NGC 2074: The Seahorse of the Large Magellanic Cloud

The Seahorse of the Large Magellanic Cloud 

Image Credit: NASA, ESA, and M. Livio (STScI)

Explanation: It may look like a grazing seahorse, but the dark object toward the image right is actually a pillar of smoky dust about 20 light years long.

The curiously-shaped dust structure occurs in our neighboring Large Magellanic Cloud, in a star forming region very near the expansive Tarantula Nebula.

The energetic nebula is creating a star cluster, NGC 2074, whose center is visible just off the top of the image in the direction of the neck of the seahorse.

The representative color image was taken in 2008 by the Hubble Space Telescope's Wide Field Planetary Camera 2 in honour of Hubble's 100,000th trip around the Earth.

As young stars in the cluster form, their light and winds will slowly erode the dust pillars away over the next million years.

ALMA and ATCA Astronomers dissect the remnants of a supernova

Simulated still showing components of Supernova Remnant 1987A. 

Credit: The International Centre for Radio Astronomy Research (ICRAR)

In research published today in the Astrophysical Journal, an Australian led team of astronomers has used radio telescopes in Australia and Chile to see inside the remains of a supernova.

The supernova, known as SN1987A, was first seen by observers in the Southern Hemisphere in 1987 when a giant star suddenly exploded at the edge of a nearby dwarf galaxy called the Large Magellanic Cloud.

In the two and a half decades since then the remnant of Supernova 1987A has continued to be a focus for researchers the world over, providing a wealth of information about one of the Universe's most extreme events.

PhD Candidate Giovanna Zanardo at The University of Western Australia node of the International Centre for Radio Astronomy Research (ICRAR) led the team that used the Atacama Large Millimetre/submillimeter Array (ALMA) in Chile's Atacama Desert and the Australia Telescope Compact Array (ATCA) in New South Wales to observe the remnant at wavelengths spanning the radio to the far infrared.

"By combining observations from the two telescopes we've been able to distinguish radiation being emitted by the supernova's expanding shock wave from the radiation caused by dust forming in the inner regions of the remnant," said Zanardo.

A panel of images showing different views of Supernova 1987A. 

Left Panel: SNR1987A as seen by the Hubble Space Telescope in 2010. 

Middle Panel: SNR1987A as seen by the ATCA in New South Wales and the ALMA in Chile. 

Right Panel: A computer generated visualisation of the remnant showing the possible location of a Pulsar. 

Credit: ATCA & ALMA Observations & data - G. Zanardo et al. / HST Image: NASA, ESA, K. France (University of Colorado, Boulder), P. Challis and R. Kirshner (Harvard-Smithsonian Center for Astrophysics)

"This is important because it means we're able to separate out the different types of emission we're seeing and look for signs of a new object which may have formed when the star's core collapsed. It's like doing a forensic investigation into the death of a star."

"Our observations with the ATCA and ALMA radio telescopes have shown signs of something never seen before, located at the centre or the remnant. It could be a pulsar wind nebula, driven by the spinning neutron star, or pulsar, which astronomers have been searching for since 1987."

"It's amazing that only now, with large telescopes like ALMA and the upgraded ATCA, we can peek through the bulk of debris ejected when the star exploded and see what's hiding underneath."

More research published recently in the Astrophysical Journal also attempts to shine a light on another long-standing mystery surrounding the supernova remnant.

Since 1992 the radio emission from one side of the remnant has appeared 'brighter' than the other.

More information: 'Spectral and Morphological Analysis of the Remnant of Supernova 1987a with ALMA & ATCA' G. Zanardo, L. Staveley-Smith, R. Indebetouw et al. Astrophysical Journal November 10th, 2014: arxiv.org/abs/1409.7811 and iopscience.iop.org/0004-637X/796/2/82

'Multi-dimensional simulations of the expanding supernova remnant SN 1987a' T.M Potter, L Staveley-Smith, B. Reville et al. Astrophysical Journal October 20th, 20144: arxiv.org/abs/1409.4068 and iopscience.iop.org/0004-637X/794/2/174

Scientists New Estimate of Dark Matter Half previous estimate

Artist’s impression of the Milky Way and its dark matter halo (shown in blue, but in reality invisible). 

