I think I’m ready to move to another galaxy. M74 has it all. Beautiful spiral arms, puffy pink star clouds and a brand new bright supernova, the third to appear in fewer than a dozen years. Its latest exploding star, dubbed SN 2013ej was discovered by the Lick Observatory Supernova Search at Lick Observatory near San Jose, Calif.
The Lick search uses a fully robotic or automated 30-inch (76 cm) telescope dedicated to scanning the skies for new supernovae. It scooped up M74’s latest exploding star on July 25 shining at a respectable 12.4 magnitude. Two previous supernovae flared in the galaxy – SN 2002ap and SN 2003gd - and rose to 12th and 13th magnitude respectively.
So what’s going on with the Milky Way? The last supernova to flare in our neighborhood was seen by Johannes Kepler in 1604 before the telescope had even been invented. Since then, we’ve “suited up” with instruments of every kind ready to splice and dice the light of a nearby supernova in every imaginable way. Part of the reason for our perception of the Milky Way as a slacker may have to do with dust. Astronomers have discovered two recent supernovae that might have visible with the naked eye were it not for their locations deep within the galaxy, hidden by dense, dark clouds of interstellar dust.
Over the weekend I made a pilgrimage to the countryside to see this newcomer to the intergalactic scene. It still shines brightly – for a star 32 million light years from Earth – at 12.5 magnitude, making it an easy catch in 8-inch and larger telescopes. The last quarter moon was less than a fist away from M74 at the time, rendering the galaxy itself invisible. Since then, the moon has since slimmed to a thick crescent and its glare is no longer an issue.
That’s why I encourage you to use the maps provided here to seek out the star’s final farewell for yourself.
While M74 is relatively bright and appears spectacular in long-exposure photos, it looks like a large, dim featureless glow in smaller telescopes. That’s how it got its nickname the “Phantom Galaxy”. Be patient and take your time to “star hop” to the supernova.
In photos SN 2013ej looks much like the other faint stars nearby, which twinkle in the foreground and belong to the Milky Way, but it’s important to remember you’re seeing the annihilation of supergiant star at least 8 times the size of the sun.
Only days ago astronomers found an image of the likely progenitor (original star) before it blew up. They estimate is was at least 17,000 times more luminous than the sun before it ran out of fuel in its core and imploded. Now it shines with the light of nearly 10 million suns!
Supernovas come in a variety of gradations but they’re broadly divided into Type Ia and Type II. Type Ia involve the rapid and uncontrolled burning of a planet-sized white dwarf star when its penchant for funneling gas from a companion star causes it to gain too much weight. Once it passes the dreaded Chandrasekhar Limit, the dwarf becomes a thermonuclear bomb the size of the Earth with the mass of the sun.
A Type II supernova happens when a massive star burns through its fuel supply until the needle hits empty. Without nuclear burning to produce the heat to fight back the force of gravity, which has been trying to crush the star into a point ever since it was born, the star collapses and then rebounds in a titanic explosion.
Besides a legacy of radiant light, star debris, the creation of heavy elements like gold and lead, a Type II event will sometimes leave behind a tiny, city-sized, rapidly-spinning neutron star – the much compressed core of the original star.
While I remain hopeful about seeing a Milky Way supernova in my remaining years on Earth, I’m happy to have the opportunity a dozen times or more a year to watch one from afar.