Astronomers have harnessed the power of five satellite observatories and a suite of ground-based telescopes to spend an unprecedented 45 days studying a binary-star system from one end of the electromagnetic spectrum -- X-rays -- to the other -- infrared.
The goal is to understand changes in the energy-emitting plasma, or hot gas, formed within the system as material is yanked from the larger star by the gravitational pull of the smaller, but far denser star -- a white dwarf.
To observe the temporal changes within the pair of stars known as EX Hya, located about 300 light-years away in the constellation Hydra, the project has fielded a broad array of instruments to cover the electromagnetic spectrum, including five NASA space-based observatories.
The system emits radiation at varying wavelengths because of the extreme temperature differences within the binary system, from about 10,000 to 1 million degrees Kelvin (17,540 to 1.8 million degrees Fahrenheit).
"To cover a huge temperature range, you have to look at it in a bunch of wavelengths," said Steve Howell, head of the Astrophysics Group at the Planetary Science Institute in Tucson, Arizona.
NASAs Extreme Ultraviolet Explorer (EUVE) kicked off the campaign on Tuesday. Five other satellite instruments will join it at various times. They include: the Chandra X-ray Observatory (CXO), the Rossi X-ray Timing Explorer (RXTE), the Far Ultraviolet Spectroscopic Explorer (FUSE), and the Hubble Space Telescope (HST), as well as the Naval Research Laboratory Advanced Research and Global Observation Satellite (ARGOS).
Furthermore, ground-based telescopes in the Canary Islands, New Mexico and Hawaii will assist with optical and infrared observations, as will amateur astronomers.
EX Hya consists of two stars separated by about the diameter of our sun, or about 862,000 miles (1.39 million kilometers). The two stars orbit each other every 98 minutes in their tight embrace.
The smaller star, with a mass 80 percent of that our sun but about the size of the Earth, is a white dwarf. As it spins, its gravitational pull draws material from its companion, which is 100 times larger than it is in size, but has a mass equal to just 20 percent of our sun.
The matter drawn toward the white dwarf forms an orbiting disk of accreted material. That material swirls around the fast spinning white dwarf, which has a strong magnetic field, 10 million times that of Earth.
That combination forces the material in the accretion disk to funnel toward the white dwarfs magnetic poles, clearing out, so to speak, the inner area of the disk.
The whole process, from when material is pulled off the one star to when it rains down on its companions poles, can take as little as 25 minutes, Howell said.
Through the campaigns careful monitoring of the binary system, astronomers seek to detect temporal changes in the plasma brought on by small variations in the rate that material is accreted.
"Our hope is if a large amount of material should be pulled off the larger star, we should be able to see that material propagate through the entire system," Howell said.
The project will also keep tabs on the temperature and density of the gas in EX Hya during each orbit.
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