The most famous celestial nursery in the heavens, the Orion Nebula, is much closer than previously thought, astronomers have discovered.
The 20 per cent difference has profound implications because it means the stars are much fainter than thought and so are twice as old as had been estimated.
Observations of stars at the centre of the nebula, also known as Messier 42, were made using a technique called parallax. This involves observing them six months apart, when the Earth-bound telescopes are on opposite sides of the Sun, to see how they have shifted against the stelllar background.
The ten telescopes used to make the discovery stretch from Hawaii to the Caribbean and are known as the Very Long Baseline Array (VLBA). Operated by the US National Science Foundation, they work together to study the universe in great detail.
Astronomer Geoff Bower, of the University of California, said: “This measurement is four times more precise than previous distance estimates. Because our measurement reduces the distance to this region, it tells us that the stars there are less bright than thought before, and changes the estimates of their ages.”
The scientists determined the distance to one particular star, called GMR A, by measuring the
slight shift in its apparent position as the Earth circled the Sun.
Bower added: “These stars are nearly twice as old as previously thought.’
Colleague J E G Peek said: Getting a more-accurate distance is going to pay off in many ways by improving our understanding of what is one of the most frequently-studied star-forming regions in the Universe.” The new results will appear this week in the Astrophysical Journal.
The photo is a Hubble close-up of the central region of the Orion nebula. A dramatic image of the gas cloud was produced last year by the Hubble and Spitzer space telescopes.
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