Credit: NASA, ESA, and A. Feild (STScI)
Astronomers used the Hubble Space Telescope to determine the distance of the farthest galaxy that has ever been observed. The galaxy existed only 400 million years after the Big Band, when the Dark Ages of the Universe were just ending and before the cosmic reionization era start. This means that it belongs to the very first galaxies that formed.
The huge distance of the galaxy means that we now observe how the galaxy looked more than 13 billion years ago, when the universe was only 3 percent of its current age. Compared to our Galaxy, it is 25 times smaller and has just one percent of the Milky Way’s mass in stars. Although the galaxy seems extremely faint when observed from the Earth, because of the huge distance that separates us, it is intrinsically extremely luminous for a galaxy at such an early time. Its unexpected luminosity is due to its high star formation rate, which is about 20 times greater than that of our Galaxy.
The distant galaxy was first observed with the Spitzer space telescope, but its distance was estimated from its spectrum that was obtained using the Hubble Space Telescope. As astronomers said, this new discovery suggests that the James Webb Space Telescope, the successor to the Hubble Space Telescope, will be able to similarly and easily confirm such distant sources and characterize their physical properties. The James Webb Space Telescope is scheduled to launch in 2018.
Publication: Oesch et al. 2016