Kwitter to use the Hubble telescope to conduct research

Karen Kwitter, Ebenezer Fitch Professor of Astronomy and chair of the department, received authorization to use NASA’s Hubble Space Telescope (HST) for research to study the composition of planetary nebulae over the next year.

She will be working with two of her colleagues, Reginald Dufour of Rice University and Richard Henry of the University of Oklahoma, on their project entitled “C III Imagery of Planetary Nebulae and H II Regions.”

Kwitter will use the HST to accurately measure carbon abundances in certain gas clouds. A comparison of the data obtained from this study with data from ground telescopes will allow her to verify and improve current methods of measuring carbon abundances in clouds.

“Our project is to use the HST’s Wide Field/Planetary Camera to take pictures of glowing nebulae (gas clouds) through a filter that passes only a particular ultraviolet wavelength of light emitted by carbon atoms in order to calculate the amount of carbon in the nebula,” Kwitter said.

“We need to use the HST because this light is absorbed by the atmosphere, and can’t be detected on the ground. The derived carbon abundances in these nebulae are very useful because we can compare them with theoretical predictions of how much there ought to be,” she said.

The investigation of the makeup of stars and the maturation of the universe has always been the context of Kwitter’s research.

“My colleagues and I are interested in the chemical evolution of our Milky Way Galaxy and other galaxies, entirely composed of hydrogen and helium,” she said. “Something has obviously been going on over billions of years, because, for example, here we are, made of carbon and oxygen and nitrogen and iron, clearly not the original material.”

Kwitter remarked that the study of the abundances of elements such as carbon and nitrogen in gas clouds yields important clues to the growth of stars and the formation of new stars.

She continued to explain that lighter elements tucked away deep within the cores of stars continually transform into heavier elements as stars grow and undergo chemical reactions.

During this process, these elements rise up from the core to the surface of stars where the expulsion of the outer layer takes place. This is how glowing gas clouds are formed around stars; observing the substances present in the gas clouds can tell us much about the history of these spatial phenomena.

To summarize her research, Kwitter commented, “We are studying the ejected outer layers of stars like the sun, as well as glowing gas around newly-forming stars. Determining the amount of carbon as well as of nitrogen and oxygen, allows us to assess the various theoretical models of nuclear processing inside stars.”

Out of 5700 orbits in a year, Kwitter and her colleagues were granted sev17 orbits, or 27 hours of Hubble time for their project. In response to the question of whether this was enough time to get the data she needed, she replied, “We asked for and were awarded the amount of time we calculated was just enough to do our project well – 17 orbits, or about 27 hours. When you write a proposal, you want to ask for what you really need, but you don’t want to be perceived as greedy.”

Kwitter went on to say that HST is oversubscribed by a factor of five, which means that every minute of observing time would have to be given out five times over to satisfy all the observing time requests. This is her third proposal and her first approved one. She was very excited when she found out about it in May: “I was so happy I jumped up and down in my office,” she said.

The NASA control center staff will distribute the 27 hours of Hubble time over the course of this year. Kwitter plans to research her topic an additional year after working with the HST .

There will be a student participating in the project this coming summer. For the future, Kwitter is considering the possibility of making a proposal for the new infrared satellite, “SIRTF,” that was just launched.

“There are some elements like sulfur that emit strongly in the infrared. That would be fun to try,” she said.