Hubble Directly Observes the Disc Around a Black Hole

ESA - Hubble Space Telescope logo.

4 November 2011

 Gravitationally lensed quasar HE 1104-1805

A team of scientists has used the NASA/ESA Hubble Space Telescope to observe a quasar accretion disc — a brightly glowing disc of matter that is slowly being sucked into its galaxy’s central black hole. Their study makes use of a novel technique that uses gravitational lensing to give an immense boost to the power of the telescope. The incredible precision of the method has allowed astronomers to directly measure the disc’s size and plot the temperature across different parts of the disc.

An international team of astronomers has used a new technique to study the bright disc of matter surrounding a faraway black hole. Using the NASA/ESA Hubble Space Telescope, combined with the gravitational lensing effect of stars in a distant galaxy [1], the team measured the disc’s size and studied the colours (and hence the temperatures) of different parts of the disc. These observations show a level of precision equivalent to spotting individual grains of sand on the surface of the Moon.

Using gravitational lensing to observe the disc around a black hole

While black holes themselves are invisible, the forces they unleash cause some of the brightest phenomena in the Universe. Quasars — short for quasi-stellar objects — are glowing discs of matter that orbit supermassive black holes, heating up and emitting extremely bright radiation as they do so.

“A quasar accretion disc has a typical size of a few light-days, or around 100 billion kilometres across, but they lie billions of light-years away. This means their apparent size when viewed from Earth is so small that we will probably never have a telescope powerful enough to see their structure directly,” explains Jose Muñoz, the lead scientist in this study.

Until now, the minute apparent size of quasars has meant that most of our knowledge of their inner structure has been based on theoretical extrapolations, rather than direct observations.

Observing a quasar accretion disc using gravitational lensing

The team therefore used an innovative method to study the quasar: using the stars in an intervening galaxy as a scanning microscope to probe features in the quasar’s disc that would otherwise be far too small to see. As these stars move across the light from the quasar, gravitational effects amplify the light from different parts of the quasar, giving detailed colour information for a line that crosses through the accretion disc.

The team observed a group of distant quasars that are gravitationally lensed by the chance alignment of other galaxies in the foreground, producing several images of the quasar.

They spotted subtle differences in colour between the images, and changes in colour over the time the observations were carried out. Part of these colour differences are caused by the properties of dust in the intervening galaxies: the light coming from each one of the lensed images has followed a different path through the galaxy, so that the various colours encapsulate information about the material within the galaxy. Measuring the way and extent to which the dust within the galaxies blocks light (known to astronomers as the extinction law) at such distances is itself an important result in the study.

For one of the quasars they studied, though, there were clear signs that stars in the intervening galaxy were passing through the path of the light from the quasar [2]. Just as the gravitational effect due to the whole intervening galaxy can bend and amplify the quasar’s light, so can that of the stars within the intervening galaxy subtly bend and amplify the light from different parts of the accretion disc as they pass through the path of the quasar’s light.

By recording the variation in colour, the team were able to reconstruct the colour profile across the accretion disc. This is important because the temperature of an accretion disc increases the closer it is to the black hole, and the colours emitted by the hot matter get bluer the hotter they are. This allowed the team to measure the diameter of the disc of hot matter, and plot how hot it is at different distances from the centre.

They found that the disc is between four and eleven light-days across (approximately 100 to 300 billion kilometres). While this measurement shows large uncertainties, it is still a remarkably accurate measurement for a small object at such a great distance, and the method holds great potential for increased accuracy in the future.

“This result is very relevant because it implies we are now able to obtain observational data on the structure of these systems, rather than relying on theory alone,” says Muñoz. “Quasars’ physical properties are not yet well understood. This new ability to obtain observational measurements is therefore opening a new window to help understand the nature of these objects.”

Notes:

The Hubble Space Telescope is a project of international cooperation between ESA and NASA.

