An image of globular cluster M54 taken by the Very Large Telescope Survey Telescope at the European Southern Observatory's Paranal Observatory in northern Chile. Credit: ESO
This new picture of M54 — a part of a satellite galaxy to the Milky Way called the Sagittarius Dwarf Galaxy — is part of a “test case” astronomers have to figure out a mystery of missing lithium.
For decades, astronomers have been aware of a dearth of lithium in our own galaxy, the Milky Way. This image from the Very Large Telescope’s Survey Telescope represents the first effort to probe for the element outside of our galaxy.
“Most of the light chemical element lithium now present in the Universe was produced during the Big Bang, along with hydrogen and helium, but in much smaller quantities,” the European Southern Observatory stated.
“Astronomers can calculate quite accurately how much lithium they expect to find in the early Universe, and from this work out how much they should see in old stars. But the numbers don’t match — there is about three times less lithium in stars than expected. This mystery remains, despite several decades of work.”
In any case, observations of M54 show that the amount of lithium there is similar to the Milky Way — meaning that the lithium problem is not confined to our own galaxy. A paper based on the research was published in the Monthly Notices of the Royal Astronomical Society. The research was led by Alessio Mucciarelli at the University of Bologna in Italy.
On either side of the white line in the picture are two models of how dark matter is distributed in a galaxy similar to the Milky Way. At left, non-interacting cold dark matter creates satellite galaxies. At right, dark matter interacting with other particles makes the number of observed satellite galaxies smaller. Credit: Durham University
Funny how small particle interactions can have such a big effect on the neighbors of the Milky Way. For a while, scientists have been puzzled about the dearth of small satellite galaxies surrounding our home galaxy.
They thought that cold dark matter in our galaxy should encourage small galaxies to form, which created a puzzle. Now, a new set of research suggests the dark matter actually interacted with small bits of normal matter (photons and neutrinos) and the dark matter scattered away, reducing the amount of material available for building galaxies.
“We don’t know how strong these interactions should be, so this is where our simulations come in,” stated Celine Boehm, a particle physicist at Durham University who led the research. “By tuning the strength of the scattering of particles, we change the number of small galaxies, which lets us learn more about the physics of dark matter and how it might interact with other particles in the Universe.”
Artist’s conception of the Milky Way galaxy based on the latest survey data from ESO’s VISTA telescope at the Paranal Observatory. A prominent bar of older, yellower stars lies at galaxy center surrounded by a series of spiral arms. The galaxy spans some 100,000 light years. Credit: NASA/JPL-Caltech, ESO, J. Hurt
Dark matter is a poorly understood part of the Universe, which is frustrating for scientists because it (along with dark energy) is believed to make up the majority of our Cosmos. There are several postulated types of it, but the main thing to understand is dark matter is hard to detect (except, in certain cases, through its interactions with gravity.)
This isn’t the only explanation for why the galaxies are missing, the scientists caution. Perhaps the universe’s first stars were so hot that they affected the gas that other stars formed from, for example.
Is Earth going at warp speed in this image? This is a composite of two photographs, one for the foreground and one for the sky. The photographer zoomed in on the image of the Milky Way for the last 10 seconds of the exposure to give it a 'warp speed' look. Credit and copyright: Mike Taylor/Mike Taylor Photography.
Whoa! Having just returned from the science and science fiction mashup that is Dragon Con, my mind is still combining the two. Then I saw this image from Mike Taylor, which is one of the most unique Milky Way images I’ve ever seen. Perfect!
Mike said he combined two images, one for the foreground and one for the night sky image of the Milky Way. “I zoomed in on the Milky Way for the last 10 seconds of the exposure to give it the “warp speed” look,” he said.
He calls the image “Somniloquy” which is a term that describes the act of talking while asleep. Yep. I’m pretty sure that happened at Dragon Con, too….
Check out another awesome Milky Way image by Mike, below.
