Tagged: UCL Toggle Comment Threads | Keyboard Shortcuts

  • richardmitnick 3:54 pm on February 27, 2017 Permalink | Reply
    Tags: , , , , First evidence of rocky planet formation in Tatooine system, , GMOS Gemini South, SDSS 1557, UCL   

    From Gemini: “First evidence of rocky planet formation in Tatooine system” 

    NOAO

    Gemini Observatory
    Gemini Observatory

    February 23, 2017

    1
    A disc of rocky debris from a disrupted planetesimal surrounds white dwarf plus brown dwarf binary star. The white dwarf is the burn-out core of a star that was probably similar to the Sun, the brown dwarf is only ~60 times heavier than Jupiter, and the two stars go around each other in only a bit over two hours. Credit: Mark Garlick, UCL, University of Warwick and University of Sheffield.

    Using the Gemini Multi-Object Spectrograph (GMOS) on Gemini South, a team led by Jay Farihi (University College London) found, for the first time, a dust and debris disk surrounding a binary star with a white dwarf as a substellar companion.

    3
    GMOS on Gemini South

    To date, almost all of the known planetary systems which include a white dwarf are single stars. Using GMOS spectra Farihi et al. identified critical metal features in the spectrum as well as the higher Balmer lines. From the Gemini data the team estimated a surface temperature of 21,800 Kelvin (about 3.5 times hotter than the Sun) and a mass of ~0.4 solar masses for the white dwarf star and a mass of ~0.063 solar masses for the companion.

    The research is published in the February 27th online issue of Nature Astronomy.

    Evidence of planetary debris surrounding a double sun, ‘Tatooine-like’ system has been found for the first time by a UCL-led team of researchers.

    Published today in Nature Astronomy and funded by the Science and Technology Facilities Council and the European Research Council, the study finds the remains of shattered asteroids orbiting a double sun consisting of a white dwarf and a brown dwarf roughly 1000 light-years away in a system called SDSS 1557.

    The discovery is remarkable because the debris appears to be rocky and suggests that terrestrial planets like Tatooine – Luke Skywalker’s home world in Star Wars – might exist in the system. To date, all exoplanets discovered in orbit around double stars are gas giants, similar to Jupiter, and are thought to form in the icy regions of their systems.

    In contrast to the carbon-rich icy material found in other double star systems, the planetary material identified in the SDSS 1557 system has a high metal content, including silicon and magnesium. These elements were identified as the debris flowed from its orbit onto the surface of the star, polluting it temporarily with at least 1017 g (or 1.1 trillion US tons) of matter, equating it to an asteroid at least 4 km in size.

    Lead author, Dr Jay Farihi (UCL Physics & Astronomy), said: “Building rocky planets around two suns is a challenge because the gravity of both stars can push and pull tremendously, preventing bits of rock and dust from sticking together and growing into full-fledged planets. With the discovery of asteroid debris in the SDSS 1557 system, we see clear signatures of rocky planet assembly via large asteroids that formed, helping us understand how rocky exoplanets are made in double star systems.”

    In the Solar System, the asteroid belt contains the leftover building blocks for the terrestrial planets Mercury, Venus, Earth, and Mars, so planetary scientists study the asteroids to gain a better understanding of how rocky, and potentially habitable planets are formed. The same approach was used by the team to study the SDSS 1557 system as any planets within it cannot yet be detected directly but the debris is spread in a large belt around the double stars, which is a much larger target for analysis.

    The discovery came as a complete surprise, as the team assumed the dusty white dwarf was a single star but co-author Dr Steven Parsons (University of Valparaíso and University of Sheffield), an expert in double star (or binary) systems noticed the tell-tale signs. “We know of thousands of binaries similar to SDSS 1557 but this is the first time we’ve seen asteroid debris and pollution. The brown dwarf was effectively hidden by the dust until we looked with the right instrument”, added Parsons, “but when we observed SDSS 1557 in detail we recognised the brown dwarf’s subtle gravitational pull on the white dwarf.”

    The team studied the binary system and the chemical composition of the debris by measuring the absorption of different wavelengths of light or ‘spectra’, using the Gemini Observatory South telescope and the European Southern Observatory Very Large Telescope, both located in Chile.

