18 septembre 2015

Découverte de la plus ancienne galaxie

On vient de découvrir la galaxie la plus ancienne et la plus lointaine connue à ce jour:

After spending years searching the cosmos, a research team from CalTech may have found the oldest and most distant galaxy yet. As part of its search, the team combed through data collected by the Hubble Space Telescope and the Spitzer Space telescope, and ultimately identified the galaxy EGS8p7 as a target to investigate further. 

The team then performed a spectrographic analysis of EGS8p7 using the Keck Observatory’s multi-object spectrometer for infrared exploration (MOSFIRE) to calculate its redshift. Redshift is a result of the Doppler effect – like when an ambulance drives by and the siren fades as it passes. In astronomy, instead of sound waves, light from the galaxy is stretched and shifted towards the red end of the spectrum as it moves farther away. Based on the data collected, the team estimates that EGS8p7 is over 13.2 billion years old, meaning it was formed only around 600 million years after the Big Bang.



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