by The amazing images produced so far by the James Webb Space Telescope (JWST) have captured the media.
They are easy to find online. just search images of the James Webb Space Telescope. A very interesting news has just been released. It shows what looks rather like a fingerprint in space. To see it, see the link, (www.nasa.gov/feature/jpl/star-duo-forms-fingerprint-in-space-nasa-s-webb-finds)
It shows a pair of nearby stars surrounded by a set of at least 17 uniform, concentric, expanding ripples of dusty material. These dust ripples are due to one of the stars being a Wolf Rayet star, about 30 times the mass of the Sun.
Wolf-Rayet stars, discovered in 1867 by Charles Wolf and Georges Rayet, astronomers at the Paris Observatory, are bright, massive stars nearing the end of their lives. These stars have a mass of 25 or more times the mass of the sun, but they shine 100,000 times to a million times brighter, so they use up their fuel at an amazing rate. The sun is 4.5 billion years old and good for billions more. Stars that become Wolf-Rayet stars last for 10-30 million years before running out of fuel, collapsing and exploding.
As they begin to run out of hydrogen, they begin to use heavier elements to get energy, resulting in the waste of even heavier elements, such as iron. Normally these accumulate in the cores of stars and remain there until the star finally explodes, sending them out into the universe. However, the circulation of material in Wolf-Rayet stars is so intense that heavy elements find their way to the surface, where they are ejected as a particularly dense, fast version of the wind produced by our sun – the solar wind. These heavy elements accumulate as a cloud of dust surrounding the star.
However, in this case the Wolf-Rayet story is a bit more interesting. The star in the JSWT image has a companion and the two stars orbit each other. Their paths around each other are quite elliptical, and each time the stars pass close to each other, their winds collide, creating another ring around the stars. This moves outward and on the next close approach another ring is added. The result is a neat system of evenly spaced, neat, sharply defined rings. Just how good Wolf-Rayet stars are at creating dust is easy to see in this image.
Bright stars that spend their retirement as Wolf-Rayet stars are not good places to look for life-bearing planets. A star that lives maybe 30 million years isn’t going to give its planets time to produce living things. Furthermore, such a strong wind from the star is likely to remove the atmospheres of any nearby planets. If anything survives this, they will be annihilated by the final explosion at the end of the star’s life.
This is not to say that these stars are not important to the development of life in our galaxy and seemingly in other galaxies throughout the universe. Many of the other JWST images are beautiful combinations of stars and either bright or dark dust clouds. This dust was produced by previous generations of large, bright stars. At the beginning of the universe there was nothing but hydrogen, helium and maybe a little lithium. Within the clouds of gas and dust, new stars and planets are born, and there are the ingredients for the creation of living things.
These bright stars may never support life, but what they do makes life possible, and this JWST image of a pair of stars making dust ripples shows part of the process very well and beautifully.
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Mercury, the closest planet to the sun, is very low in the pre-dawn sunrise. In the early evening, Jupiter is in the east and Saturn in the southeast. The Moon will reach first quarter on the 31st. There will be some moonlight this Halloween.
Ken Tapping is an astronomer with the National Research Council’s Dominion Radio Astrophysical Observatory, Penticton
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