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News Article
Site: phys.org

The winning name is Thestias, the grandfather in Greek mythology of Pollux, which is the name of this 'exoworld's' star. Astronomy community groups around the globe were invited by the IAU to suggest names for 19 'exoplanet' systems spanning the galaxy. The suggested names were then put to a worldwide public vote, and theSkyNet project's suggestion came out on top for one of the 19 planet groups. To determine which suggestion would be submitted to the IAU, theSkyNet's volunteers were invited to pitch their best planet names to an internal competition. Based at the International Centre for Radio Astronomy Research (ICRAR), theSkyNet has over 200,000 volunteers globally, more than 7,000 of which are active at any one time. After 43 ideas and an internal vote amongst volunteers, the submission was made for the planet around Pollux. Pollux is a bright star in the constellation Gemini, right near the constellation Orion, and the 'saucepan'—a grouping of stars that's well known throughout Australia. The planet now known as Thestias is more than twice as large as Jupiter and was officially discovered in 2006 by astronomers in the United States. As part of the naming of Thestias, the team at theSkyNet will also have the chance to name a minor planet within the solar system's asteroid belt, the name of which will become official sometime in mid-2016. Volunteer Rich Matthews from the USA submitted the original proposal to name the planet around Pollux to theSkyNet, and after a change suggested by the IAU to avoid confusion with other objects in space, Thestias was officially named today. More information is available in the following announcement from the International Astronomical Union. Images and press contacts are included at the bottom of the release. The votes are in—the names of 19 "ExoWorlds" (14 stars and 31 exoplanets orbiting around them) have been chosen by public vote in the NameExoWorlds contest, and accepted by the IAU. Reflecting the truly international interest in astronomy, over half a million votes from 182 countries and territories contributed to the new official designations of the alien worlds. Although people have been naming celestial objects for millennia, the International Astronomical Union (IAU) is the authority responsible for assigning official names to celestial bodies. The NameExoWorlds contest provided the first opportunity for the public to name exoplanets, and their stars. The winning names are to be used freely in parallel with the existing scientific nomenclature, with due credit to the clubs or organizations that proposed them. With voting concluding on 31 October 2015, a total of 573,242 votes from the public have contributed to the naming of 31 exoplanets and 14 "host stars" beyond our own. Proposers of the winning names are to be awarded a plaque commemorating their contribution to astronomy, and they will be given the exciting opportunity to name a minor planet. The public voted on the 274 proposed ExoWorld names submitted by a wide variety of astronomy organizations from 45 countries all over the world (www.iau.org/news/pressreleases/detail/iau1511)—these included amateur astronomy groups, schools, universities and planetariums. The successful entries were received from across the globe—4 were received from North America (USA, Canada), 1 from Latin America (Mexico), 2 from the Middle East & Africa (Morocco, Syria), 6 from Europe (France, Italy, Netherlands, Spain, Switzerland), and 6 from Asia-Pacific (Australia, Japan, Thailand). The IAU Executive Committee Working Group on the Public Naming of Planets and Planetary Satellites validated all individual cases of the winning names from the vote, as stipulated in the guidelines, and made appropriate modifications to the original proposals where necessary, in full agreement with the proposers. However, after extensive deliberation, the Committee decided to annul the vote for one particular ExoWorld—tau Boötis—as the winning name was judged not to conform with the IAU rules for naming exoplanets. To this end, the IAU will organize a new contest to decide the name of tau Boötis in the future. The newly adopted names take the form of different mythological figures from a wide variety of cultures from across history, as well as famous scientists, fictional characters, ancient cities and words selected from bygone languages: Explore further: Can one buy the right to name a planet? IAU responds


