(ORDO NEWS) — An international team of astronomers conducted spectroscopic and photometric observations of the young massive cluster NGC 1850 to study the effect of stellar rotation on its stellar population.
Young massive clusters are dense clusters of young stars that give astronomers the opportunity to study the effect of stellar rotation on groups of stars of the same age but different stellar masses.
NGC 1850 is a young massive cluster about 168,000 light-years away in the northwestern part of the Large Magellanic Cloud (LMC).
The cluster has a radius of about 16.2 light years, a mass of about 42,000 solar masses, and an estimated age of 100 million years.
A team of researchers led by Sebastian Kamann of Liverpool’s John Moores University in Liverpool, UK, conducted a multi-stage observing campaign for NGC 1850 using the Multi-Unit Spectroscopic Explorer (MUSE) instrument on the Very Large Telescope (VLT) in Chile.
Their study was complemented by photometric data from the Hubble Space Telescope.
The astronomers looked at individual stellar spectra and studied the stacked spectra obtained by summing the MUSE spectra obtained from stars that are expected to rotate quickly or slowly, based on their position on the color and magnitude diagram.
As a result, scientists received a sample of 2184 stars with MUSE spectra. Subsequently, astronomers conducted an analysis to understand the distribution of stellar rotation throughout the stellar population of NGC 1850.
The study found a clear correlation between the color of stars that leave the Main sequence turnoff (MSTO) and the value of their rotation speed, since rapidly rotating stars appear more red.
This may indicate that the extended MSTO phenomenon is due to the distribution of stellar rotation.
The results show that the two branches of the main sequence have different distributions of rotational velocities, with the blue branch consisting mainly of slowly rotating stars, while the red branch consists of rapidly rotating stars.
Moreover, MSTO NGC 1850 shows no stars with rotation velocities close to the predicted critical value of 400 km/s.
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