Posted on by Tammy Plotner

Australian Telescope Leads the World In Astronomy Research

The AAT - Photograph courtesy of Chris McCowage

[/caption]

While the Anglo-Australian Telescope is far from being the world’s largest, or even located in the world’s best observing site, it’s still the world’s most productive in terms of astronomy research. According to recently released productivity ratings, the number of scientific papers resulting from observations made with the AAOmega fibre-fed optical spectrograph, SPIRAL Integral Field Unit, IRIS2, University College London Echelle Spectrograph (UCLES), or Ultra High Resolution Facility (UHRF) made the AAT the number one ranked 4-metre-class telescope in the world for more than two years between 2001 and 2003. But what’s going on today is even more important…

When we think of research telescopes, some of the world’s top rated are the Hubble Space Telescope (located in Earth orbit), Keck (more than twice the AAT’s size) in Hawaii, the Very Large Telescope (VLT, which comprises four telescopes twice the size of the AAT) in Chile, the Sloan Digital Sky Survey and the 2MASS telescope. So where does that leave the humble Anglo-Australian? Try number five. “The AAT has a remarkable track record of scientific productivity and impact,” says Prof. Matthew Colless, Director of the Anglo-Australian Observatory. “This is an extraordinary achievement.”

When the Anglo-Australian Observatory opened for business in the early 1970’s, the 4 meter telescope was the standard by which all others were judged. Since that time, research telescope aperture has more than doubled and while the AAT can’t compete in some respects, it has advantages that give it an edge for research. While it isn’t Mauna Kea, Australia still offers up some of the best skies to study our Galaxy and other nearby galaxies and the ability to undertake long-term observations and programs that just won’t work with other observatories. Add to that some very unique instrumentation such as Echidna – a fibre positioner for FMOS, UKidna – A multi-fibre positioner for the UKST, OZPOZ – a fibre positioner for ESO and part of FLAMES, DAZLE – The Dark Age z (redshift) Lyman-alpha Explorer, MOMFOS – Multi-Object Multi-Fibre Optical Spectrograph, ODC – Optical Detector Controllers and AAOmega – next generation optical spectrograph for the AAT and you have a recipe for research. This explains why demand for the telescope remains strong, with 2.5 times as many applications for telescope time as can actually be handled. “The AAO believes that the AAT can maintain this high level of productivity and impact for another decade.” says Prof. Colless.

Over a period of time, the the AAO has produced some of the most inspiring astronomy images ever seen – those taken by David Malin. These are the most extraordinary wide-field astrophotographs made with professional telescopes anywhere and every effort has been made to capture the true colours of distant stars, galaxies and nebulae using innovative photographic techniques and CCD detectors. The images have detailed captions and the full NGC 2000.0 catalogue entry. Galaxy images also carry NASA/IPAC Extragalactic Database (NED) data links. They are a standard of astronomers everywhere. But, progress hasn’t stopped. The AAT’s prime focus has recently been upgraded to accommodate a new generation of highly sensitive CCD detectors. The first colour images made with the new facility are now available, currently only in digital form. Most of the photographic images have recently been digitally re-mastered from the original 3-colour separations. This has allowed the AAO to create new, high resolution versions of many existing images and some new pictures that could not be made photographically.

Just this year a “uniquely ambitious, far-sighted” project won an Australian and UK astronomy team the first Group Achievement Award from the UK’s Royal Astronomical Society. Led by Professor Matthew Colless (Anglo-Australian Observatory) in Australia and Professor John Peacock (University of Edinburgh) in the UK, the thirty-three-member team spent ten years mapping the distribution in space of 220,000 galaxies using the 3.9-m Anglo-Australian Telescope (AAT) in New South Wales — a project called the 2-degree Field Galaxy Redshift Survey (2dFGRS). “The scale of this project made it ground-breaking,” said Matthew Colless. “For the first time we were able to map the positions of a huge number of galaxies and see the subtle effects that reveal the different types of matter in the universe.”