Credit: ESO/L. Calçada

A new measurement of dark matter in the Milky Way has revealed there is half as much of the mysterious substance as previously thought.

Australian astronomers used a method developed almost 100 years ago to discover that the weight of dark matter in our own galaxy is 800 000 000 000 (or 8 x 1011) times the mass of the Sun.

They probed the edge of the Milky Way, looking closely, for the first time, at the fringes of the galaxy about 5 million billion kilometres from Earth.

Astrophysicist Dr Prajwal Kafle, from The University of Western Australia node of the International Centre for Radio Astronomy Research (ICRAR), said we have known for a while that most of the Universe is hidden.

"Stars, dust, you and me, all the things that we see, only make up about 4 per cent of the entire Universe," he said.

"About 25 per cent is dark matter and the rest is dark energy."

Dr Kafle, who is originally from Nepal, was able to measure the mass of the dark matter in the Milky Way by studying the speed of stars throughout the galaxy, including the edges, which had never been studied to this detail before.

He used a robust technique developed by British astronomer James Jeans in 1915, decades before the discovery of dark matter.

Dr Kafle's measurement helps to solve a mystery that has been haunting theorists for almost two decades.

"The current idea of galaxy formation and evolution, called the Lambda Cold Dark Matter theory, predicts that there should be a handful of big satellite galaxies around the Milky Way that are visible with the naked eye, but we don't see that," Dr Kafle said.



"When you use our measurement of the mass of the dark matter the theory predicts that there should only be three satellite galaxies out there, which is exactly what we see; the Large Magellanic Cloud, the Small Magellanic Cloud and the Sagittarius Dwarf Galaxy."

University of Sydney astrophysicist Professor Geraint Lewis, who was also involved in the research, said the missing satellite problem had been "a thorn in the cosmological side for almost 15 years."

"Dr Kafle's work has shown that it might not be as bad as everyone thought, although there are still problems to overcome," he said.

The study also presented a holistic model of the Milky Way, which allowed the scientists to measure several interesting things such as the speed required to leave the galaxy.

"Be prepared to hit 550 kilometres per second if you want to escape the gravitational clutches of our galaxy," Dr Kafle said.

"A rocket launched from Earth needs just 11 kilometres per second to leave its surface, which is already about 300 times faster than the maximum Australian speed limit in a car!"

More information: 'On the Shoulders of Giants: Properties of the Stellar Halo and the Milky Way Mass Distribution' P. R. Kafle, S. Sharma, G. F. Lewis, and J. Bland-Hawthorn. Published in the Astrophysical Journal October 10th, 2014. Available at: iopscience.iop.org/0004-637X/794/1/59/. arxiv.org/abs/1408.1787

NASA Chandra Image: Companion star survives supernova blast

Credit X-ray: NASA /CXC /SAO /F.Seward et al; Optical: NOAO /CTIO /MCELS, DSS

When a massive star runs out fuel, it collapses and explodes as a supernova.

Although these explosions are extremely powerful, it is possible for a companion star to endure the blast.

A team of astronomers using NASA's Chandra X-ray Observatory and other telescopes has found evidence for one of these survivors.

This hardy star is in a stellar explosion's debris field, also called its supernova remnant, located in an HII region called DEM L241.

An HII region is created when the radiation from hot, young stars strips away the electrons from neutral hydrogen atoms (HI) to form clouds of ionized hydrogen (HII).

This HII region is located in the Large Magellanic Cloud, a small companion galaxy to the Milky Way.

A new composite image of DEM L241 contains Chandra data (purple) that outlines the supernova remnant.

The remnant remains hot and therefore X-ray bright for thousands of years after the original explosion occurred.

Also included in this image are optical data from the Magellanic Cloud Emission Line Survey (MCELS) taken from ground-based telescopes in Chile (yellow and cyan), which trace the HII emission produced by DEM L241.

Additional optical data from the Digitized Sky Survey (white) are also included, showing stars in the field.

R. Davies, K. Elliott, and J. Meaburn, whose last initials were combined to give the object the first half of its name, first mapped DEM L241 in 1976.

