The Milky Way May be 50 Percent Bigger Than Thought
A ring-like filament of stars wrapping around the Milky Way may actually belong to the galaxy itself, rippling above and below the relatively flat galactic plane, making it far bigger than previously thought.
A ring-like filament of stars wrapping around the Milky Way may actually belong to the galaxy itself, rippling above and below the relatively flat galactic plane. If so, that would expand the size of the known galaxy by 50 percent and raise intriguing questions about what caused the waves of stars.
Scientists used data collected by the Sloan Digital Sky Survey to reanalyze the brightness and distance of stars at the edge of the galaxy. They found that the fringe of the disk is puckered into ridges and grooves of stars, like corrugated cardboard.
"It looks to me like maybe these patterns are following the spiral structure of the Milky Way, so they may be related," astronomer Heidi Newberg, with Rensselaer Polytechnic Institute in New York, told Discovery News.
She and colleagues suspect that a dwarf galaxy may have plunged through the disk of the Milky Way, setting off ripples, like a pebble falling into a pond.
Intruder galaxies also may have set up spiral wave patterns that later trigger star formation in the gas along waves, leading to spiral arms in galaxies.
Evidence that the so-called Monoceros Ring, located more than 65,000 light-years from the center of the galaxy, actually is part of the Milky Way surprised Newberg, who was on a team that discovered the ring in 2002.
"We thought it was a tidal debris stream -- a dwarf galaxy that came in and spread itself out in this big ring. For 15 years, there's been a controversy in the field where half the astronomers think it's a tidal stream and half the astronomers think its something in the disk. I was in the stream camp," Newberg said.
"What I was trying to do was find more evidence that it was streams. It took a very long time to get this result, partly because I had to change my whole way of thinking. It now looks to me like it's part of the disk," she said.
Incorporating the ring into the map of the Milky Way expands the galaxy's span from 100,000 light-years to 150,000 light-years, said astronomer Yan Xu, with the National Astronomical Observatories of China and a former visiting scientist at Rensselaer.
Light travels at 186,000 miles per second, so one light-year is nearly 6 trillion miles.
Astronomers are eager for a higher-resolution, three-dimensional views of the Monoceros Ring, and another ring even farther out, from Europe's Gaia telescope.
Meanwhile, they are interested in seeing if ripples found in gases in the Milky Way are related to what has been observed in the stars.
"In the gas, we have seen a couple of perturbations, these vertical oscillations, in the outer part of the galaxy," astronomer Leo Blitz, with the University of California, Berkeley, told Discovery News.
As far as signs of an intruder galaxy, one may have already been found, he added. Publication of that discovery is pending.
The research by Newberg and colleagues will be published this week in the Astrophysical Journal.
A long exposure photograph taken with a fish eye lens shows the Milky Way in the night sky above Hakskeenpan, South Africa.
Traveling through capital cities is always a stressful occasion and this time was no exception. I had left myself a whole hour to get from the train station to the Royal Observatory Greenwich in London for The Astronomy Photographer of the Year 2013, and it seems an hour was only just enough! But once I'd arrived, I settled back in the very comfortable seats of the Peter Harrison Planetarium and the lights dimmed as the winning photographs were presented to the excited audience. There was a tangible buzz as the images appeared right over our heads on the inside of the planetarium dome against a beautiful background of glittering stars.
This years winners did not disappoint, there was a wide range of skills and techniques on show from the stunning "Deep Space" category where the photos had taken literally days to capture and process to the simple yet enigmatically beautiful "People and Space" category. As I watched the beautiful images appearing above me it reminded me just how powerful images of space can be in communicating the wonder of the Universe. The shortlisted photographs entered into the competition came from 49 countries. The overall winning image was taken by Mark Gee from Australia and was titled 'Guiding Light to the Stars' (shown here), depicting the stunning sight of the Milky Way with a glowing beacon of a lighthouse to the right of the scene. The composition reflects the way the stars used to be employed as a way of navigation in contrast to modern navigation techniques. Mark's image also won the "Earth and Space" category.
Adam Block from the United States won the Deep Space category with his image called "Celestial Impasto." The picture beautifully captures the delicate shades in the dust and dark nebulae of Sh2-239 in the Taurus molecular cloud about 450 light-years away.
The winner of the "Solar System" category was Man-To Hui from China with this beautifully captured image of the Australian solar eclipse of 2012. Phenomenal levels of detail can be seen in the usually hidden solar corona which can only be seen at the moment of totality during a solar eclipse.
Jacob Marchio from the United States was the winner of the Young Astronomy Photographer of the Year and at the age of 14 was able to capture this beautiful image captioned simply "The Milky Way." The image is a beautiful reminder of our place in the Universe as the stars from our galaxy shine with a lovely warm glow.
There were three special categories too this year, the first "People and Space" was won by Mark Gee with this beautifully composed image of an observation platform silhouetted against the moon. Mark took this picture from a distance of about 3 kilometers and used a zoom lens to get the shot.
The winner of the Sir Patrick Moore Prize for Best Newcomer was Sam Cornwell form the UK who managed, against the odds of the British weather, to capture a glimpse of the 2012 Venus transit just before it finished. The cloud really adds atmosphere to the picture and wonderfully represents the challenges facing astronomers suffering adverse weather conditions.
The Robotic Scope Image of the Year was picked up by László Francsics from Hungary with an amazing picture of the famous Trapezium Cluster in the Orion Nebula.
The shifting lights of the Aurora Borealis can take on many shapes and forms as they are molded by the Earth’s complex magnetic field. Sheets and planes of glowing gas appear to be twisted into a giant vortex above Grøtfjord in Norway.