    Co-author Professor Boris Gänsicke (University of Warwick) analysed these data and found they all told a consistent and compelling story. “Any metals we see in the white dwarf will disappear within a few weeks, and sink down into the interior, unless the debris is continuously flowing onto the star. We’ll be looking at SDSS 1557 next with Hubble, to conclusively show the dust is made of rock rather than ice.”

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    Gemini/North telescope at Mauna Kea, Hawaii, USA
    Gemini/North telescope at Mauna Kea, Hawaii, USA

    Gemini South
    Gemini South telescope, Cerro Tololo Inter-American Observatory (CTIO) campus near La Serena, Chile

    AURA Icon

    Gemini’s mission is to advance our knowledge of the Universe by providing the international Gemini Community with forefront access to the entire sky.

    The Gemini Observatory is an international collaboration with two identical 8-meter telescopes. The Frederick C. Gillett Gemini Telescope is located on Mauna Kea, Hawai’i (Gemini North) and the other telescope on Cerro Pachón in central Chile (Gemini South); together the twin telescopes provide full coverage over both hemispheres of the sky. The telescopes incorporate technologies that allow large, relatively thin mirrors, under active control, to collect and focus both visible and infrared radiation from space.

    The Gemini Observatory provides the astronomical communities in six partner countries with state-of-the-art astronomical facilities that allocate observing time in proportion to each country’s contribution. In addition to financial support, each country also contributes significant scientific and technical resources. The national research agencies that form the Gemini partnership include: the US National Science Foundation (NSF), the Canadian National Research Council (NRC), the Chilean Comisión Nacional de Investigación Cientifica y Tecnológica (CONICYT), the Australian Research Council (ARC), the Argentinean Ministerio de Ciencia, Tecnología e Innovación Productiva, and the Brazilian Ministério da Ciência, Tecnologia e Inovação. The observatory is managed by the Association of Universities for Research in Astronomy, Inc. (AURA) under a cooperative agreement with the NSF. The NSF also serves as the executive agency for the international partnership.

     
  • richardmitnick 12:33 pm on September 22, 2016 Permalink | Reply
    Tags: , , Cosmology is safe, , Scientists confirm the universe has no direction, UCL   

    From ICL: “Scientists confirm the universe has no direction” 

    Imperial College London
    Imperial College London

    22 September 2016
    Hayley Dunning

    1
    The universe is not spinning or stretched in any particular direction, according to the most stringent test yet.

    Looking out into the night sky, we see a clumpy universe: planets orbit stars in solar systems and stars are grouped into galaxies, which in turn form enormous galaxy clusters. But cosmologists assume this effect is only local: that if we look on sufficiently large scales, the universe is actually uniform.

    The vast majority of calculations made about our universe start with this assumption: that the universe is broadly the same, whatever your position and in whichever direction you look.

    If, however, the universe was stretching preferentially in one direction, or spinning about an axis in a similar way to the Earth rotating, this fundamental assumption, and all the calculations that hinge on it, would be wrong.

    Now, scientists from University College London and Imperial College London have put this assumption through its most stringent test yet and found only a 1 in 121,000 chance that the universe is not the same in all directions.

    Oldest light in the universe

    To do this, they used maps of the cosmic microwave background (CMB) radiation: the oldest light in the universe created shortly after the Big Bang.

    CMB per ESA/Planck
    CMB per ESA/Planck

    The maps were produced using measurements of the CMB taken between 2009 and 2013 by the European Space Agency’s Planck satellite, providing a picture of the intensity and, for the first time, polarisation (in essence, the orientation) of the CMB across the whole sky.

    Previously, scientists had looked for patterns in the CMB map that might hint at a rotating universe. The new study considered the widest possible range of universes with preferred directions or spins and determined what patterns these would create in the CMB.

    A universe spinning about an axis, for example, would create spiral patterns, whereas a universe expanding at different speeds along different axes would create elongated hot and cold spots.

    2
    Four potential CMB patterns for universes with direction. No image credit.

    Dr Stephen Feeney, from the Department of Physics at Imperial, worked with a team led by Daniela Saadeh at University College London to search for these patterns in the observed CMB. The results, published today in the journal Physical Review Letters, show that none were a match, and that the universe is most likely directionless.

    Cosmology is safe

    Dr Feeney said: “This work is important because it tests one of the fundamental assumptions on which almost all cosmological calculations are based: that the universe is the same in every direction. If this assumption is wrong, and our universe spins or stretches in one direction more than another, we’d have to rethink our basic picture of the universe.