The study, entitled “A study of gravitational lens chromaticity with the Hubble Space Telescope”, will appear in the December 1 issue of the Astrophysical Journal. The international team of astronomers consists of: J. A. Muñoz (University of Valencia, Spain), E. Mediavilla (Instituto de Astrofísica de Canarias, Spain), C. S. Kochanek (Ohio State University, USA), E. E. Falco (Harvard-Smithsonian Center for Astrophysics, USA) and A. M. Mosquera (University of Valencia and Ohio State University).

[1] Gravity bends the structure of spacetime, and hence deflects beams of light. When the alignment is right, with one object directly behind another, the foreground object’s gravity ‘bends’ the light like a lens, a process called gravitational lensing. Gravitational lenses typically produce multiple, distorted images of the distant object.

The most dramatic effects from gravitational lensing are the amplification and distortion of light from distant galaxies as it passes through massive galaxy clusters.

This effect also takes place on smaller scales, with galaxies at an intermediate distance lensing the light of distant quasars, producing multiple images of them that are visible through the lens galaxy.

Individual stars can also lens light, although this effect, called gravitational microlensing, is much more subtle and can only be detected by measuring how the lensing effect increases the source’s brightness.

This study makes use of gravitational microlensing by stars in a foreground galaxy to study the accretion disc of a quasar in the background. It also uses the interplay of quasar light and gravitational lensing to probe the gas and dust content of intermediate galaxies.

[2] The lens galaxy in which this phenomenon was observed is called [WKK93] G; the lensed quasar is called HE 1104-1805.

Links:

    Science paper: http://www.spacetelescope.org/static/archives/releases/science_papers/heic1116.pdf

    Images of Hubble: http://www.spacetelescope.org/images/archive/category/spacecraft/

    University of Valencia press release (in Catalan): http://www.uv.es/uvweb/universitat/ca/llista-noticies/universitat-identifica-caracteristiques-disc-acrecio-forat-negre-telescopi-hubble-1285846070123/Noticia.html?id=1285847485245

    University of Valencia press release (in Spanish): http://www.uv.es/uvweb/universitat/es/llista-noticies/universitat-identifica-caracteristiques-disc-acrecio-forat-negre-telescopi-hubble-1285846070123/Noticia.html?id=1285847485245

Images, Text, Credit: NASA / ESA and J.A. Muñoz (University of Valencia) / Oli Usher / Video: NASA / ESA / L. Calçada.

Cheers, Orbiter.ch

Welcome back and thank you, Mars500

ESA - Mars500 Mission patch / ROSCOSMOS - Mars500 / IMBP patch.

4 November 2011

Shortly after ‘landing’

The record-breaking simulated mission to Mars has ended with smiling faces after 17 months. Mars500’s six brave volunteers stepped out of their ‘spacecraft’ today to be welcomed by the waiting scientists – happy that the venture had worked even better than expected.

Mars500, the first full-length, high-fidelity simulation of a human mission to our neighbouring planet, started 520 days ago, on 3 June 2010, at the Institute of Biomedical Problems in Moscow.

The international crew were isolated in their interplanetary spacecraft mock-up, faithfully following the phases of a real mission: a long flight to Mars, insertion into orbit around the planet, landing, surface exploration, return to orbit, a monotonous return flight and arrival at Earth.

During the ‘flight’, the crew performed more than 100 experiments, all linked to the problems of long-duration missions in deep space.

Crew enjoying breakfast

To add to their isolation, communications with mission control were artificially delayed to mimic the natural delays over the great distances on a real Mars flight.

The crew of three Russians, one Chinese and two Europeans have performed exceptionally well. They have kept together and showed that motivation and team spirit can keep humans going under very difficult conditions. Scientists are pleased at their exceptional discipline.

“Thank you very much for your outstanding effort,” said ESA’s Director General Jean-Jacques Dordain in his greeting from Paris after the crew stepped from their module.

“I welcome the courage, determination and generosity of these young people who have devoted almost two years of their lives to this project, for the progress of human space exploration.”

Touching reunions

The hatch was opened at 14:00 local time (11:00 CET, 10:00 GMT) and the six ‘marsonauts’ walked out from their modules led by Alexey Sitev, mission commander.

