By Dr David Whitehouse
BBC News Online science editor
The Hubble Space Telescope has observed the most dramatic and most energetic stellar nursery ever found in space.
Artist's impression of the stellar nursery
It lies at the edge of the Universe. It was detected nestling behind a distant cluster of galaxies.
Because of its distance we see the object as it was when the Universe was young, some 12 billion years ago.
A million bluish stars - hotter than today's stars - have been formed out of this cocoon of gas, which must have been common when the cosmos was young.
A mysterious arc of light found behind a distant cluster of galaxies has turned out to be the biggest, brightest and hottest star-forming region ever seen in space.
The so-called Lynx Arc is a million times brighter than the well-known Orion Nebula, a nearby stellar nursery visible with the unaided eye.
The newly identified supercluster contains a million blue-white stars that are twice as hot as similar stars seen in our own Milky Way galaxy.
Astronomers say it is a rare example of the early days of the Universe when furious firestorms of star birth blazed across the skies. The spectacular cluster's brilliance is dimmed when seen from Earth only because it is 12 billion light-years away.
It was found as a result of a systematic study of distant clusters of galaxies carried out with major X-ray, optical, and infrared telescopes, including the Hubble Space Telescope.
The cluster of young stars appears as a mysterious red arc behind a distant galaxy cluster that is itself 5.4 billion light-years away.
The arc is the stretched and magnified image of a mysterious celestial object far beyond the cluster of galaxies.
The object lies behind this cluster
Bob Fosbury, of the European Space Agency's Hubble Space Telescope team, and colleagues, first tried to identify the arc by analysing its light, but the team was not able to recognise the pattern of colours in the spectral signature of the remote object.
While looking for matches with the object's spectrum, Fosbury realised that its light was related to that of the nearby Orion Nebula.
However, the Orion Nebula is powered by only four hot and bright blue stars; the Lynx Arc must contain around a million such stars.
Though there are much bigger and brighter star-forming regions than the Orion Nebula in our local Universe, none are as bright as the
Lynx Arc, nor do they contain such large numbers of hot stars.
Astronomers speculate that stars forming from the original pristine gas in the early Universe could be more massive and consequently much hotter than today's stars.
Such super-hot stars are thought to be the first luminous objects to condense after the Big Bang cooled. Astronomers believe that these first stars formed considerably earlier than the Lynx Arc - up to 1.8 billion years earlier.
"This remarkable object is the closest we have come so far to seeing what such primordial objects might look like when our telescopes become powerful enough to see them," says Fosbury.