What was needed was for the area of sky surveyed to be much bigger than, rather than the same size as, the “walls” and “strings” of galaxies being detected. Almost ten times larger than any previous survey, the 2dFGRS was the first study to meet this crucial condition. The survey measured patterns in the distribution of galaxies, on scales from 100 million to 1 billion light-years. Two wedge-shaped pieces of sky were surveyed, so when the galaxies within them were mapped out, the result looked like a bow-tie cut from a sponge: a network of voids and dense regions. The size of the 2dF Galaxy Redshift Survey was made possible only by technological advances developed at the Anglo-Australian Observatory (AAO). The 2dF spectrograph used robotic technology to place optical fibres onto the telescope’s focal plane, where each fibre could collect the light from a single galaxy. By using up to 400 optical fibres, this system allowed the light from up to 400 galaxies to be captured simultaneously.

And the AAT is ensuring that it doesn’t fall behind the times with future technological advancement either….

“We are currently investing $4 million in refurbishing the telescope to ensure that it can operate reliably and efficiently for another ten years, and more than $6 million in a major new instrument, the 400-fibre HERMES high-resolution Spectrograph,” says Prof. Colless. “The primary science drivers for HERMES are ‘Galactic archaeology’ surveys to uncover the formation history of the Milky Way,’ he adds. ‘Extragalactic surveys using the AAOmega instrument and galactic surveys using HERMES will be the flagship science carried out on the AAT over the next 5-10 years. AAOmega and HERMES, and other upgrades to existing instruments, will provide astronomers with powerful tools that will enable them to do competitive, high-impact research using the AAT throughout the coming decade.”

Original Source: SpaceInfo.com

Posted on by Nancy Atkinson

‘Laser Comb’ To Measure the Accelerating Universe

Back in April, UT published an article about using a device called a ‘laser comb’ to search for Earth-like planets. But astronomers also hope to use the device to search for dark energy in an ambitious project that would measure the velocities of distant galaxies and quasars over a 20-year period. This would let astronomers test Einstein’s theory of general relativity and the nature of the mysterious dark energy. The device uses femto-second (one millionth of one billionth of a second) pulses of laser light coupled with an atomic clock to provide a precise standard for measuring wavelengths of light. Also known as an “astro-comb,” these devices should give astronomers the ability to use the Doppler shift method with incredible precision to measure spectral lines of starlight up to 60 times greater than any current high-tech method. Astronomers have been testing the device, and hope to use one in conjunction with the new Extremely Large Telescope which is being designed by ESO, the European Southern Observatory.

Astronomers use instruments called spectrographs to spread the light from celestial objects into its component colors, or frequencies, in the same way water droplets create a rainbow from sunlight. They can then measure the velocities of stars, galaxies and quasars, search for planets around other stars, or study the expansion of the Universe. A spectrograph must be accurately calibrated so that the frequencies of light can be correctly measured. This is similar to how we need accurate rulers to measure lengths correctly. In the present case, a laser provides a sort of ruler, for measuring colors rather than distances, with an extremely accurate and fine grid.

New, extremely precise spectrographs will be needed in experiments planned for the future Extremely Large Telescope.

“We’ll need something beyond what current technology can offer, and that’s where the laser frequency comb comes in. It is worth recalling that the kind of precision required, 1 cm/s, corresponds, on the focal plane of a typical high-resolution spectrograph, to a shift of a few tenths of a nanometre, that is, the size of some molecules,” explains PhD student and team member Constanza Araujo-Hauck from ESO.

The new calibration technique comes from the combination of astronomy and quantum optics, in a collaboration between researchers at ESO and the Max Planck Institute for Quantum Optics. It uses ultra-short pulses of laser light to create a ‘frequency comb’ – light at many frequencies separated by a constant interval – to create just the kind of precise ‘ruler’ needed to calibrate a spectrograph.

The device has been tested on a solar telescope, a new version of the system is now being built for the HARPS planet-finder instrument on ESO’s 3.6-metre telescope at La Silla in Chile, before being considered for future generations of instruments.

More information on laser combs.

Source: ESO

Posted on by Nancy Atkinson

New Eye to the Universe Under Construction

The LSST, or the Large Synoptic Survey Telescope is a large survey telescope being constructed in northern Chile. When operational in 2015, it will be the widest, fastest, deepest eye of the new digital age, providing timelapse digital imaging across the entire night sky every three days, mapping the structure of our dynamic universe in three dimensions and exploring the nature of dark matter and dark energy. LSST hit a major milestone in its construction when the primary mirror blank was recently created. Project astronomers say the single-piece primary and tertiary mirror blank cast for the LSST is “perfect.”

