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Peekaboo: the “hidden” extremely metal poor dwarf galaxy

Russian version

    A nearby dwarf galaxy with an extremely low heavy element abundance has been discovered. The gas-rich galaxy HIPASS J1131-31 with a radial velocity of 716 km/s was detected as an emission source in the neutral hydrogen line in the southern sky survey at the Parkes radio telescope. It was resolved into individual stars in our observations with the Hubble Space Telescope. The galaxy is concealed in such close proximity of a bright star that we call it “hidden” (Peekaboo). The Peekaboo dwarf galaxy is located on the outskirts of a galaxy group at a distance of 6.8±0.7 Mpc from us. The red giant branch of the system is tenuous compared with the prominence of the features of young populations in the color-magnitude diagram, inviting speculation that star formation in the galaxy only began in the last few Gyr. Spectral observations with the 10-meter South African telescope reveal HIPASS J1131-31 to be one of the most extremely metal-poor galaxies known with an oxygen abundance smaller than 2% of the Sun's. The proximity of the discovered galaxy makes it an important target for further study of the cosmic abundance of chemical elements and the nature of young galaxies.
Fig.1. Two-color image of the dwarf galaxy HIPASS J1131-31 obtained with the Hubble Space Telescope in the F606W (blue) and F814W (red) filters. The image size is 70×45 arcseconds, North is at the top.

Karachentsev I.D., Makarova L.N., Koribalski B.S., Anand G.S., Tully R.B., Kniazev A.Y., “Peekaboo: the extremely metal poor dwarf galaxy HIPASS J1131-31”, MNRAS, Volume 518, Issue 4, pp. 5893-5903, DOI: 10.1093/mnras/stac3284

Contact person - Karachentsev I.D., DSc, Prof., Chief Researcher in the Extragalactic Astrophysics and Cosmology Laboratory, SAO RAS.