New Supernova In M65 Plays Game Of Hide-and-seek

M65 (top right) joins M66 (bottom) right and NGC 3628 in the constellation Leo the Lion. The three, nicknamed the Leo Triplet, are all easily visible in small telescopes and approximately 35 million light years from Earth. Credit: Hunter Wilson

Hundreds of supernovas are discovered every year, most in dim galaxies with names like UGC 10610 or NGC 2554. It takes a good star chart and a determined amateur astronomer to find these little buggers concealed in their galactic hideouts. That’s why when news comes of a supernova in a Messier galaxy, we get excited.

All 110 Messiers objects. M1 at upper left; M110 at lower right. M65 is boxed in red. Click for large version. Credit: Rolando Ligustri

Galaxies in the catalog prepared by 18th century French comet hunter Charles Messier are bright and relatively close. After all, those were the only ones astronomers could see at the time using the technology of the day. Messier’s favorite scope had a mirror only 7.5 inches (19 cm) in diameter, barely equivalent to one of today’s common 6-inch reflecting telescopes, but with it, he discovered numerous new star clusters and galaxies.

Supernova 2013am shines forth on March 28, 2013 in the galaxy M65.  The explosion is a Type II supernova that happens when a supergiant star runs out of fuel at the end of its life. With no energy to push back the force of gravity, the star collapses in on itself,  rebounds with explosive force and rips itself to shreds. Credit: William Wiethoff

So when news came on March 21 that M. Sugano, of Kakogawa, Japan had spotted a new supernova in the galaxy M65 – the 65th entry in Messier’s catalog of 110 objects – amateur astronomers expected the star to brighten to magnitude 11 or 12, shiny enough to nab in even a pedestrian 4.5-inch reflector.

Fine and good, but thanks to dust, that may never happen. Now known officially as supernova 2013am, the new star was very faint when Sugano first spotted it. Nothing unusual there. Both amateur and professional astronomers keep such a close eye on the sky these days with nightly vigils and automated surveys, most supernovas are discovered near the start of their eruptions when they’re still dim.

Within a week, a typical nearby supernova beams brightly enough to show in amateur telescopes. Not 2013am. It’s been 10 days and the star remains stubbornly faint. Professional astronomers examined the light of the supernova on March 22 and gleaned a couple interesting tidbits. First, the blast is tearing the it apart, sending debris into space at over 4,300 miles (7,000 km) per second. Second, the star’s light is “reddened” or dimmed by dust along our line of sight.

This color photo taken on March 31 clearly shows the red hue of the new supernova (arrowed) in M65. Just to the right and below the star is a small, dark patch of interstellar dust. Credit: Bill Williams

Looking at photos of M65 you can see that the supernova lies along or inside a dark patch of interstellar dust, so called because it’s sprinkled among and between the stars. The dust originates from current and previous generations of stars that have lost material to space both gently as they evolve and through supernova explosions.

Sunsets are red for a similar reason stars are reddened by interstellar dust. Dust and other fine aerosols in the atmosphere scatter away the blues and greens of light while the red and oranges penetrate without difficulty. Photo: Bob King

My hunch is that this dusty redoubt blocks and reddens the light of 2013am much the way a volcanic dust or a sand storm absorbs and reddens the light of the sun. Astronomers called the phenomenon extinction. When it comes to dimming stars, all colors of light are not created equal. Fine dust preferentially scatters away more blue light than red, giving otherwise hot blue stars a warm red tone shown so well in Bill’s photo.

2013am is laying low and playing hard to see for now. It’s possible the star may still brighten enough to show in small telescopes. We’ll just have to wait and see. You can monitor Dave Bishop’s M65 supernova page for further developments.

Last night under a very dark sky I glimpsed it in a 15-inch (37 cm) telescope at the limit of my vision at around magnitude 16. It reminded me of finding one of my daughters hidden behind the closet door in a game of hide-and-seek. Gotcha!

4 Responses

  1. Kevin Hudson

    Hey Bob,
    I came across your article on April 2. I decided to try and capture SN 2013am. A cloud front moved in during imaging but I still managed to capture M65 and SN 2013am with success. Thanks for the tip!

  2. Hi, I imaged this galaxy on March09 and I cannot find the SN in the image. I guess it blew up a few days (or hours) after …

    1. astrobob

      Hi Dennys,
      Nice image! Yes, the supernova wasn’t discovered until 3/21. I bet if you tried again, you’d have it.

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