geminiann09012 — Anuncio
Ultra-deep GNIRS Spectrum Explores Stellar "Birth Control" in Early Universe
8 Junio 2009: Using the Gemini Near-Infrared Spectrograph (GNIRS), astronomers have obtained an ultra-deep (~29 hour integration) near-infrared spectrum of a massive compact quiescent galaxy at a redshift of about 2.2 (when the universe was only about three billion years old). Understanding how a massive galaxy–especially this early in the history of the universe–can squelch star birth with such efficiency is a challenging problem for both observational and theoretical astrophysicists. The team, led by Mariska Kriek of Princeton University, used GNIRS on Gemini South to dissect the light of the galaxy, identified as 1255-0, in what is the deepest single-slit near infrared spectrum ever taken of a galaxy with a redshift greater than 2 (Figure 1). The spectrum, for the first time, shows absorption line features in this type of galaxy that allow for accurate redshift determination (Figure 2) and is providing insights into this unique category of galaxies that are very massive …