Peekaboo Galaxy

The Peekaboo Galaxy (officially known as HIPASS J1131-31 and PGC 5060432) is an irregular compact blue (suggesting hot young stars) dwarf galaxy in the constellation Hydra. The galaxy is relatively small, at about 1,200 light-year across. It is also relatively nearby, at a distance of around 22 e6light-year from Earth. The Peekaboo Galaxy is considered one of the most metal-poor ("extremely metal-poor" (XMP)), least chemically enriched, and seemingly primordial, galaxies known.

History of observation
The Peekaboo Galaxy was hidden behind a relatively fast-moving foreground star, named TYC 7215-199-1, but during the second half of the 20th century, the star moved aside, clearing the view to the obscured galaxy, which gave the galaxy its name.

Detailed studies of the galaxy were reported in November 2022, and were based on work using the Hubble Space Telescope. The astronomers were able to closely examine about 60 of the individual stars in the galaxy, all appearing relatively young, a few billion years old or younger. In the words of Bärbel Koribalski, astronomer at CSIRO in Australia, original discoverer of the galaxy in 2001, and coauthor of the 2022 study of the galaxy, "At first we did not realize how special this little galaxy is ... Now with combined data from the Hubble Space Telescope, the Southern African Large Telescope (SALT), and others, we know that the Peekaboo Galaxy is one of the most metal-poor galaxies ever detected."

According to current thinking, early in the formation of the universe, 13.8 billion years ago, the earliest first stars were made, and were mostly composed of hydrogen and helium. Later, these very early stars fused their hydrogen and helium into heavier elements, up to, and including, iron. Heavier elements, beyond iron, were later produced as a result of violent supernova explosions, scattering these newly formed heavier elements throughout the Universe, where they would be incorporated into the formation of newer stars. The detection of the relatively close extremely metal-poor Peekaboo Galaxy may help astronomers better understand the formation of the very earliest stars and galaxies.

Future studies
Karachentsev et al. write that the age of the Peekaboo Galaxy is "decidedly ambiguous".

Future further studies of the galaxy with the Hubble Space Telescope and the James Webb Space Telescope are being considered.