Astronomers identify over 1,000 new star cluster candidates

By analyzing images captured by the James Webb Space Telescope (JWST), an international team of astronomers has managed to identify over 1,000 new star cluster candidates in the Cigar Galaxy. The discovery was reported in a research paper published on the preprint server arXiv on August 8. The Cigar Galaxy (also known as Messier 82, M 82, or NGC 3034) is a small, irregular starburst galaxy located in the constellation Ursa Major, about 11.73 million light-years away. With a size of about 40,800 light-years and a dynamic mass of about 10 billion solar masses, it is one of the closest starburst galaxies to Earth. Previous observations of the Cigar Galaxy have identified 260 star clusters within 3,000 light-years of the galaxy’s center and 363 star clusters outside this central region. Now, a group of astronomers led by Rebecca C. Levy of Steward Observatory in Tucson, Arizona, has used JWST’s Near-Infrared Camera (NIRCam) to more precisely count the population of star clusters in the Cigar Galaxy. Using NIRCam, they were able to detect, catalog, and analyze new candidate star clusters that emit near-infrared light. “In this letter, we compile and present the JWST NIRCam star cluster catalog in the central region of the M 82 starburst,” the researchers wrote. Levy’s team initially identified a total of 2,472 star cluster candidates in the Cigar Galaxy. During further analysis, almost half of these were removed as interference sources, leaving 1,357 cluster candidates with masses of at least 10,000 solar masses. Of these, about 87% were discovered for the first time. The cluster candidates described in this study have an average radius of about 3.3 light years and stellar masses of up to 1 million solar masses. The total stellar mass of these cluster candidates is estimated to be about 40 million solar masses. The astronomers calculated that the mass function of the cluster candidate is 1.9. They found this value to be in good agreement with studies of clusters in other starburst galaxies. The study also found that the discovered cluster candidate still exhibits strong dust extinction. The researchers therefore concluded that the identified sample represents a relatively young, highly reddened population at the center of the Cigar Galaxy. The authors of the paper plan further studies on the reported cluster candidate. First of all, they want to carry out more precise mass measurements, which should be possible based on new spectroscopic observations in the near-infrared and mid-infrared ranges.

source: https://dx.doi.org/10.48550/arxiv.2408.04135