This is a 7 image vertical panorama of the night sky in Maine where the late Summer Milky Way makes a dramatic background for a small shack and tree. Credit and copyright: Mike Taylor/Mike Taylor Photography.
Mike noted this image was taken right next to a cell tower that emits a red light over the landscape throughout the night. “Normally I would change the color balance but I decided to leave the red color in the foreground (although I toned it down quite a bit) to add to the overall feeling of the image,” he said. Mike stitched the images together via PTGui and processed through Lightroom 5 & Photoshop CS5.
Nikon D600 & 14-24 @ 14mm
f/2.8 – 7 x 30 secs – ISO 4000
08/28/14 – 10:20PM
Milky Way image taken with a Nikon D600 & 14-24mm at 24mm, f/2.8 – 30 seconds at ISO 4000 on 05/30/14 at 1:38 AM at Goblin Valley State Park, Utah.
Foreground image also taken with the same camera at f/5.6 – 1/60 seconds at ISO 100 on 05/25/14 at 6:28 PM, on Potash Rd near Moab, Utah.
Mike offers photography classes, and you can find out more about when/where here.
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A northern hemisphere summertime view of the Milky Way in Sagittarius. Credit and copyright: Greg Redfern.
What a gorgeous view of the dusty cloud of the Milky Way arch hovering over clouds low on the horizon here on Earth! Fellow NASA Solar System Ambassador Greg Redfern took this image of our galactic center in the constellation Sagittarius.
“If you have dark skies look to the south to see this grand spectacle,” Greg said via email. “It stretches across the entire sky.”
Greg shot the image during the Almost Heaven Star Party, an annual astronomy event sponsored by the Northern Virginia Astronomy Club. The star party is held in Spruce Knob, West Virginia, which boasts the darkest skies in the mid-Atlantic region of the US.
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LDN 673, a molecular cloud complex in the constellation Aquila. Credit and copyright: Callum Hayton.
What a stunning view of this dark region of space! This image, by astrophotographer Callum Hayton shows LDN 673, a molecular cloud complex that lies in the constellation Aquila. This region is massive — around 67 trillion kilometers (42 trillion miles across), and it is between 300-600 light years from Earth. Observers in the northern hemisphere can find this region in the summer skies near the bright star Altair and the Summer Triangle.
Because the cloud lies on the galactic plane, the dark dust is back-lit by millions of stars in the Milky Way galaxy. This dusty cloud likely contains enough raw material to form hundreds of thousands of stars. Hayton explained on Flickr how the dust gets “eroded” away by stellar formation:
“When some of these clouds reach a certain mass they begin to collapse and fragment creating protostars,” Hayton wrote. “As the temperature and pressure at the centre of the protostar rises, sometimes it becomes so great that nuclear fusion begins and a star is born. In this image you can see where at least two young stars have eroded the dust around them and are now above the clouds casting light down on to the dust below.”
Gorgeous!
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It feels like a real stargazing session watching this video. You head out at dusk, waiting for the first few stars to emerge. Then there’s a moment when — if you’re in the right spot — whammo. The Milky Way pops out. The sky turns into a three-dimensional playground.
Combine that feeling with the Apollo 14 launch audio from 1971, and this timelapse is a lot of fun.
The rise of the Milky Way and a spectacular lightning display in Mersing, Malaysia on June 28, 2014. Credit and copyright: Justin Ng.
Here’s another beautiful astrophoto, courtesy of photographer Justin Ng from Singapore. He’s currently on a photography trip to Malaysia and by chance captured this absolutely stunning view.
“Knowing that the sky would clear after sunset, I led a group of photographers to this location to film a time-lapse of the rising Milky Way above a lonely boat,” Justin explained via email, “but what happened soon after we started shooting was amazing. We were treated to a spectacular lightning display for about an hour from 9:30pm onwards before the clouds caught up with the rising Milky Way and dominated the skies eventually.”
The image is a result of stacking 12 photos (11 shots of lightnings and 1 shot for everything else) from his time-lapse sequence.
We’re looking forward to seeing the timelapse!
