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  • richardmitnick 7:44 pm on August 24, 2017 Permalink | Reply
    Tags: , , , , Kavli Institute for Cosmology, , , U Cambridge   

    From Kavli Institute for Cosmology, U Cambridge: “Ripples in Cosmic Web Measured Using Rare Double Quasars” 

    KavliFoundation

    The Kavli Foundation

    Kavli Institute for Cosmology, Cambridge

    Apr 28, 2017 [Where has this been?]

    1
    Volume rendering of the output from a supercomputer simulation showing part of the cosmic web, 11.5 billion years ago.

    The most barren regions of the Universe are the far-flung corners of intergalactic space. In these vast expanses between the galaxies there are only a few atoms per cubic meter – a diffuse haze of hydrogen gas left over from the Big Bang. Viewed on the largest scales, this diffuse material nevertheless accounts for the majority of atoms in the Universe, and fills the cosmic web, its tangled strands spanning billions of light years.

    Now a team of astronomers including Alberto Rorai and Girish Kulkarni, post-doctoral researchers at the Kavli Institute for Cosmology, University of Cambridge, have made the first measurements of small scale ripples in this primeval hydrogen gas. Although the regions of cosmic web they studied lie nearly 11 billion light years away, they were able to measure variations in its structure on scales a hundred thousand times smaller, comparable to the size of a single galaxy. Their results appear in the journal Science.

    2
    Schematic representation of the technique used to probe the small-scale structure of the cosmic web using light from a rare quasar pair. The spectra (bottom right) contain information about the hydrogen gas the light has encountered, as well as the distance of that gas. Image: Springel et al. (2005) (cosmic web) / J. Neidel, MPIA

    Intergalactic gas is so tenuous that it emits no light of its own. Instead astronomers study it indirectly by observing how it selectively absorbs the light coming from faraway sources known as quasars. Quasars constitute a brief hyper luminous phase of the galactic life-cycle, powered by the infall of matter onto a galaxy’s central supermassive black hole. Quasars act like cosmic lighthouses – bright, distant beacons that allow astronomers to study intergalactic atoms residing between the quasars location and Earth. But because these hyper luminous episodes last only a tiny fraction of a galaxy’s lifetime, quasars are correspondingly rare on the sky, and are typically separated by hundreds of millions of light years from each other.

    In order to probe the cosmic web on much smaller length scales, the astronomers exploited a fortuitous cosmic coincidence: they identified exceedingly rare pairs of quasars, right next to each other on the sky, and measured subtle differences in the absorption of intergalactic atoms measured along the two sightlines.

    Rorai, lead author of the study, says “One of the biggest challenges was developing the mathematical and statistical tools to quantify the tiny differences we measure in this new kind of data”. Rorai developed these tools as part of the research for his doctoral degree, and applied his tools to spectra of quasars obtained with the largest telescopes in the world, including the 10m diameter Keck telescopes at the summit of Mauna Kea in Hawaii, as well as ESO’s 8m diameter Very Large Telescope on Cerro Paranal, and the 6.5m diameter Magellan telescope at Las Campanas Observatory, both located in the Chilean Atacama Desert.

    The astronomers compared their measurements to supercomputer models that simulate the formation of cosmic structures from the Big Bang to the present. “The input to our simulations are the laws of Physics and the output is an artificial Universe which can be directly compared to astronomical data. I was delighted to see that these new measurements agree with the well-established paradigm for how cosmic structures form.” says Jose Oñorbe, a post-doctoral researcher at the Max Planck Institute for Astronomy in Heidelberg, who led the supercomputer simulation effort. On a single laptop, these complex calculations would have required almost a thousand years to complete, but modern supercomputers enabled the researchers to carry them out in just a few weeks.

    Joseph Hennawi, professor of physics at UC Santa Barbara who led the search for these rare quasar pairs, explains “One reason why these small-scale fluctuations are so interesting is that they encode information about the temperature of gas in the cosmic web just a few billion years after the Big Bang.” Astronomers believe that the matter in the Universe went through phase transitions billions of years ago, which dramatically changed its temperature. These phase transitions, known as cosmic reionization, occurred when the collective ultraviolet glow of all stars and quasars in the Universe became intense enough to strip electrons off of the atoms in intergalactic space. How and when reionization occurred is one of the biggest open questions in the field of cosmology, and these new measurements provide important clues that will help narrate this chapter of cosmic history.

    3
    Spectra of both members of a close quasar pair used in the study. The subtle differences in the absorption features between the two sightlines allow the researchers to probe the small-scale structure of the cosmic web. Image: Rorai et al. / MPIA

    See the full article here .
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    The Kavli Foundation, based in Oxnard, California, is dedicated to the goals of advancing science for the benefit of humanity and promoting increased public understanding and support for scientists and their work.

    The Foundation’s mission is implemented through an international program of research institutes, professorships, and symposia in the fields of astrophysics, nanoscience, neuroscience, and theoretical physics as well as prizes in the fields of astrophysics, nanoscience, and neuroscience.

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  • richardmitnick 10:03 am on July 12, 2017 Permalink | Reply
    Tags: , , , , Smallest-ever star discovered by astronomers EBLM J0555-57Ab, U Cambridge   

    From U Cambridge: “Smallest-ever star discovered by astronomers” 

    U Cambridge bloc

    Cambridge University

    12 Jul 2017
    Sarah Collins
    sarah.collins@admin.cam.ac.uk

    1
    A star about the size of Saturn – the smallest ever measured – has been identified by astronomers. No image credit.

    The smallest star yet measured has been discovered by a team of astronomers led by the University of Cambridge. With a size just a sliver larger than that of Saturn, the gravitational pull at its stellar surface is about 300 times stronger than what humans feel on Earth.

    The star is likely as small as stars can possibly become, as it has just enough mass to enable the fusion of hydrogen nuclei into helium. If it were any smaller, the pressure at the centre of the star would no longer be sufficient to enable this process to take place. Hydrogen fusion is also what powers the Sun, and scientists are attempting to replicate it as a powerful energy source here on Earth.

    These very small and dim stars are also the best possible candidates for detecting Earth-sized planets which can have liquid water on their surfaces, such as TRAPPIST-1, an ultracool dwarf surrounded by seven temperate Earth-sized worlds.

    The TRAPPIST-1 star, an ultracool dwarf, is orbited by seven Earth-size planets (NASA).

    ESO Belgian robotic Trappist National Telescope at Cerro La Silla, Chile interior

    ESO Belgian robotic Trappist-South National Telescope at Cerro La Silla, Chile

    The newly-measured star, called EBLM J0555-57Ab, is located about six hundred light years away. It is part of a binary system, and was identified as it passed in front of its much larger companion, a method which is usually used to detect planets, not stars. Details will be published in the journal Astronomy & Astrophysics.

    “Our discovery reveals how small stars can be,” said Alexander Boetticher, the lead author of the study, and a Master’s student at Cambridge’s Cavendish Laboratory and Institute of Astronomy. “Had this star formed with only a slightly lower mass, the fusion reaction of hydrogen in its core could not be sustained, and the star would instead have transformed into a brown dwarf.”

