Hello again. No new image this week as we have not had a clear night since November 27th (2024). I am not going to go into a rambling preamble about the state of the weather, suffice to say it's crap. Anyway, I thought why not do a blog post for a change? It has been ages since the last one. And I can well imagine a few of you thinking, actually it has not been long enough. As you can see the title of this post is VY Canis Majoris and that is the star we are going to have a look at.
As you can see on the star chart above, VY Canis Majoris is located in the rather southern constellation of Canis Major. At this time of year (Winter), this constellation can be seen to the east (left) of Orion but very low down and indeed from UK shores it never rises very high. Of course, the constellation contains the famous and brightest star in the sky, Sirius. This is easily seen at this time of year despite being low down depending on your vantage point. Having said that, it is practically unmissable if you look towards the south. But I digress. VY Canis Majoris is even lower down in the constellation and incredibly needs a telescope to be seen. I say incredibly because this star is one of the largest stars known. This star is an extreme oxygen-rich red hypergiant and pulsating variable star 3,900 light years from our solar system. Not only is it massive, it is one of the most luminous stars in our galaxy, the Milky Way. The radius of VY CMa is 1,420 times that of our Sun and has a volume nearly 3 billion times of our Sun. This means it would take 3 billion times of our Sun to fill VY Canis Majoris. If this star replaced our Sun, its surface would extend beyond the orbit of Jupiter but not quite Saturn!! Yes, yes, I hear you say, facts and figures are all very well, but give us something to compare it with. Ok, take a look at the graphic below and prepare to be shocked..
Now, is that one of the most insane things you have ever seen? Can you see how tiny our huge star, the Sun is? Just absolutely mindblowing! VY Canis Majoris is a highly evolved star, yet less than 10 million years old. The star has aged rapidly because of its high mass. The time spent to the red hypergiant phase is estimated to be between 100,000 and 500,000 years, and thus VY CMa most likely left its main sequence phase more than a million years ago. The future evolution of VY CMa is uncertain, but like most cool supergiants, the star will certainly explode as a supernova. It has begun to fuse helium into carbon at a massive rate, and like Betelgeuse in Orion, it is losing mass and is expected to explode as a supernova within the next 100,000 years or so. The star is very unstable due to constant coronal mass ejections.
The first known recorded observation of VY Canis Majoris is in the star catalogue of the French astronomer Jérôme Lalande in 1801, which lists it as a 7th magnitude star. Further studies of its apparent magnitude imply the light of the star as viewed from Earth has faded since 1850, which could be due to emission changes. Since 1847, VY Canis Majoris has been described as a crimson star. During the 19th century, observers measured at least six discrete components, suggesting that it might be a multiple star. These are now known to be bright zones in the host nebula surrounding the star. Observations in 1957 and high-resolution imaging in 1998 all but rule out any companion stars whatsoever.
Stock image of VY Canis Majoris.
When this star explodes it will produce a shock wave of a speed of a few thousand kilometers per second that will hit the surrounding envelope of material, causing strong emissions for many years after the explosion. For a star so large, the remnant will probably be a black hole rather than a neutron star. I am unable to image VY Canis Majoris myself from my vantage point as it is too low down and from our back garden the house is in the way, so I include a stock image of the star as above, in a nice field of stars. It is somewhat difficult to imagine that an innocuous star as it appears in the image could be so incredible in it's nature. I hope that you have enjoyed this post and hopefully learned something new about our amazing universe, that never ceases to give and surprise us. As this post goes out on December 21st, I hope you all have a great and peaceful Christmas. Hope to see you next time with a new image. Until then, take care and try not to overindulge, haha...
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