Fireballs Are Flying!

Try to imagine you are an astronomer, studying another star some 2,000 light years away, V Hydra. It’s an odd star; bloated, red, old, and pulsing - getting brighter, then dimmer, and sometimes getting much dimmer. It may be nearing the end of its life, to start again as a planetary nebula, and if that happens during your lifetime, you want to see it.

And then it throws fireballs.

No, it doesn’t explode. No, these aren’t corona ejections. They are fireballs.

How did it do that?

In October 2016, astronomers were left scratching their heads as Hubble revealed that’s exactly what happened. They studied the star and its surroundings, and eventually they came up with a theory.

V Hydra has a visible companion star (we’ll call it NNS - No Name Star, because they never mentioned a name for it). NNS is an orange dwarf about 46” distance from V Hydra. Yeah, I know, 46 inches doesn’t make any sense to me, either, but that’s actually 46 arcseconds in astronomy notation. They ‘measure’ the distance between these 2 stars by noting the angle change from looking at one to looking at the other. An arcsecond is 1/60th of an arcminute, which is 1/60 of a second... Look, take 2 meter sticks and lay one on top of the other. Stick 2 pieces of paper between them at one end. The angle at the opposite end is about 50 arcseconds. So V Hydra and NNS look like 2 bumps together from Earth, but being 20,000 light years away from us, there’s a good bit of distance between them. Chances are anything NNS might be doing would not cause V Hydra to throw fireballs around.

It appears that V Hydra has a second companion star, this one too dim to be seen directly from Earth, but astronomers have their magic math formulas to figure these things out. We’ll call this one DIM, because it’s so dim. Anyway, DIM orbits V Hydra every 8.5 years in a very elliptical orbit. This orbit is so elliptical that - now that V Hydra is bloated in its death throes - DIM no longer comes close to V Hydra, it actually travels through V Hydra’s outer atmosphere. Wow. Hot enough for ya?

As DIM travels through V Hydra’s outer atmosphere, it greedily grabs a bunch of V Hydra’s material and stores it in a disk about itself. Remember, planets are born from left-over materials in a disk around the new-born star, so I guess maybe DIM wants to start a family.

But, alas, DIM just isn’t very smart, and starts sending its ‘fledgling planets’ away long before they actually make planets. When DIM emerges from V Hydra’s atmosphere, its storage disk breaks apart, forming superhot blobs of plasma about twice the size of Mars that are tossed into the unknown at a speed that they could travel from the moon to Earth in about a half hour.

Poor DIM. Heart-breaking, isn’t it? Now consider that astronomers believe this has been happening every 8.5 years for about 400 years.

The mind boggles, right? But what can we do? I mean, sending DIM a sympathy card every 8.5 years is a bit much, don’t you think? Probably doesn’t want to talk about it, anyway.

How much would it cost to send a card 20,000 light years? Will a regular stamp do?

http://www.astronomy.com/news/2016/10/cannonballs-shooting-from-star

https://en.wikipedia.org/wiki/V_Hydrae