Sisters astronomers spot new star

Approximately 23 million years ago, in a galaxy not too terribly far away, a massive star blew itself apart and its light is just now reaching the earth. And a handful of local amateur astronomers are witnesses to the celestial catastrophe.

The exploding star, called supernova 2011dh, was discovered on June 2 by French astronomer Amédée Riou. It is located in the famous Whirlpool galaxy, which resides near the handle of the Big Dipper. Although the brightness of the ill-fated star peaked around June 19, it was still far too dim to be seen without optical aid. In fact, even medium size instruments strained to pick up the feeble light. But a few members of the Sisters Astronomy Club (SAC) were able to make the sighting with their telescopes.

SAC member Forrest Babcock, who owns a 15-inch telescope that he built himself, made his sighting on June 24. "From what I see, the supernova is the brightest object in the galaxy...it is clearly visible in my 15-inch (telescope)," said Babcock.

Jim Hammond, using his 12.5-inch Dobsonian-mounted telescope, did his viewing on June 30. "I also spotted the supernova last night. (It) is about magnitude 12.5, I think. This ranks up there with having someone with about a 24-inch scope let me look at a very distant quasar when I was at the Oregon Star Party in 2006," Hammond explained.

Thomas Jeffrey loaded his 11-inch Celestron "go-to" telescope into his truck and drove up Highway 16 to the upper Three Creek Sno-Park, where I met him to do our observing. His scope quickly found the galaxy and we were able to easily identify the "new" star. "Since we are looking millions of years into the past, the supernova is either a neutron star or a black hole by now," remarked Jeffrey.

Lynn Carroll, who works part-time at the Sunriver Nature Center observatory, has spent many years watching the night sky. He used the Sunriver facility's 20-inch telescope to view the supernova. "I first saw the supernova in early June. It appeared as a bright star in the galaxy," said Carroll. Over the span of the next two weeks, he continued to monitor the exploding star, as it got a little brighter. "The last supernova I observed was in a galaxy in the constellation of Leo," recalled Carroll.

Medium- to low-mass stars, such as our sun, live relatively long lives before gently morphing into white dwarf stars when their fuel source is exhausted. High mass stars, on the other hand, have short lives as they "burn" their fuel at a furious rate while manufacturing heavy elements in their cores. When a sufficient amount of iron has built up in the core, the fusion process ends and the star can no longer support the weight of its outer layers.

Gravity eventually wins the battle as the star's interior rapidly collapses in on itself. The rebounding shock wave blows the star apart sending heavy element-rich material into space where it may be used in the formation of future stars. Normally, all that remains of a supernova is a neutron star or a black hole, depending on the star's initial mass.

This is the third supernova to be recorded in the Whirlpool galaxy in 17 years. That's a lot for a single galaxy. By contrast, no supernova has been recorded in our Milky Way galaxy since 1604. Studies of supernovae remnants in our own galaxy, however, indicate on average an event occurs about once every 50 years.

Perhaps we are well overdue.

If you wish to learn about viewing the night sky, the next Stars Over Sisters star watch will be held on Friday, July 29, at Sisters Park & Recreation District beginning at 9 p.m. Telescopes will be set up for viewing on the Sisters High School soccer field. All are welcome to attend.