According to the accepted theory, water arrived on Earth from icy asteroids and comets in the early stages of the planet's formation. The new star system observed by Spitzer, called NGC 1333-IRAS 4B, allowed scientists to view for the first time how water, falling towards a young star, vaporizes on arrival. This water vapor will later freeze again and form asteroids and comets that can hit planets which might form around the new star, similarly to what happened on Earth.
According to astronomers, water is abundant throughout our universe and was detected in the past as ice or gas around various types of stars and even in the space between stars. Luckily, water is easier to detect than many other molecules, and can be used to probe the accretion disk of newborn stars in order to study their physics and chemistry.
In a study conducted by Dan Watson of the University of Rochester in N.Y., some 30 of the youngest known stellar embryos where inspected using Spitzer's infrared spectrograph (an instrument that splits infrared light into different wavelengths), revealing a variety of different molecules. Out of the 30 stellar embryos that the team studied, only one, named NGC 1333-IRAS 4B, was found to posses a clear signature of water vapor. This vapor is readily detectable by Spitzer, because as ice hits the star's accretion disk, it heats up very rapidly and glows with infrared light. The scientists explain that the possible reason for such a low number of newborn stars with substantial amounts of water vapor is that Spitzer must be at the right angle and just at the right time in the lifecycle of the newborn star in order to observe the existence of these amounts of water vapor.
TFOT recently reported several other important discoveries made using NASA's Spitzer space telescope, including the discovery of the first conclusive evidence for water on an extrasolar planet located some 63 light years away from Earth. Spitzer was also recently used by astronomers from the University of California to detect the first ever quadruple-star system, which may also contain planets.
More information on NGC 1333-IRAS 4B and the newly discovered water vapors can be found on NASA's Jet Propulsion Laboratory website.