Closing the hatch 520 days ago

After their first taste of freedom and greetings from mission directors, they were led to meet doctors and their families and close friends.

“It is great to see you all again,” said Diego Urbina, ESA’s Italian crewmember, after emerging.

“On the Mars500 mission we have accomplished on Earth the longest space voyage ever so that humankind can one day greet a new dawn on a distant but reachable planet.

Diego Urbina after the highlight of the mission: the Marswalk in February 2011

“And, as a European Space Agency crewmember, I am honoured to have been part of this remarkable challenge together with five of the most professional, friendly and resilient individuals I have ever worked with.

“I’ll be forever thankful to those who, even from a distance, always stood close to me during this space odyssey.”

Romain Charles, ESA’s French crewmember, continued: “One year and a half ago, I was selected by the European Space Agency to be part of the Mars500 crew. Today, after a motionless trip of 520 days, I'm proud to prove, with my international crewmates, that a human journey to the Red Planet is feasible.

Romain Charles in the control room of the Mars500 facility

“We have all acquired a lot of valuable experience that will help in designing and planning future missions to Mars.

“We're ready to embark on the next spaceship going there!”

During their first few days of liberty, the crew will undergo extensive medical checks and psychological evaluation. They will also enjoy some private time and relaxation before talking to the media on 8 November in Moscow.

Their mission continues into early December, as they go through an exhaustive series of debriefings, tests and evaluations to collect the mission’s final data.

Weightless on 1 April

Related links:

Fresh photos: Mars500 crew coming out from the facility:  http://www.esa.int/SPECIALS/Mars500/SEM4OELUBUG_mg_1.html

Mars500 quick facts: http://www.esa.int/SPECIALS/Mars500/SEMGX9U889G_0.html

Mars500 crew: http://www.esa.int/SPECIALS/Mars500/SEMO4BU889G_0.html

Online video:

ESA TV: One year inside: http://multimedia.esa.int/Videos/2011/05/Mars-500-one-year-inside

Partners:

Institute of Biomedical Problems (IBMP): http://www.imbp.ru/

Mars500 (IMBP): http://mars500.imbp.ru/

Images, Text, Credits: ESA / Mars500 crew.

Greetings, Orbiter.ch

NASA Airborne Mission Maps Remote, Deteriorating Glaciers

NASA - Operation IceBridge patch.

Nov.3, 2011

UPDATE: In further research, it has come to our attention that Pine Island Glacier last calved a large iceberg in 2007.

A close-up image of the crack spreading across the ice shelf of Pine Island Glacier shows the details of the boulder-like blocks of ice that fell into the rift when it split. For most of the 18-mile stretch of the crack that NASA’s DC-8 flew over on Oct. 26, 2011, it stretched about 240 feet wide, as roughly seen here. The deepest points ranged from about 165 to 190 feet, roughly equal to the top of the ice shelf down to sea level. Scientists expect the crack to propagate and the ice shelf to calve an iceberg of more than 300 square miles in the coming months. This image was captured by the Digital Mapping System (DMS) aboard the DC-8. Credit: NASA / DMS.

NASA's airborne expedition over Antarctica this October and November has measured the change in glaciers vital to sea level rise projections and mapped others rarely traversed by humans.

Operation IceBridge, nearing completion of its third year, is the largest airborne campaign ever flown over the world's polar regions. Bridging a gap between two ice elevation mapping satellites, and breaking new scientific ground on its own, IceBridge this fall has charted the continued rapid acceleration and mass loss of Pine Island Glacier.

IceBridge has now generated three years of laser altimetry data over certain locations to continue the record from NASA's Ice Climate and Elevation Satellite (ICESat), which stopped operating in 2009. IceBridge measurements show Pine Island following its rapid deterioration that began around 2006. Combined IceBridge and ICESat data show the glacier is losing more than six times as much mass per year -- mass loss was measured at 7 gigatons a year in 2005 and about 46 gigatons a year in 2010 – making it one of the most significant climate change response trends that scientists see worldwide. For comparison, the Chesapeake Bay holds about 70 gigatons of water.

