And now for something completely different
August 15, 2007 9:56 PM   Subscribe

And now for something completely different: A star with a tail like a comet. (Cool pic). Don't know how we missed it. It's one of the most well-known stars in the sky and the tail is 13 light-years long, or about 20,000 times the average distance of Pluto from the sun.
posted by spock (44 comments total) 9 users marked this as a favorite
My God... it's full of stars.

posted by Poolio at 9:58 PM on August 15, 2007

A real star trek: Mira is moving along at 291,000 miles per hour and shedding this material behind her.
posted by spock at 9:59 PM on August 15, 2007

My Burnham's Celestial Handbook (Vol. 1) states that "Mira-type stars" (long period pulsating variable stars that vary widely in brightness over the course of time) "form the most numerous class of variables known in the Universe . . . nearly 4000 having been catalogued". (1978)

This makes me wonder if the shedding of material (tail) might also be a characteristic of many/most of them. I would imagine that this question has already occurred to those in the survey program.
posted by spock at 10:10 PM on August 15, 2007

posted by spock

posted by infinitywaltz at 10:12 PM on August 15, 2007 [1 favorite]


Eponological, Captain.

*raises eyebrow*
posted by Avenger at 10:21 PM on August 15, 2007 [13 favorites]

posted by spock at 10:23 PM on August 15, 2007 [2 favorites]

thank you for posting this.

ahhhh, my daily dose of pop culture nostalgia, fanx mefi...
posted by lonefrontranger at 10:28 PM on August 15, 2007

Since no post is complete without a YouTube link: "We are made of star stuff." (Carl Sagan)
posted by spock at 10:34 PM on August 15, 2007

Potentially leaving civilizations in its wake...

Imagine if you were in its path... 9/11 would look like child's play!
posted by wigu at 10:38 PM on August 15, 2007

The video is really worth a look, too.

I'm a bit of a physics/astronomy moron, could someone please explain why it's taken so long to detect this in a well-known star? (Whaddyamean you never pushed that "ultraviolet" button on yer telescope?!?")

Also, can we expect news soon as to whether this phenomenon is typical of many or most other stars?
posted by snifty at 10:46 PM on August 15, 2007

The comparison to contrails and boat wakes is misleading, since those involve a surrounding medium. Equally, a comet's tail results from the solar wind blowing surface matter off, and nothing equivalent seems to be present here, either, even assuming something equivalent is even possible given the vastly greater physical and time scale. This is like neither of those. Presumably this is ejected matter from its internal processes, and it more or less stands to reason that the matter ejected to the rear would tend to leave a trail, while that ejected in other directions would dissipate outward. But why that matter still glows in the UV range tens of thousands of years later is pretty mysterious.
posted by George_Spiggott at 10:47 PM on August 15, 2007

This is cool. Thanks for posting it.
posted by Effigy2000 at 11:13 PM on August 15, 2007

Thanks for posting this spock. I got busy and then I forgot about it. I find the phenomenon quite interesting.
posted by Cranberry at 11:17 PM on August 15, 2007

George: as is written in the article:
"This is an utterly new phenomenon to us, and we are still in the process of understanding the physics involved,"
Spock: thanks - I like.
posted by birdsquared at 11:17 PM on August 15, 2007

George_Spiggott, an interstellar medium exists, and plays a role in this image. That is what is causing the bow shock on the star. You are correct, however, that the wake is matter from internal processes. Mira, being a supergiant, is unstable. Here is a very good description of what is going on in the image.
posted by moonbiter at 11:27 PM on August 15, 2007

OTOH, some hint of what's going on here might possibly be found in the following quotes:

"I read of one planet off in the seventh dimension that got used as a ball in a game of intergalactic bar billiards. Got potted straight into a black hole. Killed ten billion people."
"That's mad."
"Yes, only scored thirty points too."
- Ford Prefect and Arthur Dent in The Restaurant at the End of the Universe

"As flies to wanton boys are we to the gods; they kill us for their sport."
-- Gloucester in King Lear
posted by George_Spiggott at 11:32 PM on August 15, 2007

snifty - I think that it's likely that telescopes with good enough ultraviolet imaging was available until recently.

Now it got around* to being pointed at this thing and because of either greater sensitivity or a new technology it's now possible to see the shedding of stellar matter from a particular fast-moving star.

*there are lots and lots of stars and lots and (well, not that lots) of atronomers who want to look at different things with a shared telescope
posted by porpoise at 11:38 PM on August 15, 2007

(Whaddyamean you never pushed that "ultraviolet" button on yer telescope?!?")

lots of things that are transparent to visible light absorb pretty strongly in the ultraviolet, including most glasses used for optical elements, as well as the atmosphere (see, for instance, ozone layer). so while the ability to build a uv scope has been around a long time, you have to plan for it - and there just arent anywhere near as many of them, due to the higher cost of the materials, need for a uv imaging device, and so on. it's probably a question of having 10 eyes vs. having 10 million eyes.
posted by sergeant sandwich at 12:12 AM on August 16, 2007

Like a real comet, the tail probably doesn't mark where the body has been. It's probably just being ejected off into some random direction. After all, there's no spatial atmosphere to create drag.
posted by Citizen Premier at 12:26 AM on August 16, 2007

What sergeant sandwich said (thanks to preview, I just did a lot of backspacing!). Remember that GALEX, the telescope here, is in space, which solves a lot of those problems but hasn't been doable until recently.
posted by edd at 12:41 AM on August 16, 2007

It now plows along at 130 kilometers per second, or 291,000 miles per hour.

