Refurbished Hubble gets
off to a flying start
EMILY BALDWIN & KEITH COOPER
Posted: September 9, 2009
NASA scientists today unveiled the first spectacular images captured by the recently repaired Hubble Space Telescope.
Space Shuttle Atlantis astronauts upgraded the troubled space telescope during the dedicated STS-125 mission in May, a final makeover that will extend the telescope's life expectancy well into the next decade. New instruments included the Cosmic Origins Spectrograph (COS) which is set to map out the ‘cosmic web’ of galaxies and gas clouds that span the Universe. It will gather the ultraviolet light of brilliant quasars that can be seen shining through this intervening cosmic web, and spectroscopy will reveal the composition of these galaxies and gas clouds. The Wide Field Camera 3 (WFC3) replaces the old Wide Field and Planetary Camera 2, and is already producing breathtaking images. The Advanced Camera for Surveys received upgraded technology to improve its sensitivity, and the Space Telescope Imaging Spectrograph was brought back to life.
Today NASA scientists revealed that Hubble is well and truly back in business, releasing an impressive bounty of new images and data to set the scene for a new era of observations. "The instruments are working splendidly," said David Leckrone, senior project scientist for Hubble during today's dedicated press conference. "Hubble's observing power is increased by a factor of ten," added Ed Weiler, Science Mission Directorate at NASA Headquarters.
Here is a selection of some of the images released today. All images: NASA/ESA/Hubble SM4 ERO Team.
A butterfly emerges from stellar demise in planetary nebula NGC 6302, but things are far from serene. The butterfly's 'wings' are giant cauldrons of gas boiling at 20,000 degrees Celsius and ripping through space at over 900,000 kilometres per hour. At the centre of this fury was a star once five times the mass of the Sun, which has unleashed layers of gas and radiation in a dramatic death cry. The WFPC3 camera has revealed a complex history of ejections from the star. First, on evolving into a red giant star it lost its outer layers, cast off from its equator to create a donut shaped ring. Other gas was ejected perpendicular to the ring at higher speeds, giving wise to the 'wings'. As the central star heated up a stream of stellar wind charged through the wing-shaped structure to modify its shape. Fingers of material appear to point back to the central star that may represent denser material that has resisted the pressure from the stellar wind.
Hubble’s brand new Cosmic Origins Spectrograph, which breaks up the light from distant objects and identifies the elements and molecules producing the different colours of that light, has scanned the expanding debris of a supernova, N132D in the Large Magellanic Cloud, picking out fresh gas from the explosion that occurred in our skies 3,000 years ago. COS, scanning in ultraviolet light, identified pristine carbon and oxygen gas that has not yet become polluted with the dirty, dusty gas of the interstellar medium that resides between the stars. COS was also able to detect carbon, magnesium and silicon, and is the first instrument that Hubble has ever had that has been able to distinguish between pristine gas and the gas that has begun to be mixed into the interstellar medium.
This vibrant assortment of some 100,000 stars in the core of globular cluster Omega Centauri resembles the colourful array of sweets in a pic 'n' mix, yet this is just a small scoop of the cluster which boasts a population of 10 million stars. Omega Centauri's denizens range between 10 and 12 billion years old and show yellow-white stars like our own Sun, to older, cooler red-orange stars. After ejecting most of their mass and exhausting much of their hydrogen fuel, the stars appear bright blue. The new image demonstrates the sharpness of the WFC3, which is capable of resolving each of the stars individually.
The black hole powerhouse at the centre of the ringed spiral galaxy Markarian 817 has been seen driving bubbles of hot gas out from the galaxy and into deep space. In 1997 Hubble detected a large gas cloud flowing away from this galaxy on a wind of radiation emitted by gusty jets from the central black hole, which is 40 million times more massive than our Sun, and ten times more massive than the black hole in our Galaxy. When the Cosmic Origins Spectrograph (COS) studied the galaxy, it saw that this gas cloud had disappeared, having been completely blown out from the galaxy. This result is important because astronomers want to know whether gas blown out of a galaxy leaves it forever, or whether it falls back onto the spiral disc to create more stars. By studying galaxies like Markarian 817, they can ascertain how massive a black hole needs to be before its radiation jets become so powerful that they blow most of the star-forming gas out of a galaxy, effectively preventing any further star formation and growth of that galaxy. COS is able to detect the signatures of elements and molecules in the gas being blown out of the galaxy, telling astronomers exactly what the gas is that is being expelled.
A favourite among many astronomers, the new image releases also include the cosmic pile up known as Stephan's Quintet. Three of the galaxies have distorted shapes moulded by the gravitational interaction as the they made their dangerously close encounters. These interactions have also sparked a frenzy of star birth in the central pair of galaxies. The image was taken in visible and infrared light and showcases WFPC3's broad wavelength range, tracing the ages of stellar populations over hundreds of millions of years and peering through thick blankets of dust to see stars that cannot be seen in visible light.
There isn’t purely empty space between the galaxies. In the vast expanses between these island universes is a sea of dark, diffuse filaments of gas that we call the ‘cosmic web’, but to be able to study this gas in detail we need something to illuminate it. The Cosmic Origins Spectrograph has detected light from a quasar 6.4 billion light years away being filtered through this diffuse gas between us and the quasar, PKS 0405-123. The intervening gas absorbs some of the quasar’s light, and in the spectrum measured by COS it is possible to see what molecules in the cosmic web are doing the absorbing. It detected up to five times more lower density filaments of hydrogen than had been previously seen when looking in this direction. COS also saw warm, glowing nitrogen and oxygen gas excited as gas clouds in the web cascade onto one another, or are buffeted from radiation winds emitted by active galaxies like Markarian 817. COS is ten times more sensitive than any such instrument Hubble has ever had, and provides astronomers the ability to detect thousands of quasars in ultraviolet light. By looking at these quasars all across the sky, it is possible to build up a picture of the greater structure of the cosmic web.
The newly repaired Advanced Camera for Surveys peered back nearly five billion light years to resolve fine detail in the galaxy cluster Abell 370, one of the first clusters to reveal the phenomenon of gravitational lensing. Where the cluster's gravitational field distorts the light from galaxies far behind it, arcs streak across the image. Zooming in to the red streak in the upper right of this image – nicknamed the dragon by Hubble scientists – reveals the previously unresolved and stunning detail of the distant galaxy. Gravitational lensing proves a vital tool for astronomers when measuring the dark matter distribution in massive clusters, since the mass distribution can be reconstructed from its gravitational effects.
An instrument on Hubble that had been left for dead prior to the servicing mission earlier this year has revealed some of the composition of the gas ejected by the mighty star eta Carinae during its dramatic outburst all the way back in 1843. That material is today billowing out into a double-lobed cloud that shrouds the star inside, which is one of the most massive known and will eventually explode as a supernova. The Space Telescope Imaging Spectrograph (STIS) failed in 2004 but was fixed by astronauts during May’s servicing mission. STIS detected iron and nitrogen on the outer edges of the expanding lobes that are being blown outwards by a powerful wind of radiation from the star, which is 7,500 light years away. Argon was also detected where the wind from eta Carinae buffets the much weaker wind from its smaller binary companion.
Leckrone concluded his presentation with: "I'm not able to report any failure or problem on the spacecraft. It is a beautifully operating space telescope." And long may it last!