Satellites still operating, such as NASA's Gravity Recovery and Climate Experiment (GRACE), can provide a large-scale picture of this trend. But it takes a more focused mission such as Operation IceBridge to gather higher-resolution data near the surface to piece together the dynamic interactions of ice, bedrock and ocean currents behind specific changes, and to improve the models that scientists use to predict how much an unstable ice sheet like West Antarctica will contribute to sea level rise.

Two planes make up this year's Antarctica 2011 campaign – NASA's DC-8 flying laboratory, based at Dryden Flight Research Center, Palmdale, Cal., and a Gulfstream-V (G-V) owned by the National Science Foundation and operated by the National Center for Atmospheric Research. The campaign also spotted and flew over a large rift developing across the Pine Island ice shelf on Oct. 14. A natural process, the crack could calve a new iceberg of about 350 square miles of surface area in the coming weeks or months. Pine Island Glacier hasn't calved a major iceberg since 2001.

Image above: The National Science Foundations/National Center for Atmospheric Research (NSF/NCAR) Gulfstream-V flew high-attitude missions during IceBridge Antarctica 2011. Credit: NCAR.

On a follow-up flight on Oct. 26 to gather data around Pine Island's grounding line, the DC-8 was able to fly along the crack for about 18 miles at an altitude of 3,000 feet, making what are believed to be the first detailed airborne measurements of an active calving rift.

Image above: NASA's DC-8 handled the low-attitude missions and carried the bulk of the IceBridge science instruments. Credit: NASA / Tony Landis.

In flights to Slessor and Recovery glaciers, which have only been traversed by humans once and twice respectively, IceBridge made a historic and scientifically important suite of measurements. Perhaps most significantly for these rarely studied regions of East Antarctica, an ice-penetrating radar instrument onboard the DC-8 was able to measure the topography of the bedrock underneath the ice sheet. Without a better understanding of the shape and contour of the bedrock, it is impossible to know how much ice sits on top of the continent in all. Topography also greatly influences the speed and direction of a glacier's ice flow.

"At a time when glaciers and ice sheets are showing rapid changes, we need consistent data that shows how and why that change is happening," IceBridge project scientist Michael Studinger said. "With three years of IceBridge data in hand, we have successfully continued the ice sheet elevation record in key areas and broken new ground in understanding the nature of the bedrock under ice sheets and the shape of the seafloor under ice shelves."

A gravimeter aboard the DC-8 senses changes in gravity fields to map the sea floor. This bathymetry controls ocean currents, which can inject warming waters under ice shelves and accelerate their thinning, as is happening at Pine Island and other glaciers.

The G-V was outfitted with one instrument for this campaign – a laser-ranging topographic mapper called the Land, Vegetation and Ice Sensor (LVIS). The instrument is suited for measuring large swaths of the surface at high altitudes. The G-V flew at around 45,000 feet for most of its 2011 missions.

Meanwhile, the DC-8 carries multiple instruments which are better suited for low-altitude flying. Once the plane reaches its science target, it flies at about 1,500 feet, allowing the radars, gravimeter, digital cameras and the Airborne Topographic Mapper (ATM), which captures higher resolution details of the ice surface than is possible from satellites. The DC-8's range and speed can also reach more remote, unstudied locations and cover more ground than smaller aircraft or ground traverses.

"This has been an excellent campaign for the science side of the mission, and it's our job to put the plane in positions to make that possible," said Mission Manager Walter Klein, based at Dryden.

One example of the flight side of the mission enabling science occurred during the second Pine Island Glacier flight, when the pilots flew the DC-8 by sight over the calving rift in the glacier's ice shelf at an altitude of 3,000 feet.