    EBLM J0555-57Ab was identified by WASP, a planet-finding experiment run by the Universities of Keele, Warwick, Leicester and St Andrews.

    SuperWASP telescope, located on the island of La Palma amongst the Isaac Newton Group of telescopes (ING)

    EBLM J0555-57Ab was detected when it passed in front of, or transited, its larger parent star, forming what is called an eclipsing stellar binary system.

    Planet transit. NASA/Ames

    The parent star became dimmer in a periodic fashion, the signature of an orbiting object. Thanks to this special configuration, researchers can accurately measure the mass and size of any orbiting companions, in this case a small star. The mass of EBLM J0555-57Ab was established via the Doppler, wobble method, using data from the CORALIE spectrograph.

    ESO Swiss 1.2 meter Leonhard Euler Telescope at La Silla, using the CORALIE spectrograph

    “This star is smaller, and likely colder than many of the gas giant exoplanets that have so far been identified,” said von Boetticher. “While a fascinating feature of stellar physics, it is often harder to measure the size of such dim low-mass stars than for many of the larger planets. Thankfully, we can find these small stars with planet-hunting equipment, when they orbit a larger host star in a binary system. It might sound incredible, but finding a star can at times be harder than finding a planet.”

    This newly-measured star has a mass comparable to the current estimate for TRAPPIST-1, but has a radius that is nearly 30% smaller. “The smallest stars provide optimal conditions for the discovery of Earth-like planets, and for the remote exploration of their atmospheres,” said co-author Amaury Triaud, senior researcher at Cambridge’s Institute of Astronomy. “However, before we can study planets, we absolutely need to understand their star; this is fundamental.”

    Although they are the most numerous stars in the Universe, stars with sizes and masses less than 20% that of the Sun are poorly understood, since they are difficult to detect due to their small size and low brightness. The EBLM project, which identified the star in this study, aims to plug that lapse in knowledge. “Thanks to the EBLM project, we will achieve a far greater understanding of the planets orbiting the most common stars that exist, planets like those orbiting TRAPPIST-1,” said co-author Professor Didier Queloz of Cambridge’ Cavendish Laboratory.

    See the full article here .

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    U Cambridge Campus

    The University of Cambridge (abbreviated as Cantab in post-nominal letters) is a collegiate public research university in Cambridge, England. Founded in 1209, Cambridge is the second-oldest university in the English-speaking world and the world’s fourth-oldest surviving university. It grew out of an association of scholars who left the University of Oxford after a dispute with townsfolk. The two ancient universities share many common features and are often jointly referred to as “Oxbridge”.

    Cambridge is formed from a variety of institutions which include 31 constituent colleges and over 100 academic departments organised into six schools. The university occupies buildings throughout the town, many of which are of historical importance. The colleges are self-governing institutions founded as integral parts of the university. In the year ended 31 July 2014, the university had a total income of £1.51 billion, of which £371 million was from research grants and contracts. The central university and colleges have a combined endowment of around £4.9 billion, the largest of any university outside the United States. Cambridge is a member of many associations and forms part of the “golden triangle” of leading English universities and Cambridge University Health Partners, an academic health science centre. The university is closely linked with the development of the high-tech business cluster known as “Silicon Fen”.

     
  • richardmitnick 1:46 pm on July 5, 2017 Permalink | Reply
    Tags: , , , , , , , , U Cambridge   

    From U Cambridge: “Fastest stars in the Milky Way are ‘runaways’ from another galaxy” 

    U Cambridge bloc

    Cambridge University

    05 Jul 2017
    Sarah Collins
    sarah.collins@admin.cam.ac.uk

    1
    Artist’s impression of a runaway star. Credit: Amanda Smith, Institute of Astronomy.

    A group of astronomers have shown that the fastest-moving stars in our galaxy – which are travelling so fast that they can escape the Milky Way – are in fact runaways from a much smaller galaxy in orbit around our own. A group of astronomers have shown that the fastest-moving stars in our galaxy – which are travelling so fast that they can escape the Milky Way – are in fact runaways from a much smaller galaxy in orbit around our own.

    The researchers, from the University of Cambridge, used data from the Sloan Digital Sky Survey and computer simulations to demonstrate that these stellar sprinters originated in the Large Magellanic Cloud (LMC), a dwarf galaxy in orbit around the Milky Way.

    SDSS Telescope at Apache Point Observatory, NM, USA

    Large Magellanic Cloud. Adrian Pingstone December 2003

    These fast-moving stars, known as hypervelocity stars, were able to escape their original home when the explosion of one star in a binary system caused the other to fly off with such speed that it was able to escape the gravity of the LMC and get absorbed into the Milky Way. The results are published in the Monthly Notices of the Royal Astronomical Society, and will be presented today (5 July) at the National Astronomy Meeting in Hull.

    Astronomers first thought that the hypervelocity stars, which are large blue stars, may have been expelled from the centre of the Milky Way by a supermassive black hole. Other scenarios involving disintegrating dwarf galaxies or chaotic star clusters can also account for the speeds of these stars but all three mechanisms fail to explain why they are only found in a certain part of the sky.

    To date, roughly 20 hypervelocity stars have been observed, mostly in the northern hemisphere, although it’s possible that there are many more that can only be observed in the southern hemisphere.

    “Earlier explanations for the origin of hypervelocity stars did not satisfy me,” said Douglas Boubert, a PhD student at Cambridge’s Institute of Astronomy and the paper’s lead author. “The hypervelocity stars are mostly found in the Leo and Sextans constellations – we wondered why that is the case.”

    An alternative explanation to the origin of hypervelocity stars is that they are runaways from a binary system. In binary star systems, the closer the two stars are, the faster they orbit one another. If one star explodes as a supernova, it can break up the binary and the remaining star flies off at the speed it was orbiting. The escaping star is known as a runaway. Runaway stars originating in the Milky Way are not fast enough to be hypervelocity because blue stars can’t orbit close enough without the two stars merging. But a fast-moving galaxy could give rise to these speedy stars.

    The LMC is the largest and fastest of the dozens of dwarf galaxies in orbit around the Milky Way. It only has 10% of the mass of the Milky Way, and so the fastest runaways born in this dwarf galaxy can easily escape its gravity. The LMC flies around the Milky Way at 400 kilometres per second and, like a bullet fired from a moving train, the speed of these runaway stars is the velocity they were ejected at plus the velocity of the LMC. This is fast enough for them to be the hypervelocity stars.

    “These stars have just jumped from an express train – no wonder they’re fast,” said co-author Rob Izzard, a Rutherford fellow at the Institute of Astronomy. “This also explains their position in the sky, because the fastest runaways are ejected along the orbit of the LMC towards the constellations of Leo and Sextans.”
    Astronomers first thought that the hypervelocity stars, which are large blue stars, may have been expelled from the centre of the Milky Way by a supermassive black hole. Other scenarios involving disintegrating dwarf galaxies or chaotic star clusters can also account for the speeds of these stars but all three mechanisms fail to explain why they are only found in a certain part of the sky.