The 51,900 pound (23,540 kg) mirror blank was fired in the oven at the University of Arizona’s Steward Observatory Mirror lab in Tucson, Arizona. It consists of an outer 27.5-foot diameter (8.4-meter) primary mirror and an inner 16.5-foot (5-meter) third mirror cast in one mold. It is the first time a combined primary and tertiary mirror has been produced on such a large scale.

LSST will have three large mirrors to give crisp images over a the largest field of view that will be available. The two largest of these mirrors are concentric and fit neatly onto a single mirror blank.
LSST was recently the recipient of two large gifts: $20 million from the Charles Simonyi Fund for Arts and Sciences, and $10 million from Bill Gates. The finished mirror is scheduled to be delivered in 2012.

More information about LSST.

News Source: LSST press release

Posted on by Tammy Plotner

How Far Would You Go For Dark Skies?

Arkaroola Wilderness Sanctuary

[/caption]

In the age of global light pollution, one thing both amateur and professional astronomers have in common is the need for clear, dark skies. While almost all of us are aware of the impact of light pollution when it comes to pure observing, the “light factor” plays a far more serious role when it comes to astronomical studies. But, there’s far deeper reasons for observatories to become increasingly remote.

While escaping light sources such as brightly-lit cities is mandatory for amateur astronomers and astrophotographers to enjoy their hobby, professional observatories seek some of the world’s most remote locations for other reasons. Both in studying and in astrophotography, splitting the light into its component colors – the spectra – of an object becomes important. For example, when studying a distant galaxy through spectroscopy, astronomers rely on the different lines in the spectral signature as a unique indicator of the presence of a certain chemical. Through the strengths of these lines, astronomers can then determine the chemical composition and temperature. What’s more, by noting how far to the red side of the spectrum the lines are shifted, astronomers can also determine how fast the object is moving…

And light pollution wrecks spectrographs.

Besides light pollution, other enemies of astrophotography and spectroscopy are high-flying airplanes, clouds, inclement weather and atmospheric conditions. One of the reasons the Hubble is so successful in the lack of atmosphere, and that’s the major reason why most remote observatories choose to locate on high peaks – the less atmosphere and the more stable the atmosphere, the better. In some circumstances, and for some equipment and telescopes, humidity can also be a problem. This is why remote observatories are also often located in desert regions as well. So, in a world that looks like this…

Earthlights - Credit: NASA
Earthlights - Credit: NASA

How far would you go for dark skies?

In a report done by ABC news a study has found that more than 40 per cent of Australia remains undamaged – and unpolluted – by humans. This means the “land down under” offers exciting possibilities for astronomical studies, not only from the perspective of viewing southern hemisphere skies, but doing research from a pristine location. This is why you’ll find research facilities such as the Anglo-Australian Observatory, Australia Telescope National Facility, Melbourne Observatory, Perth Observatory, Sydney Observatory, Siding Springs, Mills Cross Telescope, Paul Wild Observatory, Mount Stromlo Observatory and Southern Galactic International Telescope Facility.

Flinders Range
Flinders Range
While the Cobaw Plateau region on the north face of the Great Dividing Range has proved to be an excellent site for Southern Galactic Telescope Hosting, the next step is to expand operations into the Arkaroola Wilderness Sanctuary. Located 600km north of Adelaide and 130km east of Leigh Creek, and in the more rugged and spectacular northern Flinders Ranges, this 610sq km multi award-winning Wilderness Sanctuary, contains some of Australia’s most spectacular mountain views – and darkest, clearest skies. The Southern Galactic Observatory and International Telescope Hosting Facility, an internationally renowned astronomical observatory based in Victoria, is pleased to announce the establishment of its exclusive Site 2 location at the Arkaroola Wilderness Sanctuary in the Northern Flinders Ranges of South Australia. This new location will be run as part of the Australian operations in partnership with the Directors of the Arkaroola Wilderness Sanctuary and will enable research in the areas of optical / radio astronomy, planetary studies, and space atmospheric sciences by providing specific telescope hosting services and remote control accessability together with logistical support to private and commercial international users and research scientists.

