Institute of Astronomy

Astronomy News

Black hole made peek-a-boo galaxy go mysteriously dark

24 June 2014 - 11:49am
A bright galaxy that suddenly went dark was obscured by wind spurting from its central black hole – enhancing our understanding of these distant objects






Spectral ‘ruler’ is first standardised way to measure stars

24 June 2014 - 9:44am

Previously, as with the longitude problem 300 years earlier for fixing locations on Earth, there was no unified system of reference for calibrating the heavens.

But now, when investigating the atmospheric structure and chemical make-up of stars, astronomers can use a new stellar scale as a ‘ruler’ – making it much easier for them to classify and compare data on star discoveries.

In fact, the work is a critical first step in the Gaia satellite’s mission to map the Milky Way, as the unprecedented levels of stellar data that will result need “consistent stellar parameters”, the same way we need values to measure everything from temperature to time, say astronomers.

The guidelines are free to download and are already being used by the world’s largest astronomy projects. The work has recently been published in the journal Astronomy & Astrophysics

The team, including Dr Paula Jofre from the University of Cambridge’s Institute of Astronomy, selected 34 initial ‘benchmark’ stars to represent the different kinds of stellar populations in our galaxy, such as hot stars, cold stars, red giants and dwarfs, as well as stars that cover the different chemical patterns – or ‘metallicity’ – in their spectrum, as this is the “cosmic clock” which allows astronomers to read a star’s age.

This detailed range of information on the 34 stars form the first value set for measuring the millions of stars Gaia aims to catalogue. Many of the benchmark stars can be seen with the human eye, and have been studied for most of human history – dating back to the very first astronomical records from ancient Babylon.          

“We took stars which had been measured a lot so the parameters are very well-known, but needed to be brought to the same scale for the new benchmark - essentially, using the stars we know most about to help measure the stars we know nothing about,” said Jofre. 

“In previous galactic studies, the Sun is used as the standard to show a method is working, along with a few other well-known stars. But I choose this one because it works for my method, you choose a different one for different reasons; data may not match.

“This is the first attempt to cover a wide range of stellar classifications, and do everything from the beginning – methodically and homogenously.”    

Launched at the end of last year, Gaia will gather data on over a billion stars in the Milky Way, allowing astronomers to study for the first time in close detail its myriad stars and planetary systems. Petabytes of data will be sent back to Earth – roughly the equivalent of all the information held in all the libraries of the world today.

The new value system was needed to ensure that analysis of this extraordinary amount of data is done in the most effective and efficient way, a template to measure the vast stream of data against.

Jofre focused on spectroscopic data to work out metallicity: the chemical combination that makes up a star. Just as a raindrop can split sunlight into the colours of the rainbow, spectroscopes split the light from a star into its chemical elements – and the results can be read like a musical score, with high notes or low notes in the scale giving clues as to the star’s age. On average, the higher a star’s metal content the younger it is.

Jofre created a ‘spectral’ library, combining the best data on the atmospheric structure of benchmark stars to determine a uniform scale for metallicity. Together with definitive scales for the stars’ temperatures and surface gravities, produced with colleagues at the University of Uppsala and the University of Bordeaux, her work completes the measuring system that will be used to gauge data from Gaia.

“Now this set of data scales for the benchmark stars can be used as a way of making definitive measurements of others stars – invaluable to astronomers working on a wide range of projects,” Jofre said.

The benchmark stars are already being used as a standardising model by Gaia’s sister project, the Gaia-ESO survey, which is observing stellar spectra at a high resolution from the Very Large Telescope in Chile. They will also provide the basis for the thousands of reference stars needed to set the parameters for the hugely ambitious Gaia satellite once it starts mapping the entire galaxy – the “pillars for the enormous calibrators”.

The fact that the ideal benchmark stars needed to be ones we already have a lot of data on means that many are bright and relatively near to the Earth – and have been the subject of wonder across civilisations.

Aldebaran, Arcturus, Pollux, Procyon and Alpha Centauri have played a part in the culture and mythology of mankind since they were first identified thousands of years ago. Babylonian astronomers used them as a reference point to describe the positions of the moon and planets as they moved through the night sky, appearing in the Babylonian Astronomical Diaries dating back to almost 1000 years BC.

“Many people interested in astronomy know these stars, their position in constellations, and the best time of year to see them. It is amazing that there is still so much to learn about the physics of these most well-known stars," said Dr. Ulrike Heiter from the Uppsala University.

“While stars do move over millennia, for humans they are fixed points – used to navigate the Earth for centuries. We are still using them as fixed points, but this time for navigating the galaxy,” Jofre said.

UK Gaia lead Professor Gerry Gilmore added: “Advances in understanding the history and structure of our Galaxy with ambitious projects are possible only because, like Newton, we see farther by standing on the shoulders of giants. For reliably determining what chemical elements the stars are made of, those giants are the benchmark stars. All our vastly expanding knowledge depends on really understanding the few."

Inset images: Crab Nebula and graphic rendering of the Gaia satellite

A team of astronomers have created the first standardised set of measurement guidelines for analysing and cataloguing stars.

