Jan 9 2006
From The Space Library
Researchers announced at a meeting of the American Astronomical Society (AAS) that, using NASA’s Hubble Space Telescope (HST), they had been able for the first time to observe directly the close companion star to Polaris (the North Star). The newly observed star, one of two in the near vicinity of Polaris, is approximately 3.2 billion kilometers (2 billion miles) from Polaris and hundreds of times fainter. Polaris is Earth’s nearest example of a Cepheid variable star. Scientists use the variations in the brightness of Cepheid stars to judge the distances of galaxies and the expansion rate of the universe. Imaging its companion star had enabled scientists to estimate Polaris’s mass at 4.3 times that of the Sun, but future measurements of the companion star’s motion during its 30-year orbit would enable scientists to make a more accurate determination of Polaris’s mass. Knowledge of mass size is critical to understanding the composition and evolution of Cepheids.
NASA, “There’s More to the North Star Than Meets the Eye,” news release 06-004, 9 January 2006, http://www.nasa.gov/home/hqnews/2006/ja/HQ_06004_hubble.html (accessed 14 September 2009); Maggie McKee, “Hubble Reveals Pole Star’s Closest Companion,” New Scientist, 10 January 2006.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
