Astronomers investigate recent star formation history of the Fireworks Galaxy

Astronomers from the College of Washington in Seattle and elsewhere have performed Hubble Area Telescope (HST) observations of the close by Fireworks Galaxy. Outcomes of the observational marketing campaign, offered July 10 on the preprint server arXiv, yield essential insights into the current star formation historical past of this galaxy.

Found in 1798, the Fireworks Galaxy (also called NGC 6946) is a close-by face-on star forming spiral galaxy situated some 25.5 million gentle years away. The galaxy has a measurement of 87,300 light years and its title was coined on account of an unusually giant variety of supernovae noticed in it—about ten instances greater than within the Milky Way.

Though many research of the Fireworks Galaxy have been performed so far, its star formation charge (SFR) just isn’t properly constrained, estimated to be between three and 12 solar masses per 12 months. This discrepancy is especially because of the various strategies of measuring star formation rate and the big selection of various distances used.

A group of astronomers led by Debby Tran has carried out HST observations of the Fireworks Galaxy, with the primary purpose of figuring out its SFR and to higher perceive its star formation historical past.

“We analyze its resolved near-ultraviolet (NUV) stellar photometry measured from photographs taken with the Hubble Area Telescope’s (HST) Extensive Subject Digital camera 3 (WFC3) with F275W and F336W filters. We mannequin the color-magnitude diagrams (CMD) of the UV photometry to derive the spatially-resolved star formation historical past (SFH) of NGC 6946 during the last 25 Myr,” the researchers wrote within the paper.

The HST knowledge allowed Tran’s group to supply maps of the spatial distribution of younger stellar populations and measure the total current SFR of practically the complete younger stellar disk. The research was complemented by knowledge from ESA’s Gaia satellite.

All in all, the researchers discovered that the worldwide SFR for the Fireworks Galaxy during the last 25 million years was roughly 13.16 solar lots per 12 months. The SFR was even at a degree of 23.38 solar lots per 12 months 16 to 25 million years in the past and afterward it monotonically decreased between 10 and 16 million years in the past, reaching a gentle SFR of 5.31 solar lots per 12 months within the final 10 million years.

The observations additionally discovered that the 2 areas of the Fireworks Galaxy exhibiting excessive star-forming exercise—one HII area (area of ionized atomic hydrogen) situated on the tip of the galaxy’s northeast spiral arm and the so-called Hodge Advanced (an excellent star cluster containing a number of younger star clusters)—include a better quantity of current star formation than anticipated for areas of their measurement. The astronomers famous that the Hodge Advanced showcases more moderen star formation relative to the declining international star formation.

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