SKA and CAASTRO: Forecast Sky bubbling with exploding stars

It is hard to imagine that any astronomical phenomenon could escape our latest and most powerful telescopes, but an international research team has now forecast some of the exotic discoveries that will only be able to be studied with the forthcoming Square Kilometre Array (SKA).

Giancarlo Ghirlanda

The team, led by Dr Giancarlo Ghirlanda at the National Institute for Astrophysics (INAF) in Italy and including CAASTRO members Dr Davide Burlon and Dr Tara Murphy from the University of Sydney, has calculated that the SKA will reveal the lingering footprints of tens of thousands of enigmatic cosmic explosions known as "gamma-ray bursts".

Davide Burlon

"With current telescopes, we see a bright gamma-ray burst somewhere in the Universe around once per day, but new radio telescopes will soon be able to see an afterglow of the explosion after the initial burst has faded away," explains CAASTRO postdoctoral researcher Dr Burlon.

"This afterglow can generally take weeks to gradually decay and teaches us incredible amounts about both the initial explosion and its neighbourhood."

The catch is that a gamma-ray burst is not an explosion that we can see from all directions but is comprised of a very narrow, energetic jet, so we need to be looking down the barrel of the jet at the right time.

Otherwise it is invisible, equivalent to only seeing the beam of a laser pointer when it points directly at us.

The radio afterglow should be visible from any direction though and for long periods of time, even if we missed the burst.

Tara Murphy

These afterglows without a burst are known as "orphan" afterglows, they're a phenomenon that astronomers have until now been looking for without success.

"From the rate at which we detect gamma-ray bursts, we were able to predict that with the power of a sensitive new telescope like the SKA, orphan afterglows should be seen 700 times more often than their gamma-ray bursts." says Dr Burlon.

"The unprecedented sensitivity and wide field-of view of the SKA means that orphan afterglows should be visible for months or even years before eventually disappearing, bubbling across the sky more than ten thousand times per year."

Of course, the SKA's view of the sky will be full of all sorts of objects and events, such as supernova explosions and flaring black holes that are more common than orphan afterglows.

"In this new era of radio astronomy, one of the challenges will be to disentangle these different classes of radio sources." says Dr Tara Murphy, CAASTRO Associate Investigator and project leader of the "Variables and Slow Transients (VAST)" survey with the Australian SKA Pathfinder (ASKAP).

The SKA will join the Australian SKA precursor telescope ASKAP and the South African SKA precursor MeerKAT in painting an entirely new picture of the "radio sky".

"The SKA will not only allow us to finally see these orphan afterglows but help us understand how gamma-ray bursts (GRB) produce such powerful, narrow jets and will cast new light on the big question of just what causes gamma-ray bursts in the first place," concludes Dr Ghirlanda.

More information: G. Ghirlanda, D. Burlon, G. Ghisellini, R. Salvaterra, M. G. Bernardini, S. Campana, S. Covino, P. D'Avanzo, V. D'Elia, A. Melandri, T. Murphy, L. Nava, S. D. Vergani, G. Tagliaferri: "GRB orphan afterglows in present and future radio transient surveys" in The Publications of the Astronomical Society of Australia (PASA). arXiv:1402.6338 [astro-ph.HE] arxiv.org/abs/1402.6338

Gemini South Telescope: A new eye to scan the sky for exoplanets

The Gemini South telescope houses the latest gear to hunt down and snap photos of exoplanets. 

Credit: Gemini Observatory, CC BY 

There is excitement in astronomy and planetary science departments worldwide as the new Gemini Planet Imager (GPI), housed in the Gemini South Telescope in the Chilean Andes, turns its razor-sharp gaze to the skies.

This device, known as GPI for short, is the first of a small handful of sophisticated instruments to attempt a task that until recently was considered all but impossible: to image the faint mote of light betraying the presence of a planet nestled against the overwhelming glare of its host star.

Planets in orbit around distant stars, exoplanets, are now known to adorn more than 1,000 star systems. There is possibly five times that number under strong suspicion awaiting only final confirmatory data to join the club.

You could be forgiven for thinking this avalanche of discovery – all coming in the past 20 years – has settled most of the important questions in exoplanetary science.

The reality, though, is it hasn't.


Location, location, location
The sample of exoplanets we now have tells us far more about the limitations of the techniques we use to find them than it does about the exoplanets themselves. We have only seen the tip of the iceberg.

The search can be likened to the proverbial scientist in a dark car park searching for a set of dropped car keys under the only streetlight.

A passer-by asks: "Did you drop your keys there?" "No," you reply. "I dropped them somewhere over there in the dark, but I can only see here."