During the IceBridge Antarctica 2011 campaign, the DC-8 has flown 13 missions covering 51,600 miles, while the G-V has flown 11 science missions covering about 50,000 miles. As planned, the G-V left Punta Arenas to return to the United States on Weds., Nov. 2. The DC-8 is scheduled to remain in Punt Arenas up to mid-November, when it will return to its home base of Dryden Flight Research Center in Palmdale, Cal.

The next flight leg of IceBridge once the mission team wraps up in Punta Arenas will be based in Greenland in the Northern Hemisphere spring of 2012. IceBridge is scheduled to fly one Arctic and one Antarctic leg each year until ICESat-2 launches in 2016.

Related Links:

Download presentation pdf: http://www.nasa.gov/pdf/600736main_OIB_media_presentation_Nov_3.pdf

IceBridge mission page: http://www.nasa.gov/mission_pages/icebridge/

Images (mentioned), Text, Credit: NASA's Earth Science News Team / Patrick Lynch.

Greetings, Orbiter.ch

NASA's Fermi Finds Youngest Millisecond Pulsar, 100 Pulsars To-Date

NASA - Fermi Space Telescope logo.

Nov. 3, 2011

An international team of scientists using NASA's Fermi Gamma-ray Space Telescope has discovered a surprisingly powerful millisecond pulsar that challenges existing theories about how these objects form.

At the same time, another team has located nine new gamma-ray pulsars in Fermi data, using improved analytical techniques.

Fermi Discovers Youngest Millisecond Pulsar

Video above: In three years, NASA's Fermi has detected more than 100 gamma-ray pulsars, but something new has appeared. Among a type of pulsar with ages typically numbering a billion years or more, Fermi has found one that appears to have been born only millions of years ago. (Credit: NASA's Goddard Space Flight Center).

A pulsar is a type of neutron star that emits electromagnetic energy at periodic intervals. A neutron star is the closest thing to a black hole that astronomers can observe directly, crushing half a million times more mass than Earth into a sphere no larger than a city. This matter is so compressed that even a teaspoonful weighs as much as Mount Everest.

"With this new batch of pulsars, Fermi now has detected more than 100, which is an exciting milestone when you consider that, before Fermi's launch in 2008, only seven of them were known to emit gamma rays," said Pablo Saz Parkinson, an astrophysicist at the Santa Cruz Institute for Particle Physics at the University of California Santa Cruz, and a co-author on two papers detailing the findings.

Image above: This plot shows the positions of nine new pulsars (magenta) discovered by Fermi and of an unusual millisecond pulsar (green) that Fermi data reveal to be the youngest such object known. With this new batch of discoveries, Fermi has detected more than 100 pulsars in gamma rays. Credit: NASA / DOE / Fermi LAT Collaboration.

One group of pulsars combines incredible density with extreme rotation. The fastest of these so-called millisecond pulsars whirls at 43,000 revolutions per minute.

Millisecond pulsars are thought to achieve such speeds because they are gravitationally bound in binary systems with normal stars. During part of their stellar lives, gas flows from the normal star to the pulsar. Over time, the impact of this falling gas gradually spins up the pulsar's rotation.

The strong magnetic fields and rapid rotation of pulsars cause them to emit powerful beams of energy, from radio waves to gamma rays. Because the star is transferring rotational energy to the pulsar, the pulsar's spin eventually slows as the star loses matter.

This image shows the on and off state of gamma rays from pulsar J1823-3021A as seen by Fermi's Large Area Telescope (LAT). The object pulses 183.8 times a second and has a spin period of 5.44 milliseconds, which translates to 11,000 rpm. Credit: NASA / DOE / Fermi LAT Collaboration.

Typically, millisecond pulsars are around a billion years old. However, in the Nov. 3 issue of Science, the Fermi team reveals a bright, energetic millisecond pulsar only 25 million years old.

The object, named PSR J1823−3021A, lies within NGC 6624, a spherical collection of ancient stars called a globular cluster, one of about 160 similar objects that orbit our galaxy. The cluster is about 10 billion years old and lies about 27,000 light-years away toward the constellation Sagittarius.

