A powerful telescope has observed a massive galaxy collision caused by one galaxy traveling at 2 million mph (3.2 million km/h) in unprecedented detail. This dramatic event occurred in Stephan’s Quintet, a nearby galaxy group first discovered nearly 150 years ago. The collision generated a powerful shockwave, similar to a “sonic boom from a jet fighter,” one of the most striking phenomena in the universe.
Stephan’s Quintet is a “galactic “crossroads where past galaxy collisions have created a complex debris field, which was reactivated by the passage of galaxy NGC 7318b. Scientists using the newly launched William Herschel Telescope Enhanced Area Velocity Explorer (WEAVE) in La Palma, Spain, observed the collision.
This state-of-the-art facility, costing 20 million euros (£16.7 million), will not only help reveal the formation of our Milky Way but also provide valuable insights into millions of other galaxies across the universe.
A team of over 60 astronomers discovered NGC 7318b colliding with Stephan’s Quintet, providing an ideal environment for studying the chaotic and violent interactions between galaxies, making it the focus of the first-light observation by the WEAVE Large Integral Field Unit (LIFU). This observation aims to deepen our understanding of these galactic collisions.
Lead researcher Dr. Marina Arnaudova from the University of Hertfordshire explained that Stephan’s Quintet, discovered in 1877, has fascinated astronomers due to its role as a galactic crossroad, where past galaxy collisions have left a complex debris field.
University of Hertfordshire
This activity has been reignited by a galaxy traveling at over 2 million mph (3.2 million km/h), causing a shockwave similar to a jet fighter’s sonic boom. The international team has also uncovered a dual nature behind the shock front, a previously unknown aspect to astronomers.
Dr Arnaudova said, “As the shock moves through pockets of cold gas, it travels at hypersonic speeds – several times the speed of sound in the intergalactic medium of Stephan’s Quintet* – powerful enough to rip apart electrons from atoms, leaving behind a glowing trail of charged gas, as seen with WEAVE.”
However, when the shock passes through the surrounding hot gas, it becomes much weaker. Instead of causing significant disruption, the weak shock compresses the hot gas, resulting in radio waves picked up by radio telescopes like the Low-Frequency Array (LOFAR).
The new insights and unprecedented details were obtained using WEAVE’s Large Integral Field Unit (LIFU), which combined data from other advanced instruments, including LOFAR, the Very Large Array (VLA), and the James Webb Space Telescope (JWST). This collaboration of cutting-edge technologies provided a deeper understanding of the galaxy collision in Stephan’s Quintet.
WEAVE uses a spectroscope to analyze the light from stars, revealing the elements they are made of by creating a barcode-like pattern within a spectrum of colors. It was designed through a collaboration between France, Italy, and the countries in the Isaac Newton Group of Telescopes (the UK, Spain, and the Netherlands). Astronomers hope that WEAVE will provide unprecedented insights into the formation of our galaxy and transform our understanding of the universe.
Dr. Daniel Smith of the University of Hertfordshire praised the work of Dr. Marina Arnaudova and her team, noting that the first WEAVE science paper is just a glimpse of the discoveries to come as WEAVE becomes fully operational over the next five years.
Professor Gavin Dalton, WEAVE’s principal investigator, highlighted the exceptional detail uncovered by WEAVE. Not only did WEAVE reveal the shock and collision in Stephan’s Quintet, but it also offered new insights into the formation and evolution of faint galaxies at the limits of current technology.
Dr. Marc Balcells, director of the Isaac Newton Group of Telescopes, expressed excitement over the high-impact results from WEAVE’s first observations and anticipated more groundbreaking discoveries in the years ahead.
Journal Reference:
- M I Arnaudova, S Das, D J B Smith et al. WEAVE First Light Observations: Origin and Dynamics of the Shock Front in Stephan’s Quintet—Monthly Notices of the Royal Astronomical Society. DOI: 10.1093/mnras/stae2235