That patch of discovery illuminated by our present instruments particularly favours the largest planets in the closest orbits about their host stars.

The extreme examples of this (and the most celebrated exoplanet discovery, of 51 Peg, that launched the field in 1995) are known as "hot Jupiters".

The name understates their inhospitable crushing gravity combined with searing radiation field from the looming host star.

In a quest to identify planets capable of supporting life hot Jupiters score low. Astronomers are working on a valuation scheme that would identify those that lie within the so-called "habitable zone".

New Wave Energy UK: Power plants in sky - Wireless Transmission Drones

Here is the idea: flying power plants in the sky as a means of providing clean, renewable energy.

Here is more of the idea: this would be a high-altitude aerial power plant that harvests energy from solar, wind and other sources, and beams it wirelessly to the ground.

Now the idea gets more interesting: The power plant would be using networks of unmanned drones.

The company is New Wave Energy UK, formed in 2012, self-described as "an upcoming energy provider within the UK currently working towards researching and constructing our own novel form of power plant." (New Wave Energy UK is not associated or affiliated with US-based New Wave Energy Corp.)

In a November 15 press release, the company announced that "A new and exciting venture into a whole new form of power plant is currently in incubation within the UK."

The company said the "patent pending technology" is a drone-based power plant for combined solar, wind, heat and emerging new forms of energy generation.

The technology is to incorporate wireless power transmission from the drones (and their wireless network) to the Earth's surface," according to the release.

Details about the drone are in a recent Gizmag article on New Wave Energy UK.

According to the article, the company's ambition is for each drone to have four rotors, multiple wind turbines and a flat base for generating solar power.

With energy harvested, the devices will power themselves and also 50 kW more that can be transmitted wirelessly to the ground.

Rectenna arrays installed inland or on offshore installations would receive electromagnetic waves and convert them into usable power.

According to New Wave Energy, "The technology is tailored to operate at 50,000 ft where wind patterns are more reliable, solar production is greater and there is little or no interference from weather patterns."

In the November 15 press release, the company said it was seeking further investment to advance the project.

New Wave Energy UK is turning to crowdfunding as one such step. "To raise such equity New Wave Energy UK Ltd are hoping to raise £300,000 through crowd funding on Kickstarter.

New Wave Energy UK Ltd also intend to acquire a total of £32 million from private investors during the crucial stages of the project to commercialise the application."

Exmoor - Europe's First International Dark Sky Reserve

Click on the picture to visit the BAA Journal and the full article.

The Super Sky Cycle

The Super Sky Cycle, which has been designed by inventor Larry Neal, can fly at 35 mph and has a top speed of 65mph on the ground.

According to Neal he has been developing the aircraft for several years.

The biggest issue he had to overcome was just what do with the wings when the vehicle was on the ground.

However, he cracked that thanks to an ingenious system that allows the rotor to be neatly folded away.

This means the unusual vehicle can not only be flown but also used like a normal tricycle on the road. The Super Sky Cycle can reach an altitude of 2,100m (7,000ft) and cruise for 240km (150 miles) before needing to refuel.

Picture: Unimedia Images / Rex Features

2011 Perseid Meteor Shower Images

Skywatcher and photographer Nick Rose snapped this stunning view of a Perseid meteor from Millbrae, Calif., on Aug. 10, 2011 as the annual Perseid meteor shower neared its peak.

[See more amazing Perseid meteor shower photos from 2011]

ESA SKYLON: 'no impediments' for spaceplane development

After nearly 30 years of service, the Space Shuttle fleet is due to enter retirement with the last ever mission scheduled for takeoff on July 8, 2011.

In its lifetime, the world's first Reusable Launch Vehicle (RLV) has provided information that will prove invaluable for the next generation of spacecraft that will succeed it.

One such craft is the Skylon, an unpiloted, single-stage, reusable spaceplane currently under development by UK-based Reaction Engines Ltd. (REL).

The Skylon got a shot in the arm last month with the release of a technical review of Skylon carried out by the European Space Agency (ESA) that concluded there are "no impediments" that would prevent the continued development of the Skylon and its SABRE engine.

The Skylon design, which grew out of the HOTOL (Horizontal Take-Off and Landing) program by Rolls Royce and British Aerospace that was terminated in 1988.

The design consists of a slender fuselage containing propellant tankage and payload bay, with delta wings attached midway along the fuselage carrying the SABRE engines in axismmetric nacelles on the wingtips.

With a payload bay measuring 4.6 m (15 ft) in diameter and 12.3 m (40 ft) long, Skylon is designed to transport up to 15 tons of cargo into Low Earth Orbit (LEO, approx. 300 km /186 mile) at about 1/50th of the cost of traditional expendable launch vehicles, such as rockets. It could also carry 10.5 tons to a 460 km (286 mile) equatorial space station, or 9.5 tons to a 460 km x 28.5 degree space station, when operating from an equatorial site.

