Coma cluster prepares for its close-up

By Jane Christmas, April 11, 2006

    Doug Welch
Doug Welch, professor of physics & astronomy, received some good news this week: NASA has allocated 180 orbits of the Hubble Space Telescope for Welch's latest research.

Welch's study will focus on a distant cluster of galaxies to study the expansion of the universe, and to find the specific stars, known as standard candles, that astronomers commonly use to gauge distances in space.

"The Coma cluster of galaxies is located within the boundaries of the constellation Coma Berenices (Bernice's Hair)," says Welch. "It's estimated to be 370 million light-years away."

Spiral cluster in Coma Berenices
Spiral cluster in Coma Berenices.

The further away a galaxy is, the faster it moves away from us. Welch says this particular cluster is moving away from our galaxy is at the rate of 7,000 kilometres per second, or 25-million kilometres per hour.

"The Hubble Constant is found by dividing the recession velocity by the distance," says Welch. "Our observations - if there are no mechanical problems with the Hubble Space Telescope - will give the best and most accurate distance to the Coma cluster and therefore the best determination of the Hubble Constant at this epoch in the Universe."

Project is risky because it's the most distant project this technology has been used for, and the Hubble is nearing the end of its work life: the slightest instrument failure could kill the entire project, he says.

The project, which will take place between December 2006, and March, 2007, is a collaborative venture with Lawrence Livermore Laboratory in California, the University of California at Davis, the Hertzberg Institute of Astrophysics in Victoria, and the National Optical Astronomy Laboratory in Tuscon.