A Nova's Nuclear Fireball in Unprecedented Detail
Astronomers have imaged the nuclear fireball of a nova with unprecedented clarity and at its earliest stage of beautiful and destructive awesomeness.
I always liked the term Nova but it simply means “New” in latin which is kinda boring if you think about it (“Look… a New…a New). The word though initially referred to a new star that has appeared in the heavens and that was a big deal for a universe that’s supposed to be static and unchanging.
The process itself, as we understand it, is pretty fascinating. A white dwarf which is a degenerate-matter stellar-corpse the size of the earth with the mass of the sun, siphons material from a nearby star slowly accreting gasses like hydrogen onto its surface. This ocean of hydrogen builds up until about one Saturn’s worth of mass is accumulated which makes it about 200 meters deep. Imagine squeezing Saturn into a shell around the earth. The density would have to be pretty wicked and the wickedest part is on the bottom being simultaneously compressed from above and pulled down from the titanic gravitational pull. This bottom layer becomes so hot it fuses. This fusion happens to only 5% of the hydrogen but that’s enough to explode in a nuclear fireball and eject everything that’s been collected into space at velocities of hundreds of kilometers per second. After just one day, that fireball is as big as earth’s orbit.
It was at this point that Astronomers at Georgia State University’s Center for High Angular Resolution Astronomy (CHARA) first took a serious look at what’s now called Nova Delphinus 2013. They looked at it using the telescopes of the CHARA Array. The science news site PhysOrg describes it this way:
The CHARA Array uses the principles of optical interferometry to combine the light from six telescopes to create images with very high resolution, equivalent to a telescope with a diameter of more than 300 meters. This makes it capable of seeing details far smaller in angular extent than traditional telescopes on the ground or in space. It has the power to resolve an object the size of a U.S nickel on top of the Eiffel tower in Paris from the distance of Los Angeles, Calif.
The results of their sleepless night revealed that the fireball’s expansion is more complicated than expected. This results in a more elliptical shape rather than a spherical one. They also determined that even though the outer layers of the fireball became more diffuse and transparent, it became brighter possible due to the formation of infrared emitting dust grains.
If I’ve piqued your interest at all, please Google or Bing around for Delphinus or even the latin word for New; there’s a seemingly never-ending supply of interesting things to learn about these beautiful and deadly astronomical phenomena.
P.S. If you’re worried about the host white-dwarf star, there’s no need. As destructive as these events are, most often, they shrug-off the explosion and live to Nova again.
Image Credit: David Hardy/ astroart.org/NASA