The Hubble Space Telescope has captured captivating images of two dwarf galaxies, offering a glimpse into their intriguing features and the intricate processes of galaxy formation and merging. One image showcases IC 3430, a small dwarf galaxy located 45 million light-years away. Classified as both a dwarf galaxy due to its size and an elliptical galaxy due to its shape, IC 3430 presents a smooth, oval form that is typical of elliptical galaxies. Unlike spiral galaxies like our Milky Way, which possess a defined structure with a central hub and spiral arms, elliptical galaxies are characterized by their lack of distinct features and their smooth, blob-like appearance.
While elliptical galaxies are generally composed of older stars as they lack the necessary gas to form new ones, IC 3430 exhibits an unusual characteristic. At its core, a cluster of hot, blue stars shines brightly, indicating the presence of younger stars, a rarity for elliptical galaxies.
The second image from Hubble captures NGC 5238, another dwarf galaxy, located 14.5 million light-years away. However, NGC 5238 boasts a more complex structure than its elliptical counterpart. It displays bright, glowing spots known as globular clusters, dense groups of stars. The structure of NGC 5238 provides clues about its history. Astronomers believe its intricate form is a result of a past merger, when another galaxy came too close and the two galaxies merged into one. This gravitational interaction caused pockets of stars to form as the gravitational forces pulled and pushed on the gas within the galaxies.
Further evidence of this merger is found in the chemical properties of the star groups within NGC 5238. These groups exhibit different chemical compositions, suggesting they formed in distinct environments from their neighbors, a hallmark of galaxy mergers.
By meticulously studying these smaller galaxies, astronomers gain valuable insights into the larger processes of galaxy formation and merging. As Hubble scientists explain in a press release accompanying these images, one prominent theory of galaxy evolution suggests that galaxies formed in a “bottom-up” manner, with star clusters and smaller galaxies emerging first from gas and dark matter. Over time, the force of gravity gradually brought these smaller structures together to form galaxy clusters and superclusters, ultimately giving rise to the vast, complex structures we observe in the universe today. These observations of dwarf galaxies provide crucial pieces in the puzzle of understanding the evolution of galaxies on a grand scale.