Fermi's Large Area Telescope (LAT) showed that eleven globular clusters emit gamma rays, the cumulative emission of dozens of millisecond pulsars too faint for even Fermi to detect individually. But that's not the case for NGC 6624.

Video above: Fermi's LAT records the precise time and position of the gamma rays it detects, but to identify a pulsar requires additional information -- its position in the sky, its pulse period, and the way the pulse changes over time. Additionally, even Fermi's sensitive LAT detects few gamma rays from these objects -- as few as one photon per 100,000 rotations. New analysis methods allow computers to check many different combinations of position and period against 8,000 photons Fermi's LAT has collected during its three years in orbit. When photons from the pulses align in time, a new gamma-ray pulsar has been discovered. (Credit: AEI / NASA's Goddard Space Flight Center).

"It's amazing that all of the gamma rays we see from this cluster are coming from a single object. It must have formed recently based on how rapidly it's emitting energy. It's a bit like finding a screaming baby in a quiet retirement home," said Paulo Freire, the study's lead author, at the Max Planck Institute for Radio Astronomy in Bonn, Germany.

J1823−3021A was previously identified as a pulsar by its radio emission, yet of the nine new pulsars, none are millisecond pulsars, and only one was later found to emit radio waves.

Despite its sensitivity, Fermi's LAT may detect only one gamma ray for every 100,000 rotations of some of these faint pulsars. Yet new analysis techniques applied to the precise position and arrival time of photons collected by the LAT since 2008 were able to identify them.

To celebrate these achievements, the Fermi team has created an interactive feature on pulsars. Called the Fermi Pulsar Explorer, the interactive includes an all-sky map that links to information about each of the 101 Fermi pulsars known so far, as well as video and background information on Fermi and gamma-ray astronomy. View interactive: http://www.nasa.gov/externalflash/fermipulsar/

"We adapted methods originally devised for studying gravitational waves to the problem of finding gamma-ray pulsars, and we were quickly rewarded," said Bruce Allen, director of the Max Planck Institute for Gravitational Physics in Hannover, Germany. Allen co-authored a paper on the discoveries that was published online today in The Astrophysical Journal.

Allen also directs the Einstein@Home project, a distributed computing effort that uses downtime on computers of volunteers to process astronomical data. In July, the project extended the search for gamma-ray pulsars to the general public by including Femi LAT data in the work processed by Einstein@Home users.

NASA's Fermi Gamma-ray Space Telescope is an astrophysics and particle physics partnership. It is managed by NASA's Goddard Space Flight Center in Greenbelt, Md. It was developed in collaboration with the U.S. Department of Energy, with important contributions from academic institutions and partners in France, Germany, Italy, Japan, Sweden and the United States.

For more information, images and animations, please visit: http://www.nasa.gov/fermi

Related Link:

Albert Einstein Institute release: http://www.aei.mpg.de/english/contemporaryIssues/akt_news/gamma_pulsars/

Images (mentioned), Videos (mentioned), Text, Credit: NASA.

Greetings, Orbiter.ch

Successful Docking for Shenzhou-8 with Tiangong-1 Space Lab Module

CNSA - Shenzhou-8 / Tiangong-1 Space Lab Module Docking Mission patch.

Nov. 3, 2011

Image above: The graphics shows the procedure of Shenzhou-8 spacecraft docking with Tiangong-1 space lab module on Nov. 3, 2011. Photo: Xinhua.

The unmanned Shenzhou-8 spacecraft successfully docked with the Tiangong-1 space lab module early this morning after five orbit changes, the first in the country's space program.

After the 15-minute procedure, the two spacecraft will fly together for 12 days, then separate and prepare for another docking on November 14. Following two more days of flying together, Shenzhou-8 will leave Tiangong-1 and head back to Earth on November 17.

Shenzhou-8 Rendezvous and Docking with Tiangong-1

Zhang Bonan, chief designer of the spacecraft, told the Beijing Times that the successful launching and docking of the Shenzhou-8 marks a landmark in China's manned space history, marking the finalization of China's Shenzhou spacecraft technology.