    To date, roughly 20 hypervelocity stars have been observed, mostly in the northern hemisphere, although it’s possible that there are many more that can only be observed in the southern hemisphere.

    “Earlier explanations for the origin of hypervelocity stars did not satisfy me,” said Douglas Boubert, a PhD student at Cambridge’s Institute of Astronomy and the paper’s lead author. “The hypervelocity stars are mostly found in the Leo and Sextans constellations – we wondered why that is the case.”

    An alternative explanation to the origin of hypervelocity stars is that they are runaways from a binary system. In binary star systems, the closer the two stars are, the faster they orbit one another. If one star explodes as a supernova, it can break up the binary and the remaining star flies off at the speed it was orbiting. The escaping star is known as a runaway. Runaway stars originating in the Milky Way are not fast enough to be hypervelocity because blue stars can’t orbit close enough without the two stars merging. But a fast-moving galaxy could give rise to these speedy stars.

    The LMC is the largest and fastest of the dozens of dwarf galaxies in orbit around the Milky Way. It only has 10% of the mass of the Milky Way, and so the fastest runaways born in this dwarf galaxy can easily escape its gravity. The LMC flies around the Milky Way at 400 kilometres per second and, like a bullet fired from a moving train, the speed of these runaway stars is the velocity they were ejected at plus the velocity of the LMC. This is fast enough for them to be the hypervelocity stars.

    “These stars have just jumped from an express train – no wonder they’re fast,” said co-author Rob Izzard, a Rutherford fellow at the Institute of Astronomy. “This also explains their position in the sky, because the fastest runaways are ejected along the orbit of the LMC towards the constellations of Leo and Sextans.”

    The researchers used a combination of data from the Sloan Digital Sky Survey and computer simulations to model how hypervelocity stars might escape the LMC and end up in the Milky Way. The researchers simulated the birth and death of stars in the LMC over the past two billion years, and noted down every runaway star. The orbit of the runaway stars after they were kicked out of the LMC was then followed in a second simulation that included the gravity of the LMC and the Milky Way. These simulations allow the researchers to predict where on the sky we would expect to find runaway stars from the LMC.

    “We are the first to simulate the ejection of runaway stars from the LMC – we predict that there are 10,000 runaways spread across the sky,” said Boubert. Half of the simulated stars which escape the LMC are fast enough to escape the gravity of the Milky Way, making them hypervelocity stars. If the previously known hypervelocity stars are runaway stars it would also explain their position in the sky.

    Massive blue stars end their lives by collapsing to a neutron star or black hole after hundreds of millions of years and runaway stars are no different. Most of the runaway stars in the simulation died ‘in flight’ after being kicked out of the LMC. The neutron stars and black holes that are left behind just continue on their way and so, along with the 10,000 runaway stars, the researchers also predict a million runaway neutron stars and black holes flying through the Milky Way.

    “We’ll know soon enough whether we’re right,” said Boubert. “The European Space Agency’s Gaia satellite will report data on billions of stars next year, and there should be a trail of hypervelocity stars across the sky between the Leo and Sextans constellations in the North and the LMC in the South.”

    ESA/GAIA satellite

    See the full article here .

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    U Cambridge Campus

    The University of Cambridge (abbreviated as Cantab in post-nominal letters) is a collegiate public research university in Cambridge, England. Founded in 1209, Cambridge is the second-oldest university in the English-speaking world and the world’s fourth-oldest surviving university. It grew out of an association of scholars who left the University of Oxford after a dispute with townsfolk. The two ancient universities share many common features and are often jointly referred to as “Oxbridge”.

    Cambridge is formed from a variety of institutions which include 31 constituent colleges and over 100 academic departments organised into six schools. The university occupies buildings throughout the town, many of which are of historical importance. The colleges are self-governing institutions founded as integral parts of the university. In the year ended 31 July 2014, the university had a total income of £1.51 billion, of which £371 million was from research grants and contracts. The central university and colleges have a combined endowment of around £4.9 billion, the largest of any university outside the United States. Cambridge is a member of many associations and forms part of the “golden triangle” of leading English universities and Cambridge University Health Partners, an academic health science centre. The university is closely linked with the development of the high-tech business cluster known as “Silicon Fen”.

     
  • richardmitnick 3:58 pm on June 13, 2017 Permalink | Reply
    Tags: , Dr Su Metcalfe, , , U Cambridge   

    From Cambridge: “Meet the Cambridge scientist on verge of curing Multiple Sclerosis” 

    U Cambridge bloc

    Cambridge University

    11 Jun,2017

    1

    Dr Su Metcalfe is sitting quietly reading through some documents in the lobby of the Judge Business School when I arrive for our interview. It would be easy to walk right past her and not know you were in the presence of a woman who could be on the verge of curing multiple sclerosis.

    MS, an auto-immune condition which affects 2.3 million people around the world, attacks cells in the brain and the spinal cord, causing an array of physical and mental side effects including blindness and muscle weakness. At the moment there’s no cure, but Su and her company, LIFNano, hope to change that.

    “Some people get progressive MS, so go straight to the severe form of the disease, but the majority have a relapsing or remitting version,” she says.

    “It can start from the age of 30, and there’s no cure, so all you can do is suppress the immune response, but the drugs that do that have side effects, and you can’t repair the brain. The cost of those drugs is very high, and in the UK there are a lot of people who don’t get treated at all.”

    But now a solution could be in sight thanks to Su, who has married one of the body’s cleverest functions with some cutting-edge technology. The natural side of the equation is provided by a stem cell particle called a LIF.

    Su was working at the university’s department of surgery when she made her big breakthrough: “I was looking to see what controls the immune response and stops it auto-attacking us,” she explains.

    “I discovered a small binary switch, controlled by a LIF, which regulates inside the immune cell itself. LIF is able to control the cell to ensure it doesn’t attack your own body but then releases the attack when needed.

    “That LIF, in addition to regulating and protecting us against attack, also plays a major role in keeping the brain and spinal cord healthy. In fact it plays a major role in tissue repair generally, turning on stem cells that are naturally occurring in the body, making it a natural regenerative medicine, but also plays a big part in repairing the brain when it’s been damaged.

    “So I thought, this is fantastic. We can treat auto-immune disease, and we’ve got something to treat MS, which attacks both the brain and the spinal cord. So you have a double whammy that can stop and reverse the auto-immunity, and also repair the damage caused in the brain.”

    Presumably Su, who has been in Cambridge since she was an undergraduate but retains a soft accent from her native Yorkshire, was dancing a jig of delight around her lab at this point, but she soon hit a snag; the LIF could only survive outside the cell for 20 minutes before being broken down by the body, meaning there was not enough time to deploy it in a therapy. And this is where the technology, in the form of nano-particles, comes in.

    “They are made from the same material as soluble stitches, so they’re compatible with the body and they slowly dissolve,” says Su.

    “We load the cargo of the LIF into those particles, which become the delivery device that slowly dissolve and deliver the LIF over five days. The nano-particle itself is a protective environment, and the enzymes that break it down can’t access it. You can also decorate the surface of the particles with antibodies, so it becomes a homing device that can target specific parts of the brain, for example. So you get the right dose, in the right place, and at the right time.”

