- A Grand Extravaganza of New Stars
- Sarah Brightman to Sing Live from Space
- Philae Phone Home: Scientists Will Try to Contact the Comet Lander on March 12
- New Dwarf Galaxies Discovered in Orbit Around the Milky Way
- Dust Disks Survive Cosmic Firework Near Young Massive Stars
- Mysterious Phenomena in a Gigantic Galaxy-Cluster Collision
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Posted: 11 Mar 2015 06:57 AM PDT
This dramatic landscape in the southern constellation of Ara (The Altar) is a treasure trove of celestial objects. Star clusters, emission nebulae and active star-forming regions are just some of the riches observed in this region lying some 4000 light-years from Earth. This beautiful new image is the most detailed view of this part of the sky so far, and was taken using the VLT Survey Telescope at ESO’s Paranal Observatory in Chile. At the centre of the image is the open star cluster NGC 6193, containing around thirty bright stars and forming the heart of the Ara OB1 association. The two brightest stars are very hot giant stars. Together, they provide the main source of illumination for the nearby emission nebula, the Rim Nebula, or NGC 6188, which is visible to the right of the cluster.
A stellar association is a large grouping of loosely bound stars that have not yet completely drifted away from their initial formation site. OB associations consist largely of very young blue–white stars, which are about 100 000 times brighter than the Sun and between 10 and 50 times more massive. The Rim Nebula is the prominent wall of dark and bright clouds marking the boundary between an active star-forming region within the molecular cloud, known as RCW 108, and the rest of the association. The area around RCW 108 is made up of mostly hydrogen — the primary ingredient in star formation. Such areas are also known as H II regions. The ultraviolet radiation and intense stellar wind from the stars of NGC 6193 seem to be driving the next generation of star formation in the surrounding clouds of gas and dust. As cloud fragments collapse they heat up and eventually form new stars. As the cloud creates new stars, it is simultaneously being eroded by the winds and radiation emitted by previous stars, and by violent supernova explosions. In this way, such star-forming H II regions tend to have a lifespan of just a few million years. Star formation is a very inefficient process, with only around 10% of the available material contributing to the process — the rest is blown off into space. The Rim Nebula also shows signs of being in the early phase of “pillar formation”, meaning that in the future it could end up looking similar to other well-known star-forming regions, such as the Eagle Nebula (Messier 16, containing the famous Pillars of Creation) and the Cone Nebula (part of NGC 2264). This single spectacular image was actually created from more than 500 individual pictures taken through four different colour filters with the VLT Survey Telescope. The total exposure time was more than 56 hours. It is the most detailed view of this region yet achieved.
Credit: ESO
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Posted: 11 Mar 2015 12:28 AM PDT
British soprano singer Sarah Brightman is preparing for a live concert from space. During a press conference on Tuesday in London's West End theatre district, around the corner from where her stage career took off in "Cats", Brightman described the challenges of singing while orbiting 250 miles (400 kilometres) above Earth. "I'm trying to find a piece which is beautiful and simple in its message, as well as not too complicated to sing," she said. "Because of the complexities of this, I don't want to promise too much." Brightman will be the eighth space tourist, and first professional singer, traveling as one of a three-person team to the International Space Station in a Soyuz capsule that's due for a Sept. 1 launch from the Baikonur cosmodrome in Kazakhstan. She will spend 10 days orbiting the Earth.
She has been training since January after being accepted by the Russian Federal Space Agency as a spaceflight participant candidate for a planned flight arranged by Space Adventures, Ltd. Learning everything from wilderness survival to the Russian language, Sarah’s passion for space is about to become a reality.
“When I was 9 years old, I watched the first man on the moon,” she said, “It actually changed my perception about life. Suddenly, my mind opened and I started to really work on the career I have now.
“I thank that moment, it was pivotal in my life. I never really talked about it as it could never be a reality, it was all very abstract. But it was always my ambition to fly to space, it’s something I dreamed about and wanted.
“I now have the luck, I’m going up on the Russian Soyuz to the International Space Station. And if possible, I want others to take inspiration from my journey and chase their own dreams.”