The recent data from Chandra revealed the presence of a point-like X-ray source at the same location as a young massive star within DEM L241's supernova remnant.

Astronomers can look at the details of the Chandra data to glean important clues about the nature of X-ray sources.

For example, how bright the X-rays are, how they change over time, and how they are distributed across the range of energy that Chandra observes.

In this case, the data suggest that the point-like source is one component of a binary star system.

In such a celestial pair, either a neutron star or black hole (formed when the star went supernova) is in orbit with a star much larger than our Sun.

As they orbit one another, the dense neutron star or black hole pulls material away its companion star through the wind of particles that flows away from its surface.

If this result is confirmed, DEM L241 would be only the third binary containing both a massive star and a neutron star or black hole ever found in the aftermath of a supernova.

More information: A paper describing these results is available online and was published in the November 10, 2012, issue of The Astrophysical Journal: dx.doi.org/10.1088/0004-637X/759/2/123

Large Magellanic Cloud‎'s clockwork motion captured in nearby galaxy - Video

This photo illustration shows Hubble measurements of the rotation of the Large Magellanic Cloud (LMC), the nearest visible galaxy to our Milky Way. 

The LMC appears in the Southern Hemisphere's night sky. In this photo illustration, the image contrast in a ground-based photo was enhanced to highlight the LMC’s faint outer regions, which are not visible to the naked eye. 

To illustrate the LMC's large apparent size on the sky, an image of the full moon is shown at bottom right. A horizon has been added for perspective. 

The arrows represent the highest-quality Hubble measurements of the motion of the LMC's stars to show how this galaxy rotates. 

Each arrow reveals the predicted motion over the next 7 million years. The motion of each star measured by Hubble over a few years’ time is a million times smaller than the length of each arrow. 

The LMC completes a rotation every 250 million years. 

Credit: NASA, ESA, A. Feild and Z. Levay (STScI), Y. Beletsky (Las Campanas Observatory), and R. van der Marel (STScI)

Using the NASA /ESA Hubble Space Telescope, astronomers have for the first time precisely measured the rotation rate of a galaxy based on the clock-like movement of its stars.

According to their analysis, the central part of the neighboring galaxy, called the Large Magellanic Cloud (LMC), completes a rotation every 250 million years.

Coincidentally, it takes our Sun the same amount of time to complete a rotation around the center of our Milky Way galaxy.

Roeland van der Marel

The Hubble team, composed of Roeland van der Marel of the Space Telescope Science Institute (STSI) in Baltimore, Md., and Nitya Kallivayalil of the University of Virginia in Charlottesville, Va., used Hubble to measure the average motion of hundreds of individual stars in the LMC, located 170,000 light-years away.

Hubble recorded the stars' slight movements over a seven-year period.

Disk-shaped spiral galaxies, like the Milky Way and the LMC, generally rotate like a carousel.

Hubble's precision tracking offers a new way to determine a galaxy's rotation by the "sideways" proper motion of its stars, as seen in the plane of sky.

Astronomers have long measured the sideways motions of nearby celestial objects, but this is the first time that the precision has become sufficient to see another distant galaxy rotate.

For the past century astronomers have calculated galaxy rotation rates by observing a slight shift in the spectrum, called the Doppler effect, of its starlight.

On one side of a galaxy's spinning stellar disk, the stars swinging in the direction of Earth will show a spectral blueshift (the compression of light waves due to motion toward the observer).

Stars swinging away from Earth on the opposite side of a galaxy will show a spectral redshift (the stretching of light to redder wavelengths due to motion away from the observer).

The newly measured Hubble sideways motions and the Doppler motions measured previously each provide complementary information about the LMC's rotation rate. 

By combining the results, the Hubble team for the first time obtained a fully three-dimensional view of stellar motions in another galaxy.

This animation illustrates the rotation rate of the Large Magellanic Cloud (LMC). 

Hubble Space Telescope observations have determined that the central part of the LMC completes a rotation every 250 million years. 

Hence, it takes more than 10 million years for even the small amount of rotation illustrated here. 

