Observations shed more light on the star formation history of galaxy NGC 2915

Utilizing the Very Giant Telescope (VLT), Chinese language astronomers have investigated a close-by blue compact dwarf galaxy often called NGC 2915. Outcomes of the examine, introduced in a paper printed October 12 on arXiv.org, yield essential insights concerning the star formation historical past of 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 as a result of extremely concentrated starburst actions.

At a distance of some 13.4 million mild years, NGC 2915 (often known as PGC 26761) is among the closest BCDs to Earth. It’s an excessive case of BCDs within the native universe as its impartial atomic hydrogen (H I) gasoline content material could be very excessive and intensely prolonged in distribution. Furthermore, virtually all of the younger stellar populations and areas of ionized atomic hydrogen (H II) are positioned close to the middle of this galaxy.

Nevertheless, though NGC 2915 is extraordinarily wealthy in gasoline, the star formation exercise is barely detected in its prolonged outer H I disk. Moreover, the triggering mechanism of the extremely concentrated star formation on this galaxy stays unclear.

Subsequently, with a view to additional examine the star formation exercise in NGC 2915, a bunch of astronomers led by Yimeng Tang of the College of Science and Expertise of China in Hefei, China, carried out a complete evaluation of deep integral subject spectroscopic observations of the galaxy’s central area made with VLT’s Multi Unit Spectroscopic Explorer (MUSE).

“To unveil the starburst-triggering thriller of NGC 2915, we carry out a complete evaluation of deep VLT/MUSE integral subject spectroscopic observations that cowl the central kiloparsec star-forming area,” the researchers wrote within the paper.

The examine discovered that world star formation in NGC 2915 peaked round a few billion years in the past, when essentially the most huge star cluster was shaped. The outcomes recommend that the newest episode of bursty star formation came about round 50 million years in the past, has lasted for about 50–100 million years and was liable for the formation of some 3% of the galaxy’s total stellar mass.

Based on the analysis, episodes of bursty star formation much like the newest one might have recurred for lower than 4 instances in several areas within the final billion years. Nevertheless, these episodes turned out to be largely confined inside the galaxy’s central area (with a radius of roughly 1,300 mild years).

The examine additionally discovered that the stellar disk of NGC 2915 displays a comparatively weak however important rotation inside the central 1,600 light years in radius and that the stellar rotation axis seems to be anti-parallel to that of the prolonged impartial H I disk. This discovering signifies that the current episodes of bursty star formation have been sustained by externally accreted gasoline.

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