In preparation for her 10 day stay aboard the International Space Station, she is learning to conduct various scientific experiments, one of which will be the effect of zero gravity on her voice.
On top of the intense training in Star City, Russia, she has not forgotten about music and intends to become the first ever international artist to perform live from space.
“I live with the thought of this travel every second of my life. I wake up with it, I go to sleep with it, I dream of it. I cannot believe this is happening.”
On a break in training, she has been working with her most famous collaborator, Lord Andrew Lloyd Webber who has written a song for Sarah to celebrate her space flight, recorded in New York in the last week. Later this year, she will release a retrospective of her career that will include this special song.
On Tuesday, she revealed her personal Mission Patch, which every Cosmonaut designs for their mission. It captures the classic historic spirit of space travel and exploration, while using a female figure as the central motif – highlighting the potential of women to succeed in the worlds of science and technology, traditionally the preserve of men. The patch displays her chosen motto, "Chasing Dreams, Shaping Futures."
"'Chasing Dreams,' I mean this has been a dream of mine so obvious that's there, and 'Shaping Futures' is obviously space is going to be everybody's future," the singer said. "'Shaping Futures' is really about children and their future and what it is going to be."
Brightman is working together with Challenger Center and NASA, to launch a programme to excite students about science, technology, engineering and mathematics and teach them how the arts can help unleash innovation and inspiration. Students will create videos using lyrics from one of Sarah Brightman’s songs. Video entries will be posted online for public viewing and voting and the top entries and other fan favorites will be used to create one musical mashup video.
The summer-long initiative will culminate in a special event during her time aboard the ISS. After the video premiere, students at Challenger Learning Centers in the UK and the U.S. will have a chance to chat with Brightman live. The event will be streamed online.
She has also donated to and supports the Galactic Unite STEM Scholarship Program. Galactic Unite is a global initiative, driven by Virgin Galactic’s community of Future Astronaut customers, designed to inspire and support students as they seek answers to global challenges through science, technology, engineering and mathematics education (STEM) and business entrepreneurship.
She is also proud to be a UNESCO Artist For Peace Ambassador, supporting their education programmes around the world.
Credit: spaceadventures.com, c
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Posted: 10 Mar 2015 03:24 PM PDT
Scientists from the German Aerospace Center (DLR) will make the first attempt to contact the stranded comet lander Philae on Thursday Mar. 12. “The first attempt will take place already this week, on March 12,” Stephan Ulamec, Lander Project Manager at DLR, told astrowatch.net. If we’re lucky, the first signal will be received by ESA’s Rosetta spacecraft at 05:00 CET. Philae came to rest on Nov. 12 2014 in a rather shaded location on Comet 67P/Churyumov-Gerasimenko and it needs to receive sufficient energy before it can wake up.
Several conditions must be met for Philae to start operating again. First, the interior of the lander must be at least at –45ºC before Philae can wake up from its winter sleep. At its new landing site – Abydos – only a little sunlight reaches Philae, and the temperatures are significantly lower than at the originally planned landing location. The lander must also be able to generate at least 5.5 watts using its solar panels to wake up.
Ulamec believes that even better opportunity to restore the communication with the lander will come in May. “I think we do have a fair chance to get contact with the lander again. I do see it more likely though, to have Philae re-activated around May, when comet and lander are closer to the sun,” he said.
Once awakened, Philae will switch on its receiver every 30 minutes and will listen for a signal from the Rosetta spacecraft.
Philae needs a total of 19 watts to begin operating and allow two-way communication. It could be that the lander has already woken up from its winter sleep some 500 million kilometers away from Earth, but does not yet have sufficient power to communicate with Rosetta.
Ulamec hopes that if the lander wakes up, it will still be able to conduct scientific experiments. “This depends on the power and energy available. First, we will have to be modest and conduct temperature measurements etc. If it is possible to re-charge the battery, more demanding activities, like another attempt to take samples or another radar-scan, could be performed,” he revealed.