    “We have put this assumption to its most exacting examination yet, testing for a huge variety of spinning and stretching universes that have never been considered before. When we compare these predictions to the Planck satellite’s latest measurements, we find overwhelming evidence that the universe is the same in all directions.”

    Lead author Daniela Saadeh from University College London added: “You can never rule it out completely, but we now calculate the odds that the universe prefers one direction over another at just 1 in 121,000. We’re very glad that our work vindicates what most cosmologists assume. For now, cosmology is safe.”

    The work was kindly supported by the Perren Fund, IMPACT fund, Royal Astronomical Society, Science and Technology Facilities Council, Royal Society, European Research Council, and Engineering and Physical Sciences Research Council.

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    Imperial College London

    Imperial College London is a science-based university with an international reputation for excellence in teaching and research. Consistently rated amongst the world’s best universities, Imperial is committed to developing the next generation of researchers, scientists and academics through collaboration across disciplines. Located in the heart of London, Imperial is a multidisciplinary space for education, research, translation and commercialisation, harnessing science and innovation to tackle global challenges.

     
  • richardmitnick 12:35 pm on July 6, 2016 Permalink | Reply
    Tags: , , , Magnetic Rope' observed for the first time between Saturn and the Sun, UCL   

    From UCL: ” ‘Magnetic Rope’ observed for the first time between Saturn and the Sun” 

    UCL bloc

    University College London

    6 July 2016
    No writer credit

    This post is dedicated to J.T., who just accessed social media.

    A twisted magnetic field structure, previously never seen before at Saturn, has now been detected for the first time, using instrumentation built at UCL and Imperial College.

    When the Sun’s magnetic field interacts with the Earth’s magnetic field (the magnetosphere), a complex process occurs called magnetic reconnection which can twist the field into a helical shape.

    2
    No image caption. No image credit

    These twisted helically structured magnetic fields are called flux ropes or “flux transfer events” (FTEs) and are observed at Earth and even more commonly at Mercury. The conditions that allow FTEs to be generated at a planet worsen with distance from the Sun, however they have been observed at all the planets out to Jupiter.

    The observation of this phenomenon at Saturn has been elusive. Searches have been undertaken to find an FTE with NASA’s Cassini spacecraft, with reports published of none being found. Up until now….

    NASA/ESA/ASI Cassini Spacecraft
    NASA/ESA/ASI Cassini Spacecraft

    The Cassini spacecraft has been in orbit around Saturn since 2004, and after many years analyzing the data collected, Cassini has observed the first FTE at Saturn. The observed magnetic signature was successfully compared to that of a model to show that Cassini indeed observed a flux rope at this giant magnetosphere, and that the spacecraft passed close to the structure’s center. It is also estimated that the flux rope could be up to 8300 kilometers wide.

    “Contrary to previous ideas about Saturn’s magnetosphere being unlike its terrestrial counterpart, these findings reveal that Saturn at times behaves and interacts with the Sun in much the same way as Earth.” Jamie Jasinski, UCL Space and Climate Physics PhD graduate now based at the University of Michigan, and lead author of the new paper published today in Geophysical Research Letters. Click here for link to paper.

    This not only shows that magnetic reconnection occurs at Saturn but also that Saturn’s magnetic field can at times interact with the Sun in much the same way as at Earth.

    The analysis was completed using a particle spectrometer built at UCL and a magnetometer built at Imperial College, both of which are onboard NASA’s Cassini spacecraft.

    The Cassini mission will end in November 2017, when the spacecraft will be steered into the planet to study it, before disintegrating in Saturn’s thick atmosphere.

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    UCL campus

    UCL was founded in 1826 to open up higher education in England to those who had been excluded from it – becoming the first university in England to admit women students on equal terms with men in 1878.

    Academic excellence and research that addresses real-world problems inform our ethos to this day and are central to our 20-year strategy.

     
  • richardmitnick 1:44 pm on December 20, 2015 Permalink | Reply
    Tags: , , Earth's oxygenation, UCL   

    From UCL: “Life exploded on Earth after slow rise of oxygen” 

    UCL bloc

    University College London

    18 December 2015
    Bex Caygill
    Tel: +44 (0)20 3108 3846
    Email: r.caygill [at] ucl.ac.uk

    It took 100 million years for oxygen levels in the oceans and atmosphere to increase to the level that allowed the explosion of animal life on Earth about 600 million years ago, according to a UCL-led study funded by the Natural Environment Research Council.

