(ORDO NEWS) — The galaxy that has teased astronomers since they first spotted a hint of its presence more than 20 years ago has finally come out of hiding.
It is called HIPASS J1131-31, or Peekaboo, and is only 22 million light-years away. And it was so hard to see because it’s tiny and hidden by a bright star in the Milky Way that’s almost directly in front of it.
Through a collaborative effort involving space and ground-based telescopes. , scientists have learned that the extremely small Peekaboo galaxy is also very young and close, giving us a snapshot of the galactic infancy.
“The discovery of the Peekaboo galaxy is like discovering a direct window into the past, allowing us to study its extreme conditions and stars at a level of detail that was not available in the distant early universe,” says astronomer Gagandeep Anand of the Space Telescope Science Institute in Baltimore.
Given the absolute predominance of matter in space. Universe, quite often foreground objects are located in front of more distant ones.
So when the HI Parkes All Sky Survey in the early 2000s found the galaxy peeking out from behind the bright star TYC 7215-199-1, it wasn’t much of a surprise.
Ultraviolet observations have shown that Peekaboo is what is known as a compact blue dwarf galaxy: a small galaxy in which young stars are forming, the brightest of which appear blue.
But the light from the star TYC 7215-199-1 and its diffraction artifacts hid the galaxy from a clear view.
Perhaps this was the case, but it turned out that the star was moving fast, and the direction of its movement was far from the galaxy.
If we looked 100 years ago, we might not see the galaxy at all. Over the past couple of decades, this gap has continued to widen. And our space surveillance technologies are becoming more and more powerful.
Therefore, an international team led by astronomer Igor Karachentsev from the Russian Academy of Sciences again visited Pikabu to get to know him better.
They used the Hubble Space Telescope for optical observations, the South African Large Telescope for optical spectra, and the Australian Telescope Compact Array (ATCA) for radio observations.
These observations not only resolved about 60 individual stars in Peekaboo. but helped researchers determine what stars are made of.
“We didn’t realize at first how special this little galaxy was,” says astronomer Berbel Koribalski of the Commonwealth Scientific and Industrial Research Organization (CSIRO). in Australia and the researcher who first discovered the presence of HIPASS J1131-31.
“Now, with combined data from the Hubble Space Telescope, the South African Large Telescope and others, we know that the Peekaboo galaxy is one of the most metal-poor galaxies ever discovered.”
All of the stars resolved by Hubble appear to be no more than a few billion years old, meaning that Peekaboo appears to be very young in the universe.
And Peekaboo has a strikingly low metal content. Generally, low metallicity indicates that the object formed in the early universe; later objects have higher abundances of heavy elements.
This is because there weren’t many metals in the very early universe. In the era following the Big Bang 13.8 billion years ago, the universe was predominantly composed of hydrogen and helium.
It was from these elements that the first stars formed, fusing hydrogen and helium into heavier elements, up to iron.
Metals heavier than iron were forged in violent supernova explosions as stars died as they dispersed. to the Universe, where they could participate in the formation of new stars.
In addition to its young stellar population, researchers have made only minor detections of old star signatures, suggesting that star formation in Peekaboo only began a few billion years ago.
This means that this could be an example of what an early generation of galaxies looked like and the stellar population within.
It’s essentially a time capsule and practically next door, cosmically speaking. Because Hubble’s observations weren’t particularly detailed, the researchers hope to revisit the galaxy with the JWST to compile a more detailed catalog of its chemical composition.
“Thanks to Peekaboo’s proximity to us, we can make detailed observations, opening up opportunities to see an environment that resembles the early universe in unprecedented detail,” says Anand.
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