The Euclid satellite mission has recently provided scientists with the first images of over 1,500 billion orphan stars scattered throughout the Perseus cluster of galaxies. This valuable discovery sheds light on the origins of these orphan stars, which were found drifting between the galaxies within the massive Perseus cluster located 240 million light-years away from Earth. Despite the natural formation of stars within galaxies, the presence of orphan stars outside of these structures raised interesting questions about their origins; which could help in mapping dark matter if their origins are understood. The study was led by Professor Nina Hatch from the University of Nottingham, who expressed surprise at their ability to detect the subtle colors of the orphan stars, indicating that they originated from small galaxies.
The orphan stars were identified by their bluish hue and clustered arrangement, leading astronomers to believe they were torn from the outskirts of galaxies and from smaller cluster galaxies called dwarfs that have been completely disrupted. Surprisingly, instead of orbiting the largest galaxy within the Perseus cluster, the orphan stars were found to be circulating between the two most luminous galaxies in the cluster. Dr Jesse Golden-Marx, a Nottingham astronomer involved in the study, suggested that this unexpected arrangement could be the result of a recent galaxy merger that caused a gravitational disturbance, deviating either the massive galaxy or the orphan stars from their expected orbits.
Dr Matthias Kluge, first author on the study from the Max-Planck Institute for Extraterrestrial Physics, highlighted the importance of the discovery, noting that the diffuse light emitted by the orphan stars accounts for about 20% of the luminosity of the entire Perseus cluster. The faintness of this light, which is more than 100,000 times fainter than the darkest night sky on Earth, underscores the challenge of capturing these images with the Euclid satellite. The Euclid mission, designed by the European Space Agency (ESA), aims to explore the dark Universe by creating a map of the large-scale structure of the Universe across space and time by observing billions of galaxies up to 10 billion light-years away.
Dr Mireia Montes, an astronomer from the Institute of Astrophysics on the Canary Islands, emphasized the crucial role that Euclid’s sensitivity and sharpness played in enabling this groundbreaking research. Euclid’s revolutionary design allows it to capture images with similar sharpness as the Hubble Space Telescope but with a coverage area 175 times larger. The Euclid mission will provide valuable insights into how the Universe has expanded and how structure has formed over cosmic history, shedding more light on the role of gravity, dark energy, and dark matter. The discovery of orphan stars in the Perseus cluster not only provides valuable insights into the origins of these celestial wanderers but also highlights the power and potential of the Euclid mission in advancing our understanding of the Universe.