    1
    Fictional Snowball Earth (courtesy of Neethis via Wikimedia Commons)

    Before now it was not known how quickly Earth’s oceans and atmosphere became oxygenated and if animal life expanded before or after oxygen levels rose. The new study, published today in Nature Communications, shows the increase began significantly earlier than previously thought and occurred in fits and starts spread over a vast period. It is therefore likely that early animal evolution was kick-started by increased amounts of oxygen, rather than a change in animal behaviour leading to oxygenation.

    Lead researcher, Dr Philip Pogge von Strandmann (UCL Earth Sciences), said: “We want to find out how the evolution of life links to the evolution of our climate. The question on how strongly life has actively modified Earth’s climate, and why the Earth has been habitable for so long is extremely important for understanding both the climate system, and why life is on Earth in the first place.”

    Researchers from UCL, Birkbeck, Bristol University, University of Washington, University of Leeds, Utah State University and University of Southern Denmark tracked what was happening with oxygen levels globally 770 – 520 million years ago (Ma) using new tracers in rocks across the US, Canada and China.

    Samples of rocks that were laid down under the sea at different times were taken from different locations to piece together the global picture of the oxygen levels of Earth’s oceans and atmosphere. By measuring selenium isotopes in the rocks, the team revealed that it took 100 million years for the amount of oxygen in the atmosphere to climb from less than 1% to over 10% of today’s current level. This was arguably the most significant oxygenation event in Earth history because it ushered in an age of animal life that continues to this day.

    Dr Pogge von Strandmann, said: “We took a new approach by using selenium isotope tracers to analyse marine shales which gave us more information about the gradual changes in oxygen levels than is possible using the more conventional techniques used previously. We were surprised to see how long it took Earth to produce oxygen and our findings dispel theories that it was a quick process caused by a change in animal behaviour.”

    During the period studied, three big glaciations –the ‘snowball Earth’ Sturtian (~716Ma), and Marinoan (~635Ma) glaciations and the smaller Gaskiers glaciation (~580Ma) – occurred whereby the Earth’s land was covered in ice and most of the oceans were frozen from the poles to the tropics. During these periods, temperatures plummeted and rose again, causing glacial melting and an influx of nutrients into the ocean, which researchers think caused oxygen levels to rise deep in the oceans.

    Increased nutrients means more ocean plankton, which will bury organic carbon in seafloor sediments when they die. Burying carbon results in oxygen increasing, dramatically changing conditions on Earth. Until now, oxygenation was thought to have occurred after the relatively small Gaskiers glaciation melted. The findings from this study pushes it much earlier, to the Marinoan glaciation, after which animals began to flourish in the improved conditions, leading to the first big expansion of animal life.

    Co-author Professor David Catling (University of Washington Earth and Space Sciences), added: “Oxygen was like a slow fuse to the explosion of animal life. Around 635 Ma, enough oxygen probably existed to support tiny sponges. Then, after 580 Ma, strange creatures, as thin as crêpes, lived on a lightly oxygenated seafloor. Fifty million years later, vertebrate ancestors were gliding through oxygen-rich seawater. Tracking how oxygen increased is the first step towards understanding why it took so long. Ultimately, a grasp of geologic controls on oxygen levels can help us understand whether animal-like life might exist or not on Earth-like planets elsewhere.”

    Links

    Paper in Nature Communications

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    UCL campus

    UCL was founded in 1826 to open up higher education in England to those who had been excluded from it – becoming the first university in England to admit women students on equal terms with men in 1878.

    Academic excellence and research that addresses real-world problems inform our ethos to this day and are central to our 20-year strategy.

     
  • richardmitnick 9:35 am on February 7, 2015 Permalink | Reply
    Tags: , , , Twinkle project, UCL   

    From astrobio.net: “New Mission, Twinkle, on Fast-Track to Unveil Exoplanet Atmospheres” 

    Astrobiology Magazine

    Astrobiology Magazine

    Feb 6, 2015

    1
    Artist’s impression of a hot Neptune-sized planet orbiting a star beyond our Sun. Credit:NASA/JPL-Caltech

    A team of UK scientists and engineers have announced plans for a small satellite, named “Twinkle,” that will give radical new insights into the chemistry, formation and evolution of planets orbiting other stars.

