Researchers at the Dublin Institute for Advanced Studies last week received fresh data from the Hubble Space Telescope, part of an Irish experiment to study an active star-forming region.
It involves a detailed analysis of nebula NGC1999, a mere 1,000 light years away towards the constellation Orion the Hunter and the closest place to Earth where young stars are being born. The star under most active study was a true infant, explained Prof Tom Ray of the Institute, who with Dr Dave Corcoran of the University of Limerick and Prof Bob Odell of Rice University in Houston, Texas, had "control" of the Hubble when the data were recorded.
"Our observations were done on January 21st, within days of Hubble coming back into operation," explained Prof Ray. "We were looking at a very young star only about 100,000 years old." The data and images were delivered to the institute only last week, he added, and pictures of NGC1999 have just been released by NASA and the European Space Agency, which jointly operate Hubble.
The baby star is still surrounded by space dust, the "placental cloud" from which the star formed, he said. "Our sun would have looked like that when it was first formed five billion years ago." Being 1,000 light years away, the images represent the way the star would have appeared at about the time the Battle of Clontarf took place.
The nebula is a large area of dust in which stars are being born. "Stars are being formed all the time, on average in our galaxy one a year," Prof Ray said. Nebula NGC1999 has no "name" such as the Horsehead or Crab nebulas, but it might readily be called the "Harp nebula", he said, given the harp shape seen in the images captured by Hubble.
It is not visible to the naked eye because it does not emit light in its own right. It comes into view by reflecting light from two nearby stars, one of them the target of Prof Ray's work. It can be seen with a telescope, however, and the nebula is also a powerful infra-red source which makes it visible in two ways to Hubble's instruments.
NGC1999 was first observed and recorded by Sir William Herschel who, with his sister, Caroline, during the late 1700s and early 1800s, used telescopes of his own construction to discover many new objects.
"We are trying to figure out what happens within the first few hundred thousand years of a star's life," Prof Ray said. "The star itself is a double system." The local dust won't clear for perhaps a million years, by which time the star pair will be as bright as our own, perhaps brighter.
Prof Ray had a half-day of Hubble time last October and has time booked for October 2000, research work selected from among thousands of proposals which are peer-reviewed for the quality of the science. Ireland is an ESA member which gives Irish researchers a right to apply for Hubble time.
This project was somewhat different, however, coming under what is described as the Hubble Heritage programme, observations made because of the visual impact of the object.
NGC1999 qualified under this category, so Hubble's controllers sought out someone to define what scientific research might be done when the pictures were being taken. As Prof Ray had some years earlier done extensive ground-based work on the nebula, he was a natural choice to organise the science for this observation and was invited to do so.
The two space agencies were also hoping, however, to cash in on the end-of-century millennium hype, given the date in the nebula's name. Prof Ray was to have had the last hour of 1999 to observe the nebula, but the telescope was "parked" after yet another gyroscope breakdown last November.
The team got their observation time within days of Hubble coming back into service, and the images were captured with 10 times the resolution that would have been available using ground-based observation. The result is the dramatic image shown here.