News Article
Site: phys.org

The finding challenges an earlier theory that high levels of gas cause clumpy galaxies and sheds light on the conditions that brought about the birth of most of the stars in the Universe. Lead author Dr Danail Obreschkow, from The University of Western Australia node of the International Centre for Radio Astronomy Research (ICRAR), said that ten billion years ago the Universe was full of clumpy galaxies but these developed into more regular objects as they evolved. He said the majority of stars in the sky today, including our five billion-year-old Sun, were probably born inside these clumpy formations. "The clumpy galaxies produce stars at phenomenal rates," Dr Obreschkow said. "A new star pops up about once a week, whereas spiral galaxies like our Milky Way only form about one new star a year." The research team—a collaboration between ICRAR and Swinburne University of Technology—focused on a few rare galaxies, known as the DYNAMO galaxies. They still look clumpy even though they're seen "only" 500 million years in the past. Dr Obreschkow said looking at galaxies 500 million years ago was like looking at a passport photo taken a year ago. "We see that galaxy the way it probably looks now… something could have happened to it but it's very unlikely," he said. "The galaxies that are 10 billion light years away, that's comparable to a picture from when you were three or four years old, that's very different." The team used the Keck and Gemini observatories in Hawaii to measure the spin of the galaxies, along with millimetre and radio telescopes to measure the amount of gas they contained. Dr Obreschkow said the DYNAMO galaxies had a low spin and this was the dominant cause of their clumpiness, rather than their high gas content as previously thought. "While the Milky Way appears to have a lot of spin, the galaxies we studied here have a low spin, about three times lower," he said. Swinburne University astronomer Professor Karl Glazebrook, co-author and leader of the survey team, said the finding was exciting because the first observation that galaxies rotate was made exactly 100 years ago. "Today we are still revealing the important role that the spin of the initial cloud of gas plays in galaxy formation," he said. "This novel result suggests that spin is fundamental to explaining why early galaxies are gas-rich and lumpy while modern galaxies display beautiful symmetric patterns." Explore further: Fat or flat: Getting galaxies into shape More information: Danail Obreschkow, Karl Glazebrook, Robert Bassett, David B. Fisher, Roberto G. Abraham, Emily Wisnioski, Andrew W. Green, Peter J. McGrego, Ivana Damjanov, Attila Popping, Inger Jorgensen; Low Angular Momentum in Clumpy, Turbulent Disk Galaxies; The Astrophysical Journal arxiv.org/pdf/1508.04768v2.pdf


We describe a new method which achieves high-precision very long baseline interferometry (VLBI) astrometry in observations at millimeter (mm) wavelengths. It combines fast frequency-switching observations, to correct for the dominant non-dispersive tropospheric fluctuations, with slow source-switching observations, for the remaining ionospheric dispersive terms. We call this method source-frequency phase referencing. Provided that the switching cycles match the properties of the propagation media, one can recover the source astrometry. We present an analytic description of the two-step calibration strategy, along with an error analysis to characterize its performance. Also, we provide observational demonstrations of a successful application with observations using the Very Long Baseline Array at 86GHz of the pairs of sources 3C274 and 3C273 and 1308+326 and 1308+328 under various conditions. We conclude that this method is widely applicable to mm-VLBI observations of many target sources, and unique in providing bona fide astrometrically registered images and high-precision relative astrometric measurements in mm-VLBI using existing and newly built instruments, including space VLBI. © 2011. The American Astronomical Society. All rights reserved.


Zadko Telescope Director Associate Professor David Coward, from UWA's School of Physics, said the collaboration follows the recent revelation that the skies are teeming with short-lived exotic phenomena, named the "Transient Universe". The new project, SUPERB (SUrvey for Pulsars and Extragalactic Radio Bursts) will try and understand the origin of mysterious radio flashes. "These transients – flashes of light and radio bursts – are believed to originate from colliding black-holes or the formation of neutron stars, but no one knows for sure," Associate Professor Coward said. "They are completely unpredictable so we don't know when the next flash will occur, and where in the sky it will happen. To really understand such a phenomenon requires combining the signals from optical and radio telescopes, something that hasn't been successful in the past. "Until now it has taken many hours to interrupt other observing programs and to point telescopes in the same direction as the radio burst – our new collaboration will change all of that." Associate Professor Coward said the Zadko Telescope had already slashed the world record for the fastest response to a Parkes discovery of a radio burst – a near zero time delay – which was achieved by 'shadowing' Parkes, the NSW-based telescope made famous by the 2001 film "The Dish". "The Parkes Radio Telescope is in constant communication with the Zadko Telescope through the internet to ensure they are both pointing at the same sky location, something that is only possible when it is done robotically, with no human involvement," he said. In December 2015 the Zadko Telescope was shadowing Parkes at the same time a radio burst occurred. "The team is still searching for such an optical signature in the data – if a coincident signal is found it could reveal the hidden source of the flashes," Associate Professor Coward said. The cutting-edge project is led by Associate Professor Coward in collaboration with Dr Richard Dodson from the International Centre for Radio Astronomy Research (ICRAR) and French PhD student Damien Turpin, from Toulouse University. Dr Dodson said UWA's ownership of the Zadko Telescope, WA's premier optical telescope, provided a research-class resource. "It has an exceptionally wide view of the sky, where almost all the observing time can be dedicated to in-house projects, a combination of factors which has allowed us to perform some very unique science.," he said. Explore further: 11 billion year-old blast from the past captured by UWA Zadko Telescope


