MAUNAKEA, Hawaii — UCLA astronomers have used the W. M. Keck Observatory on Maunakea, Hawaii to make the first accurate measurement of the abundance of oxygen in a distant galaxy.
“Close galaxies are much brighter, and we have a very good method of determining the amount of oxygen in nearby galaxies,” Sanders said.
Keck Observatory’s MOSFIRE collects visible-light photons from objects billions of light years away whose wavelengths have been stretched or “redshifted” to the infrared by the expansion of the Universe. Due to the finite speed of light, MOSFIRE is providing a view of these galaxies as they existed billions of years ago, when the light first started traveling to Earth. MOSFIRE is a type of instrument known as a “spectrograph,” which spreads the light from astronomical objects out into a spectrum of separate wavelengths (colors), indicating the specific amount of energy emitted at each wavelength. Spectrographs enable astronomers to determine the chemical contents of galaxies, because different chemical elements — such as oxygen, carbon, iron or hydrogen — each provide a unique spectral fingerprint, emitting light at specific wavelengths.
W. M. Keck Observatory
Source: W.M. Keck Observatory