When stars blow up they make beautiful messes. One of the most stunning happened about 10,000 years ago and created the Veil Nebula in the constellation Cygnus the Swan. The Veil lies about 2,100 light-years away and spans some 100 light-years, big enough to reach from the Earth and encompass most of the stars in the Big Dipper. If you could look up and see it with the unaided eye it would span six full-moons (3°).
The Veil is what astronomers call a supernova remnant, the remains of a supergiant star 20 times the mass of the sun that exploded when mammoths still walked the Earth. Big stars burn their energy reserves rapidly because they're incredibly hot. Like rock artist Kurt Cobain and actor James Dean, they live fast and die young. While the sun has been around for nearly five billion years (with another four or five to go), a typical supergiant's lifespan ranges from 30 million to a few hundred thousand years.
Once a giant star's gas tank hits empty, gravity quickly gains the upper hand. Without the outward heat and pressure produced by nuclear burning, the star collapses, then rebounds and explodes in a shattering blast visible across half the universe. Despite this stellar violence, the shockwaves and debris from the explosion can create scenes of great beauty like the Veil Nebula’s delicate tendrils of ionized gas.
The Hubble image only records a small portion of the Veil, but through a modest telescope two halves are seen which together roughly outline the perimeter of an expanding sphere. Astronomers believe that before the star self-destructed it blew bubbles of its own atmosphere into space. Later, when the blast wave slammed into the material — and anything else that happened to be in the way — it shocked and energized the gases, setting them aglow. The shock wave permeated the nebula, hollowing out innumerable cavities outlined by glowing filaments.
While a supernova should appear about every 50 years in a galaxy like our own Milky Way, it's been more than 400 years since the last bright one, which occurred in 1604. If we turn our gaze to the universe at large, they're pretty common. Multiple surveys by professional observatories turn up thousands each year in galaxies near and far. Last year alone, 19,242 were discovered, and the count in 2021 is already up to 6,485!
One of the brightest and most recent, supernova 2021hiz, was found on March 30th in the galaxy IC 2233A in Virgo. While the galaxy is faint, the supernova shines at 13th magnitude, putting it within the reach of an 8-inch telescope. Not bad for a galaxy that's some 40 million light-years from Earth. Imagine what it must look like to the local residents!
"Astro" Bob King is a freelance writer for the Duluth News Tribune. Read more of his work at duluthnewstribune.com/astrobob.