Astronomers explore stellar populations of an extremely metal-poor dwarf galaxy

Utilizing the James Webb House Telescope, astronomers have carried out near- and mid-infrared observations of an especially metal-poor blue compact dwarf galaxy referred to as I Zwicky 18. Outcomes of the observational marketing campaign, offered in a paper revealed March 11 on the arXiv preprint server, ship necessary info relating to stellar populations on this galaxy.

Blue compact dwarfs (BCDs) are low-luminosity and low-metal content material dwarf galaxies experiencing violent bursts of star formation. They’re characterised by a compact optical look and H II-region-like spectra because of extremely concentrated starburst actions.

I Zwicky 18 is the archetypal BCD positioned about 59 million light years away within the constellation Ursa Main. This BCD is likely one of the most extraordinarily metal-poor galaxies referred to as it’s nearly solely composed of hydrogen and helium.

Earlier observations have discovered that I Zwicky 18 is at the moment experiencing a interval of intensely elevated star-formation charge (SFR) and could also be nonetheless creating Inhabitants III stars—hypothetical extraordinarily large stars, poor in components heavier than helium, believed to have been shaped within the early universe. Therefore, this galaxy is perceived as an excellent laboratory to check each the younger and developed star demographics in an setting analogous to that discovered shortly after the Massive Bang.

That’s the reason a group of astronomers led by Alec S. Hirschauer of the House Telescope Science Institute (STScI) in Baltimore, Maryland, determined to take a better take a look at I Zwicky 18. They employed JWST’s Close to Infrared Digicam (NIRCam) and Mid-Infrared Instrument (MIRI) to analyze the stellar content material of this galaxy.

The observations carried out by Hirschauer’s group recognized excessive populations of vivid, not too long ago shaped massive stars in I Zwicky 18, positioned predominantly among the many galaxy’s two central lobes of star formation—the northwest (NW) and southeast (SE) parts. The obtained pictures additionally present massive supershells of dust and ionized gasoline carved out by earlier star formation and supernovae exercise.

The collected knowledge allowed the astronomers to detect candidate populations of dusty developed stars (red supergiants and asymptotic big department stars) in I Zwicky 18, alongside vivid younger stellar objects (YSOs). The researchers estimated the tip of the pink big department (TRGB) and divided these sources that lie above it into left- and right-branch populations, associated to youthful (higher important sequence, UMS stars) and older (developed) stars, respectively.

In line with the authors of the paper, their findings recommend that the prevailing demographics of I Zw 18’s NW and SE star-formation areas mirror that of youthful and older stellar populations. The examine additionally proves how necessary is JWST in investigating dusty and developed stars in compact dwarf galaxies within the early universe.

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