    The mission, which is being led by University College London (UCL) and Surrey Satellite Technology Ltd. (SSTL), will be launched within four years. An overview of the science case and instrument design will be presented today at an open meeting at the Royal Astronomical Society.

    “Twinkle is a very ambitious mission,” said lead scientist, Prof. Giovanna Tinetti of UCL. “Nearly two thousand exoplanets — planets orbiting stars other than our Sun — have been discovered to date, but we know very little about these alien worlds. We can measure their mass, density and distance from their star. From that, we can deduce that that some are freezing cold, some are so hot that they have molten surfaces, some are vast balls of gas, like Jupiter, or small and rocky, like Earth. But beyond that, we just don’t know. Twinkle will be the first mission dedicated to analyzing exoplanets atmospheres, and will give us a completely new picture of what these worlds are really like.”

    When an exoplanet passes in front of the star that it orbits, a tiny amount of starlight is filtered through the molecules and clouds in the planet’s atmosphere. Twinkle will measure this light and pick out the characteristic spectral “fingerprints” that show if gases like water vapor or methane are present on the planet.

    Tinetti played a key role in the team that pioneered this technique through observations with the Hubble and Spitzer Space Telescopes.

    NASA Hubble Telescope
    Hubble

    NASA Spitzer Telescope
    Spitzer

    Knowledge of the chemical composition of exoplanet atmospheres is essential for understanding whether a planet was born in the orbit in which it is currently observed or whether it has migrated from a different part of its planetary system.

    The make-up, evolution, chemistry and physical processes driving an exoplanet’s atmosphere are strongly affected by the distance from its parent star. The atmospheres of small, terrestrial type-planets may have evolved quite dramatically from their initial composition. The loss of lighter molecules, impacts with other bodies, such as comets or asteroids, volcanic activity, or even life can significantly alter the composition of primordial atmospheres. Atmospheric composition is therefore a tracer of an exoplanet’s history as well as whether it might be habitable — or even host life.

    twinkle
    Rendering of the Twinkle mission spacecraft, which will be built by Surrey Satellite Technology Ltd. Credit: Twinkle/SSTL

    Twinkle will analyze at least 100 exoplanets in the Milky Way. Its infrared spectrograph will enable observations of a wide range of planet types including super-Earths (rocky planets 1-10 times the mass of Earth) and hot Jupiters (gas giants orbiting very close to their suns).

    2

    Some of the target planets are orbiting stars similar to our Sun and some are orbiting cooler red dwarfs. For the largest planets orbiting bright stars, Twinkle will even be able to produce maps of clouds and temperature.

    “The light filtered through the planet’s atmosphere is only about one ten thousandth of the overall light from the star,” said Tinetti. “That’s a big challenge and one that requires a very stable platform outside the screening effects of Earth’s atmosphere.”

    While the construction of Twinkle’s scientific instrument is led by UCL, the spacecraft itself will be built by SSTL, based in Guildford, Surrey. SSTL has innovated the concept of rapid and cost-effective spacecraft development, which has resulted in a significant export market for commercial and government Earth observation missions.

    “This is an exciting opportunity to adapt the high-performance capacity we have developed at SSTL to deliver ground-breaking science,” said Dr. Susan Jason, lead engineer from SSTL.

    Twinkle will be launched into a polar low-Earth orbit. The spacecraft will be built to operate for a minimum of three years, with the possibility of an extended lifetime of five years or more. The mission will be funded through a mixture of private and public sources. With a total mission cost of around £50 million, including launch, Twinkle is a factor of 10 times cheaper to build and operate than other astrophysical spacecraft developed through international space agency programs. The short development timescale and low budget are made possible through expertise already developed at UK institutions and the use of off-the-shelf components.

    “The UK has already made an outstanding contribution to exoplanet detection with the WASP survey program. Twinkle is a unique chance for the UK to build on this and take the world lead in understanding exoplanet science, as well as to inspire the next generation of scientists and engineers,” said Prof. Jonathan Tennyson, senior advisor for the Twinkle mission.

    Twinkle project press release

    See the full article here.

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    NASA

     
c
Compose new post
j
Next post/Next comment
k
Previous post/Previous comment
r
Reply
e
Edit
o
Show/Hide comments
t
Go to top
l
Go to login
h
Show/Hide help
shift + esc
Cancel
%d bloggers like this: