Yale University astronomers tell the story of a galaxy that ran out of gas.
It's a story as old as the universe itself: A galaxy is born, brimming with new stars, its spiral arms stretching and curving. But then it runs into trouble, too close to the center of a nearby galaxy cluster.
D100 in the massive, Coma galaxy cluster, starting approximately 300 million years ago ago. Images from NASA's Hubble Space Telescope
"This galaxy stands out as a particularly extreme example of processes common in massive clusters, where a galaxy goes from being a healthy spiral full of star formation to a 'red and dead' galaxy, said William Cramer, a graduate student in Yale's Department of Astronomy who led the new research.
The process, called "ram pressure stripping," occurs when a galaxy falls near the dense center of a massive cluster of thousands of galaxies. During its plunge, the galaxy plows through intra-cluster material that is even more dense. This material pushes gas and dust-making fuel from the galaxy. Once the galaxy loses all of its gas, it meets an untimely death because it can no longer create new stars.
In the coma cluster, this violent gas-loss process occurs in many galaxies. But D100 is unique, note the scientists. Its long, thin tail, for example, extends nearly 200,000 light years-about the length of two Milky Way galaxies. In addition, the tail is narrow, only 7,000 light years wide.
"The dust tail is remarkably well-defined, straight, and smooth, and has clear edges," said Yale astronomer Jeffrey Kenney, co-author of the study. The clear edges and filamentary structures of the dust tail suggest the magnetic fields play a prominent role in the computer simulation The computer simulations show that the magnetic fields form filaments in the tail's gas.
The Subaru Telescope in Hawaii uncovered the long, glowing hydrogen tail in 2007 during a survey of Coma cluster galaxies. But astronomers needed Hubble observations to confirm the hot gas was a signature of star formation. The researchers said: "Without the depth and resolution of Hubble," he said.
The researchers' main goal was to study star formation in the tail, which was fueled by D100's ongoing gas loss. However, Hubble did not find many stars as the team expected, based on the amount of hydrogen gas contained in the tail. 200,000 stars.
The Hubble data shows that the gas stripping process began on the outskirts of D100 and is moving towards the center. Based on the images, the gas has been cleared out all the way down to the galaxy's central region.
Another image reveals D100's eventual fate. It's an image of galaxy D99, which underwent the same violent gas loss that D100 is now undergoing.
"D100 will look like D99 in a few hundred million years," Kenney said.
The Coma cluster is located 330 million light years from Earth.
The study appears in The Astrophysical Journal .
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W.J. Cramer et al. Spectacular Hubble Space Telescope Observations of the Coma D100 Galaxy and Star Formation in Its Ram Pressure-stripped Tail, The Astrophysical Journal (2019). DOI: 10.3847 / 1538-4357 / aaefff, https://arxiv.org/abs/1811.04916