This is the first attempt to cover a wide range of stellar classifications, and do everything from the beginning – methodically and homogenouslyPaula JofreAmanda Smith/Institute of AstronomyThe first standardised way to measure stars has been developed for Gaia mission

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YesNews type: News

Clingy dark matter may slow the spin of corpse stars

23 June 2014 - 6:40pm
Dark matter with a tiny electrical charge could put the brakes on pulsars, offering a new way to look for clues to the nature of the mysterious substance






A (personal) call for a giant space telescope from Martin Barstow. He'll talk ab...

22 June 2014 - 10:40am
A (personal) call for a giant space telescope from Martin Barstow. He'll talk about this on Tuesday at the National Astronomy Meeting. http://www.ras.org.uk/news-and-press/news-archive/254-news-2014/2474-time-to-think-big-a-call-for-a-giant-space-telescope


Time to think big: a call for a giant space telescope
www.ras.org.uk
In the nearly 25 years since the launch of the Hubble Space Telescope (HST), astronomers and the public alike have enjoyed ground-breaking views of the cosmos and the suite of scientific discoveries that followed. The successor to HST, the James Webb Space Telescope should launch in 2018 but will have a comparatively short lifetime. Now Prof Martin Barstow of the University of Leicester is looking to the future. In his talk at the National Astronomy Meeting (NAM 2014) in Portsmouth on Tuesday 24 June, he calls for governments and space agencies around the world to back the Advanced Technologies Large Aperture Space Telescope (ATLAST), an instrument that would give scientists a good chance of detecting hints of life on planets around other stars.

Mountain top exploded to make way for ghost telescope

20 June 2014 - 2:56pm
The telescope that will live on the now-flat summit of Cerro Amazones in the Atacama desert will be the largest of its kind in the world - and a ghost






Confidence drop for Big Bang signal

20 June 2014 - 12:25am
Scientists who claimed to have found a pattern in the sky left by the super-rapid expansion of space just fractions of a second after the Big Bang say they are now less confident of their result.

Groundbreaking for the E-ELT

19 June 2014 - 10:20pm
Today a groundbreaking ceremony took place to mark the next major milestone towards ESO’s European Extremely Large Telescope (E-ELT). Part of the 3000-metre peak of Cerro Armazones was blasted away as a step towards levelling the summit in preparation for the construction of the largest optical/infrared telescope in the world.

Swiftly Moving Gas Streamer Eclipses Supermassive Black Hole

19 June 2014 - 7:00pm

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Active galaxies host supermassive black holes in their cores. The intense gravity of the black hole creates a turbulent cauldron of extreme physics. These galaxies, such as NGC 5548 in this study, are too far away for the plasma fireworks to be directly imaged. Therefore astronomers use X-ray and ultraviolet spectroscopy to infer what is happening near the black hole. The new twist is the detection of a clumpy stream of gas that has swept in front of the black hole, blocking its radiation. This deep look into a black hole's environment yields clues to the behavior of active galaxies.

Hubble:Swiftly moving gas streamer eclipses supermassive black hole [heic1413]

19 June 2014 - 7:00pm
Astronomers have discovered strange and unexpected behaviour around the supermassive black hole at the heart of the galaxy NGC 5548. The international team of researchers detected a clumpy gas stream flowing quickly outwards and blocking 90 percent of the X-rays emitted by the black hole. This activity could provide insights into how supermassive black holes interact with their host galaxies.

Big Bang breakthrough team back-pedals on major result

19 June 2014 - 6:56pm
For the first time, the BICEP2 team – hailed for their gravitational wave discovery earlier this year – have dialled back on the certainty of the result






Doubts about big bang breakthrough won't kill inflation

19 June 2014 - 5:09pm
Cosmic inflation is sound whether or not we have found primordial gravitational waves, says the theory's co-founder Andrei Linde






Swiftly Moving Gas Streamer Eclipses Supermassive Black Hole

19 June 2014 - 5:00pm
An international team of astronomers, using data from several NASA and European Space Agency (ESA) space observatories, has discovered unexpected behavior from the supermassive black hole at the heart of the galaxy NGC 5548, located 244.6 million light-years from Earth. This behavior may provide new insights into how supermassive black holes interact with their host galaxies.

NASA's Hubble Finds Dwarf Galaxies Formed More Than Their Fair Share of Universe's Stars

19 June 2014 - 2:51pm
They may be little, but they pack a big star-forming punch. New observations from NASA's Hubble Space Telescope show small galaxies, also known as dwarf galaxies, are responsible for forming a large proportion of the universe's stars.

Rosetta: Icy quarry coming into view

19 June 2014 - 2:44pm
The Rosetta spacecraft is now 165,000km from Comet 67P/Churyumov-Gerasimenko, and closing. Pictures of the 4km-wide ice ball will now get more and more detailed.

