Astrophoto: A Cosmic Jellyfish

The entire universe in blog form
Sept. 4 2013 10:27 AM

Cnidareidolia: Jellyfish Nebula

Space exploration is inherently risky. The environment can kill an unprotected human in minutes: the hard vacuum, the heat from a nearby star or the cold from deep space, the gravity gradients near a black hole, the intense radiation blasting out from a massive star, solar storm, or a supernova.

Phil Plait Phil Plait

Phil Plait writes Slate’s Bad Astronomy blog and is an astronomer, public speaker, science evangelizer, and author of Death From the Skies!  

And then, of course, there are the gigantic space jellyfish.

HFG1 a cosmic jellyfish
Not pictured: A cosmic Spongebob Squarepants with a net. Click to gelatinate.

Photo by T.A. Rector (University of Alaska Anchorage) and H. Schweiker (WIYN and NOAO/AURA/NSF)

Advertisement

OK, so this isn’t some light-years-long cosmic cnidarian. It’s actually HFG1, a fairly weird nebula created by an aging pair of stars called V664 Cas. The key to understanding the peculiar shape of the gas cloud is in the stars themselves.

One of the two stars is a white dwarf, the exposed core left over when a star grew old, puffed up into a red giant, and blew off its outer layers. That white dwarf is hot, about 50,000 – 60,000° C (90,000 – 110,000° F). The other star is more like the Sun is now, but the two are very close together: They orbit each other every 14 hours, meaning they’re incredibly close to each other, only a few million kilometers apart at most.

That means that when the first star was still a red giant, it probably engulfed the other star! Drag from the atmosphere of the big star would’ve drawn the second star in closer, and when the first one finally ejected the last bits of its outer parts, we were left with this weird binary system.

The nebula is formed from material ejected from the system. With a binary star like this we usually get some weird nebula, something shaped like a football or a space station or the Firefox logo or a flaming skull. Like those last two cases, V664 is screaming through space at high velocity (probably several dozen kilometers per second, toward the upper right in the photo) and there happens to be a lot of material in its location, floating between the stars. As it rams this stuff a bow wave forms ahead of it, and the stuff blown out in the other, downwind direction gets left behind as dangly bits. The result is HFG1, which really does look like a giant jellyfish a light year or more across.

This photo was taken by my friend Travis Rector (and Heidi Schweiker), using the Kitt Peak 4-meter telescope, and is the highest-resolution and deepest image of HFG1 I’ve seen. I was rather amazed to find the nebula was only discovered a few years ago, and until this image was taken its fine structure had not been observed. Images like this are more than jaw-droppingly pretty; they tell us a lot about the way stars die—for example, the length of the tail and the speed of the stars’ motion tell us the nebula is probably about 100,000 years old. The part of the downwind tail is older, so we can puzzle out the history of the stars over time, too.

We can also learn about the environment around the stars—like how dense it is, how hot or cold it is, how clumpy it is—by observing nebulae like HFG1. These stars are doing us a favor by poking that interstellar material and letting us see the results.

Mind you, it’s this same environment that would kill a human mercilessly. As gruesome a thought as that is, I find it more than somewhat mitigating to know that the same harsh characteristics in space that would do us in are so conducive to the creation of such magnificent objects.

[Note: “Pareidolia” is the term for seeing familiar shapes in otherwise completely unrelated patterns, like seeing faces in clouds. Hence the title of this post. I write about pareidolia a lot, as I think it’s totally cool.]

TODAY IN SLATE

Jurisprudence

Scalia’s Liberal Streak

The conservative justice’s most brilliant—and surprisingly progressive—moments on the bench.

Colorado Is Ground Zero for the Fight Over Female Voters

There’s a Way to Keep Ex-Cons Out of Prison That Pays for Itself. Why Don’t More States Use It?

The NFL Explains How It Sees “the Role of the Female”

The Music Industry Is Ignoring Some of the Best Black Women Singing R&B

Culturebox

Theo’s Joint and Vanessa’s Whiskey

No sitcom did the “Very Special Episode” as well as The Cosby Show.

Television

The Other Huxtable Effect

Thirty years ago, The Cosby Show gave us one of TV’s great feminists.

Cliff Huxtable Explains the World: Five Lessons From TV’s Greatest Dad

Why Television Needs a New Cosby Show Right Now

  News & Politics
Weigel
Sept. 18 2014 8:20 PM A Clever Attempt at Explaining Away a Vote Against the Farm Bill
  Business
Moneybox
Sept. 18 2014 6:02 PM A Chinese Company Just Announced the Biggest IPO in U.S. History
  Life
The Slate Quiz
Sept. 18 2014 11:44 PM Play the Slate News Quiz With Jeopardy! superchampion Ken Jennings.
  Double X
Doublex
Sept. 18 2014 8:07 PM Crying Rape False rape accusations exist, and they are a serious problem.
  Slate Plus
Behind the Scenes
Sept. 18 2014 1:23 PM “It’s Not Every Day That You Can Beat the World Champion” An exclusive interview with chess grandmaster Fabiano Caruana.
  Arts
Brow Beat
Sept. 18 2014 4:33 PM The Top 5 Dadsplaining Moments From The Cosby Show
  Technology
Future Tense
Sept. 18 2014 6:48 PM By 2100 the World's Population Could Be 11 Billion
  Health & Science
Science
Sept. 18 2014 3:35 PM Do People Still Die of Rabies? And how do you know if an animal is rabid?
  Sports
Sports Nut
Sept. 18 2014 11:42 AM Grandmaster Clash One of the most amazing feats in chess history just happened, and no one noticed.