But carving the way out of the wilderness isn’t going to be easy. First a site needs to be chosen and then the logistics need to be considered. According to SG director, Dr. Bert Candusio; “The end result ultimately dictates if the effort is justified. In this case, the northern Flinders Ranges consistently proved to be the best observatory location Australia has to offer. The other factor in our site selection was availability of research support in such a remote location. Fortunately, the Arkaroola Village is fully self-contained and maintains all manner of activities from machine workshops, plant and equipment facilities all the way to visitor interpretation staff, high speed internet capabilities and support.”

Dodwell <br> Observatory
Dodwell Observatory
While the thought of having a village nearby might seem like another access to light pollution, stargazers don’t need to worry. The Arkaroola Wilderness Sanctuary is also home to three astronomical institutions – Dodwell, Sir Mark Oliphant and R. Sprigg Observatories – and soon to be the Southern Galactic Mt. Spriggina Observatory. Located 4km south of the AWS village and high atop it own 425 meters peak, this new facility is expected to have six positions open to researchers and private individuals in late 2008, early 2009.

“The SG Mt. Spriggina location presents a unique opportunity for advanced research and astrophotography outcomes to organizations, educators and individuals to be operational under perhaps Australia’s foremost astromony location.” says Dr. Candusio. “The site’s uniqueness in such a remote location towards Central Australia’s wilderness has never been offered to the private and corporate sector internationally before. According to a commissioned report on the seeing quality of the northern Flinders Ranges, the area receives less cloud cover than any other region of the Australian mainland and the seeing FWHM figures were considerably better when compared to the Anglo Australia Telescope at Siding Springs location.”

So who will be manning the telescopes in a remote observatory? Nah. As cute and cuddly as the Euro ‘roo can be, the Southern Galactic facility will offer a professionally trained support staff to oversee operations. According to Dr. Candusio, “Since Arkaroola hosts numerous visitors , there are several permanent on-site staff available to conduct tours of the existing Observatory Facilities at Arkaroola. The experience of these individuals will play a vital role in helping to keep the Mount Spriggina site functioning at all times.”

Just how far would you go?

Posted on by Nancy Atkinson

GLAST is Now Fermi

First light image reveals bright emission in the plane of the Milky Way (center), bright pulsars and super-massive black holes. Credit: NASA/DOE/International LAT Team

[/caption]

With “first light” successfully observed by the Gamma Ray Large Area Space Telescope, or GLAST, as it has been called until now, NASA has christened the space observatory with its new official name: The Fermi Gamma Ray Space Telescope. Named for Italian physicist Enrico Fermi, the telescope will delve into the mysteries of the high energy end of the electromagnetic spectrum. This new space telescope will try to determine what the mysterious dark matter is composed of, how black holes emit immense jets of material to nearly the speed of light, and help crack the mysteries of solar flares, cosmic rays and the power explosions called gamma ray bursts. At a news conference today to announce the new name and first light observations, Steve Ritz, Project Scientist for the telescope said scientists world-wide are very excited about the telescope’s breakthrough capability. “GLAST has great discovery potential. We’re expecting surprises,” he said.

Since the spacecraft’s launch on June 11, the project team has been busy turning on the spacecraft’s various subsystems and calibrating the instruments. GLAST was developed in cooperation with the US Department of Energy and international partners in France, Germany, Italy, Japan and Sweden. Over 100 international scientists are collaborating on this project. Fermi’s primary mission is for five years, with a goal of ten years of total operations.

The first image as seen above shows the bright gamma ray emissions in the plane of the Milky Way (center), bright pulsars and super-massive black holes. The Fermi Telescope saw in four days what a previous gamma ray mission, EGRET (Energetic Gamma Ray Experiment Telescope) imaged in nine years.

It also made detections of two active galaxies, and a blazar in the southern galactic plane, called 3C454.3, located about 7 billion light years from Earth, and a pulsar, called the Vela Pulsar located about 10 billion 1000 light years from Earth.

Fermi Gamma-ray Space Telescope's first all-sky map made into a sphere to produce this view of the gamma-ray universe. Credit: NASA/DOE/International LAT Team
Fermi Gamma-ray Space Telescope's first all-sky map made into a sphere to produce this view of the gamma-ray universe. Credit: NASA/DOE/International LAT Team

Video of Fermi’s first light detections.