Pang Zhihao, a researcher from the Chinese Research Institute of Space Technology, told the Global Times that the achievement enables China to carry out scaled production of its Shenzhou spacecraft, which will significantly cut down expenses, shorten research and preparation time, and guarantee stable performance of vessels.

The Shenzhou-8 is the most advanced spacecraft developed by China, and utilizes a large number of domestic devices and new technologies. According to Zhou Yanfei, a researcher with the China Manned Space Engineering, the space docking is carried out first automatically and is then manually controlled, reducing risk to the crew.

Shenzhou-8 / Tiangong-1 Space Lab Module Docking

"The unmanned operation will also pave the way for space station programs in the future," Pan told the Global Times. Dummy astronauts are being used to run tests for the manned space program to come.

Experts believe the success of the space docking will lay a solid foundation for China to set up a permanent space station around 2020.

China Space Station

Zhou Jianping, chief designer of China's manned space program, said to the Xinhua News Agency that once China has mastered the docking technology, the country will have the ability to build a permanent space station.

Paul Dempsey, a director with the Institute of Air and Space Law at McGill University, told the Global Times that China is demonstrating its leadership by conducting a series of space exploration journeys, and China intends to land on the moon.

Dempsey said that one of the reasons China did not participate in the International Space Station (ISS) may be that US prohibits export of technology and there has always been some reticence from the US over sharing space technology.

For more information about China National Space Administration, visit: http://www.cnsa.gov.cn/n615709/cindex.html

Images, Video, Text, Credits: CNSA / Xinhua / Global Times (CN) / Hao Di / Xu Wen / Tian Chi / CNTV.

Best regards, Orbiter.ch

LHC proton run for 2011 reaches successful conclusion

CERN - European Organization for Nuclear Research logo.

Oct. 2, 2011

Image above: LHC control screen displaying the dump of the last beams for the LHC's 2011 proton run. The image on the right shows the cross section of the beam just before it was stopped. Credit: CERN.

After some 180 days of running and four hundred trillion (4x1014) proton-proton collisions, the LHC's 2011 proton run came to an end last Sunday evening. For the second year running, the LHC team has largely surpassed its operational objectives, steadily increasing the rate at which the LHC has delivered data to the experiments.

At the beginning of the year’s run, the objective for the LHC was to deliver a quantity of data known to physicists as one inverse femtobarn during the course of 2011. The first inverse femtobarn came on 17 June, setting the experiments up well for the major physics conferences of the summer and requiring the 2011 data objective to be revised upwards to five inverse femtobarns. That milestone was passed by 18 October, with the grand total for the year being almost six inverse femtobarns delivered to each of the two general-purpose experiments ATLAS and CMS.

“At the end of this year’s proton running, the LHC is reaching cruising speed,” said CERN’s Director for Accelerators and Technology, Steve Myers. “To put things in context, the present data production rate is a factor of 4 million higher than in the first run in 2010 and a factor of 30 higher than at the beginning of 2011.”

Physics highlights from this year’s proton running include closing down the space available for the long sought Higgs and supersymmetric particles to hide in, putting the Standard Model of particle physics through increasingly gruelling tests, and advancing our understanding of the primordial universe.

“It has been a remarkable and exciting year for the whole LHC scientific community, in particular for our students and post-docs from all over the world. We have made a huge number of measurements of the Standard Model and accessed unexplored territory in searches for new physics. In particular, we have constrained the Higgs particle to the light end of its possible mass range, if it exists at all,” said ATLAS Spokesperson Fabiola Gianotti. “This is where both theory and experimental data expected it would be, but it’s the hardest mass range to study.”

 “Looking back at this fantastic year I have the impression of living in a sort of a dream,” said CMS Spokesperson Guido Tonelli. “We have produced tens of new measurements and constrained significantly the space available for models of new physics and the best is still to come. As we speak hundreds of young scientists are still analysing the huge amount of data accumulated so far; we’ll soon have new results and, maybe, something important to say on the Standard Model Higgs Boson.”