Read more here: ESA review finds 'no impediments' for SKYLON spaceplane development

NASA: Carina Nebula - MAD ESO's VLT

This impressive image of the open cluster known as Trumpler 14 was obtained with the Multi-conjugate Adaptive optics Demonstrator (MAD) mounted on ESO's Very Large Telescope.

The cluster, which is found to be only 500 000 years old - a blink of an eye in the Universe's history - resides at the outskirts of the central region of the Carina Nebula, located some 8000 light-years away towards the constellation of Carina (the Keel).

Trumpler 14 is not only the youngest, but also one of the most populous clusters within the nebula.

Astronomers counted about 2000 stars in the very central parts of this cluster.

The MAD instrument allows astronomers to obtain very sharp images over a wide area and this image is the adaptive optics image that so far covers the widest area on the sky. The field of view is about 2 arcminutes across and the image is based on data obtained through two different filters (K and H).

Read and See More ESO Images......

Picture: ESO / AFP/GETTY

Today's Lecture: Why is Space Black and the sky Blue?

A simple enough question but it is actually quite difficult to answer! It is a question that many scientists pondered for many centuries - including Johannes Kepler, Edmond Halley , and German physician-astronomer Wilhelm Olbers.

Let's take the easy one first and ask "why is the daytime sky blue here on Earth?"

That is a question we can answer. The daytime sky is blue because light from the nearby Sun hits molecules in the Earth's atmosphere and scatters off in all directions. The blue color of the sky is a result of this scattering process.

At night, when that part of Earth is facing away from the Sun, space looks black because there is no nearby bright source of light, like the Sun, to be scattered. If you were on the Moon, which has no atmosphere, the sky would be black both night and day. You can see this in photographs taken during the Apollo Moon landings.

So, now on to the harder part - if the Universe is full of stars, why doesn't the light from all of them add up to make the whole sky bright all the time?

It turns out that if the Universe was infinitely large and infinitely old, then we would expect the night sky to be bright from the light of all those stars. Every direction you looked in space you would be looking at a star. Yet we know from experience that space is black!

This paradox is known as Olbers' Paradox. It is a paradox because of the apparent contradiction between our expectation that the night sky be bright and our experience that it is black.

Many different explanations have been put forward to resolve Olbers' Paradox. The best solution at present is that the Universe is not infinitely old; it is somewhere around 15 billion years old. That means we can only see objects as far away as the distance light can travel in 15 billion years. The light from stars farther away than that has not yet had time to reach us and so can't contribute to making the sky bright.

Another reason that the sky may not be bright with the visible light of all the stars is because when a source of light is moving away from you, the wavelength of that light is made longer. This lengthening of the wavelength makes the light appear more red than blue.

This means that the light from stars that are moving away from us will become shifted towards red, and may shift so far that it is no longer visible at all. This is called the Doppler Effect or Dopler Shift.

The Human Eye

All living creatures on our planet have a limited range of light that they can detect and tolerate. There is an upper and lower threshold. If you look at it from the simple Goldilocks selectiveness perspective; some frequencies are too low, some are too high and some are just right.

Many birds, animals and insects can see very well in low light because they spend most of their time out of the sun. Therefore there ability to detect a fixed range of light is limited to the light that they most often hunt, live and work in, low light. This range selection will be part of their evolutionary development, allowing the animal to thrive, breed and prosper.

Equally, we humans exist mainly in the bright light of day, therefore the range or intensity of light that our eyes can detect are limited to the brighter end of the spectrum. We cannot and need not, detect low light ranges, we have devised other ways of penetrating the darkness. Our eyes have developed in such a way as to attenuate and normalise the intensity of light that we can detect, allowing us to function at our best, during the appropriate time of day.

What we cannot do, is to detect all light ranges and neither can other living creatures on the planet. There is no evolutionary 'advantage' to be gain from this. Therefore if the sky appears black to us, it is because there is simply not a high enough intensity or frequency of light entering the eye receptors, to stimulate a detectable reaction. It is not because there is no light present.

Artificial detection

We believe from science, astrophysics and our academic studies that the full range of light frequencies can be detected artificially by the use of intervening filters, attenuators and sensitive materials. We have enhanced our human vision by the use of these 'systems' and can penetrate the darkness and extend our perception of the universe and the night sky.

The night sky is not black it is simply bathed in a low frequency light that is difficult for us to detect, through the clouds and polluted atmosphere of our only planet.