(ORDO NEWS) — Using ground and space telescopes, astronomers have discovered and explored the most distant known galaxy, designated HD1. It is located at a distance of about 13.5 billion light years from Earth and glows extremely brightly in the ultraviolet range.
“We have two ideas why this galaxy is so bright. Or it is forming stars at an astonishing rate and may even contain population III stars, which are the very first in the universe and have never been seen before.
Or the galaxy is hiding a gigantic black hole with a mass about 100 million times that of the sun. However, uncovering the nature of a source so far away is very difficult, it is a long game of analysis and elimination of implausible scenarios, ”say the authors of the study.
Galaxy HD1. Credit: Harikane et al
In analyzing the observational data, the researchers first assumed that HD1 is a standard starburst galaxy. But by calculating how many stars it must produce to match its brightness, they got an “incredible rate” of more than 100 stars in one Earth year. This is at least 10 times higher than expected for galaxies of that era.
It was then that astronomers began to suspect that HD1 could possibly form stars that are not familiar to us today.
“The stars of the very first population were more massive, brighter and hotter than modern ones. If we assume that they are formed in HD1, then its unusual properties can be explained, ”explained the authors of the study.
The very first stars in the universe
However, the supermassive black hole could also be the source of HD1’s exceptional brightness, since there must be a huge amount of hot gas in its vicinity, emitting high-energy photons.
If so, it is the earliest known supermassive black hole observed much closer in time to the Big Bang than the current record holder.
“Soon we will be able to make repeated observations of HD1 with the James Webb Space Telescope, which will allow us to check the distance of the galaxy from Earth, as well as to study its nature in more depth and lean towards one of our ideas explaining its brightness,” the authors of the study concluded.
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