News Excerpt:
NASA’s James Webb Space Telescope (JWST) has spotted the earliest-known galaxy, one that is surprisingly bright and big considering it formed during the universe’s infancy at only 2% its current age.
More detail about news:
- JWST, which by peering across vast cosmic distances is looking way back in time, observed the galaxy as it existed about 290 million years after the Big Bang event that initiated the universe roughly 13.8 billion years ago.
- This period spanning the universe’s first few hundred million years is called cosmic dawn.
- The discovery was made by an international team of astronomers, who used JWST to observe galaxies as part of the JWST Advanced Deep Extragalactic Survey (JADES) program.
About New Discovery
- This galaxy, called JADES-GS-z14-0, measures about 1,700-light years across.
- A light year is the distance light travels in a year, which is 9.5 trillion km. The galaxy has a mass equivalent to 500 million stars the size of our Sun and is rapidly forming new stars — about 20 every year.
- Until now, the earliest-known galaxy dated to about 320 million years after the Big Bang, as announced by the JADES team last year.
- It makes sense to call the galaxy big, because it’s significantly larger than other galaxies that the JADES team has measured at these distances, and it’s going to be challenging to understand just how something this large could form in only a few hundred million years.
- The fact that it’s so bright is also fascinating, given that galaxies tend to grow larger as the universe evolves, implying that it would potentially get significantly brighter in the next many hundred million years.
- The JADES team in the same study disclosed the discovery of the second oldest-known galaxy, from about 303 million years post-Big Bang. That one, JADES-GS-z14-1, is smaller — with a mass equal to about 100 million sun-sized stars, measuring roughly 1,000 light years across and forming about two new stars per year.
Why is the galaxy so bright?
- Three main hypotheses have been advanced to explain the luminosity of early galaxies.
- The first attributed it to supermassive black holes in these galaxies gobbling up material.
- That appears to have been ruled out by the new findings because the light observed is spread over an area wider than would be expected from black hole gluttony.
