result of its slow orbit around the Earth. You won’t be able to miss what looks to be a bright star just below the Moon – this is the planet Jupiter. Grab a pair of binoculars and see if you can make out some tiny pinpricks of light on either side of the planet – these are the moons discovered by Galileo; Ganymede, Europa, Io and Callisto. Try to see all four – you might find there are two on each side of Jupiter, or one and three, or all four on one side – depending on where they are in their orbits around the planet. You might find that one or more are missing – this’ll be because that moon or moons is currently hidden behind Jupiter, or in the glare in front of the planet.

View showing the position of the Moon on 11 Feb

On the evening of 10 February, the Moon (not shown to scale) will be just above the planet Jupiter.

12 Feb

Today the Moon will reach the farthest point in its orbit around Earth, apogee, at a distance of 406,231 kilometres.

15 Feb

Full Moon occurs today at 10:53am Sydney time. If you’re out stargazing tonight and look just above (or north of) the Moon, you’ll see a bright blue star. This is Regulus, the brightest star in the constellation Leo. Located about 77.5 light years from Earth, Regulus is not one star but four, grouped into two pairs – with the naked eye we see only the brightest of the four. Multiple star systems are very common throughout the Milky Way galaxy.

20 Feb

Take a look around midnight tonight and you’ll see the Moon just below what appears to be a brightish red star. This is not actually a star but the planet Mars. A small planet, it doesn’t give away much detail even when viewed through a telescope.

Just below the Moon is Spica, the brightest star in the constellation Virgo. Like Regulus, Spica is a member of a multiple star system, in this case a binary (or two) star system. The two stars orbit each other so close together that not even a telescope can show them separated. In fact, so close are they that their mutual gravitational pull distorts each of them from a round shape into an egg shape. The Spica system is about 260 light years from Earth.

View showing the position of the Moon on 20 February

If you’re up after midnight on 20 February, you’ll be greeted by the sight of the Moon with the star Spica above and the planet Mars below.

22 Feb

Tonight it’s Saturn‘s turn, with the ringed planet appearing just below and to the right of the Moon. If you have access to even a small telescope, take a look at Saturn’s amazing rings.

23 Feb

It is Last Quarter Moon today at 4:15am Sydney time. In the early hours of this morning you’ll find the star Antares above and to the right of the Moon. Antares is the brightest star in the constellation Scorpius. Like Mars, it is a red colour too – in fact, the name Antares means ‘rival of Mars’. Because they’re both in the same part of the sky, this is a good time to compare the two.

26 Feb

If you’re up before dawn, take a look out to the east and you’ll see the thin crescent Moon just above a bright ‘star’ – this is actually the planet Venus, which, aside from the Sun and the Moon, is the brightest object in the sky. Because it is in our morning sky at present, it is called the ‘morning star’. Later in the year it will be visible to west in the evening sky, and will be known as the ‘evening star’.

View showing the position of the Moon on 26 February

This shows the view out to the east less than an hour before sunrise on 26 February. The thin crescent Moon is just above the planet Venus. Very low down on the horizon, and difficult to see, is the planet Mercury. The Moon will be just to the left of Mercury on 28 February.

28 Feb

Today the Moon will be at the closest point in its orbit, called perigee, which is the opposite of apogee. The distance between the two bodies today will be 360,438 kilometres. If you’re up and about before dawn, and you have an unobstructed (by buildings, trees, hills etc) view of the eastern horizon, see if you can spot the planet Mercury just to right of the very thin crescent Moon. It won’t be easy to see either Mercury or the Moon, but give it a try.

Here are some more great sources of southern stargazing information:

Melbourne Planetarium

Royal Astronomical Society of New Zealand

If you have any questions or comments on the night sky, we’d be happy to answer them. Please use the Feedback Form below. Happy stargazing!

Images courtesy IAU.

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