Hubble Observes Incredible Star Formation Rates in NGC 5253, a Dwarf 'Starburst Galaxy

This week, the Hubble Space Telescope's Picture of the Week highlights the blue compact dwarf galaxy NGC 5253, situated in the constellation Centaurus, approximately 11 million light-years from Earth. The stunning new image is a composite of data captured by Hubble’s Advanced Camera for Surveys (ACS) with its Wide Field Channel and the older Wide Field and Planetary Camera 2 (WFPC2). As an added bonus, a second image created using data from the High Resolution Channel (HRC) of ACS is also featured. The HRC, although operational for only a few years, was optimized for detailed studies of star-dense environments.

Why has NGC 5253 garnered such intense interest from astronomers that three of Hubble’s instruments were employed to study it extensively over a decade? This galaxy lies at the intersection of several key research areas where Hubble’s advanced capabilities are crucial. Dwarf galaxies like NGC 5253 are invaluable for understanding the evolution of stars and galaxies over time, as they are akin to ancient, distant galaxies.

NGC 5253 is categorized as both a “starburst galaxy” and a “blue compact dwarf.” These designations signify that the galaxy is forming clusters of bright, massive stars at an extraordinary rate. The Hubble image vividly reveals the dense nebula being consumed to birth these stars, positioning NGC 5253 as a prime laboratory for investigating stellar composition, star formation, and star clusters.

NGC 5253 exhibits an exceptionally high rate of star formation, leading to the creation of star clusters. However, this galaxy surpasses typical star formation phenomena: within a small core region, the star formation is so intense that NGC 5253 hosts no fewer than three “super star clusters” (SSCs). These SSCs are incredibly bright, populous, and massive open clusters, which are believed to evolve into globular clusters over time.

Globular clusters provide unique insights into star formation and evolution, but their origins remain enigmatic. The HRC sub-instrument, with its remarkable resolution, was therefore utilized to focus on these small, densely packed clusters of stars. This detailed observation aims to unravel the complexities of SSCs and their role in the broader context of galactic evolution.

The study of NGC 5253 through Hubble’s powerful instruments offers astronomers a window into the processes that govern star and galaxy formation. By analyzing the intense star-forming activity and the resulting star clusters, researchers can draw parallels to the early stages of galaxy evolution and gain a deeper understanding of the forces shaping our universe.

Credit: ESA/Hubble & NASA, A. Zezas, D. Calzetti