The big advantage is Fermi’s huge field of view compared to previous gamma ray observatories. The entire sky is viewed about every two orbits or every 3 hours. Scientists say this is especially important because the gamma ray sky is constantly changing. With the telescope’s Burst Monitor, about one gamma ray burst has been detected every day from all areas of the sky.

Turning on the telescope has gone extremely smooth. “Everything worked as expected and then some,” said Ritz. “None of us could have asked for such a smooth turn on. It’s a credit to the world wide team of engineers, scientists, programmers and support people who all worked together as a seamless team over many years. It went like clockwork that went ahead of the clock. That doesn’t happen by accident. It was due to the great preparation work.”

Jon Morse from NASA’s Astrophysics Division calls the Fermi Telescope ‘The Extreme Machine’ and said to expect an exciting pace of new discoveries in the days and years ahead.

Here’s Fermi’s new logo:

New Logo for the Fermi Telescope
New Logo for the Fermi Telescope

Posted on by Ian O'Neill

XMM-Newton Discovers Strange-Shaped Supernova Remnant

X-ray emission from supernova remnant (to the left) and neutron star (to the right). (ESA/XMM-Newton/EPIC)

XMM-Newton has just released this beautiful image of a supernova remnant and its companion neutron star. To be more accurate, it didn’t “discover” the object, remnant G350.1-0.3 had previously been mistaken to be a distant galaxy. The X-ray observatory has reclassified the object as a Milky Way binary system with one neutron star and the remnant of a young supernova. A wonderful tale about mistaken identity and re-opening a cosmic cold-case, a thousand years after the event…

G350.1-0.3 is special in so many ways. Many astronomers have dubbed this object a “celestial gem” because it is a strikingly beautiful X-ray observation. Apart from its looks, this re-classification by XMM-Newton is very significant to astrophysicists studying the chemical composition, formation and cause of a supernova event. This said, G350.1-0.3 isn’t any normal supernova remnant.

Supernova remnants are usually observed as symmetrical, expanding “bubbles” of hot stellar plasma. Generally, as a massive star finally dies, the explosion should send material out equally in all directions, it is for this reason they are usually easy to distinguish from background galaxies. G350.1-0.3 doesn’t obey this rule; some outside influence had given the remnant a rather odd shape. In the 1980’s, this celestial object was observed in high-resolution images and the knotted gases in the image gave astronomers the impression that the object was “just another distant galaxy” and then forgotten about. That was until NASA’s X-ray observatory XMM-Newton re-examined the object. It quickly became apparent that it was a supernova remnant in the Milky Way, not a far-flung galaxy.

Radio and X-ray emissions from the supernova remnant (ESA/XMM-Newton/EPIC)

This is also a very young supernova remnant. According to Bryan Gaensler and Anant Tanna, from the University of Sydney, who used XMM-Newton to not only prove appearances can be deceptive, but also that the remnant is only 1000 years old. Finding such a young remnant is extremely valuable. “We’re seeing these heavy elements fresh out of the oven,” said Gaensler when referring to G350.1-0.3. Generally, any supernova remnant over 20,000 years old is pretty much the same as another remnant of that age. Finding one so young, so bright and so close gives astrophysicists a prime opportunity to understand the dynamics of a supernova only a short period of time after it blew.

But why the strange shape? It turns out the supernova detonated right next to a dense cloud of gas about 15,000 light-years from Earth. The cloud strongly influenced the expanding gas, preventing the hot matter from expanding uniformly in all directions. This is rare, misshapen supernova remnants aren’t seen very often.

The supernova may have occurred around the time when William the Conqueror invaded England in 1066; perhaps the Battle of Hastings was being waged when the explosion happened overhead. Unfortunately, it may not have been witnessed:

“The X-ray data tell us that there’s a lot of dust lying between it and Earth. Even if you’d been looking straight at it when it exploded, it would’ve been invisible to the naked eye.” – Bryan Gaensler

This is some tremendous detective work by the Australian team and the XMM-Newton telescope, ensuring G350.1-0.3 will never be forgotten again. I just hope they give it a better name soon!

Source: ESA

Posted on by Ian O'Neill

Arecibo Joins Forces with Global Antennae to Simulate 6,800 Mile Telescope

The Arecibo radio telescope in Puerto Rico.

