All posts tagged: galaxy evolution

Hubble and JWST reveal thousands of young star clusters emerging from their birth clouds

Hubble and JWST reveal thousands of young star clusters emerging from their birth clouds

Published by Jenni Sidey

A young star cluster does not begin life in the open. It starts buried inside thick clouds of gas and dust, hidden from ordinary view while newborn stars heat, ionize, and push against the material around them. Now, observations from the Hubble and James Webb space telescopes suggest that the biggest clusters do not stay hidden for long. In four nearby galaxies, astronomers found that more massive young star clusters clear away their birth clouds faster than smaller ones do. That means the brightest, most energetic clusters can begin flooding their host galaxies with radiation sooner, with consequences that reach from galaxy evolution to planet formation. “I was excited to see that the emerging timescale of a star cluster is related to its mass in stars. This has implications on a range of research fields, from planet formation to galaxy evolution”, said Alex Pedrini, a PhD student at Stockholm University’s Department of Astronomy and the first and corresponding author of the study. The work, published in Nature Astronomy, draws on a large census of roughly …

For the first time, astronomers identify the edge of the Milky Way’s disc

For the first time, astronomers identify the edge of the Milky Way’s disc

Published by Jenni Sidey

The Milky Way does not come with a clean outer line. Its disc does not stop the way a coastline does. It fades, becoming harder and harder to define as stars grow sparse and the structure stretches into the dark. That uncertainty has made one question especially stubborn for astronomers: where does the galaxy’s star-forming disc actually end? A new analysis points to an answer. By tracing the ages of stars across the Milky Way, an international team of astronomers found that most of the galaxy’s star formation is confined to a region within about 40,000 light-years of the Galactic Centre. Past that point, the pattern of stellar ages shifts in a way that suggests the main star-forming disc has already run out. According to Dr. Karl Fiteni from the University of Insubria, “The extent of the Milky Way’s star-forming disc has long been an open question in Galactic archaeology. By mapping how stellar ages change across the disc, we now have a clear, quantitative answer.” Inside the star-forming disc abundant cold gas fuels star …

Cosmic simulations reveal how galaxies formed and evolved over billions of years

Cosmic simulations reveal how galaxies formed and evolved over billions of years

Published by Jenni Sidey

Cold gas does not look dramatic at first glance. Neither does dust. Yet those two quiet ingredients sit at the center of a new effort to build a far more realistic picture of how galaxies formed. They help explain how galaxies changed and spread across the universe over billions of years. A new suite of simulations called COLIBRE now tracks both, along with the violent push and pull from stars and black holes, in a way earlier large-scale models usually could not. The result is a set of virtual universes that, according to the research team, reproduces real galaxies with striking accuracy, from the nearby universe to the distant young cosmos seen by the James Webb Space Telescope. That matters because galaxy simulations have become one of astronomy’s main testing grounds. They let scientists check whether the standard cosmological model can actually produce the kinds of galaxies telescopes observe. In this case, the answer looks stronger than before. Essential components “Much of the gas inside real galaxies is cold and dusty, but most previous large …

‘Dancing jets’ from black hole reveal their immense power

‘Dancing jets’ from black hole reveal their immense power

Published by Jenni Sidey

The jets do not move in a straight, obedient line. Around Cygnus X-1, a black hole and a massive supergiant star circle each other every 5.6 days. The black hole’s jets get shoved sideways by the star’s powerful wind. Over time, that pressure makes the outflow twist and bend. This creates what one researcher called “dancing jets.” Now, by tracking those bends in fine detail, astronomers have pulled off something that has long been out of reach. They have made a direct, instantaneous measurement of how much power the jets carry away from a feeding black hole. That matters well beyond one binary system. Black hole jets are thought to help shape galaxies and larger cosmic structures by stirring gas, driving shocks, and dumping energy into their surroundings. Scientists have built that idea into large simulations of the Universe for years. However, confirming the key assumptions by observation has been difficult. Cygnus X-1 offered a rare opening. Artist’s impression of the Cygnus X-1 binary system, showing how the wind of the supergiant star bends the …

‘Space archaeologists’ use oxygen map to reconstruct a galaxy’s 12-billion-year past

‘Space archaeologists’ use oxygen map to reconstruct a galaxy’s 12-billion-year past

Published by Jenni Sidey

The oxygen in a galaxy does not sit still. It spreads, thins out, piles up, and leaves behind a record of where stars formed, where gas moved, and when smaller galaxies crashed in. In the nearby spiral galaxy NGC 1365, astronomers have now read that record in unusual detail, using oxygen as a kind of fossil trail. That work, published in Nature Astronomy, marks what the researchers describe as the first use of galactic archaeology beyond the Milky Way at this level of precision. The team, led by the Center for Astrophysics | Harvard and Smithsonian, calls the approach “extragalactic archaeology,” a way to reconstruct how a distant galaxy grew by studying the chemical fingerprints in its gas. “This is the first time that a chemical archaeology method has been used with such fine detail outside our own galaxy,” said Lisa Kewley, lead author, Harvard professor, and director of the Center for Astrophysics. “We want to understand how we got here. How did our own Milky Way form, and how did we end up breathing …

Astronomers built the largest and most accurate 3D map of the ultraviolet universe

Astronomers built the largest and most accurate 3D map of the ultraviolet universe

Published by Jenni Sidey

The space between galaxies is not empty. In a new map of the early universe, those “blank” stretches take on a faint, hydrogen-blue glow that had mostly escaped surveys until now. Astronomers working with the Hobby-Eberly Telescope Dark Energy Experiment, better known as HETDEX, say they have built the largest and most accurate 3D map yet of a specific ultraviolet fingerprint from hydrogen called Lyman alpha. The map covers light emitted roughly 9 billion to 11 billion years ago, a period when the universe was busy making stars, and lighting up hydrogen atoms across enormous distances. “Observing the early universe gives us an idea of how galaxies evolved into their current form, and what role intergalactic gas played in this process,” said Maja Lujan Niemeyer, a HETDEX scientist and recent graduate from the Max Planck Institute for Astrophysics who led the map’s development. “But because they are far away, many objects in this time are faint and difficult to observe.” IFU coordinates in the Fall (top panel), Spring (middle panel), and NEP (bottom panel) fields. …

Astronomers spot ‘jellyfish galaxy’ torn apart 8.5 billion years ago

Astronomers spot ‘jellyfish galaxy’ torn apart 8.5 billion years ago

Published by Jenni Sidey

Long strands of glowing gas stretch behind a distant galaxy, dotted with pockets of newborn stars. The shape looks almost biological, like tentacles drifting through water. Yet this structure formed in one of the most extreme environments in the universe. Astronomers have identified what may be the most distant known “jellyfish galaxy,” a system caught in the act of being stripped apart by its surroundings about 8.5 billion years ago. The object, cataloged as COSMOS2020-635829, sits at a redshift of 1.156 and appears to be plunging through a dense cluster environment that is tearing gas from its disk. The discovery comes from a team led by researchers at the University of Waterloo, who analyzed deep observations from the James Webb Space Telescope alongside spectroscopy from the Gemini Observatory. Their findings suggest that galaxy clusters were already harsh environments much earlier in cosmic history than many astronomers expected. “We were looking through a large amount of data from this well-studied region in the sky with the hopes of spotting jellyfish galaxies that haven’t been studied before,” …