I'm sure this has an answer but I don't know it: 291,000 mph relative to what?
posted by flaterik at 12:49 AM on August 16, 2007

relative to what?

Galactic core.
posted by porpoise at 12:52 AM on August 16, 2007

Presumably this is ejected matter from its internal processes, and it more or less stands to reason that the matter ejected to the rear would tend to leave a trail, while that ejected in other directions would dissipate outward.

So basically it is a star fart.
posted by srboisvert at 1:13 AM on August 16, 2007

There are no farts thirteen light years long. I refuse to believe in any such fart: I consider it an article of personal faith that there can be no fart so large as that. Never, never, never, never, never.
posted by cgc373 at 1:23 AM on August 16, 2007

This is great. Thanks for posting.
posted by ClanvidHorse at 2:30 AM on August 16, 2007

thats right, ozone layer! ya gots to be above it for the uv astronomy...the OAO and the IUE sure stayed up a long probably has been observed before...

also, its got to be a radioactive star fart to keep glowing that long, right? i've never heard of stars shedding significant amounts of isotopes from their atmospheres before, though...usually u only see that kind of nucleosynthesis in supernovae...whats going on here?
posted by sexyrobot at 3:00 AM on August 16, 2007

My star? It's full of gods.
posted by Eideteker at 4:41 AM on August 16, 2007

"There are no farts thirteen light years long. I refuse to believe in any such fart: I consider it an article of personal faith that there can be no fart so large as that. Never, never, never, never, never."

Mrs. mcable begs to differ.
posted by Mcable at 5:36 AM on August 16, 2007

I emailed Mark Seibert last night (one of the co-authors of the Nature paper, asking the question regarding the possibility of other Mira-type stars exhibiting a tail. He replied within the hour (gotta love the scientific community)!

Here's what he said:
Thanks! I think there are over 6000 cataloged now. We have looked at only a few serendipitously where they just happen to fall in survey
areas. No such tail on those. It begs for someone to do a methodical study.

The fact that Mira is the nearest AGB star and it has a tail suggests that there are lots of these things waiting to be discovered. It does require two things - a mass shedding star and a high enough velocity to generate a bow shock. So that will cut the number down, but AGB stars are older stars often associated with the thick disk of the galaxy and therefore typically have higher velocities than your average thin disk star.

You can propose to use GALEX. Would be a good project.

By "you" I presume he means real astronomers, and he is assuming by my question that I am one. I wish
posted by spock at 5:37 AM on August 16, 2007 [2 favorites]

sexyrobot, Mira-type variables shed atmosphere because they are very old, unstable red giants. Towards the end of life for a star like our own sun, it throws off it's atmosphere to form a planetary nebula because it's burning hydrogen unevenly in a shell outside of its core. This is normal. In this case, Mira is moving at a fairly high speed relative to the interstellar medium (the "atmosphere of space"), so it's leaving behind a trail.

I just realized that my second link above is broken. Here is the good description I was talking about.
posted by moonbiter at 5:39 AM on August 16, 2007

"its atmosphere" gah! I hate that mistake.
posted by moonbiter at 5:41 AM on August 16, 2007

Cool post, spock, and nice cometary tail with Seibert's letter.
posted by bru at 6:18 AM on August 16, 2007

I had not been aware of GALEX before this, but interestingly "GALEX data is populating a large, unprecedented archive available to the entire astronomical community and to the general public".

Getting started with GALEX. How to use it: GALEX web site tutorials. Searching MAST for a target or mission.
posted by spock at 7:08 AM on August 16, 2007 [1 favorite]

this is an amazing example of what i was referring to here. from a physics point of view there's very little that is new or interesting about this, except that it's a pretty picture.

maybe it helps if you translate it to another field. if this were biology it it would be the equivalent of someone finding a new, pretty, butterfly and then writing a press release about how this will "shed new light on the evolution of the fragile ecosystem in which we live". yes, in some vague sense it's true, but the "real" value comes from the fact that it's pretty and it's a chance to use long words to make people think their money is being spent wisely.

again, i have nothing against beauty. what i don't understand is why poets don't receive funding to push poetry in exactly the same way. why isn't there a national poetry agency that writes poet press releases and provides funding for the exploration and development of the art?
posted by andrew cooke at 7:35 AM on August 16, 2007

Please don't feed troll.
posted by spock at 7:53 AM on August 16, 2007

[This would be good]

Except I'm pretty sure it means we are about to be taken over by the Necromongers.
posted by quin at 9:31 AM on August 16, 2007