See more images from his current trip here, and you can see more of Justin’s fantastic astrophotography at his website, on G+, Facebook and Twitter.
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A 10 panel panorama of the Milkyway, as seen from the top of the Amphitheatre mountain range in the Drakensberg, South Africa. Credit and copyright: Tanja Sund.
During the summer months, many of us hit the trails and do a little camping. But how often do you get a view like this?
Wow! Click on the image above to see larger versions on Flickr.
Astrophotographer Tanja Sund and a companion pitched their tent in the Drakensberg Mountains of South Africa, a 200-kilometer-long mountainous range in the province of KwaZulu-Natal, with the tent sitting just 10 meters from a 1 kilometer-high vertical drop. “This is the home of the Tugela Waterfall, second highest waterfall in the world,” Tanja wrote on Flickr.
“The hike up to the top of the Amphitheatre took about 3 hours from the Sentinel car park, using the chain ladders to reach the summit,” Tanja said. “This is the only day hiking trail which leads to the top of the Drakensberg escarpment. We overnighted next to the Tugela falls to catch the Milkyway, which rises to the east over the local settlements.”
The image was taken on June 29, 2014.
According to the website about Drakensberg, the Zulu people named it ‘Ukhahlamba’ and the Dutch Voortrekkers ‘The Dragon Mountain.’ The Drakensberg Mountains are known for the hiking trails, areas for rock or ice-climbing, abseiling, white water rafting or helicopter rides to view the “awe-inspiring basalt cliffs, snowcapped in winter, that tower over riverine bush, lush yellowwood forests and cascading waterfalls.” At the top of Sani Pass is the highest pub in Africa, at 3,000 meters above sea level. Something for everyone!
Here’s the specs:
Canon 5D Mark III
24-70mm LII f/2.8
Shot at 24mm, F/3.2
20sec single exposures
10x image panorama
Processed in LightRoom & Photoshop.
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The band of the Milky Way stretches from Cygnus (left) to the Sagittarius in this wide-angle, guided photo. Credit: Bob King
Look east on a dark June night and you’ll get a face full of stars. Billions of them. With the moon now out of the sky for a couple weeks, the summer Milky Way is putting on a grand show. Some of its members are brilliant like Vega, Deneb and Altair in the Summer Triangle, but most are so far away their weak light blends into a hazy, luminous band that stretches the sky from northeast to southwest. Ever wonder just where in the galaxy you’re looking on a summer night? Down which spiral arm your gaze takes you?
Artist’s conception of the Milky Way galaxy based on the latest survey data from ESO’s VISTA telescope at the Paranal Observatory. A prominent bar of older, yellower stars lies at galaxy center surrounded by a series of spiral arms. The galaxy spans some 100,000 light years. Credit: NASA/JPL-Caltech, ESO, J. HurtTwo different perspectives on our galaxy help us better understand its shape. A face-on artist’s view at left reveals the core, spiral arms and the sun’s position. At right, we see an edge-on perspective photographed by the Cosmic Background Explorer probe. Because the sun and planets orbit in the galaxy’s plane, we’re ‘stuck’ with an edge-on view until we build a fast-enough rocket to take us above our galactic home. Credit: NASA/JPL et. all (left) and NASA
Because all stars are too far away for us to perceive depth, they appear pasted on the sky in two dimensions. We know this is only an illusion. Stars shine from every corner of the galaxy, congregating in its bar-shaped core, outer halo and along its shapely spiral arms. The trick is using your mind’s eye to see them that way.
Employing optical, infrared and radio telescopes, astronomers have mapped the broad outlines of the home galaxy, placing the sun in a minor spiral arm called the Orion or Local Arm some 26,000 light years from the galactic center. Spiral arms are named for the constellation(s) in which they appear. The grand Perseus Arm unfurls beyond our local whorl and beyond it, the Outer Arm. Peering in the direction of the galaxy’s core we first encounter the Sagittarius Arm, home to sumptuous star clusters and nebulae that make Sagittarius a favorite hunting ground for amateur astronomers.
