Astronomers have been captivated by a mysterious phenomenon occurring in the Small Magellanic Cloud, a satellite galaxy of the Milky Way. Young stars have been observed spiralling into the centre of a massive cluster of stars, an oddly shaped stellar nursery known as NGC 346. A river-like motion of gas and stars appears to be feeding star formation in this area, creating an efficient way to fuel star birth.
The Small Magellanic Cloud (SMC) is a unique window into the early universe. Located at 200,000 light-years away, it is one of our closest galactic neighbors but its chemical composition is quite different than that of the Milky Way. The SMC is made up of simpler elements than our galaxy, making it similar to galaxies that were formed in the younger Universe when these heavier elements were more scarce. This means that the stars in the SMC burn hotter and use up their fuel faster than those in our Milky Way.
This provides an opportunity to study how stars form in a place much closer to the early universe. By studying the SMC, we can get a better understanding of what was happening billions of years ago when the Universe was undergoing a “baby boom” about two to three billion years after the Big Bang (the Universe is now 13.8 billion years old).
One particularly interesting object located within the SMC is NGC 346. This star formation region is only 150 light-years in diameter but has the mass of 50,000 Suns! Its unusual shape and high rate of star formation has been puzzling scientists for years. Now, thanks to the combined power of NASA/ESA’s Hubble Space Telescope and ESO’s VLT, we are starting to understand this mysterious star formation site better.
The results show that the process of star formation in NGC 346 is quite similar to what we observe in our own Milky Way. This adds to our understanding of how stars form and gives us new insight into how things were happening in the early universe. As Elena Sabbi from the Space Telescope Science Institute explains: “Stars are the machines that sculpt the Universe. We would not have life without them, and yet we don’t fully understand how they form. We have several models that make predictions, and some of these predictions are contradictory. We want to determine what is regulating the process of star formation, because these are the laws that we need to also understand what we see in the early Universe.”
Studying the motion of stars in NGC 346 has been a topic of hot debate among astronomers. In a published study, two teams of researchers have determined the motion of stars in NGC 346 in two different ways. Using the Hubble Space Telescope, Sabbi and her team measured the changes in the stars’ positions over 11 years. The stars are moving at an average velocity of 3200 kilometres per hour, resulting in a distance travelled of 320 million kilometres over the course of 11 years. This is equivalent to twice the distance between Earth and the Sun!
Despite the large distances involved, Hubble’s exceptional resolution and sensitivity allowed for extraordinarily precise observations. Additionally, its lengthy history of observations provided astronomers with a baseline for tracking minute celestial motions over time. the second team, led by Peter Zeidler, used the ground-based VLT’s Multi Unit Spectroscopic Explorer (MUSE) instrument to measure radial velocity, which determines whether an object is approaching or receding from an observer. This method allowed for the measurement of gas motion in the third dimension, which confirmed the theory that the stars were indeed spiralling inwards.
The remarkable thing about this study is that despite using two completely different methods with different tools, both teams arrived at the same conclusion independently. This speaks to the power of modern astronomical techniques and tools used to study distant objects. It also serves as a reminder of how much more we have yet to learn about our universe, and we can only imagine what new discoveries will be made in the years to come!
Why stars form in a spiral pattern?
Have you ever wondered why stars form in a spiral pattern? The answer lies in the natural flow of gas and stars from the outside to the centre of a star cluster. Astronomers have now confirmed this phenomenon in a very young star cluster, NGC 346, using Hubble observations.The Hubble Space Telescope has been in operation for more than 32 years, which means that astronomers have access to a wealth of archival data to power unprecedented, long-term studies. In this case, the data was used to trace the motion of stars in NGC 346 over an 11-year period.
Using the Hubble data, astronomers found that gas and stars move from the outside to the center of the cluster in a spiral pattern.This is known as “the good, natural way to feed star formation”, according to researcher Zeidler.It is also the most efficient way for stars and gas to move towards the center of a cluster.The spiral patterns observed in star clusters may be further studied with the James Webb Space Telescope, which should be able to resolve lower-mass stars in NGC 346. This will allow astronomers to compare the motion of higher- and lower-mass stars and learn more about the dynamics of star formation.
Spiral patterns are not only seen in star clusters: they are also seen in galaxies like our own Milky Way. Astronomers believe that these patterns are created by the rotation of clouds of gas and dust around a center, which is what triggers star formation. Spiral patterns are a beautiful example of how nature creates an efficient and elegant solution for star formation.