The two stars in Wolf-Rayet 140 produce shells of dust every eight years that look like rings, as seen in this image from NASA’s James Webb Space Telescope. Each ring was created when the stars came close together and their stellar winds collided, compressing the gas and forming dust. Credit: NASA, ESA, CSA, STScI, JPL-Caltech
A new Webb image shows at least 17 dust rings created by a rare type of star and its companion locked in a celestial dance.
A remarkable cosmic sight is revealed in a new image from NASA’s James Webb Space Telescope. At least 17 concentric dust rings are seen mysteriously emanating from a pair of stars. Collectively known as Wolf-Rayet 140, the duo is located just over 5,000 light-years from Earth.
Wolf-Rayet (often abbreviated as W-R or WR) stars are unusual stars that are very massive (over 40 times the mass of our Sun), extremely hot (from 20,000 K to around 210,000 K), and exceptionally bright. Wolf-Rayet stars were discovered in 1867 by C. J. Wolf and G. Rayet. These stars continually eject their outer atmosphere in bubble-like shells of particles and gas, creating a strong stellar wind. About 500 of these stars have been cataloged thus far in the
The two stars in Wolf-Rayet 140 produce rings, or shells, of dust every time their orbits bring them together. A visualization of their orbits, shown in this video, helps to illustrate how their interaction produces the fingerprint-like pattern observed bySome other Wolf-Rayet systems form dust, but none is known to make rings like Wolf-Rayet 140 does. The unique ring pattern forms because the orbit of the Wolf-Rayet star in WR 140 is elongated, not circular. Only when the stars come close together – about the same distance between Earth and the Sun – and their winds collide is the gas under sufficient pressure to form dust. With circular orbits, Wolf-Rayet binaries can produce dust continuously.
This graphic shows the relative size of the Sun, upper left, compared to the two stars in the system known as Wolf-Rayet 140. The O-type star is roughly 30 times the mass of the Sun, while its companion is about 10 times the mass of the Sun.
Credit: NASA/JPL-CaltechLau and his co-authors think WR 140’s winds also swept the surrounding area clear of residual material they might otherwise collide with, which may be why the rings remain so pristine rather than smeared or dispersed. There are likely even more rings that have become so faint and dispersed, not even Webb can see them in the data.
Wolf-Rayet stars may seem exotic compared to our Sun, but they may have played a role in star and planet formation. When a Wolf-Rayet star clears an area, the swept-up material can pile up at the outskirts and become dense enough for new stars to form. There is some evidence the Sun formed in such a scenario.
Using data from MIRI’s Medium Resolution Spectroscopy mode, the new study provides the best evidence yet that Wolf-Rayet stars produce carbon-rich dust molecules. What’s more, the preservation of the dust shells indicates that this dust can survive in the hostile environment between stars, going on to supply material for future stars and planets.
The catch is that while astronomers estimate that there should be at least a few thousand Wolf-Rayet stars in our galaxy, only about 600 have been found to date.
“Even though Wolf-Rayet stars are rare in our galaxy because they are short-lived as far as stars go, it’s possible they’ve been producing lots of dust throughout the history of the galaxy before they explode and/or form black holes,” said Patrick Morris, an astrophysicist at Caltech in Pasadena, California, and a co-author of the new study. “I think with NASA’s new space telescope we’re going to learn a lot more about how these stars shape the material between stars and trigger new star formation in galaxies.”
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