Eposode 114: Adrift in a hypernova remnant

Comic Transcript

Panel 1.
[Epo’s interior is dark and damaged.]
Alkina: …oh…the star went hypernova, didn’t it?
Epo: About one month ago by my calculations. I can detect the remaining afterglow.

Panel 2.
Alkina: We really should have seen that coming.
Epo: Since gamma rays travel at the speed of light, it would not have been possible to detect their approach.

Panel 3.
Alkina: It’s a figure of speech Epo, what’s our status?
Epo: I am repairing our telescopes and propulsion systems, it may take some time.

Panel 4.
Alkina: And where are we now?
Epo: Approaching the expanding hypernova remnant.

Panel 5.
[A beeping sound eminates through Epo’s speakers.]
Epo: We have an incoming communication.

Panel 6.
[An alien prospector is seen on Epo’s display.]
Prospector: This here is my claim consarn it! Keep your proton pick’n fingers off my metals!

What does it mean?

Hypernova remnant – The expanding cloud of material ejected by the star during a hypernova explosion.

Afterglow – The fading x-ray, optical, and infrared emissions from the remnants of a gamma-ray burst.

In human speak please!

In addition to the gamma-ray burst, Epo and Alkina also encountered a hypernova remnant in this episode. A hypernova remnant is similar to a supernova remnant. Both are the expanding shell of material that is ejected from a star during a titanic explosion, but hypernovae expand at a somewhat faster rate. Both types of explosions are powered by the collapse of the core of a massive star into a compact object, and both types of remnants can include material swept up as the remnant expands into the space surrounding the exploded star. The edge of the remnant will often contain a shockwave, initially moving outward at speeds of ten thousand of kilometers per second or more. While fast, this is still only a few percent the speed of the light leaving the remnant.

The other object left behind at the end of a massive star’s life is a compact object, the remains of the stellar core. This will be found near the center of the expanding cloud that forms the hypernova or supernova remnant. Astronomers’ models suggest that if a star is formed with a mass in the range of 10 to about 25 or 30 solar masses, the explosion will be a supernova and will leave behind either a neutron star or a black hole. If the star is initially slightly more massive, around 30 to 35 solar masses, it is likely to create a hypernova, but only if it has lost most of its outer layers of hydrogen before the collapse of its core occurs. In this case a black hole is formed. Some of the hypernova explosions are accompanied by a gamma-ray burst.

If a star is extremely massive at the time of the core collapse, no explosion will happen at all. In that case the entire star collapses into the black hole formed at its center. No visible trace of its prior existence is evident. The details of these ideas are still under investigation, and so the exact mass limits quoted above will likely change somewhat in the future. In general though, this seems to be how massive stars end their lives.

Is that all?

Why a “Hypernova?” – A more detailed explanation of a super-charged supernova and its link to gamma-ray bursts.

Hypernova visualized – An animation of what a hypernova would look like if we could see it up close.

A short history on the discovery of hypernovae and possible candidate of star in our own galaxy that might explode next.