Nov. 1, 2005
CUA Researcher Leads Discovery of Elusive Companion Star
WASHINGTON, D.C.— Catholic University research scientist Rosina C. Iping and a team of collaborators used a NASA satellite to make the first direct detection of a companion star of Eta Carinae, one of the most massive and elusive stars in the Milky Way.
The team’s findings are
detailed in a paper titled “Detection of a Hot Binary Companion of Eta Carinae” by
lead author Iping, George Sonneborn and Theodore R.
Gull of NASA Goddard Space Flight Center, Derck L. Massa of SGT Inc. and D. John Hillier of the
“Until now Eta Carinae’s partner has evaded direct detection,” said Iping, who is a member of CUA’s Institute for Astrophysics and Computational Sciences. “This discovery significantly advances our understanding of the enigmatic star.”
Binary stars are two companion stars that are locked in each others’ gravitational pull and spend their entire lives spinning around each other. Astronomers estimate that 60 percent of all stars are members of multiple-star systems.
Iping and her collaborators used NASA’s Far Ultraviolet Spectroscopic Explorer satellite to detect the light of Eta Carinae’s companion star. In the past, other scientists, using ground-based telescopes as well as the Hubble Space Telescope, were unsuccessful in detecting light from Eta Carinae’s companion.
Detecting the light of the companion star was a formidable task because it’s actually much fainter than Eta Carinae. But the companion star was found to be much hotter than Eta Carinae, making it brighter at shorter wavelengths, i.e. in ultraviolet light. Iping and her collaborators used the FUSE satellite, which can detect even shorter ultraviolet wavelengths than the Hubble.
Eta Carinae, an unstable star thought to be rapidly approaching the final stage of its life, is clearly visible from the southern hemisphere and has been the subject of intense studies for decades. The huge star produces 5 million times more energy than the Sun, meaning it emits more light in 6 seconds than the Sun generates in a year.
Evidence that Eta Carinae might part of a double-star system was inferred from a repeating pattern of changes in visual, X-ray, radio and infrared light from the star. Astronomers thought that a star in orbit around Eta Carinae might cause the repeated changes in its light.
The mysterious star is located about 7,500 light years from Earth in the constellation Carina. (A light year — the distance light travels in a year — is almost 9.5 trillion kilometers or nearly 6 trillion miles.)
Institute for Astrophysics and Computational Sciences is based at the Goddard
Space Flight Center in Greenbelt, Md. Established in October 1996, the
institute develops strong research and educational programs in the areas of
astrophysics and computational sciences and promotes closer cooperation between
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