“We’ve got from the LHC the amount of data we dreamt of at the beginning of the year and our results are putting the Standard Model of particle physics through a very tough test ” said LHCb Spokesperson Pierluigi Campana. “So far, it has come through with flying colours, but thanks to the great performance of the LHC, we are reaching levels of sensitivity where we can see beyond the Standard Model. The researchers, especially the young ones, are experiencing great excitement, looking forward to new physics.”

LHC tunnel

Over the coming days and weeks, the LHC experiments will be analysing the full 2011 data set to home in further on new physics.  However, while it is possible that new physics may emerge, it is equally likely that the full 10 inverse femtobarns initially foreseen for 2011 and 2012 will be required.

As in 2010, the LHC is now being prepared for four weeks of lead-ion running, but in a new development this year, the world’s largest particle accelerator will also attempt to demonstrate that large can also be agile by colliding protons with lead ions in two dedicated periods of machine development. If successful, these tests will lead to a new strand of LHC operation, using protons to probe the internal structure of the much more massive lead ions.

This is important for the lead-ion programme, whose goal is to study quark-gluon plasma, the primordial soup of particles from which the ordinary matter of today’s visible universe evolved.

“Smashing lead ions together allows us to produce and study tiny pieces of primordial soup,” said ALICE Spokesperson Paolo Giubellino, “but as any good cook will tell you, to understand a recipe fully, it’s vital to understand the ingredients, and in the case of quark-gluon plasma, this is what proton-lead ion collisions could bring.”

Note:

CERN, the European Organization for Nuclear Research, is the world's leading laboratory for particle physics. It has its headquarters in Geneva. At present, its Member States are Austria, Belgium, Bulgaria, the Czech Republic, Denmark, Finland, France, Germany, Greece, Hungary, Italy, the Netherlands, Norway, Poland, Portugal, Slovakia, Spain, Sweden, Switzerland and the United Kingdom. Romania is a candidate for accession. Israel is an Associate Member in the pre-stage to Membership. India, Japan, the Russian Federation, the United States of America, Turkey, the European Commission and UNESCO have Observer status.

Follow CERN at:

    http://www.cern.ch
    http://twitter.com/cern/
    http://www.youtube.com/user/CERNTV
    http://www.quantumdiaries.org/

Image, Text, Credit: CERN Press Office.

Cheers, Orbiter.ch

Ancient White Dwarf Stars

NASA - Hubble Space Telescope patch.

Oct. 2, 2011

Pushing the limits of its powerful vision, NASA's Hubble Space Telescope uncovered the oldest burned-out stars in our Milky Way Galaxy in this image from 2002. These extremely old, dim "clockwork stars" provide a completely independent reading on the age of the universe without relying on measurements of the expansion of the universe.

The ancient white dwarf stars, as seen by Hubble, turn out to be 12 to 13 billion years old. Because earlier Hubble observations show that the first stars formed less than 1 billion years after the universe's birth in the big bang, finding the oldest stars puts astronomers well within arm's reach of calculating the absolute age of the universe.

Though previous Hubble research sets the age of the universe at 13 to 14 billion years based on the rate of expansion of space, the universe's birthday is such a fundamental and profound value that astronomers have long sought other age-dating techniques to cross-check their conclusions.

The new age-dating observations were done using Hubble to hunt for elusive ancient stars hidden inside a globular star cluster located 5,600 light-years away in the constellation Scorpius.

Hubble is a project of international cooperation between NASA and the European Space Agency. NASA's Goddard Space Flight Center in Greenbelt, Md., manages the telescope. The Space Telescope Science Institute (STScI) in Baltimore conducts Hubble science operations. STScI is operated for NASA by the Association of Universities for Research in Astronomy Inc. in Washington.

For images and more information about Hubble, visit:

NASA Hubble website: http://www.nasa.gov/hubble

ESA Hubble website: http://www.spacetelescope.org/

Image, Text, Credit: NASA and H. Richer (University of British Columbia).

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