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YORK AND ALABAMA ASTRONOMERS "SEE THE LIGHT" AFTER UNMASKING OBSCURED GALAXIES TORONTO, January 15, 1997: By lifting a veil of dust and stars, two astronomers have identified three of the five brightest galaxies in the northern sky and revealed more information about this group of galaxies than has ever before been known. Astronomers Marshall McCall of York University in Toronto, Canada, and Ronald Buta of the University of Alabama, U.S.A., have dug their way through a thick layer of dust and tens of thousands of stars to undertake the world's most in-depth study of the group of 15 galaxies known as IC342-Maffei 1. This research is significant because it will help piece together the history of our corner of the universe since the Big Bang. The pair presented its work today in a display at the 189th conference of the American Astronomical Society in Toronto, co-hosted by York University. McCall and Buta made astronomical news in 1995 when they discovered two galaxies -- since named MB1 and MB2 -- in the same part of the sky, only 10 million light years from us. "We have seen the light -- literally and figuratively," said McCall. "Through our research, we have been able to unmask three jewels of the northern sky, hitherto neglected galaxies that are far brighter and larger than anyone else ever imagined." The three brightest galaxies in the group are called IC342, Maffei 1, and Maffei 2. If not for the dust, the first two would be as large as the full Moon and so brilliant they could be seen with the naked eye from the Earth's northern hemisphere. There is so much dust between the stars of the Milky Way -- through which we must look to view the universe -- that a clear view was dependent on detecting the infrared light of the galaxies. Astronomers now believe there have been gravitational interactions between different galaxies since the Big Bang, and that these interactions have altered the paths of galaxies through space. The IC342-Maffei 1 group of galaxies was probably involved in a chain of events that affected our neighbourhood in the sky, McCall said, and therefore the group may have played a role in the history and movement of our galaxy, and, of course, our solar system. "There can be little doubt that IC342, Maffei 1, and Maffei 2, would be among the best-studied galaxies in the sky, were it not for the thick veil of dust between us and them," said Buta. "Our images provide the best views of these galaxies ever obtained, and now we can begin to use this information to finally pin down precisely how far these galaxies are from us, and how their gravitational interaction may have influenced the other galaxies in our neighbourhood, especially us." "Determining the brightness of these galaxies was an unbelievable challenge," said McCall. "We had to spend a long time at the telescope on each galaxy to get good enough images, but before we could do anything with them, we had to remove thousands of foreground stars. Neither of us had ever encountered such a situation in previous research, so we had to invent a way to deal with the problem." A galaxy consists of billions of stars mixed with gas and dust, and represents a distinct entity bound by gravity and floating in the universe.
McCall and Buta's new research was based on deep wide-field images of the IC342-Maffei 1 group, a loose collection of 15 galaxies located in a position that requires looking through the Milky Way in the direction of the constellations Cassiopeia, Perseus, and Camelopardalis. In the past, research on this group has been inhibited by clouds of dust which both obscure and redden the light from the galaxies, and by tens of thousands of superimposed stars in the Milky Way interfering with measurements of the properties of the members. The dust shrouds several galaxies, dimming them a hundredfold. Modern instrumentation and novel analysis techniques allowed the pair of astronomers to prove the brilliance and enormity of the three largest galaxies in the group. McCall and Buta used the Burrell-Schmidt telescope at Kitt Peak National Observatory in Arizona in 1995 to obtain images of all the known member galaxies in the group. That telescope's unique design enabled them to obtain a very large, clear picture of the sky using two filters -- one which transmits visible light and one which transmits infrared. Infrared light, which was crucial to lifting the veil, penetrates the dust more readily than visible light. A similar phenomenon makes the Sun appear to be red at sunset because the dust in the air is more effective at blocking yellow, green, and blue light. By using infrared, McCall and Buta were able to reduce the obscuring effect of the dust by 80 per cent, making the view much clearer. Using a computer program designed to measure the brightness of stars, McCall and Buta figured out a way to turn the tables, employing the software to instead remove more than 95 per cent of the contaminating objects. For each of the 15 galaxies, the process took up to seven hours on a fast workstation computer. They found that IC342, Maffei 1, and Maffei 2 are so bright that, if not for the dust obscuring them, they would be among the five brightest galaxies in the northern sky. There are only two brighter galaxies in the northern sky -- the Andromeda galaxy and the Triangulum galaxy -- and only two other galaxies in the southern sky, the small and large Magellenic Clouds, are brighter still.
For more information, call:
Prof. Marshall McCall
Prof. Ronald Buta
Mary Ann Horgan
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