    The particles themselves were developed at Yale University, which is listed as co-inventor with Su on the IP. But LIFNano has the worldwide licence to deploy them, and Su believes we are on the verge of a step-change in medicine.

    She says: “Nano-medicine is a new era, and big pharma has already entered this space to deliver drugs while trying to avoid the side effects. The quantum leap is to actually go into biologics and tap into the natural pathways of the body.

    “We’re not using any drugs, we’re simply switching on the body’s own systems of self-tolerance and repair. There aren’t any side effects because all we’re doing is tipping the balance. Auto-immunity happens when that balance has gone awry slightly, and we simply reset that. Once you’ve done that, it becomes self-sustaining and you don’t have to keep giving therapy, because the body has its balance back.”

    LIFNano has already attracted two major funding awards, from drug firm Merck and the Government’s Innovate UK agency. Su herself is something of a novice when it comes to business, but has recruited cannily in the form of chairman Florian Kemmerich and ceo Oliver Jarry, both experienced operators in the pharma sector. With the support of the Judge, the company hopes to attract more investment, with the aim of starting clinical trials in 2020.

    “The 2020 date is ambitious, but with the funding we’ve got and the funding we’re hoping to raise, it should be possible,” says Su.

    “We’ve got everything we need in place to make the nano-particles in a clinically compliant manner, it’s just a case of flicking the switch when we have the money. We’re looking at VCs and big pharma, because they have a strong interest in this area. We’re doing all our pre-clinical work concurrently while bringing in the major funds the company needs to go forward in its own right.”

    Immune cells have been a big part of Su’s career, and as we talk, her passion for her subject is obvious. “I wanted to understand something that was so simple on one level but also so complex,” she says.

    “The immune cell is the only single cell in the body that is its own unity, so it functions alone. It’s probably one of the most powerful cells in the body because it can kill you, and if you haven’t got it you die because you haven’t got it.”

    And MS may just be the start for LIFNano.

    “MS is our key driver at the moment, but it’s going to be leading through to other major auto-immune disease areas,” Su adds.

    “Psoriasis is high up on our list, and diabetes is another. Downstream there are all the dementias, because a LIF is a major health factor for the brain. So if we can get it into the brain we can start protecting against dementia.”

    Now that would be something.

    See the full article here .

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    U Cambridge Campus

    The University of Cambridge (abbreviated as Cantab in post-nominal letters) is a collegiate public research university in Cambridge, England. Founded in 1209, Cambridge is the second-oldest university in the English-speaking world and the world’s fourth-oldest surviving university. It grew out of an association of scholars who left the University of Oxford after a dispute with townsfolk. The two ancient universities share many common features and are often jointly referred to as “Oxbridge”.

    Cambridge is formed from a variety of institutions which include 31 constituent colleges and over 100 academic departments organised into six schools. The university occupies buildings throughout the town, many of which are of historical importance. The colleges are self-governing institutions founded as integral parts of the university. In the year ended 31 July 2014, the university had a total income of £1.51 billion, of which £371 million was from research grants and contracts. The central university and colleges have a combined endowment of around £4.9 billion, the largest of any university outside the United States. Cambridge is a member of many associations and forms part of the “golden triangle” of leading English universities and Cambridge University Health Partners, an academic health science centre. The university is closely linked with the development of the high-tech business cluster known as “Silicon Fen”.

     
  • richardmitnick 8:16 am on May 29, 2017 Permalink | Reply
    Tags: , , Speed of animal evolution enhanced by cooperative behaviour, U Cambridge   

    From Cambridge: “Speed of animal evolution enhanced by cooperative behaviour” We could all learn from that 

    U Cambridge bloc

    Cambridge University

    26 May 2017
    Stuart Roberts
    Stuart.J.Roberts@admin.cam.ac.uk

    1
    A study by scientists from the University of Cambridge has revealed how cooperative behaviour between insect family members changes how rapidly body size evolves – with the speed of evolution increasing when individual animals help one another.

    Cooperative behaviour is a key part of animal family life: parents help offspring by supplying them with food, and siblings can also work together to acquire food. The Cambridge study, published today in Nature Ecology and Evolution, looked at the burying beetle – unusual in the insect world as the parents feed their offspring.

    Larvae in small broods are well supplied with food by their parents and grow large. In the parents’ absence, larvae can also help each other to forage for food. However, in the absence of their parents, small broods of larvae are less effective at helping each other and can never grow as big.

    “For our study, we played the role of natural selection. In some experimental beetle populations, we chose only the largest beetles to breed at each generation and in some we chose only the smallest beetles,” said Benjamin Jarrett from the Department of Zoology at the University of Cambridge, who led the study.

    “Crucially, we also changed the social conditions within beetle families. In some populations, we allowed parents to help their offspring, but in other populations we removed the parents, and larvae had to help each other. We found that the social conditions made a big difference to how quickly beetle body size evolves over generations.”

    Beetles only evolved a larger body size when parents were present to help rear their young. In stark contrast, smaller body size only evolved when beetle parents were removed, and there were too few larvae to help each other.

    The experiment helps explain how different species of burying beetle might have evolved their different body sizes. In general, larger species of beetle have more diligent parents than smaller species.

    Burying beetles use the dead body of a small animal, like a mouse or bird, for reproduction. The parents shave and bury the carcass, to make it into an edible nest for their larvae. The larvae can feed themselves on the carrion, but the parent beetles also regurgitate partly digested food to them. The species used in this study has quite variable levels of parental care: occasionally larvae have to fend for themselves on the carcass because they have been abandoned by their parents.

    “Previous work has focused on the puzzle of how cooperative behaviour evolves, because natural selection seems to favour animals that are selfish,” said Professor Rebecca Kilner, who is senior author of this paper. “We have shown that what happens next, in evolutionary terms, is just as interesting. Once cooperation has evolved, it can change the way in which evolution then unfolds.”

    The researchers now hope to uses experimental evolution to understand what happens across many generations when changing the extent of parental care.

    “We can remove parents from caring for their offspring in one generation, and we do this to their offspring too, and their grandoffspring, and so on,” added Jarrett. “We currently have populations of beetles that have not had parents looking after them as they grow up for 25 generations.

    “What this does is change what evolution is working on. Natural selection is usually acting on the combination of parents and offspring, and now, by removing parents, we have changed the traits on which evolution acts.”

    The paper Cooperative interactions within the family enhance the capacity for evolutionary change in body size, published in Nature Ecology and Evolution, can be found here: http://dx.doi.org/10.1038/241559-017-0178

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

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    U Cambridge Campus

    The University of Cambridge (abbreviated as Cantab in post-nominal letters) is a collegiate public research university in Cambridge, England. Founded in 1209, Cambridge is the second-oldest university in the English-speaking world and the world’s fourth-oldest surviving university. It grew out of an association of scholars who left the University of Oxford after a dispute with townsfolk. The two ancient universities share many common features and are often jointly referred to as “Oxbridge”.

