Unraveling the mysteries of space may come down to understanding the humble complexities of dust, says Whitman College astronomer U. J. Sofia.
Professor Sofia is one of a handful of scientists who study interstellar dust. Why? Because the dust grains, or small solid particles, interspersed in the gasses between earth and the edge of the universe distort the light passing through space, which in turn distorts astronomers' views of the cosmos.
By studying interstellar dust, says Sofia, scientists can figure out the amount and type of distortion the dust is causing and can then determine exactly what it is they are seeing hundreds to billions of light years away. Among the many phenomena scientists would like to see more clearly are the quasars that exist at the edge of the universe. These quasars are probably young galaxies that formed when the universe itself was very young. In order to understand how the universe has evolved, astronomers are studying these ancient, distant objects. The difficulty is that no one has been able to get a good, undistorted look at them, says Sofia. We don't know how the dust toward the quasars or in the quasars is affecting their appearance.
"Most astronomers think of dust as a thorn in their side — when they're studying stars, galaxies, and quasars, it gets in their way — but I find it intrinsically interesting," says Sofia, who uses data obtained from the Hubble Space Telescope and the Interstellar Medium Absorption Profiles Spectrograph (IMAPS).
Professor U. J. Sofia studies the interstellar dust that clouds the universe's ancient, distant past.
"When I study gas in the interstellar medium, I take light and break it down into its component colors. I observe what colors are missing from the spectrum, and that tells me what atoms are in the gas and how many atoms there are. The analysis is similar to reading a bar code where the location and thickness of the bars identifies a product. For us, the bar code identifies a given composition of interstellar gas. Although we cannot observe the dust directly, we believe that we know how much of each element exists in the universe, so we simply measure the elements in the gas-phase of the interstellar medium. If we don't find all that we're expecting, then we assume the missing elements must be composing the dust grains."
This is important, says Sofia, because "once we learn the composition of the dust between here and there, we can figure out how that dust is distorting the light. We can then remove that distortion and figure out exactly what it is we're looking at. As we learn what dust is in each case, we can more accurately view our universe and its components. In this way we provide a service to the rest of the astronomical community because dust distortion affects almost every observation in astronomy."
As a byproduct of the interstellar studies, we have learned that our sun has more carbon and oxygen than most interstellar matter, says Sofia. Most stars have only two-thirds the amount of carbon and oxygen that our sun (and therefore our solar system) has. Since these two elements are critical to life, some scientists wonder if life would have developed here on earth without this phenomenon.
Sofia, the recipient of seven current science grants, is looking forward to undertaking more research with two new grants this year — one research project will make use of Hubble Space Tele-scope data, and the other will use data from FUSE, the Far Ultraviolet Spectroscopic Explorer.
"Our knowledge has changed drastically in the last decade since the introduction of the Hubble Space Telescope. The FUSE spectrograph observes at different wave lengths (of light) than the Hubble, so the depth of our knowledge will increase even further with the addition of its information," Sofia explains. "In astronomy light is important to us. We can't touch what we're studying, we can only analyze the light that gets to us."
Sofia has been doing just that for years. As a graduate student, he received a NASA fellowship to observe the galaxy's interstellar matter with the Hubble Space Telescope, and his doctoral thesis was the first to be based entirely on Hubble Space Telescope data. In addition, since 1994 he has been a science team member for the Interstellar Medium Absorption Profile Spectrograph (IMAPS). It is a high resolution far ultraviolet spectrograph that has flown as a space shuttle payload on the ORFEUS I and II missions and is expected to fly again in the next two to three years.
Two Whitman students, Brent Bryan, a senior, and Melinda Kahre, a junior, currently are working with Sofia on Hubble Space Telescope and IMAPS projects.