Sciency Words: Kilonova

Sciency Words: (proper noun) a special series here on Planet Pailly focusing on the definitions and etymologies of science or science-related terms.  Today’s Sciency Word is:

KILONOVA

In a recent presentation at Princeton University, Dr. Beverly Berger—an astrophysicist from LIGO—used a very interesting term.  Imagine a pair of neutron stars orbiting each other, spiraling closer and closer together, until suddenly “they go splat!” as Dr. Berger enthusiastically described it.

The more official-sounding term for this is kilonova, Dr. Berger then explained.  The term kilonova originates from this 2010 paper, which predicted that the merger of either two neutron stars or a neutron star and a black hole would produce a very bright flash of light.

The authors of that paper calculated that, at peek luminosity, this flash of light would be approximately a thousand times brighter than a nova explosion—hence “kilonova.”  (In case you’re wondering, a kilonova is still not as bright as a supernova—a supernova is “as much as 100 times brighter than a kilonova” according to this article from NASA.)

Of course the LIGO project is designed to detect gravitational waves, not bright flashes of light.  But as you can see in the highly technical diagram below, a kilonova is accompanied by subtle ripples in the fabric of space-time—gravitational waves, in other words.

In August of 2017, the LIGO project detected exactly the kinds of ripples that would indicate two neutron stars had “gone splat.”  As this article from the LIGO website explains, alerts were “sent out to the astronomical community, sparking a follow-up campaign that resulted in many detections of the fading light from the event, located near the galaxy NGC 4993.”

One thing I’m still not clear about: what happens after a kilonova?  It seems the scientists at LIGO are wondering about that too.  According to that same article from the LIGO website, the 2017 kilonova produced either the largest neutron star that we’ve ever observed OR the smallest black hole.  “Both possibilities are tantalizing and fascinating,” the article says, “but our data simply isn’t good enough to tell us one way or the other.”

Fortunately there are a few projects in development that might help us understand kilonovae—and similar cosmic cataclysms—a little bit better.  We’ll take a look at some of those upcoming projects in Monday’s post.

Sciency Words: Spaghettification (An A to Z Challenge Post)

Today’s post is a special A to Z Challenge edition of Sciency Words, an ongoing series here on Planet Pailly where we take a look at some interesting science or science related term so we can all expand our scientific vocabularies together. In today’s post, S is for:

SPAGHETTIFICATION

I have noted that in thought experiments involving black holes, it is traditional to enter the black hole feet first. Therefore, let’s jump feet first into a black hole and try to imagine what happens.

According to a recent paper in the Journal of Physics Special Topics (my all time favorite physics journal), there’s a reasonable chance you’d remain conscious, at least for a while, after crossing the black hole’s event horizon.

That is, assuming the black hole’s mass is greater than 19,000 solar masses. Apparently the more massive a black hole, the longer you’ll last before you pass out. The authors of the paper also assume you were in relatively good health before entering the black hole.

As you continue to fall toward the center of the black hole—a point of infinite density called the singularity—you’ll be accelerating so fast that you’ll start to lose consciousness. The human heart really struggles with pumping blood when you’re experiencing such high G-forces.

And honestly, that’s probably for the best, because things are about to get super weird. The gravity inside a black hole is so intense that, in essence, your feet are falling significantly faster than your head, and the rest of your body is being stretched out in between.

As you keep falling toward the singularity, you become so stretched and elongated that you look less and less like a person and more and more like a spaghetti noodle. And so this process is called—I kid you not—spaghettification.

Next time on Sciency Words: A to Z, if you didn’t like death by spaghettification, how do you feel about death by thagomizer?

P.S.: Other recent papers from the Journal of Physics Special Topics include:

I think you can see why this is my all time favorite physics journal.