A massive red star in the constellation Orion has shrunk in the past 15 years and astronomers don't know why.
Called Betelgeuse, the star is considered a red supergiant. Such massive stars are nearing the ends of their lives and can swell to 100 times their original size before exploding as supernovae, or possibly just collapsing to form black holes without violent explosions (as one study suggested).
Betelgeuse, one of the top 10 brightest stars in our sky, is a popular target among backyard skywatchers and was the first star ever to have its size measured, and even today is one of only a handful of stars that appears through the Hubble Space Telescope as a disk rather than a point of light. It was the first star (besides our sun) to have its surface photographed (by Hubble).
More: http://www.space.com/scienceastronomy/090609-betelgeuse-measurements.html (http://www.space.com/scienceastronomy/090609-betelgeuse-measurements.html)
The red giant star Betelgeuse in the constellation Orion - famed as the home sun of Hitchhiker's Guide to the Galaxy characters Zaphod Beeblebrox and Ford Prefect - is shrinking rapidly. Astronomers say that it has shrunk by 15 per cent since 1993, by which they mean that it actually did so in the mid 16th century. It may, in fact, already have exploded.
More: http://www.theregister.co.uk/2009/06/10/betelgeuse_shrinkage/
...and an APOD: http://apod.nasa.gov/apod/ap090805.html
...and a couple more APODs, https://apod.nasa.gov/apod/ap200101.html and https://apod.nasa.gov/apod/ap200102.html pick the story up again.
For months, astronomers have been keeping a wary eye on Betelgeuse, the bright red star in Orion's shoulder. What's attracting their attention? All of a sudden, Betelgeuse isn't bright anymore. Its luminosity has "fallen off a cliff"--a sign that the star could be on the verge of going supernova.
If Betelegeuse starts to bounce back on Feb. 21st, this whole episode might just be a deeper-than-average pulsation, and perhaps the supernova watch can be called off. However, notes Guinan, "even if the 430-day period is still working, this would indicate a minimum brightness near 0.9 mag--much brighter than the current value near 1.6 mag. So something very unusual is going on."
https://spaceweather.com/
Interesting to think that it could have gone bang as far back as the late 1300's and we still wouldn't know!
Hugh
Quote from: Hugh on Feb 09, 2020, 13:35:17
Interesting to think that it could have gone bang as far back as the late 1300's and we still wouldn't know!
Hugh
This always astounds me!
Roger