Stellar “feedback” made it possible to determine the age of the young nebula

(ORDO NEWS) — In the southern sky, about 4,300 light-years from Earth, lies the RCW 120 nebula, a giant, glittering cloud of gas and dust. This cloud, known as the emission nebula, is formed from ionized gases and emits light at various wavelengths. An international team led by researchers from the University of West Virginia, USA, studied the effect of “feedback” from stars – the process by which stars transfer energy back into the gas around them. These observations showed that stellar winds are causing a region of space to expand rapidly, allowing researchers to impose age limits on that region. The data collected indicate that RCW 120 should be less than 150,000 years old, which is a very small age for objects of this kind.

About 7 light-years from the center of the RCW 120 nebula lies the edge of this cloud, where a large number of new stars are forming. But what is the reason for their formation?

To answer this question, a team led by Matteo Luisi studied the RCW 120 nebula in detail using NASA’s SOFIA (the Stratospheric Observatory for Infrared Astronomy) infrared aircraft observatory. At the center of this nebula lies one large, massive star, emitting powerful stellar winds into the surrounding space. By observing the nebula in the line of scattered ionized carbon [CII], the researchers were able to trace the stellar “feedback” and figure out the speed of the movement of matter caused by it. According to the authors, RCW 120 is expanding at a speed of 15 kilometers per second, which is an incredibly high expansion rate for an emission nebula. Based on the speed of this expansion, Louise’s team figured out that the nebula is much younger. than expected – it is only about 150,000 years old. Using this estimate of the age of the nebula, the team concluded that the central massive star has “ignited” the peripheral zones of the nebula with its stellar winds relatively recently – which, in turn, means that positive feedback effectively “works” on small time scales, and consequently, it could significantly accelerate the formation of new stars in the early stages of the evolution of the Universe.


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