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<\/p>\nIn the southern hemisphere, in the constellation Canis Major, lies a very young, very massive red hypergiant star called VY Canis Majoris (VY CMa).<\/p>\n
A pulsating variable, its apparent magnitude (how bright it appears in the night sky) varies unpredictably. It is located 1.2 kiloparsecs, or approximately 3,900 light years, from Earth, is only 8.2 million years old, and is one of the largest stars known to exist.<\/p>\n<\/p>\n
Approximately 1,420 times the radius of the Sun, it is 7-8 AU across (with 1 AU being 149.5 million kilometers \u2014 the average distance of Earth to the Sun). If VY CMa replaced the Sun in our solar system, the star\u2019s photosphere \u2014 or surface \u2014 would stretch nearly to Saturn\u2019s orbit.<\/p>\n
It is also one of the brightest stars known in the Milky Way galaxy, being 350,000 times more luminous than the Sun. Yet for the last 220+ years, we have not been able to see it with the naked eye since a dimming event in the late-1800s that the star has never visually recovered from.<\/p>\n
So why is this star fascinating?<\/p>\n
That largely comes down to the nature of its existence. Large stars like VY CMa have extremely short lifespans on the galactic timescale. At just 8.2 million years old, it will \u2014 with near certainty \u2014 explode in a supernova event within 100,000 years, with its remnant likely to form a black hole instead of a neutron star.<\/p>\n
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VY Canis Majoris \u2013 seen by the Hubble Space Telescope \u2013 enshrouded in the nebulous gases and material it has ejected from itself over the last few thousand years. (Credit: NASA, ESA, HST, Humphreys et al.)<\/p>\n
\u201cI think what really attracts astronomers to these very luminous and active stars, first of all, is their short lifetime,\u201d said Dr. Roberta Humphreys, in an interview with NASASpaceflight on her and her team\u2019s recently published paper, \u201cThe Mass-loss History of the Red Hypergiant VY CMa\u201d.<\/p>\n
Rocket building kits (adsbygoogle = window.adsbygoogle || []).push({});<\/p>\n The paper, published in the March 2021 issue of The Astronomical Journal<\/i>, can be read here.<\/p>\n \u201cBelieve it or not, we observe changes in stars over a human lifetime. If you look at the history of VY Canis Majoris and its high mass-loss episodes, this is stuff occurring on the timescale of a human life.\u201d<\/p>\n These high mass-loss events referenced by Dr. Humphreys form the crux of her and her team\u2019s recent work, which examined the knots, clumps, and extended arcs of ejecta material that surround VY CMa.<\/p>\n By closely investigating these areas around the star, Humphreys et al. were able to correlate some of the ejecta plumes, clumps, and knots with dimming events recorded in the star\u2019s 320 year observational period dating back to 1801.<\/p>\n According to the team\u2019s results, \u201cWe find probable correlations of two to three separate mass ejections or outflows with the 19th century episode and with the 1920-1940 period suggesting that each of the minima may be related to a separate outflow.\u201d<\/p>\n<\/p>\n