All of the light which reaches the ground from space must first travel through the Earth’s atmosphere. During its journey the light can be altered by all sorts of atmospheric phenomena. Tiny ice crystals high above the ground refract the moonlight diverting it into a number of beautiful halos.
Like the snowy mountains in the foreground, the nucleus of Comet Panstarrs is composed largely of ice and rock. The nucleus itself is just a few kilometers across but as it neared the Sun in early 2013, ice evaporating from the surface formed a tail of gas and dust hundreds of thousands of kilometers long.
A great deal of careful planning, a long night of photography and hours of painstaking image processing have gone into creating this startling composite image of the Perseid meteor shower. The Perseid meteors get their name from the constellation of Perseus from where they appear to come. However, even at the peak of the shower it is impossible to predict exactly when or where the next meteor will appear. The photographer has combined 23 individual stills to convey the excitement and dynamism of this natural firework display.
The smoky appearance of the dust clouds in this image is fitting, since the grains of dust which make up the nebula are similar in size to particles of smoke here on Earth. The dust can reflect the light of nearby stars, as seen in the blue and yellow regions. It can also block and absorb the light of more distant stars, appearing brown and black in this image. To the right a bright star is ionizing a cloud of hydrogen gas, causing it to glow red, while below it far in the distance, is a globular cluster containing thousands of stars.
First discovered by astronomer Caroline Herschel in 1783, NGC 253 is a rare example of a ‘starburst galaxy’ with new stars being formed at many times the rate in our own galaxy, the Milky Way. Its mottled appearance comes from extensive lanes of dust which thread through the galactic disk. These are studded with many red clouds of ionized hydrogen gas, marking the sites where new stars are being born.
Lying at a distance of twelve million light years from Earth, M81 and M82 are galaxies with a difference. Close encounters between the two objects have forced gas down into their central regions. In M81 this influx of gas is being devoured by a supermassive black hole. In neighboring M82 the gas is fueling a burst of new star formation which in turn is blasting clouds of hydrogen (shown in red) back out into space.
Omega Centauri is a globular cluster, a spherical cloud containing several million stars. As this image shows, the stars are more densely clustered towards the center. The pronounced red color of several of the stars gives away the cluster’s great age: it is thought to have been formed billions of years ago. The cluster was first noted by the astronomer Ptolemy almost 2000 years ago and cataloged by Astronomer Royal Edmond Halley in 1677.
The awesome scale presented in this image depicts what as far as we’re concerned, are the three most significant objects in the Universe. The Sun and Moon each play an important role to us on Earth, and both are seen here, reddened by our vital atmosphere, presiding over the horizon. The third object is the Earth itself, and here its land, sea and sky meet around an amazing human megastructure, San Francisco’s Golden Gate Bridge.
The Great Nebula, also referred to as The Orion Nebula and M42 is found in the well-known constellation of Orion, just below the hunter’s belt. To the naked eye the nebula looks like another star in Orion’s sword. However, this skilful young photographer has shown there is more to it than meets the eye by producing this beautiful image that not only shows the stunning formation of this popularly observed nebula but also it diffuse nature.
The Moon seems to be emerging from the interplanetary darkness, and the young photographer has captured the contrast been the dark lava-filled lunar ‘seas’ and the mountainous southern highlands.
By keeping the camera shutter open this young photographer gathers precious light, making the desert scenery seem as bright as day. But the stars in the blue sky give the game away, showing that this dramatic photograph was actually taken in the middle of the night.
Appearing like a column of smoke rising from the horizon, a dark lane of dust marks the plane of the Milky Way in this photograph. This dust plays a vital role in the life story of our galaxy. Formed from the ashes of dead and dying stars, the dust clouds are also the regions in which new stars will form.
The darkest patches or ‘umbrae’ in this image are each about the size of Earth, with the entire region of magnetic turmoil spanning the diameter of ten Earths. This image captures rich details directly around the sunspots, and further out in the so-called ‘quiet’ Sun where simmering hot plasma rises, cools and falls back. This produces a patchwork surface like a pot of boiling water, but on an epic scale – each bubbling granule is about the size of France.
At a glance, this image may seem like a post-processed montage of objects from three separate images. However the truth is that they were all captured together providing the viewer with an amazing view of the Solar System, galaxy and Universe. Comet Lemmon only comes into our neighborhood every 11,000 years, racing around our Sun and back out to the far reaches of the Solar System. The light from the globular cluster in the center of this image took a journey of over 16,000 years to reach Earth. The furthest object in the image is a dwarf galaxy called the Small Magellanic Cloud whose starlight takes 200,000 years to reach us.
The Moon’s orbit about the Earth is not perfectly circular, so that at different times the Moon can be slightly closer or further away than usual. If the Moon passes in front of the Sun when it is at its furthest point, it will appear to be too small to entirely cover the solar disc. This is an ‘annular eclipse’ in which a ring, or annulus, of the Sun remains visible. This composite shot shows the progress of an annular eclipse in May 2013. Close to the horizon the distorting effects of Earth’s atmosphere can also be seen.
This incredibly sharp portrait brilliantly captures the jewel of our solar system, revealing the subtle banding around the orb that results from the planet’s weather. It also shows the exquisite gradation of brightness and color in the planet’s rings. The ultra-faint inner ‘D-Ring’ and outermost Encke gap are clearly visible. The hexagonal storm at the North Pole – a scientific curiosity – shows off three of its angular kinks. Images with this much clarity challenge our ideas of what can be achieved with amateur telescopes.
Full resolution versions of these photographs can be found on the National Maritime Museum (www.rmg.co.uk/astrophoto). All photographs are credited to the respective photographers and the National Maritime Museum. Photo captions for the winning entries are written by Mark Thompson; captions for runners up and highly commended entries are courtesy of the National Maritime Museum and Astronomical Photographer of the Year 2013.