I hardly think andrew cooke is a troll, spock, if it's him you are referring to? He has always been cranky, but informed. (And works at an observatory I think?)
posted by Catfry at 10:10 AM on August 16, 2007

I wouldn't call him a troll either after reading through some of his posts. However I do think he's way off... To assume we understand things well enough to put exploring astronomical and astrophysical phenomena on the back burner is ridiculously arrogant and matches the attitude prevalent in physics at the end of the 19th century. That was of course shortly before a bunch of new ideas and concepts popped up that turned our understanding of the world on its head and laid the groundwork for technological development that would otherwise have been impossible to even conceive of.
To assume that scientific exploration of astronomical phenomena has no impact on our technology and day-to-day life is ignorant. The mere process of exploration pushes technology forward through development of new sensor and processing technology even if no new science is gained from the subject of the experiments itself (which is rarely the case).
posted by Hairy Lobster at 10:41 AM on August 16, 2007

There are just so many things wrong (or ignorant) in the position that one hardly knows where to begin. Starting with a misunderstanding of what science is/does/is-supposed-to-do and how "practical applications" are (eventually) arrived at.

Calling the discovery simply "a pretty picture" misses the point in multiple ways. I doubt that anyone went out looking for a star with a comet-like tail (although they might have if its existence was predicted by a theory or formula. Then, finding its actual existence would lend credence to that particular theory or formula - taking it farther out of the realm of "theory"). The discovery was made by looking at the universe in a whole new way. This discovery is just ONE from just ONE project that has been assigned to the GALEX project. The funding that Andrew apparently is objecting to is the funding for the creation, maintenance and use of a whole new tool for looking at the universe in literally "a different light".

Now I'll grant you that most of the data/discoveries coming out of GALEX projects probably aren't going to be this photogenic. But we wouldn't even be talking about GALEX (and I wouldn't have even known it existed or what it was doing) if this news story with "the pretty picture" hadn't been presented. The importance of this discovery is not limited by its prettiness, nor is most of the other data limited in its importance by its lack of "prettiness".

To take a position that "we know all we really need to know about a particular subject, so let's draw the curtain on that subject and stop asking (or funding) questions" is so inane that I have no words.
posted by spock at 11:39 AM on August 16, 2007

Just for the sake of things, I think I'm in agreement with both above posts, and disagree with ac, but to the best of my ability to ascertain such things, andrew cooke is not a troll (at least not in general).
posted by Catfry at 11:57 AM on August 16, 2007

In his defense, andrew cooke is right about the science. There really isn't anything new here: we know that Mira variables are old, unstable red giants; we know that red giants eventually throw off their atmospheres (which then become planetary nebula); we know that there is an interstellar medium; so at the end of the day there is nothing surprising or new about the observation that this particular fast-moving red giant would be shedding matter in a wake.

Now, I don't agree with him that there shouldn't be public funding for astronomy -- after all, we do fund the arts to some extent, and that in any event I think funding for pure scientific research is a good thing (it's a hell of a lot better than funding retarded military adventures, for example). You never really do know what utility you will find. But he's not trolling.
posted by moonbiter at 12:16 PM on August 16, 2007

You're likely out of luck for submitting a proposal, Spock; according to the GALEX site, telescope time is available for "individuals associated with all categories of U.S. and non-U.S. [astronomical] organizations, including educational institutions, industry, nonprofit institutions, NASA Centers, and other Government agencies." (Some telescopes do make time available for good proposals by amateur astronomers every now and then, though - Hubble had a program like that for a couple of years, and the Gemini Multi-Object Spectrograph ran a contest once.)

My gf has actually done quite a bit of research on AGB stars (in the mid-IR). I should ask her what she knows about this ... what I know of her work makes me disagree with what Andrew Cooke said above.

The manner in which AGB stars lose mass is not very well understood, and only very recently have instruments been constructed which can examine this in any detail. Further understanding this, which means examining the mass loss in finer detail than has previously been possible, would help to explain how planetary nebulae form - for example, how does a spherical star end up producing a nebula that can be elliptical or bipolar?

It's actually very interesting stuff, as well as being a pretty picture.
posted by kyrademon at 12:51 PM on August 16, 2007

I can't resist posting another half-baked, uninformed question about this:

If these trails are several light years long, then shouldn't it be possible to detect them as "passing through" existing images captured by this telescope in this wavelength?
posted by snifty at 9:32 PM on August 16, 2007

It took me a while to understand what you are asking, snifty, but the answer would be a qualified "yes". Yes, assuming that:
1) existing images overlapped this same area in space. (A sky survey would normally not include much overlap, I don't think)
2) the exposure time was long enough to capture the same level of detail (I noticed on the project proposal page, one of the parameters that you request is the amount of exposure time. The longer the exposure time, the fainter UV signatures would be recorded.)

But yes, this feature has been there a long time and presumably will remain there a long time (in the UV spectrum) so any equivalent exposures that contain in in the view should also record it. This instrument is pretty new, however, so not sure how many "existing images" that would include it there might be.
posted by spock at 10:30 PM on August 16, 2007

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