    Cambridge is formed from a variety of institutions which include 31 constituent colleges and over 100 academic departments organised into six schools. The university occupies buildings throughout the town, many of which are of historical importance. The colleges are self-governing institutions founded as integral parts of the university. In the year ended 31 July 2014, the university had a total income of £1.51 billion, of which £371 million was from research grants and contracts. The central university and colleges have a combined endowment of around £4.9 billion, the largest of any university outside the United States. Cambridge is a member of many associations and forms part of the “golden triangle” of leading English universities and Cambridge University Health Partners, an academic health science centre. The university is closely linked with the development of the high-tech business cluster known as “Silicon Fen”.

     
  • richardmitnick 1:23 pm on May 13, 2017 Permalink | Reply
    Tags: , , , , , , , U Cambridge   

    From Cambridge via phys.org: “Scientists investigate debris disk in a nearby planetary system” 

    U Cambridge bloc

    Cambridge University

    phys.org

    May 11, 2017
    Tomasz Nowakowski

    2
    ALMA band 7 (0.86 mm) continuum image of 61 Vir with natural weights and corrected by the primary beam response (FWHM∼ 1700). Credit: Marino et al., 2017.

    ESO/NRAO/NAOJ ALMA Array in Chile in the Atacama at Chajnantor plateau, at 5,000 metres

    Astronomers have recently presented new results of observations of a nearby planetary system known as 61 Virginis (or 61 Vir for short). The observations were focused on investigating the system’s debris disk, which could hold many clues to the nature of planetary formation beyond our solar system. The study is available in a paper published May 4, 2017.

    61 Vir is a G-type, 4.6-billion-year-old main-sequence star about the size of our sun, located approximately 28 light years away. The star is known to be orbited by at least three planets that are five, 18 and 23 times more massive than Earth. One of the most intriguing features of this system is a debris disk extending from 30 to at least 100 AU from the star.

    Debris disks are clouds of planetesimals and dust found in orbits around many stars. Studying such disks could improve our understanding about planet formation and the migration history of planets in planetary systems. With this aim in mind, a team of astronomers led by Sebastian Marino of the University of Cambridge in the U.K., has performed observations of 61 Vir’s debris disk using the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile. These observations were complemented by data from the Submillimetre Common-User Bolometer Array 2 (SCUBA2) installed in the James Clerk Maxwell Telescope (JCMT) at Mauna Kea Observatory in Hawaii.

    East Asia Observatory James Clerk Maxwell telescope, Mauna Kea, Hawaii, USA

    “In this paper, we present the first observations of 61 Vir with ALMA at 0.86 mm, obtained with the aim of studying its debris disc to reveal the location of the parent planetesimals, and place constraints on the presence of planets at large separations that can shape the mass distribution in the disc. (…) In order to obtain the best disc constraints, in our analysis we combine new ALMA band 7 observations and new data at 0.85 mm from SCUBA2 installed on JCMT, thus, incorporating information from small and large angular scale structure,” the researchers wrote in the paper.

    The new study reveals that the debris disk is larger than previously thought. Marino’s team found that it extends from 30 to at least 150 AU. Combined ALMA and SCUBA2/JMCT observations also show that at 0.86 mm the total disc emission is about 3.7 mJy and the disk has a surface density distribution of millimeter sized grains with a power law slope of approximately 0.1.

    Moreover, the researchers assume that a yet unseen fourth planet may lurk somewhere in the system between 61 Vir d at 0.5 AU and the inner edge of the disc. They argue that if the disc was stirred at 150 AU by an additional planet, that unseen alien world should have a mass of at least 10 Earth masses and should orbit its host at a distance between 10 and 20 AU.

    “We found that in order to have stirred the disc out to 150 AU, the planet must be more massive than 10 Earth masses and a semi-major axis between 10 and 20 AU if it has an eccentricity lower than 0.1. Otherwise, for higher eccentricities, it could have a lower mass and a semi-major axis between 4 and 20 AU,” the team concluded.

    See the full article here .

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    The University of Cambridge (abbreviated as Cantab in post-nominal letters) is a collegiate public research university in Cambridge, England. Founded in 1209, Cambridge is the second-oldest university in the English-speaking world and the world’s fourth-oldest surviving university. It grew out of an association of scholars who left the University of Oxford after a dispute with townsfolk. The two ancient universities share many common features and are often jointly referred to as “Oxbridge”.

    Cambridge is formed from a variety of institutions which include 31 constituent colleges and over 100 academic departments organised into six schools. The university occupies buildings throughout the town, many of which are of historical importance. The colleges are self-governing institutions founded as integral parts of the university. In the year ended 31 July 2014, the university had a total income of £1.51 billion, of which £371 million was from research grants and contracts. The central university and colleges have a combined endowment of around £4.9 billion, the largest of any university outside the United States. Cambridge is a member of many associations and forms part of the “golden triangle” of leading English universities and Cambridge University Health Partners, an academic health science centre. The university is closely linked with the development of the high-tech business cluster known as “Silicon Fen”.

     
  • richardmitnick 10:58 am on September 7, 2016 Permalink | Reply
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    From U Cambridge: “Massive holes ‘punched’ through a trail of stars likely caused by dark matter” 

    U Cambridge bloc

    Cambridge University

    07 Sep 2016
    Sarah Collins
    sarah.collins@admin.cam.ac.uk

    1
    Artist’s impression of dark matter clumps around a Milky Way-like galaxy. Credit: V. Belokurov, D. Erkal, S.E. Koposov (IoA, Cambridge). Photo: Colour image of M31 from Adam Evans.

    The discovery of two massive holes punched through a stream of stars could help answer questions about the nature of dark matter, the mysterious substance holding galaxies together.

    Researchers have detected two massive holes which have been ‘punched’ through a stream of stars just outside the Milky Way, and found that they were likely caused by clumps of dark matter, the invisible substance which holds galaxies together and makes up a quarter of all matter and energy in the universe.

    The scientists, from the University of Cambridge, found the holes by studying the distribution of stars in the Milky Way. While the clumps of dark matter that likely made the holes are gigantic in comparison to our Solar System – with a mass between one million and 100 million times that of the Sun – they are actually the tiniest clumps of dark matter detected to date.

    The results, which have been submitted to the Monthly Notices of the Royal Astronomical Society, could help researchers understand the properties of dark matter, by inferring what type of particle this mysterious substance could be made of. According to their calculations and simulations, dark matter is likely made up of particles more massive and more sluggish than previously thought, although such a particle has yet to be discovered.

    “While we do not yet understand what dark matter is formed of, we know that it is everywhere,” said Dr Denis Erkal from Cambridge’s Institute of Astronomy, the paper’s lead author. “It permeates the universe and acts as scaffolding around which astrophysical objects made of ordinary matter – such as galaxies – are assembled.”

    Current theory on how the universe was formed predicts that many of these dark matter building blocks have been left unused, and there are possibly tens of thousands of small clumps of dark matter swarming in and around the Milky Way. These small clumps, known as dark matter sub-haloes, are completely dark, and don’t contain any stars, gas or dust.

