Institute of Astrophysics of Andalusia | 2015 Mar 23
A map of ionized helium in the galaxy has just been published which indicates the presence of peculiar stars similar to the first that ever shone in the universe
The first galaxies were formed some 13.3 billion years ago, mainly composed of hydrogen and helium, the primary elements that emerged from the Big Bang. Their study to date has been technically very challenging due to their great distance from us, but the observation of analogous galaxies in our vicinity has turned out to be an excellent shortcut.
"Dwarf galaxy IZw18 is the least abundant in metals (in astrophysics, elements heavier than hydrogen and helium) in the nearby universe, and one of the most akin to the primeval galaxies. Its study therefore allows us to catch glimpses of the conditions that prevailed in the primordial universe”, says Carolina Kehrig, researcher at the Institute of Astrophysics of Andalusia in charge of the study that analyses the properties of IZw18.
The study has found a very large region in this small galaxy of ionized helium, which tends to be more frequent in very distant galaxies with low presence of metals. The ionization of helium implies the presence of objects emitting a radiation intense enough to knock electrons off the helium atoms. "In this study we propose a new interpretation of the origin of this radiation in galaxy IZw18, a subject which is still enigmatic”, Kehrig says. ...
The Extended He II λ4686-emitting Region in IZw 18 Unveiled: Clues for Peculiar Ionizing Sources - Carolina Kehrig et al
- Astrophysical Journal Letters 801(2) L28 (10 Mar 2015) DOI: 10.1088/2041-8205/801/2/L28
arXiv.org > astro-ph > arXiv:1502.00522 > 02 Feb 2015