Hubble's New Image of NGC 346 Reveals Star Formation in the Small Magellanic Cloud

This splendid, new image of the young star cluster NGC 346 is part of the celebrations for the 35th anniversary of Hubble.

The cluster is located in the Small Magellanic Cloud (SMC), a satellite galaxy of the Milky Way, about 200,000 light-years away in the constellation of Tucana.

The image combines infrared, optical, and ultraviolet data, providing a complete view of the cluster and its surrounding nebula. For example, infrared allows researchers to penetrate the dust clouds, revealing hidden stars, while ultraviolet highlights regions of ionized gas.

NGC 346 hosts over 2,500 newborn stars, some of which are significantly more massive than the Sun. The associated nebula, called N66, is an H II region with the highest rate of star formation, which is an area of ​​ionized gas illuminated by ultraviolet light emitted by young, hot stars. N66 is, in fact, the largest and brightest H II region in the SMC, characterized by a bright pink color and dark, snake-like clouds that weave into the structure. 

Hubble observations, conducted over a period of 11 years, made it possible to trace the movements of the stars within the cluster. The data reveal that the stars are spiraling toward the center of the cluster, driven by gas flows coming from outward that fuel star formation. This dynamic motion is crucial to understand how interstellar matter contributes to the growth and evolution of the cluster.

The most massive stars in NGC 346, estimated to be just a few million years old, emit intense radiation and stellar winds that carve bubbles out of the surrounding nebula. These processes disperse the gas, creating complex structures and influencing the formation of new stars. The image captures such interactions, showing how stars not only form, but actively shape their environments.

The SMC is an irregular dwarf galaxy with significantly lower metallicity than the Milky Way. Metallicity, in astronomy, refers to the fraction of the mass composed of elements heavier than helium, such as carbon, oxygen, and iron, that form inside stars and are lost into the interstellar environment during events such as supernovae. The SMC's low metallicity makes it similar to conditions in the early universe; in short a "natural laboratory" to study star formation processes in the first billion years of the Universe.

The observation of NGC 346 is therefore significant for research on galactic and stellar evolution. In particular, it helps to understand the evolution of dwarf galaxies and star formation in environments with low metallicity.

-----------------------------------

Image credits: ESA/Hubble & NASA, A. Nota, P. Massey, E. Sabbi, C. Murray, M. Zamani (ESA/Hubble)

Reference➡️ Hubble Spots Stellar Sculptors in Nearby Galaxy