    Dark matter cannot be directly measured, and so its existence is usually inferred by the gravitational pull it exerts on other objects, such as by observing the movement of stars in a galaxy. But since sub-haloes don’t contain any ordinary matter, researchers need to develop alternative techniques in order to observe them.

    The technique the Cambridge researchers developed was to essentially look for giant holes punched through a stream of stars. These streams are the remnants of small satellites, either dwarf galaxies or globular clusters, which were once in orbit around our own galaxy, but the strong tidal forces of the Milky Way have torn them apart. The remnants of these former satellites are often stretched out into long and narrow tails of stars, known as stellar streams.

    “Stellar streams are actually simple and fragile structures,” said co-author Dr Sergey Koposov. “The stars in a stellar stream closely follow one another since their orbits all started from the same place. But they don’t actually feel each other’s presence, and so the apparent coherence of the stream can be fractured if a massive body passes nearby. If a dark matter sub-halo passes through a stellar stream, the result will be a gap in the stream which is proportional to the mass of the body that created it.”

    The researchers used data from the stellar streams in the Palomar 5 globular cluster to look for evidence of a sub-halo fly-by. Using a new modelling technique, they were able to observe the stream with greater precision than ever before. What they found was a pair of wrinkled tidal tails, with two gaps of different widths.

    By running thousands of computer simulations, the researchers determined that the gaps were consistent with a fly-by of a dark matter sub-halo. If confirmed, these would be the smallest dark matter clumps detected to date.

    “If dark matter can exist in clumps smaller than the smallest dwarf galaxy, then it also tells us something about the nature of the particles which dark matter is made of – namely that it must be made of very massive particles,” said co-author Dr Vasily Belokurov. “This would be a breakthrough in our understanding of dark matter.”

    The reason that researchers can make this connection is that the mass of the smallest clump of dark matter is closely linked to the mass of the yet unknown particle that dark matter is composed of. More precisely, the smaller the clumps of dark matter, the higher the mass of the particle.

    Since we do not yet know what dark matter is made of, the simplest way to characterise the particles is to assign them a particular energy or mass. If the particles are very light, then they can move and disperse into very large clumps. But if the particles are very massive, then they can’t move very fast, causing them to condense – in the first instance – into very small clumps.

    “Mass is related to how fast these particles can move, and how fast they can move tells you about their size,” said Belokurov. “So that’s why it’s so interesting to detect very small clumps of dark matter, because it tells you that the dark matter particle itself must be very massive.”

    “If our technique works as predicted, in the near future we will be able to use it to discover even smaller clumps of dark matter,” said Erkal. “It’s like putting dark matter goggles on and seeing thousands of dark clumps each more massive than a million suns whizzing around.”

    See the full article here .

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    U Cambridge Campus

    The University of Cambridge (abbreviated as Cantab in post-nominal letters) is a collegiate public research university in Cambridge, England. Founded in 1209, Cambridge is the second-oldest university in the English-speaking world and the world’s fourth-oldest surviving university. It grew out of an association of scholars who left the University of Oxford after a dispute with townsfolk. The two ancient universities share many common features and are often jointly referred to as “Oxbridge”.

    Cambridge is formed from a variety of institutions which include 31 constituent colleges and over 100 academic departments organised into six schools. The university occupies buildings throughout the town, many of which are of historical importance. The colleges are self-governing institutions founded as integral parts of the university. In the year ended 31 July 2014, the university had a total income of £1.51 billion, of which £371 million was from research grants and contracts. The central university and colleges have a combined endowment of around £4.9 billion, the largest of any university outside the United States. Cambridge is a member of many associations and forms part of the “golden triangle” of leading English universities and Cambridge University Health Partners, an academic health science centre. The university is closely linked with the development of the high-tech business cluster known as “Silicon Fen”.

     
  • richardmitnick 9:34 am on September 5, 2016 Permalink | Reply
    Tags: , , U Cambridge   

    From U Cambridge: “New exoplanet think tank will ask the big questions about extra-terrestrial worlds” 

    U Cambridge bloc

    Cambridge University

    05 Sep 2016
    Sarah Collins
    sarah.collins@admin.cam.ac.uk

    1
    Artist’s impression of the ultracool dwarf star TRAPPIST-1 from the surface of one of its planets Credit: ESO/M. Kornmesser

    ESO Trappist InteriorESO Trappist National Telescope at La Silla
    ESO Belgian Trappist National Telescope at Cerro La Silla, Chile

    An international exoplanet ‘think tank’ is meeting this week in Cambridge to deliberate on the ten most important questions that humanity could answer in the next decade about planets outside our solar system.

    With funding from The Kavli Foundation, the think tank will bring together some of the major researchers in exoplanetary science – arguably the most exciting field in modern astronomy – for a series of annual meetings to address the biggest questions in this field which humanity could conceivably answer in the next decade.

    “We’re really at the frontier in exoplanet research,” said Dr Nikku Madhusudhan of Cambridge’s Institute of Astronomy, who is leading the think tank. “The pace of new discoveries is incredible – it really feels like anything can be discovered any moment in our exploration of extra-terrestrial worlds. By bringing together some of the best minds in this field we aim to consolidate our collective wisdom and address the biggest questions in this field that humanity can ask and answer at this time.”

    Tremendous advances have been made in the study of exoplanets since the first such planet was discovered around a sun-like star in 1995 by the Cavendish Laboratory’s Professor Didier Queloz. Just last month, a potentially habitable world was discovered in our own neighbourhood, orbiting Proxima Centauri, the nearest star to the sun.

    Pale Red Dot
    Centauris Alpha Beta Proxima 27, February 2012. Skatebiker
    ESO/Pale Red Dot; Centauris Alpha Beta Proxima 27, February 2012. Skatebiker

    However, there are still plenty questions to be answered, such as whether we’re capable of detecting signatures of life on other planets within the next ten years, what the best strategies are to find habitable planets, how diverse are planets and their atmospheres, and how planets form in the first place.

    With at least four space missions and numerous large ground-based facilities scheduled to become operational in the next decade, exoplanetary scientists will be able to detect more and more exoplanets, and will also have the ability to conduct detailed studies of their atmospheres, interiors, and formation conditions. At the same time, major developments are expected in all aspects of exoplanetary theory and data interpretation.

    In order to make these major advances in the field, new interdisciplinary approaches are required. Additionally, as new scientific questions and areas emerge at an increasingly fast pace, there is a need for a focused forum where emerging questions in frontier areas of the field can be discussed. “Given the exciting advancements in exoplanetary science now is the right time to assess the state of the field and the scientific challenges and opportunities on the horizon,” said Professor Andy Fabian, director of the Institute of Astronomy at Cambridge.

    The think tank will operate in the form of a yearly Exoplanet Symposium series which will be focused on addressing pressing questions in exoplanetary science. One emerging area or theme in exoplanetary science will be chosen each year based on its critical importance to the advancement of the field, relevance to existing or imminent observational facilities, need for an interdisciplinary approach, and/or scope for fundamental breakthroughs.

    About 30 experts in the field from around the world will discuss outstanding questions, new pathways, interdisciplinary synergies, and strategic actions that could benefit the exoplanet research community.