Credit: NASA, ESA, and G. Bacon, R. van der Marel, A. Feild, L. Frattare, Z. Levay, and F. Summers (STScI)

"Determining a galaxy's rotation by measuring its instantaneous back and forth motions doesn't allow one to actually see things change over time," said van der Marel, the lead author on a paper in the Feb. 1 issue of the Astrophysical Journal describing and interpreting the results.

"By using Hubble to study the stars' motions over several years, we can actually for the first time see a galaxy rotate in the plane of the sky."

More Information: Third-epoch Magellanic Cloud Proper Motions. II. The Large Magellanic Cloud Rotation Field in Three Dimensions: Roeland P. van der Marel1 and Nitya Kallivayalil - iopscience.iop.org/0004-637X/781/2/121/article

ESA Gaia coming into focus - NGC1818

An ESA Gaia test image of the young star cluster NGC1818 in the Large Magellanic Cloud, taken as part of calibration and testing before the science phase of the mission begins.

The field-of-view is 212 x 212 arcseconds and the image is approximately oriented with north up and east left. 

The integration time of the image was 2.85 seconds and the image covers an area less than 1% of the full ESA Gaia field of view.

Gaia's overall design is optimised for making precise position measurements and the primary mirrors of its twin telescopes are rectangular rather than round.

To best match the images delivered by the telescopes, the pixels in Gaia's focal plane detectors are then also rectangular. 

To produce this image of NGC1818, the image has been resampled onto square pixels. 

Furthermore, to maximise its sensitivity to very faint stars, Gaia's main camera does not use filters and provides wide-band intensity data, not true-colour images.

The false-colour scheme used here relates to intensity only. The real colours and spectral properties of the stars are measured by other Gaia instruments. 

Image courtesy ESA /DPAC /EADS Airbus DS.

ESA's billion-star surveyor Gaia is slowly being brought into focus.

This test image shows a dense cluster of stars in the Large Magellanic Cloud, a satellite galaxy of our Milky Way.

Once Gaia starts making routine measurements, it will generate truly enormous amounts of data.

To maximise the key science of the mission, only small 'cut-outs' centred on each of the stars it detects will be sent back to Earth for analysis.

This test picture, taken as part of commissioning the mission to 'fine tune' the behaviour of the instruments, is one of the first proper 'images' to be seen from Gaia, but ironically, it will also be one of the last, as Gaia's main scientific operational mode does not involve sending full images back to Earth.

Gaia was launched on 19 December 2013, and is orbiting around a virtual point in space called L2, 1.5 million kilometres from Earth.

Annotated diagram of the Payload Module

Gaia's goal is to create the most accurate map yet of the Milky Way.

It will make precise measurements of the positions and motions of about 1% of the total population of roughly 100 billion stars in our home Galaxy to help answer questions about its origin and evolution.

Repeatedly scanning the sky, Gaia will observe each of its billion stars an average of 70 times each over five years.

In addition to positions and motions, Gaia will also measure key physical properties of each star, including its brightness, temperature and chemical composition.

To achieve its goal, Gaia will spin slowly, sweeping its two telescopes across the entire sky and focusing the light from their separate fields simultaneously onto a single digital camera - the largest ever flown in space, with nearly a billion pixels.

But first, the telescopes must be aligned and focused, along with precise calibration of the instruments, a painstaking procedure that will take several months before Gaia is ready to enter its five-year operational phase.

ESO VLA Explores Dragon's Head Nebula in Large Magellanic Cloud - Video

A lesser known region of the Large Magellanic Cloud, NGC 2035 (right), has been photographed using the European Southern Observatory Very Large Telescope (VLT) in Chile. 

The effects of new star birth and stellar death are on display.

Credit: ESO

ESO VLT: Two different gas clouds in the Large Magellanic Cloud

ESO's Very Large Telescope has captured a detailed view of a star-forming region in the Large Magellanic Cloud -- one of the Milky Way's satellite galaxies.

This sharp image reveals two glowing clouds of gas. NGC 2014 (right) is irregularly shaped and red and its neighbour, NGC 2020, is round and blue.

These odd and very different forms were both sculpted by powerful stellar winds from extremely hot newborn stars that also radiate into the gas, causing it to glow brightly. Credit: ESO

ESO's Very Large Telescope has captured an intriguing star-forming region in the Large Magellanic Cloud—one of the Milky Way's satellite galaxies.