Before the contact was lost with Philae, it has managed to deliver a lot of significant scientific data. “After the separation about 16.2 MB of data have been downloaded from Philae to Earth. There is lots of science in those, like 7 usable panorama images!” Ulamec said.
So far, Philae’s exact location has not been identified on images acquired by the Rosetta orbiter, so the operations team at DLR is currently working with the information they have from the lander’s cameras, along with the knowledge gained from the solar energy conditions experienced in November.
Rosetta is a European Space Agency mission with contributions from its Member States and NASA. The Rosetta lander, Philae, is contributed by a consortium led by DLR, the Max Planck Institute for Solar System Research (MPS), the French Space Agency (Centre National d'Etudes Spatiales; CNES) and the Italian Space Agency (Agenzia Spaziale Italiana; ASI).
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Posted: 10 Mar 2015 01:41 PM PDT
Scientists on two continents have independently discovered a set of celestial objects that seem to belong to the rare category of dwarf satellite galaxies orbiting our home galaxy, the Milky Way. Dwarf galaxies are the smallest known galaxies, and they could hold the key to understanding dark matter and the process by which larger galaxies form. A team of researchers with the Dark Energy Survey, headquartered at the U.S. Department of Energy’s Fermi National Accelerator Laboratory, and an independent group from the University of Cambridge, UK, jointly announced their findings today. Both teams used data taken during the first year of the Dark Energy Survey, all of which is publicly available, to carry out their analysis. “The large dark matter content of Milky Way satellite galaxies makes this a significant result for both astronomy and physics,” said Alex Drlica-Wagner of Fermilab, one of the leaders of the Dark Energy Survey analysis.
Satellite galaxies are small celestial objects that orbit larger galaxies, such as our own Milky Way. Dwarf galaxies can be found with fewer than 100 stars and are remarkably faint and difficult to spot. (By contrast, the Milky Way, an average-sized galaxy, contains billions of stars.)
These newly discovered objects are a billion times dimmer than the Milky Way and a million times less massive. The closest of them is about 100,000 light-years away.
“The discovery of so many satellites in such a small area of the sky was completely unexpected,” said Cambridge’s Institute of Astronomy’s Sergey Koposov, the Cambridge study’s lead author. “I could not believe my eyes.”
Scientists have previously found more than two dozen of these satellite galaxies around our Milky Way. About half of them were discovered in 2005 and 2006 by the Sloan Digital Sky Survey, the precursor to the Dark Energy Survey. After that initial explosion of discoveries, the rate fell to a trickle and dropped off entirely over the past five years.
The Dark Energy Survey is looking at a new portion of the southern hemisphere, covering a different area of sky than the Sloan Digital Sky Survey. The galaxies announced today were discovered in a search of only the first of the planned five years of Dark Energy Survey data, covering roughly one-third of the portion of sky that DES will study. Scientists expect that the full Dark Energy Survey will find up to 30 of these satellite galaxies within its area of study.
While more analysis is required to confirm any of the observed celestial objects as satellite galaxies, researchers note their size, low surface brightness and significant distance from the center of the Milky Way as evidence that they are excellent candidates. Further tests are ongoing, and data collected during the second year of the Dark Energy Survey could yield more of these potential dwarf galaxies to study.
“Dwarf satellites are the final frontier for testing our theories of dark matter,” said Vasily Belokurov of the Cambridge Institute of Astronomy, one of the study’s co-authors. “We need to find them to determine whether our cosmological picture makes sense. Finding such a large group of satellites near the Magellanic Clouds was surprising, though, as earlier surveys of the southern sky found very little, so we were not expecting to stumble on such treasure.”
Newly discovered galaxies would also present scientists with more opportunities to search for signatures of dark matter. Dwarf satellite galaxies are dark matter-dominated, meaning they have much more mass in unseen matter than in stars. The nature of this dark matter remains unknown but might consist of particles that annihilate each other and release gamma rays. Because dwarf galaxies do not host other gamma ray sources, they make ideal laboratories to search for signs of dark matter annihilation. Scientists are confident that further study of these objects will lead to even more sensitive searches for dark matter.