Further in lies the massive Scutum-Centaurus Arm and finally the inner Norma Arm. Astronomers still disagree on the number of major arms and even their names, but the basic outline of the galaxy will serve as our foundation. With it, we can look out on a dark summer night at the Milky Way band and get a sense where we are in this magnificent celestial pinwheel.
The Milky Way band arches across the east and south as seen about 11:30 p.m. in mid-late June. The center of the galaxy is in the direction of the constellation Sagittarius. The dark ‘rift’ that appears to cleave the Milky Way in two is formed of clouds of interstellar dust that blocks the light of stars beyond it. Stellarium
We’ll start with the band of the Milky Way itself. Its ribbon-like form reflects the galaxy’s flattened, lens-like profile shown in the edge-on illustration above. The sun and planets are located within the galaxy’s plane (near the equator) where the stars are concentrated in a flattened disk some 100,000 light years across. When we look into the galaxy’s plane, billions of stars pile up across thousands of light years to create a narrow band of light we call the Milky Way. The same term is applied to the galaxy as a whole.
Since the average thickness of the galaxy is only about 1,000 light years, if you look above or below the band, your gaze penetrates a relatively short distance – and fewer stars – until entering intergalactic (starless) space. That why the rest of the sky outside of the Milky Way band has so few stars compared to the hordes we see within the band.
Here’s the galactic big picture showing the outline of the galaxy with constellations added. In this edge-on view, we see that the summertime Milky Way from Cassiopeia to Sagittarius includes the central bulge (in the direction of Sagittarius) and a hefty portion of one side of the flattened disk:
The outline of the Milky Way viewed edge-on is shown in gray. The yellow box includes the summer portion of the Milky Way from Cassiopeia to Scorpius with a red dot marking the galaxy’s center. This is the section we see crossing the eastern sky in June. Click to enlarge. Credit: Richard Powell with additions by the author
If you enlarge the map, you’ll see lines of galactic latitude and longitude much like those used on Earth but applied to the entire galaxy. Latitude ranges from +90 degrees at the North Galactic Pole to -90 at the South Galactic Pole. Likewise for longitude. 0 degrees latitude, o degrees longitude marks the galactic center. The summer Milky Way band extends from about longitude 340 degrees in Scorpius to 110 in Cassiopeia.
Now that we know what section of the Milky Way we peer into this time of year, let’s take an imaginary rocket journey and see it all from above:
Viewed from above, we can now see that our gaze (red arrows) reaches down the Perseus Arm (toward the constellation Cygnus) and across the Sagittarius and Scutum-Centaurus arms (toward the constellations Scutum, Sagittarius and Ophiuchus) and directly into the central bar. Interstellar dust obscures much of the center of the galaxy. Blue arrows show the direction we face during the winter months. Credit: NASA et. all with additions by the author.
Wow! The hazy arch of June’s Milky Way takes in a lot of galactic real estate. A casual look on a dark night takes us from Cassiopeia in the outer Perseus Arm across Cygnus in our Local Arm clear over to Sagittarius, the next arm in. Interstellar dust deposited by supernovae and other evolved stars obscures much of the center of the galaxy. If we could vacuum it all up, the galaxy’s center – where so many stars are concentrated – would be bright enough to cast shadows.
A view showing the summer Milky Way from mid-northern latitudes with three prominent constellations and the spiral arms we peer into when we face them. Stellarium
Here and there, there are windows or clearings in the dust cover that allow us to see star clouds in the Scutum-Centaurus and Norma Arms. In the map, I’ve also shown the section of Milky Way we face in winter. If you’ve ever compared the winter Milky Way band to the summer’s you’ve noticed it’s much fainter. I think you can see the reason why. In winter, we face away from the galaxy’s core and out into the fringes where the stars are sparser.
Look up the next dark night and contemplate the grand architecture of our home galaxy. If you close your eyes, you might almost feel it spinning.
