Today’s Image of the Day from the European Space Agency features NGC 1792, a spiral galaxy located in the constellation Columba, about 43 million light-years away from Earth. 

This galaxy, discovered by British astronomer James Dunlop in 1826, is part of the larger NGC 1808 group of galaxies. 

Intimate view of NGC 1792

“An orange glow radiates from the center of NGC 1792, the heart of this stellar forge. Captured by the NASA/ESA Hubble Space Telescope, this intimate view of NGC 1792 gives us some insight into this galactic powerhouse,” noted ESA.

“The vast swathes of tell-tale blue seen throughout the galaxy indicate areas that are full of young, hot stars, and it is in the shades of orange, seen nearer the center, that the older, cooler stars reside.”

Vigorous star formation 

NGC 1792 is notable for its vigorous star formation, classifying it as a starburst galaxy. This high rate of star formation is thought to be triggered by gravitational interactions with neighboring galaxies, though the exact cause is still under study.

“Nestled in the constellation of Columba (The Dove), NGC 1792 is both a spiral galaxy, and a starburst galaxy,” said ESA. “Within starburst galaxies, stars are forming at comparatively exorbitant rates. The rate of star formation can be more than 10 times faster in a starburst galaxy than in the Milky Way.”

Fierce bursts of star formation

ESA noted that when galaxies have a large reservoir of gas, like NGC 1792, these short-lived starburst phases can be sparked by galactic events such as mergers and tidal interactions. 

“One might think that these starburst galaxies would easily consume all of their gas in a large forming event. However, supernova explosions and intense stellar winds produced in these powerful starbursts can inject energy into the gas and disperse it.” 

“This halts the star formation before it can completely deplete the galaxy of all its fuel. Scientists are actively working to understand this complex interplay between the dynamics that drive and quench these fierce bursts of star formation.”

Due to its distance and brightness, NGC 1792 can be observed with medium-sized telescopes under favorable conditions.

Galaxy evolution

Galaxy evolution refers to the process by which galaxies form and change over time. It begins in the early universe, shortly after the Big Bang, when small density fluctuations in the primordial gas led to the collapse of matter into the first galaxies. 

Galaxy mergers

These early galaxies were small and irregular, composed mostly of gas and dark matter. Over billions of years, galaxies grew larger by merging with one another and by accreting gas from the surrounding space. 

These interactions often triggered bursts of star formation, and collisions between galaxies sometimes led to the creation of new, more massive galaxies.

Structural changes

As galaxies evolve, their morphology – their shape and structure – can change. Early galaxies were often irregular or disk-shaped, but over time, many galaxies formed into the elliptical or spiral shapes we see today. 

Star formation

Star formation is a key driver of galaxy evolution, but it gradually slows down as galaxies age.

The gas that fuels star formation can be used up, or it can be heated and pushed out of galaxies by supernovae or black holes, reducing the galaxy’s ability to form new stars.

Galaxy environment 

The environment in which a galaxy resides also plays a role in its evolution. Galaxies in dense clusters are more likely to interact with their neighbors, which can alter their shape or trigger bursts of star formation. 

In contrast, galaxies in more isolated regions of space evolve more slowly and without as many dramatic interactions.

Dark matter

Dark matter also plays a crucial role in galaxy evolution. It provides the gravitational framework that holds galaxies together and influences their interactions with one another. 

Supermassive black holes, found at the centers of most large galaxies, can also affect their evolution by releasing energy that impacts star formation and the movement of gas within the galaxy.

Overall, galaxy evolution is a complex and ongoing process driven by interactions between stars, gas, dark matter, and black holes, and shaped by both internal processes and external influences.

Image Credit: ESA/Hubble & NASA, J. Lee

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