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The Hubble has seen farther back in time than ever before

The space telescope spotted a star from just 400 million years after the Big Bang.

Andrew Tarantola
Senior Editor
Updated ·1 min read
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NASA announced on Thursday that an international team of astronomers have used the Hubble space telescope to spot the most distant galaxy discovered to date -- not to mention one of the oldest in the visible Universe. The galaxy, dubbed GN-z11, has a measured redshift of 11.1, meaning it formed just 400 million years after the Big Bang.

This image shows the position of the most distant galaxy discovered so far within a deep sky Hubble Space Telescope survey called GOODS North (Great Observatories Origins Deep Survey North). The survey field contains tens of thousands of galaxies stretching far back into time. The remote galaxy GN-z11, shown in the inset, existed only 400 million years after the Big Bang, when the Universe was only 3 percent of its current age. It belongs to the first generation of galaxies in the Universe and its discovery provides new insights into the very early Universe. This is the first time that the distance of an object so far away has been measured from its spectrum, which makes the measurement extremely reliable. GN-z11 is actually ablaze with bright, young, blue stars but these look red in this image because its light was stretched to longer, redder, wavelengths by the expansion of the Universe.

GN-z11 is 25 percent smaller than the Milky Way and contains barely one percent of its star mass. That makes sense, given that we're looking at an infant galaxy. However, the number of new stars being formed there outpaces the Milky Way's by 20 times. It's these bright new stars that illuminate the galaxy enough to be seen by the Hubble.

"It's amazing that a galaxy so massive existed only 200 million to 300 million years after the very first stars started to form. It takes really fast growth, producing stars at a huge rate, to have formed a galaxy that is a billion solar masses so soon," Garth Illingworth of UC Santa Cruz said in a statement. If these measurements are correct, and NASA is confident they are, that would mean GN-z11 formed near the start of the epoch of reionization, the period of time in which the first galaxies coalesced.

This illustration shows a timeline of the Universe, stretching from the present day (left) back to the Big Bang, 13.8 billion years ago (right). The newly discovered galaxy GN-z11 is the most distant galaxy discovered so far, at a redshift of 11.1, which corresponds to 400 million years after the Big Bang. The previous record holder’s position is also identified. Its remote position puts GN-z11 at the beginning of the reionisation era. In this period starlight from the first galaxies started to heat and lift the fog of cold hydrogen gas filling the Universe. The previous record-holding galaxy was seen in the middle of this epoch, about 150 million years later.

The team's finding will be published in the Astrophysical Journal. "We've taken a major step back in time, beyond what we'd ever expected to be able to do with Hubble. We managed to look back in time to measure the distance to a galaxy when the Universe was only three percent of its current age," the paper's lead author, Yale's Pascal Oesch, said.