Artist's conception of the Gaia telescope backdropped by a photograph of the Milky Way taken at the European Southern Observatory. Credit: ESA/ATG medialab; background: ESO/S. Brunier
Europe’s powerful Milky Way mapper is facing some problems as controllers ready the Gaia telescope for operations. It turns out that there is “stray light” bleeding into the telescope, which will affect how well it can see the stars around it. Also, the telescope optics are also not transmitting as efficiently as the design predicted.
Controllers emphasize the light problem would only affect the faintest visible stars, and that tests are ongoing to minimize the impact on the mission. Still, there will be some effect on how well Gaia can map the stars around it due to this issue.
“While there will likely be some loss relative to Gaia’s pre-launch performance predictions, we already know that the scientific return from the mission will still be immense, revolutionizing our understanding of the formation and evolution of our Milky Way galaxy and much else,” wrote the Gaia project team in a blog post.
Both of these problems have been known publicly since April, and the team has been working hard in recent months to pinpoint the cause. Of the two of them, it appears the team is having the most success with the optics transmission problems. They have traced the issue to water vapor in the telescope that freezes (no surprise since Gaia operates between -100 degrees Celsius and -150 Celsius, or -148 Fahrenheit and -238 Fahrenheit.)
Soyuz VS06, with Gaia space observatory, lifted off from Europe’s Spaceport, French Guiana, on 19 December 2013. (ESA–S. Corvaja)
The team turned on heaters on Gaia (on its mirrors and focal plane) to get rid of the ice before turning the temperature back down so the telescope can do its work. While some ice was anticipated (that’s why the heaters were there) there was more than expected. The spacecraft is also expected to equalize its internal pressure over time, sending out gases that again, could freeze and cause interference, so more of these “decontamination” procedures are expected.
The stray light problem is proving to be more stubborn. The light waves from sunlight and brighter sources of light in the sky are likely moving around the sunshield and bleeding into the telescope optics, which was unexpected (but the team is now trying to model and explain.)
Perhaps it was more ice. The challenge is, there were no heaters placed into the thermal tent area that could be responsible for the issue, so the team at first considered moving the position of Gaia to have sunlight strike that area and melt the ice.
GAIA Telescope Array – Credit: ESA
Simulations showed no safety problems with the idea, but “there is currently no plan to do so,” the team wrote. That’s because some tests on ground equipment in European laboratories didn’t show any strong evidence for or against layers of ice interfering with the stray light. So there didn’t seem to be much point to doing the procedure.
So instead, the idea is to do “modified observing strategies” to collect the data and then tweaking the software on the spacecraft and on the ground to “best optimize the data we will collect,” Gaia managers wrote.
“The stray light is variable across Gaia’s focal plane and variable with time, and has a different effect on each of Gaia’s science instruments and the corresponding science goals. Thus, it is not easy to characterise its impact in a simple way,” they added. They predict, however, that a star at magnitude 20 (the limit of Gaia’s powers) would see its positional accuracy mapping reduced by about 50%, while stars that are brighter would have less impact.
A diagram of the Gaia telescope payload (largest size available). Credit: European Space Agency
“It is important to realize that for many of Gaia’s science goals, it is these relatively brighter stars and their much higher accuracy positions that are critical, and so it is good to see that they are essentially unaffected. Also, the total number of stars detected and measured will remain unchanged,” the managers added.
The team is also tracking a smaller issue with a system that is supposed to measure the angle of separation between the two telescopes of Gaia. It’s needed to measure how small changes in temperature affect the angle between the telescopes. While the system is just fine, the angle is varying more than expected, and more work will be needed to figure out what to do next.
But nevertheless, Gaia is just about ready to start a science session that will last about a month. The team expects to have a better handle on what the telescope is capable of, and how to work with these issues, after that time. Gaia operates about 1.5 million km (932,000 miles) away from Earth in a gravitationally stable point in space known as L2, so it’s a bit too far for a house call such as what we were used to with the Hubble Space Telescope.