    The inaugural symposium, “Kavli ExoFrontiers 2016”, is being held this week in Cambridge. The goal of this first symposium is to bring together experts from different areas of exoplanetary science to share their visions about the most pressing questions and future outlook of their respective areas. These visions will help provide both a broad outlook of the field and identify the ten most important questions in the field that could be addressed within the next decade. “We hope the think tank will provide a platform for new breakthroughs in the field through interdisciplinary and international efforts while bringing the most important scientific questions of our time to the fore,” said Madhusudhan. “We are in the golden age of exoplanetary science.”

    More information about the Kavli ExoFrontiers 2016 Symposium is available at: http://www.ast.cam.ac.uk/meetings/2016/kavli.exofrontiers.2016.symposium

    See the full article here .

    Please help promote STEM in your local schools.

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    U Cambridge Campus

    The University of Cambridge (abbreviated as Cantab in post-nominal letters) is a collegiate public research university in Cambridge, England. Founded in 1209, Cambridge is the second-oldest university in the English-speaking world and the world’s fourth-oldest surviving university. It grew out of an association of scholars who left the University of Oxford after a dispute with townsfolk. The two ancient universities share many common features and are often jointly referred to as “Oxbridge”.

    Cambridge is formed from a variety of institutions which include 31 constituent colleges and over 100 academic departments organised into six schools. The university occupies buildings throughout the town, many of which are of historical importance. The colleges are self-governing institutions founded as integral parts of the university. In the year ended 31 July 2014, the university had a total income of £1.51 billion, of which £371 million was from research grants and contracts. The central university and colleges have a combined endowment of around £4.9 billion, the largest of any university outside the United States. Cambridge is a member of many associations and forms part of the “golden triangle” of leading English universities and Cambridge University Health Partners, an academic health science centre. The university is closely linked with the development of the high-tech business cluster known as “Silicon Fen”.

     
  • richardmitnick 6:49 am on August 30, 2016 Permalink | Reply
    Tags: , , , U Cambridge   

    From U Cambridge: “Tiny changes in Parkinson’s protein can have “dramatic” impact on processes that lead to the disease” 

    U Cambridge bloc

    Cambridge University

    30 Aug 2016
    Tom Kirk
    tdk25@cam.ac.uk

    1
    Image of “amyloid fibrils”; thread-like structures which form after the protein alpha-synuclein aggregates. Plaques (protein deposits) consisting of this protein have been found in the brains of Parkinson ’s Disease patients and linked to disease. Credit: Patrick Flagmeier

    In a new study, a team of academics at the Centre for Misfolding Diseases, in the Department of Chemistry at the University of Cambridge, show that tiny changes in the amino acid sequence of the protein alpha-synuclein can have a dramatic effect on microscopic processes leading to its aggregation that may occur in the brain, eventually resulting in someone being diagnosed with Parkinson’s Disease.

    Alpha-synuclein is a protein made up of 140 amino acids, and under normal circumstances plays an important part in helping with the smooth flow of chemical signals in the brain.

    Parkinson’s Disease is thought to arise because, for reasons researchers still do not fully understand, the same protein sometimes malfunctions. Instead of adopting the specific structural form needed to do its job, it misfolds and begins to cluster, creating toxic, thread-like structures known as amyloid fibrils. In the case of Parkinson’s Disease, these protein deposits are referred to as Lewy-bodies.

    The new study examined mutated forms of alpha-synuclein which have been found in people from families with a history of Parkinson’s Disease. In all cases, these mutations involved just one change to the protein’s amino acid sequence.

    Although the differences in the sequence are small, the researchers found that they can have a profound effect on how quickly or slowly fibrils start to form. They also found that the mutations strongly influence a process called “secondary nucleation”, in which new fibrils are formed, in an auto-catalytic manner, at the surface of existing ones and thus enable the disease to spread.

    The study stresses that these findings do not explain why humans get the disease. Parkinson’s Disease does not always emerge as a result of the mutations and has multiple, complex causes, which are not fully understood.

    Patrick Flagmeier, a PhD student at St John’s College, University of Cambridge, and the study’s lead author, said: “As a finding, it helps us to understand fundamental things about the system by which this disease emerges. In the end, if we can understand all of this better, that can help us to develop therapeutic strategies to confront it. Our hope is that this study will contribute to the global effort towards comprehending why people with these mutations get the disease more frequently, or at a younger age.”

    Although people who do not have mutated forms of alpha-synuclein can still develop Parkinson’s Disease, the five mutations studied by the research team were already known as “familial” variants – meaning that they recur in families where the disease has emerged, and seem to increase the likelihood of its onset.

    What was not clear, until now, is why they have this effect. “We wanted to know how these specific changes in the protein’s sequence influence its behaviour as it aggregates into fibrils,” Flagmeier said.

    To understand this, the researchers conducted lab tests in which they added each of the five mutated forms of alpha-synuclein, as well as a standard version of the protein, to samples simulating the initiation of fibril formation, their growth and their proliferation.

    The first round of tests examined the initiation of aggregation, using artificial samples recreating conditions in which misfolded alpha-synuclein attaches itself to small structures that are present inside brain cells called lipid vesicles, and then begins to cluster.

    The researchers then tested how the different versions of the protein influence the ability of pre-formed fibrils to extend and grow. Finally, they tested the impact of mutated proteins on secondary nucleation, in which, under specific conditions, the fibrils can multiply and start to spread.

    Overall, the tests revealed that while the mutated forms of alpha-synuclein do not notably influence the fibril growth, they do have a dramatic effect on both the initial formation of the fibrils, and their secondary nucleation. Some of the mutated forms of the protein made these processes considerably faster, while others made it almost “undetectably slow”, according to the researchers’ report.

    “We have only recently discovered the autocatalytic amplification process of alpha-synuclein fibrils, and the results of the present study will help us to understand in much more detail the mechanism behind this process, and in what ways it differs from the initial formation of aggregates.” said Dr. Alexander Buell, one of the senior authors on the study.

    Why the mutations have this impact remains unclear, but the study opens the door to understanding this in detail by identifying, for the first time, that they have such a dramatic impact on very particular stages of the process.

    Dr. Céline Galvagnion, another of the senior authors on the study, said: “This study quantitatively correlates individual changes in the amino acid sequence of alpha-synuclein with its tendency to aggregate. However, the effect of these mutations on other parameters such as the loss of the protein’s function and the efficiency of clearance of alpha-synuclein needs to be taken into account to fully understand the link between the familial mutations of alpha-synuclein and the onset of Parkinson’s Disease.”

    “The effects we observed were changes of several orders of magnitude and it was unexpected to observe such dramatic effects from single-point mutations,” Flagmeier said. “It seems that these single-point mutations in the sequence of alpha-synuclein play an important role in influencing particular microscopic steps in the aggregation process that may lead to Parkinson’s Disease.”

    The full study, which also involves Professors Chris Dobson and Tuomas Knowles, is published in the journal, Proceedings of the National Academy of Sciences.