Hubble Finds That Dwarf Galaxies Formed More Than Their Fair Share of the Universe's Stars

19 June 2014 - 1:00pm

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They may be little, but they pack a big star-forming punch. Hubble astronomers have found that dwarf galaxies in the young universe were responsible for an "early wave" of star formation not long after the big bang. The galaxies churned out stars at a furiously fast rate, far above the "normal" star formation expected of galaxies. Understanding the link between a galaxy's mass and its star-forming activity helps to assemble a consistent picture of events in the early universe.

Hubble:Small but significant - Astronomers use Hubble to study bursts of star formation in the dwarf galaxies of the early Universe [heic1412]

19 June 2014 - 1:00pm
They may only be little, but they pack a star-forming punch: new observations from the NASA/ESA Hubble Space Telescope show that starbursts in dwarf galaxies played a bigger role than expected in the early history of the Universe.

Rosetta:Rosetta's comet: expect the unexpected

19 June 2014 - 12:54pm
An image snapped earlier this month by ESA's Rosetta spacecraft shows its target comet has quietened, demonstrating the unpredictable nature of these enigmatic objects.

Mountain to be blasted for telescope

19 June 2014 - 11:35am
The top of a mountain in Chile will be blown up make way for the world's largest optical and infrared telescope.

UK’s COSMOS supercomputing research facility becomes an Intel Parallel Computing Centre

18 June 2014 - 5:00pm

The COSMOS facility, which is located in the Stephen Hawking Centre for Theoretical Cosmology (CTC) at the University, is dedicated to research in cosmology, astrophysics and particle physics. It was switched on in 2012.

To date, the facility has been used to simulate the dynamics of the early Universe and for pipelines analysing the statistics of Planck satellite maps of the cosmic microwave sky. The COSMOS supercomputer was the first very large (over 10 terabyte) single-image shared-memory system to incorporate Intel Xeon Phi coprocessors, which are behind the most power-efficient computers in the world.

Intel Parallel Computing Centres (IPCC) are universities, institutions, and labs that are leaders in their field. The centres are focusing on modernising applications to increase parallelism and scalability through optimisations that leverage cores, caches, threads, and vector capabilities of microprocessors and coprocessors.

As an IPCC, the COSMOS research facility will receive enhanced Intel support from its applications and engineering teams, as well as early access to future Intel Xeon Phi and other Intel products aimed at high-performance computing. IPCC status will allow COSMOS to better focus on delivering computing advances to the scientific community it serves and also highlight the efforts Intel has put into advancing high-performance computing.

When operating at peak performance, the COSMOS Supercomputer can perform 38.6 trillion calculations per second (TFLOPS), and is based on SGI UV2000 systems with 1856 cores of Intel Xeon processors E5-2600, 14.8 TB RAM and 31 Intel® Xeon PhiTM coprocessors.

The research centre has already developed Xeon Phi for use in Planck Satellite analysis of the cosmic microwave sky and for simulations of the very early Universe. These capabilities will become even more important in the near future pending the arrival of new generations of Intel Xeon Phi coprocessors and associated technologies.

“I am very pleased that the COSMOS supercomputer centre has been selected among the vanguard of Intel Parallel Computing Centres worldwide,” said Professor Stephen Hawking, founder of the COSMOS Consortium. “These are exciting times for cosmology as we use COSMOS to directly test our mathematical theories against the latest observational data. Intel’s new technology and this additional support will accelerate our scientific research.”

“Building on COSMOS success to date with Intel’s Many Integrated Core-based technology, our new IPCC status will ensure we remain at the forefront of those exploiting many-core architectures for cosmological research,” said COSMOS director, Professor Paul Shellard. “With the SGI UV2 built around Intel Xeon processors E5-2600 family and Intel Xeon Phi processors, we have a flexible HPC platform on which we can explore Xeon Phi acceleration using distributed, offload and shared-memory programming models. Intel support will ensure fast code development timescales using MICs, enhancing COSMOS competitiveness and discovery potential.”

“Intel Parallel Computing Centres are collaborations to modernise key applications to unlock performance gains that come through parallelism, enabling the way for the next leap in discovery.

We are delighted to be working with the COSMOS team in this endeavour as they strive to understand the origins of the universe,” said Stephan Gillich, Director Technical Computing, Intel EMEA.

COSMOS is part of the Distributed Research utilising Advanced Computing (DiRAC) facility, funded by the Science & Technology Facilities Council and the Department of Business Innovation and Skills.

Cambridge’s COSMOS supercomputer, the largest shared-memory computer in Europe, has been named by computer giant Intel as one of its Parallel Computing Centres, building on a long-standing collaboration between Intel and the University of Cambridge.

computingsupercomputerSpotlight on innovationPaul ShellardStephen HawkingIntelCentre for Theoretical CosmologyDepartment of Applied Mathematics and Theoretical PhysicsSchool of the Physical SciencesThese are exciting times for cosmology as we use COSMOS to directly test our mathematical theories against the latest observational dataStephen HawkingUniversity of CambridgeCOSMOS

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YesNews type: News

Saturn's largest moon was once a titanic snowball

18 June 2014 - 4:37pm
If Titan sometimes freezes over entirely, it would help to solve the moon's methane mystery, and a probe to Pluto may offer the first test of the idea