This sharp image reveals two distinctive glowing clouds of gas: Red-hued NGC 2014, and its blue neighbour NGC 2020.

While they are very different, they were both sculpted by powerful stellar winds from extremely hot newborn stars that also radiate into the gas, causing it to glow brightly.

This image was taken by the Very Large Telescope (VLT) at ESO's Paranal Observatory in Chile—the best place in the southern hemisphere for astronomical observing.

But even without the help of telescopes like the VLT, a glance towards the southern constellation of Dorado (The Swordfish or Dolphinfish) on a clear, dark night reveals a blurry patch which, at first sight, appears to be just like a cloud in the Earth's atmosphere.

At least, this may have been explorer Ferdinand Magellan's first impression during his famous voyage to the southern hemisphere in 1519.

Although Magellan himself was killed in the Philippines before his return, his surviving crew announced the presence of this cloud and its smaller sibling when they returned to Europe, and these two small galaxies were later named in Magellan's honour.

However, they were undoubtedly seen by both earlier European explorers and observers in the southern hemisphere, although they were never reported.

The Large Magellanic Cloud (LMC) is actively producing new stars. Some of its star-forming regions can even be seen with the naked eye, for example, the famous Tarantula Nebula.

However, there are other smaller—but no less intriguing—regions that telescopes can reveal in intricate detail. This new VLT image explores an oddly mismatched pair: NGC 2014 and NGC 2020.

The pink-tinged cloud on the right, NGC 2014, is a glowing cloud of mostly hydrogen gas.

It contains a cluster of hot young stars. The energetic radiation from these new stars strips electrons from the atoms within the surrounding hydrogen gas, ionising it and producing a characteristic red glow.

This zoom video starts with a wide view of the Milky Way and ends with a close-up look at a pair of mysterious glowing gas clouds in the nearby Large Magellanic Cloud — NGC 2014, and NGC 2020, both in the southern constellation of Dorado (The Swordfish).

The final view of these clouds was captured by ESO's Very Large Telescope at the Paranal Observatory in Chile. 

Credit: ESO/Nick Risinger (skysurvey.org)/Digitized Sky Survey 2. Music: John Dyson

In addition to this strong radiation, massive young stars also produce powerful stellar winds that eventually cause the gas around them to disperse and stream away.

To the left of the main cluster, a single brilliant and very hot star seems to have started this process, creating a cavity that appears encircled by a bubble-like structure called NGC 2020.

The distinctive blueish colour of this rather mysterious object is again created by radiation from the hot star—this time by ionising oxygen instead of hydrogen.

Superbubble DEM L50: Large Magellanic Cloud

Credits: X-ray: NASA/CXC/Univ of Michigan/A.E.Jaskot, Optical: NOAO/CTIO/MCELS.

This composite image shows the superbubble DEM L50 (a.k.a. N186) located in the Large Magellanic Cloud about 160,000 light years from Earth. Superbubbles are found in regions where massive stars have formed in the last few million years.

The massive stars produce intense radiation, expel matter at high speeds, and race through their evolution to explode as supernovas. The winds and supernova shock waves carve out huge cavities called superbubbles in the surrounding gas.

X-rays from NASA's Chandra X-ray Observatory are shown in pink and optical data from the Magellanic Cloud Emission Line Survey (MCELS) are colored in red, green and blue.

The MCELS data were obtained with the University of Michigan's 0.9-meter Curtis Schmidt telescope at Cerro Tololo Inter-American Observatory (CTIO).

The shape of DEM L50 is approximately an ellipse, with a supernova remnant named SNR N186 D located on its northern edge.

Like another superbubble in the LMC, N44, DEM L50 gives off about 20 times more X-rays than expected from standard models for the evolution of superbubbles.

A Chandra study published in 2011 showed that there are two extra sources of the bright X-ray emission: supernova shock waves striking the walls of the cavities, and hot material evaporating from the cavity walls.

The Chandra study of DEM L50 was published in the Astrophysical Journal in 2011 and was led by Anne Jaskot from the University of Michigan in Ann Arbor.

The Chandra study of DEM L50 was led by Anne Jaskot from the University of Michigan in Ann Arbor.