The disappearance of a star can take many forms. It could go supernova. It could turn into a black hole. Or it could just fade away quietly. Sometimes, the last of these is actually the most interesting to observe. That is the case for one of the largest stars ever found – VY Canis Majoris, a red supergiant approximately 3840 light years away in the Canis Major constellation.
Researchers now believe it is periodically ejecting mass the equivalent to twice the mass of Jupiter as it works through its death throes. By using Hubble, astronomers, led by Dr. Roberta Humphreys of the University of Minnesota, are now able to track the ejections this supermassive star makes. Needless to say they are spectacular, even if they have caused the star to fade from sight of the naked eye.
VY Canis Majoris is not the first star to go through these sorts of periodic ejections. Betelgeuse famously went through a dimming period last year, then returned to its normal brightness. After further observation, researchers realized the famous star in the Orion constellation had ejected a jet of particles that caused it to dim for two weeks. VY Canis Majoris is undergoing a similar process, but “on steroids” according to Dr. Humphreys.
That is simply due to the scale of the two stars. VY Canis Majoris’ corona would extend out between the orbits of Jupiter and Saturn if it was located in our solar system. It shines with the brightness of 300,000 of our suns. And it is pushing out 100 times as much mass as Betelgeuse did during its dimming period.
Strangely, the VY Canis Majoris actually used to be even bigger, weighing in at 35-40 times the mass of our sun. Dr. Humphreys suggests that this is actually the second time the star has swollen to the size of a red supergiant, having previously been a blue supergiant, such as Rigel, Betelgeuse’s neighbor in the Orion constellation, swollen to a red one, and then shrunk back down before inflating again.
She also suggests this turbulent history might be the cause of such extreme outbursts as are visible in the Hubble data. It is obvious that over last few hundred years (when VY Canis Majoris was actually visible to the naked eye), it has lost significant amounts of material and been covered by a cloud of dust, both events contributing to its relatively rapid dimming.
As for what’s next as the star continues to throw ejecta out into space, Dr. Humphreys suggests it could result in a black hole rather than going supernova itself. If and when that time comes, astronomers are sure to be keeping watch with whatever successor to Hubble is available at that time. Until then we can sit back and watch the spectacular light show through one of the most prolific telescopes humankind has ever created.
Hubblesite.org – Hubble solves mystery of monster star’s dimming
Sci-news.com – VY Canis Majoris is Enshrouded in Giant Dust Clouds, Astronomers Say
IFLScience – Mystery Of Dimming Hypergiant Star Dubbed “Betelgeuse On Steroids” Solved
UT – Betelgeuse Probably Dimmed Because of Enormous Starspots
Zoomed in image of VY Canis Majoris from Hubble.
Credit: NASA, ESA, R. Humphreys (University of Minnesota), J. Olmsted (STSci)