The Arecibo Observatory in Puerto Rico has joined forces with telescopes located in North America, South America, Europe and Africa to create the observing power of a radio telescope 6,800 miles (nearly 11,000 kilometres) in diameter. This collaboration is called the Express Production Real-time e-VLBI Service (EXPReS) project, and on May 22nd, the system went “live” with all antennae observing the same part of the sky. This is an historic project where international collaboration has resulted in the most powerful radio telescope system available to date…

May 22nd heralded the first live demonstration of the EXPReS project that used radio telescopes from four continents. e-VLBI stands for “electronic Very Long Baseline Interferometery” and the system has the huge benefit of taking real-time observations. Data from the EXPReS project is transmitted to the central signal processor at the Joint Institute for VLBI in Europe (JIVE) in Holland, where speeds of data-streaming have exceeded Arecibo’s previous record four times over. Apart from being an acronym fest, the e-VLBI, EXPReS, JIVE collaboration will observe the cosmos with a resolution of 100 times better than the worlds most advanced optical telescopes.

So how can a single radio telescope dish with a diameter of 6,800 miles be simulated if the project has telescopes scattered around the planet? This is where the clever technique called Very Long Baseline Interferometery (VLBI) comes in. If you have multiple telescopes observing the same radio source in the cosmos simultaneously (and using very precise atomic clocks as a guide), the distance (or base-line) between observatories will simulate the effect of using a telescope with a diameter of that distance. The resolution of the observation is improved when the interferometer has several observatories working as one. Traditionally, the radio signal received at each antenna was recorded on a magnetic tape and then shipped to a central processing facility. The results of a campaign usually took weeks to be compiled. By using the e-VLBI system, recording data at the telescope site can be bypassed and transmitted real-time to the central processing facility along with the other telescopes observing the same source. Results are now available in a matter of hours – essential rapid processing when fast astronomical processes (such as supernovae) are in progress.

“These results are very significant for the advance of radio astronomy. It shows not only that telescopes of the future can be developed in worldwide collaboration, but that they can also be operated as truly global instruments.” – Huib Jan van Langevelde, JIVE Director.

The EXPReS project is funded by the European Commission and aims to connect 16 of the world’s most sensitive radio observatories. In the middle of this collaboration is the JIVE processor so real-time data processing can help astronomers achieve very quick results and react to transient radio sources.

Sources: Physorg.com, Arecibo Observatory

Posted on by Ian O'Neill

Can Light be “Squeezed” to Improve Sensitivity of Gravitational Wave Detectors?

Visualization of a massive body generating gravitational waves (UWM)

The search is on to detect the first evidence of gravitational waves travelling around the cosmos. How can we do this? The Laser Interferometer Gravitational-Wave Observatory (LIGO) uses a system of laser beams fired over a distance of 4 km (2.5 miles) and reflected back and forth by a system of mirrors. Should a gravitational wave pass through the volume of space-time surrounding the Earth, in theory the laser beam will detect a small change as the passing wave slightly alters the distance between mirrors. It is worth noting that this slight change will be small; so small in fact that LIGO has been designed to detect a distance fluctuation of less than one-thousandth of the width of a proton. This is impressive, but it could be better. Now scientists think they have found a way of increasing the sensitivity of LIGO; use the strange quantum properties of the photon to “squeeze” the laser beam so an increase in sensitivity can be achieved…

LIGO was designed by collaborators from MIT and Caltech to search for observational evidence of theoretical gravitational waves. Gravitational waves are thought to propagate throughout the Universe as massive objects disturb space-time. For example, if two black holes collided and merged (or collided and blasted away from each other), Einstein’s theory of general relativity predicts that a ripple will be sent throughout the fabric of space-time. To prove gravitational waves do exist, a totally different type of observatory needed to be built, not to observe electromagnetic emissions from the source, but to detect the passage of these perturbations travelling through our planet. LIGO is an attempt to measure these waves, and with a gargantuan set-up cost of $365 million, there is huge pressure for the facility to discover the first gravitational wave and its source (for more information on LIGO, see “Listening” for Gravitational Waves to Track Down Black Holes). Alas, after several years of science, none have been found. Is this because there are no gravitational waves out there? Or is LIGO simply not sensitive enough?