“These results are very puzzling,” said co-author Wyn Evans, also of the Institute of Astronomy. “Perhaps they were once satellites that orbited the Magellanic Clouds and have been thrown out by the interaction of the Small and Large Magellanic Cloud. Perhaps they were once part of a gigantic group of galaxies that – along with the Magellanic Clouds – are falling into our Milky Way galaxy.”
In a separate result also announced today, the Large Area Telescope Collaboration for NASA’s Fermi Gamma-Ray Telescope mission reported that they did not see any significant excess of gamma ray emission associated with the new Dark Energy Survey objects. This result demonstrates that new discoveries from optical telescopes can be quickly translated into tests of fundamental physics.
“We did not detect significant emission with the LAT, but the dwarf galaxies that DES has and will discover are extremely important targets for the dark matter search,” said Peter Michelson, spokesperson for the LAT collaboration. “If not leading to an identification of particle dark matter, they will certainly be useful to constrain its properties.”
The Dark Energy Survey is a five-year effort to photograph a large portion of the southern sky in unprecedented detail. Its primary instrument is the Dark Energy Camera, which – at 570 megapixels – is the most powerful digital camera in the world, able to see galaxies up to 8 billion light-years from Earth. Built and tested at Fermilab, the camera is now mounted on the 4-meter Victor M. Blanco telescope at the Cerro Tololo Inter-American Observatory in the Andes Mountains in Chile.
The survey’s five-year mission is to discover clues about the nature of dark energy, the mysterious force that makes up about 70 percent of all matter and energy in the universe. Scientists believe that dark energy may be the key to understanding why the expansion of the universe is accelerating.
“The Dark Energy Camera is a perfect instrument for discovering small satellite galaxies,” said Keith Bechtol of the Kavli Institute for Cosmological Physics at the University of Chicago, who helped lead the Dark Energy Survey analysis. “It has a very large field of view to quickly map the sky and great sensitivity, enabling us to look at very faint stars. These results show just how powerful the camera is and how significant the data it collects will be for many years to come.”
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Posted: 10 Mar 2015 01:03 PM PDT
A team of scientists led by astronomers at the University of Bonn, Germany, discovered an unusual phenomenon in the centre of the Milky Way: They detected about 20 rotating dust and gas discs in each cluster hosting exceptionally large and hot stars. The existence of these discs in the presence of the destructive UV radiation field of their massive neighbours came as a surprise. The science team is pondering how these rotating discs are able to withstand evaporation under these extreme conditions. The results are published in the most recent edition of the journal „Astronomy & Astrophysics“. The centre of the Milky Way is a nursery for young stars: In its very heart, more young stars are born in dark clouds than in any other place in the Galaxy. These stars form in rich groups such as the „Quintuplet“ and „Arches“ clusters which were the research focus of a science team under leadership of the University of Bonn's Argelander Institute for Astronomy. Both star clusters are merely a few million years young and contain stars as massive as 100 times the mass of the Sun. „We expected that the enormous radiative energy of these giant beasts evaporate the material around their smaller neighbours in less than one million years,“ says Andrea Stolte of the Argelander Institute for Astronomy at the University of Bonn.
Together with the Max-Planck-Institute for Astronomy, the Astronomical Calculation Institute of the University of Heidelberg and US-Colleagues located in Los Angeles, Honolulu, Dearborn and Baltimore, Dr. Stolte and her PhD students at the University of Bonn discovered an unexpected number of dusty discs surrounding stars in the „Quintuplet“ and „Arches“ clusters. „In such a hostile environment, we did not expect to find any circumstellar discs after more than a few hundred thousand years, and yet we found more than 20 discs in each cluster at ages of a few million years,“ says Stolte who coordinated the project. This surprising discovery contradicts the standard theories of disc survival in stellar nurseries and hints towards unrevealed processes taking place in these rich Galactic centre clusters.
