Day 55: The celestial drama of paired stars

Artist's rendition of SN 1993J. The bigger star sends seven suns' worth of mass to its little partner, then explodes in a fiery death. Credit: ESA

Today I got the chance to write for Universe Today about a new study in the journal Science. The gist of the study is that astronomers have seen, for the first time, confirmation that massive stars — around nine times or more the mass of our sun — die in massive supernova explosions.  This is a widely held theory, but it’s never actually been seen. Now, researchers have spotted two parent stars that showed up in supernovae “before” images — but not in images taken after the blasts. 

The parent of the first supernova, SN 2003gd in the contellation Pisces, was spotted in “before” images and the researchers are pretty sure it hasn’t shown up in the post-explosion images. (SN stands for supernova, and 2003 is the year the explosion was seen.) Supernova explosions kick out a lot of dust, and it may be a few more years before it clears enough to be sure the alleged parent star isn’t still lurking in there somewhere.

But the parent star of SN 1993J — now that’s a cool story.

For background: most stars occur in gravity-bound pairs. When they do, they’re called binary stars. Sometimes they’re so far from each other that their mutual graviational tug is barely noticable, on the other end of the scale, some stars so enmeshed that they “practically roll over each other’s surface,” says Otto Franz, a longtime binary star researcher at Lowell Observatory.  Some coupled stars steal each other’s mass. Others abandon their partners in explosive death displays. 

Sounds a bit like romance, yes?

So the parent star of SN 1993J was a twin, a giant star 15 times the mass of the sun. It was much more massive than its partner, which means its lifespan was naturally shorter, and in the beginning of its death throes, it cast off about seven suns’ worth of hydrogen mass, which — over the course of about 250 years — fed the smaller partner. The binary companion grew to 22 times the mass of the sun.

So, as you can see in that lead photo, SN 1993J’s final supernova explosion looked really weird!

I thought for the rest of the post, I’d present a few more photos of notable supernovae, in all their fiery glory. Most of these are composites of observations in a variety of light wavelengths, so they’re prettier what we’d actually see if we looked at them. But we’ll never be able to do that — so why not dream (in color)? Enjoy!

SN 2003gd in the galaxy M74 (in the constellation Pisces). Credit: Gemini Observatory

The titanic supernova, called SN 1987A, blazed with the power of 100 million suns for several months following its discovery on Feb. 23, 1987. Credit: NASA, ESA, P. Challis and R. Kirshner (Harvard-Smithsonian Center for Astrophysics)

Located 10,000 light-years away in the northern constellation Cassiopeia, Cassiopeia A is the remnant of a once massive star that died in a violent supernova explosion 325 years ago. It consists of a dead star, called a neutron star, and a surrounding shell of material that was blasted off as the star died.

A star's spectacular death in the constellation Taurus was observed on Earth as the supernova of 1054 A.D. Now, almost a thousand years later, a superdense neutron star left behind by the stellar death is spewing out a blizzard of extremely high-energy particles into the expanding debris field known as the Crab Nebula. NASA/JPL-Caltech/R.Gehrz (Univ. Minn.)