The first question is quickly answered by LIGO scientists: more time is needed to collect a longer period of data (there needs to be more “exposure time” before gravitational waves are detected). There is also strong theoretical reasons why gravitational waves should exist. The second question is something scientists from the US and Australia hope to improve; perhaps LIGO needs a boost in sensitivity.

The laser "squeezer" equipment (Keisuke Goda)

To make gravitational wave detectors more sensitive, Nergis Mavalvala leader of this new research and MIT physicist, has focused on the very small to help detect the very big. To understand what the researchers are hoping to achieve, a very brief crash course in quantum “fuzziness” is needed.

Detectors such as LIGO depend on highly accurate laser technology to measure perturbations in space-time. As gravitational waves travel through the Universe, they cause tiny changes in the distance between two positions in space (space is effectively being “warped” by these waves). Although LIGO has the ability to detect a perturbation of less than a thousandth of the width of a proton, it would be great if even more sensitivity is acquired. Although lasers are inherently accurate and very sensitive, laser photons are still governed by quantum dynamics. As the laser photons interact with the interferometer, there is a degree of quantum fuzziness meaning the photon is not a sharp pin-point, but slightly blurred by quantum noise. In an effort to reduce this noise, Mavalvala and her team have been able to “squeeze” laser photons.

Laser photons possess two quantities: phase and amplitude. Phase describes the photons position in time and amplitude describes the number of photons in the laser beam. In this quantum world, if the laser amplitude is reduced (removing some of the noise); quantum uncertainties in laser phase will increase (adding some noise). It is this trade-off that this new squeezing technique is base on. What is important is accuracy in the measurement of amplitude, not the phase, when trying to detect a gravitational wave with lasers.

It is hoped that this new technique can be applied to the multi-million dollar LIGO facility, possibly increasing LIGO’s sensitivity by 44%.

“The significance of this work is that it forced us to confront and solve some of the practical challenges of squeezed state injection—and there are many. We are now much better positioned to implement squeezing in the kilometer-scale detectors, and catch that elusive gravitational wave.” – Nergis Mavalvala.

Source: Physorg.com

Posted on by Nancy Atkinson

Planetary Potential from Protoplanetary Disks

How planets form is one of the major questions in astronomy. Only recently have we been able to study the disks of dust and gas surrounding other stars in an effort to understand the process of how planets coalesce and form from these “protoplanetary” materials. But this is a difficult task at best, given the observational distances. “This is a vast topic with many challenges,” said David Wilner from the Harvard-Smithsonian Center for Astronomy at his talk at the American Astronomical Society meeting this week. “But over the course of the past few decades with observations of nearby star systems, we’ve come to a basic outline of the process of solar system formation.”

There are a couple of hurdles to overcome in studying protoplanetary disks. First, the bulk of the disk mass is cold and dark, as the molecular hydrogen doesn’t radiate. These areas are probed only through a couple of minor constituents: thermal emission from dust and scattered light from the star.

Second, the amount of “stuff” astronomers are looking at is actually fairly small. Usually, the amount of protoplanetary material is about 1/100th the mass of the star, and about 1/4000th of a degree in the sky.

Through observations of many systems with several telescopes, we can see these disk systems in a variety of wavelengths in an effort to see both the star and the disk components. Wilner said there are two properties that are particularly important to know: Disk masses in general, as the luminosity is directly proportional to the mass, and second is the disk lifetime. From current knowledge, the dust disk disperses by 50% in 3 million years, and 90% by 5 million years.

As an example, Milner discussed the Rho Ophiuchi nebula, (image above), located near the constellations Scorpius and Ophiuchus, about 407 light years away from Earth.

“The Rho Oph cloud is spectacular, with beautiful dark regions that are columns of gas and dust extinguishing the background star field. This is the material that is forming stars and planets.”

Wilner said the steps in solar system formation are as follows: first the formation of a primordial proto-star disk, then the protoplanetary disk, and then debris disk within a planetary system.

But the main problems in our understanding lies in that astronomers haven’t yet actually seen all the steps in this process, and can’t prove directly that these early disks go on to form the planets. There are several clues, such as that gaps form in the dust around clumps of materials, similar to the gaps in the rings of Saturn around moons.