The unexpected phenomenon could be observed with the European Southern Obervatory's (ESO) Very Large Telescope (VLT) in the Chilean Atacama desert and the Hubble Space Telescope (HST). „We would not have been able to glimpse through the dense layers of dust into the heart of the Milky Way with visual light,“ explains Dr. Maryam Habibi. It was the VLT's and HST's capability to capture infrared light that allowed the science team to penetrate deep into the core of our Galaxy. Habibi carried out her PhD thesis at the University of Bonn during the Emmy Noether project funded by the German Science Foundation (DFG).
“Our team had previously studied smaller young star clusters in more moderate environments, further outside in our Galaxy’s disk, within the spiral arms, where the UV radiation field is less intense”, explains Wolfgang Brandner of the Max-Planck-Institute for Astronomy in Heidelberg, Germany. “We had found dust disks around stars in these clusters, and were interested whether such disks could survive the more extreme environments in the hot, dense star clusters near the Galactic Center. These clusters contain young very massive stars with temperatures around 50,000 degrees Celsius that generate intense, energetic UV radiation. The dust disks around the stars we studied are subject to that hard UV radiation. According to current understanding, the disks should have been evaporated under these conditions within few 100,000 years. The stars in the Quintuplet and Arches Clusters have ages much larger than that, 2.5 and 4 Million years respectively, and yet we discovered more than 20 dust disks around bright stars in each cluster.”
How these rotating discs survive the hellfire of their giant neighbours is puzzling. The astronomers considered two possibilities: Either the gas and dust discs display an unprecedented resistibility to their hostile environment, or a previously unobserved mechanism recharges the discs. The solution may lie in the companion stars. When two stars circle each other, the bigger companion may provide fuel to its smaller twin, possibly refueling disc material at a rate large enough to make up for the evaporated losses caused by the intense UV radiation surrounding the couple. Stolte considers the latter theory the most likely solution: „Many unknown processes take place in these rich, young star clusters. The tight interaction and mass flow between numerous close twins observed in other star-forming environments might also be the explanation for the dusty discs we found in these massive clusters.“
An even more unexpected possibility emerges with the presence of these discs, that was not considered possible in these extreme regions of the Milky Way: If dense discs of gas and dust are capable to survive for extended periods of time in this hostile environment, they may provide the conditions for planet formation. „If their is enough material – who knows?“ asks Stolte. That, however, remains speculation. One way or the other – the heart of the Milky Way offers ample opportunities for unexpected discoveries from her astronomer's perspective.
Credit: uni-bonn.de, mpia.de
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Posted: 10 Mar 2015 12:38 PM PDT
Researchers using the Karl G. Jansky Very Large Array (VLA) have produced the most detailed image yet of a fascinating region where clusters of hundreds of galaxies are colliding, creating a rich variety of mysterious phenomena visible only to radio telescopes. The scientists took advantage of new VLA capabilities to make a "true color" radio image. This image shows the region as it would appear if human eyes were sensitive to radio waves instead of light waves. In this image, red shows where longer radio waves predominate, and blue shows where shorter radio waves predominate, following the pattern we see in visible light.
The image shows a number of strange features the astronomers think are related to an ongoing collision of galaxy clusters. The region is called Abell 2256, and is about 800 million light-years from Earth and some 4 million light-years across. The image covers an area in the sky almost as large as the full moon. Studied by astronomers for more than half a century with telescopes ranging from radio to X-ray, Abell 2256 contains a fascinating variety of objects, many of whose exact origins remain unclear.
With monikers such as "Large Relic," "Halo," and "Long Tail," the features in this region are seen in greater fidelity than ever before, said Frazer Owen, of the National Radio Astronomy Observatory (NRAO). "The image reveals details of the interactions between the two merging clusters and suggests that previously unexpected physical processes are at work in such encounters," he said.
Owen worked with Lawrence Rudnick of the University of Minnesota; Jean Eilek of New Mexico Tech; and Urvashi Rau, Sanjay Bhatnagar, and Leonid Kogan of NRAO. The researchers presented their results in the Astrophysical Journal.
The National Radio Astronomy Observatory is a facility of the National Science Foundation, operated under cooperative agreement by Associated Universities, Inc.
Credit: nrao.edu
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