The research, made possible by cutting-edge AAO instrumentation, means that astronomers can now classify galaxies according to their physical properties rather than human interpretation of a galaxy's appearance. For the past 200 years, telescopes have been capable of observing galaxies beyond our own galaxy, the Milky Way. Only a few were visible to begin with but as telescopes became more powerful, more galaxies were discovered, making it crucial for astronomers to come up with a way to consistently group different types of galaxies together. In 1926, the famous American astronomer Edwin Hubble refined a system that classified galaxies into categories of spiral, elliptical, lenticular or irregular shape. This system, known as the Hubble sequence, is the most common way of classifying galaxies to this day. Despite its success, the criteria on which the Hubble scheme is based are subjective, and only indirectly related to the physical properties of galaxies. This has significantly hampered attempts to identify the evolutionary pathways followed by different types of galaxies as they slowly change over billions of years. Dr Luca Cortese, from The University of Western Australia node of the International Centre for Radio Astronomy Research (ICRAR), said the world's premier astronomical facilities are now producing surveys consisting of hundreds of thousands of galaxies rather than the hundreds that Hubble and his contemporaries were working with. "We really need a way to classify galaxies consistently using instruments that measure physical properties rather than a time consuming and subjective technique involving human interpretation," he said. In a study led by Dr Cortese, a team of astronomers has used a technique known as Integral Field Spectroscopy to quantify how gas and stars move within galaxies and reinterpret the Hubble sequence as a physically based two-dimensional classification system. "Thanks to the development of new technologies, we can map in great detail the distribution and velocity of different components of galaxies. Then, using this information we're able to determine the overall angular momentum of a galaxy, which is the key physical quantity affecting how the galaxy will evolve over billions of years. "Remarkably, the galaxy types described by the Hubble scheme appear to be determined by two primary properties of galaxies–mass and angular momentum. This provides us with a physical interpretation for the well known Hubble sequence whilst removing the subjectiveness and bias of a visual classification based on human perception rather than actual measurement." The new study involved 488 galaxies observed by the 3.9m Anglo Australian Telescope in New South Wales and an instrument attached to the telescope called the Sydney-AAO Multi-object Integral-field spectrograph or 'SAMI'. The SAMI project, led by the University of Sydney and the ARC Centre of Excellence for All-sky Astrophysics (CAASTRO), aims to create one of the first large-scale resolved survey of galaxies, measuring the velocity and distribution of gas and stars of different ages in thousands of systems. "Australia has a lot of expertise with this type of astronomy and is really at the forefront of what's being done," said Professor Warrick Couch, Director of the Australian Astronomical Observatory and CAASTRO Partner Investigator. "For the SAMI instrument we succeeded in putting 61 optical fibres within a distance that's less than half the width of a human hair. "That's no small feat, it's making this type of work possible and attracting interest from astronomers and observatories from around the world." Future upgrades of the instrument are planned that will allow astronomers to obtain even sharper maps of galaxies and further their understanding of the physical processes shaping the Hubble sequence. "As we get better at doing this and the instruments we're using are upgraded, we should be able to look for the physical triggers that cause one type of galaxy to evolve into another—that's really exciting stuff," Dr Cortese said. More information: The SAMI Galaxy Survey: the link between angular momentum and optical morphology. arxiv.org/abs/1608.00291

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