    Reference:

    Flagmeier, P. et. al: Mutations associated with familial Parkinson’s disease alter the initiation and amplification steps of α-synuclein aggregation. PNAS (2016): DOI: 10.1073/pnas.1604645113

    See the full article here .

    Please help promote STEM in your local schools.

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    U Cambridge Campus

    The University of Cambridge (abbreviated as Cantab in post-nominal letters) is a collegiate public research university in Cambridge, England. Founded in 1209, Cambridge is the second-oldest university in the English-speaking world and the world’s fourth-oldest surviving university. It grew out of an association of scholars who left the University of Oxford after a dispute with townsfolk. The two ancient universities share many common features and are often jointly referred to as “Oxbridge”.

    Cambridge is formed from a variety of institutions which include 31 constituent colleges and over 100 academic departments organised into six schools. The university occupies buildings throughout the town, many of which are of historical importance. The colleges are self-governing institutions founded as integral parts of the university. In the year ended 31 July 2014, the university had a total income of £1.51 billion, of which £371 million was from research grants and contracts. The central university and colleges have a combined endowment of around £4.9 billion, the largest of any university outside the United States. Cambridge is a member of many associations and forms part of the “golden triangle” of leading English universities and Cambridge University Health Partners, an academic health science centre. The university is closely linked with the development of the high-tech business cluster known as “Silicon Fen”.

     
  • richardmitnick 12:17 pm on August 24, 2016 Permalink | Reply
    Tags: Astronomers identify a young heavyweight star in the Milky Way, , , U Cambridge   

    From U Cambridge: “Astronomers identify a young heavyweight star in the Milky Way” 

    U Cambridge bloc

    Cambridge University

    22 Aug 2016
    Sarah Collins
    sarah.collins@admin.cam.ac.uk

    1
    A young star over 30 times more massive than the Sun could help us understand how the most extreme stars in the Universe are born.
    Credit: A. Smith, Institute of Astronomy, Cambridge

    Astronomers have identified a young star, located almost 11,000 light years away, which could help us understand how the most massive stars in the Universe are formed. This young star, already more than 30 times the mass of our Sun, is still in the process of gathering material from its parent molecular cloud, and may be even more massive when it finally reaches adulthood.

    The researchers, led by a team at the University of Cambridge, have identified a key stage in the birth of a very massive star, and found that these stars form in a similar way to much smaller stars like our Sun – from a rotating disc of gas and dust. The results will be presented this week at the Star Formation 2016 conference at the University of Exeter, and are reported in the Monthly Notices of the Royal Astronomical Society.

    In our galaxy, massive young stars – those with a mass at least eight times greater than the Sun – are much more difficult to study than smaller stars. This is because they live fast and die young, making them rare among the 100 billion stars in the Milky Way, and on average, they are much further away.

    “An average star like our Sun is formed over a few million years, whereas massive stars are formed orders of magnitude faster — around 100,000 years,” said Dr John Ilee from Cambridge’s Institute of Astronomy, the study’s lead author. “These massive stars also burn through their fuel much more quickly, so they have shorter overall lifespans, making them harder to catch when they are infants.”

    The protostar that Ilee and his colleagues identified resides in an infrared dark cloud – a very cold and dense region of space which makes for an ideal stellar nursery. However, this rich star-forming region is difficult to observe using conventional telescopes, since the young stars are surrounded by a thick, opaque cloud of gas and dust. But by using the Submillimeter Array (SMA) in Hawaii and the Karl G Jansky Very Large Array (VLA) in New Mexico, both of which use relatively long wavelengths of light to observe the sky, the researchers were able to ‘see’ through the cloud and into the stellar nursery itself.

    CfA Submillimeter Array Hawaii SAO
    CfA Submillimeter Array Hawaii SAO

    NRAO/VLA, on the Plains of San Agustin fifty miles west of Socorro, NM, USA
    NRAO/VLA, on the Plains of San Agustin fifty miles west of Socorro, NM, USA

    By measuring the amount of radiation emitted by cold dust near the star, and by using unique fingerprints of various different molecules in the gas, the researchers were able to determine the presence of a ‘Keplerian’ disc – one which rotates more quickly at its centre than at its edge.

    “This type of rotation is also seen in the Solar System – the inner planets rotate around the Sun more quickly than the outer planets,” said Ilee. “It’s exciting to find such a disc around a massive young star, because it suggests that massive stars form in a similar way to lower mass stars, like our Sun.”

    The initial phases of this work were part of an undergraduate summer research project at the University of St Andrews, funded by the Royal Astronomical Society (RAS). The undergraduate carrying out the work, Pooneh Nazari, said, “My project involved an initial exploration of the observations, and writing a piece of software to ‘weigh’ the central star. I’m very grateful to the RAS for providing me with funding for the summer project — I’d encourage anyone interested in academic research to try one!”

    From these observations, the team measured the mass of the protostar to be over 30 times the mass of the Sun. In addition, the disc surrounding the young star was also calculated to be relatively massive, between two and three times the mass of our Sun. Dr Duncan Forgan, also from St Andrews and lead author of a companion paper, said, “Our theoretical calculations suggest that the disc could in fact be hiding even more mass under layers of gas and dust. The disc may even be so massive that it can break up under its own gravity, forming a series of less massive companion protostars.”

    The next step for the researchers will be to observe the region with the Atacama Large Millimetre Array (ALMA), located in Chile. This powerful instrument will allow any potential companions to be seen, and allow researchers to learn more about this intriguing young heavyweight in our galaxy.

    This work has been supported by a grant from the European Research Council.

    References:
    J.D. Ilee et al. ‘G11.92-0361 MM1: A Keplerian disc around a massive young proto O-star. Monthly Notices of the Royal Astronomical Society (2016): DOI: 10.1093/mnras/stw1912

    D. H. Forgan et al. Self-gravitating disc candidates around massive young stars. Monthly Notices of the Royal Astronomical Society (2016): DOI: 10.1093/mnras/stw1917

    See the full article here.

    Please help promote STEM in your local schools.

    STEM Icon

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    U Cambridge Campus

    The University of Cambridge (abbreviated as Cantab in post-nominal letters) is a collegiate public research university in Cambridge, England. Founded in 1209, Cambridge is the second-oldest university in the English-speaking world and the world’s fourth-oldest surviving university. It grew out of an association of scholars who left the University of Oxford after a dispute with townsfolk. The two ancient universities share many common features and are often jointly referred to as “Oxbridge”.

    Cambridge is formed from a variety of institutions which include 31 constituent colleges and over 100 academic departments organised into six schools. The university occupies buildings throughout the town, many of which are of historical importance. The colleges are self-governing institutions founded as integral parts of the university. In the year ended 31 July 2014, the university had a total income of £1.51 billion, of which £371 million was from research grants and contracts. The central university and colleges have a combined endowment of around £4.9 billion, the largest of any university outside the United States. Cambridge is a member of many associations and forms part of the “golden triangle” of leading English universities and Cambridge University Health Partners, an academic health science centre. The university is closely linked with the development of the high-tech business cluster known as “Silicon Fen”.

     
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