For the past 15 years protoplanetary disks have been studied with various interferometers at the Keck Observatory on Mauna Kea at various wavelengths from .87 microns to 7 mm. And the past five years the Spitzer Space Telescope has lent its infrared capabilities to further our knowledge to our current understanding. But soon, a new telescope in the high Chilean desert might provide the resolution needed to offer a glimpse at not only the gaps in the disks, but a new window on how materials around emerging planets may form moons. The Atacama Large Millimeter/submillimeter Array (ALMA), will operate at wavelengths of 0.3 to 9.6 millimeters.

Wilner obviously looks forward to putting observational capabilities of this array to work. Scheduled to be completed in 2012, ALMA will help fill in the “gaps” of our knowledge about planetary formation.

Source: AAS Meeting presentation, with clarification from Chris Lintott

Posted on by Ian O'Neill

Eta Carinae and the “Cosmic Cauldron” in Unprecedented Detail – New Images from the VLT

Eta Carinae. Taken with the NACO near-infrared adaptive optics instrument on ESO's Very Large Telescope (ESO/VLT)

To celebrate the Very Large Telescope’s (VLT) 10th birthday on Tuesday, it was us who received the gifts. The European Southern Observatory (ESO) released two magnificent astronomical images of two nebulae, both very different, but spectacular all the same. One is the iconic scene of Eta Carinae (a.k.a. Homunculus, “little man” in Latin, pictured), the nebula produced by a single dying star just before it goes supernova. The second is of the large nebula NGC 3576, setting the scene for the “Cosmic Cauldron”, where the clouds are constantly churned up by the birth of newborn stars. These new images have applied some of the most advanced astronomy techniques to remove atmospheric blurring, bringing us the most detailed look into these nebulae we have ever experienced…

The VLT is located high on the Chilean mountain of Cerro Paranal, over 2.5 kilometres (1.5 miles) above sea level. The Atacama desert in northern Chile provides ideal, stable observation conditions to resolve the fine structure of astronomical objects four billion times fainter than what can be observed with the naked eye. The observatory consists of a group of four 8.2 metre telescopes, and an astronomical interferometer. For the last ten years the VLT has produced some of the most iconic images in the history of astronomy. The VLT was one of the first observatories to capture infrared images of extrasolar planets 2M1207b and GQ Lupi b. It also discovered the most distant gamma-ray burst and possibly the farthest observed (and therefore youngest) galaxy ever discovered, Abell 1835 IR1916. It has also uncovered evidence that there may be a supermassive black hole sitting in the centre of our galaxy. Still, it captures some of the deepest images of space we have ever seen.

Star forming NGC 3576, a gigantic region of glowing gas about 100 light-years across (ESO/VLT)

Probably the most familiar image is of the twin bulges of the clouds of hot matter being blown from the dying bright star of Eta Carinae (pictured top). This is one of the finest examples of a star going through the last phase of its life as a “luminous blue variable”. The hot gas forming the “Homunculus” originates from a great outburst observed in 1843 and some time in the next 100,000 years, the star will die, exploding as a supernova. This new image is 6 to 7 times better resolved than previous images of Eta Carinae as the VLT has applied some of the most advanced adaptive optical technology (called NACO) to remove the blurring effect of the atmosphere. Now, the fine scale of Eta Carinae can be seen, clearly showing the jets blasting from the central star and the bipolar structure.

A second (bigger) nebula can also be found in the direction of the constellation of Carina, it is called NGC 3576. This vast region (stretching 100 light-years across) is located in a volume of space far beyond Eta Carinae, some 9,000 light-years from the Earth. The image of NGC 3576 (pictured above) shows, in awesome detail, the violent nature of the cradle for newborn stars. The nebula is thought to be very young, only 1.5 million years old, with massive stars emitting intense radiation and stellar winds, ejecting the clouds from where they grew up.

Researchers from the University of Cologne in Germany are studying NGC 3576 using the VLT to deduce the number of young stars that still have protoplanetary disks. From this study, astronomers hope to understand the lifetime of these planet-forming disks, how the star’s radiation influences lifetime and how stellar collisions will affect disk evolution.

For now, I’ll leave the science to the researchers and enjoy the beauty of these striking VLT images…

Source: ESO