Voyagers Detect Missing Signal
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Billions
of miles from home, the Voyager spacecraft (one illustrated here) are
still collecting data. A new study of archival observations has revealed
a faint signal from the Milky Way that has long eluded instruments
closer to Earth.
NASA / JPL-Caltech
Lyman-alpha is a specific ultraviolet wavelength (121.6 nm, to be exact) emitted when a hydrogen atom’s electron drops down one orbital energy level to the ground state. It’s emitted by hydrogen atoms after they recover from being ionized by hot stars’ ultraviolet radiation or after encountering shock waves from supernovae or stellar winds. Because of these associations, Lyman-alpha is thought to be a good tracer of galaxies’ star-formation rates.
MORE: http://www.skyandtelescope.com/news/Voyagers-Detect-Missing-Signal-134918938.html
gaw
Glenn A. Walsh, Project Director,
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