Cometary Breakup
New imagery was released today by the Hubble Space Telescope showing Comet 73P/Schwassmann-Wachmann 3’s continuing disintegration. These spectacular views captured from orbit, without the burden of having to peer through our atmosphere, reveal some magnificent details previously unseen from ground-based instruments.
Hubble Space Telescope Advanced Camera for Surveys image of Comet 73P/Schwassmann-Wachmann 3 fragment B on April 18, 2006. Credit: NASA, ESA, H. Weaver (APL/JHU), M. Mutchler and Z. Levay (STScI)
The comet is currently comprised of a chain of over three dozen separate fragments, named alphabetically, stretching across several degrees on the sky. (The Sun and Moon each have an apparent diameter of about 1/2 of a degree.) Ground-based observers have noted dramatic brightening events associated with some of the fragments (as shown in the bottom frame) indicating that they are continuing to break-up and that some may disappear altogether.
Hubble caught two of the fragments, B and G, shortly after large outbursts in activity. Hubble also photographed fragment C, which was less active. The resulting images reveal that a hierarchical destruction process is taking place, in which fragments are continuing to break into smaller chunks. Several dozen “mini-fragments” are found trailing behind each main fragment, probably associated with the ejection of house-sized chunks of surface material that can only be detected in these very sensitive and high-resolution Hubble images.
73P/Schwassmann-Wachmann 3 fragment B on April 19, 2006.
Sequential Hubble images of the B fragment, taken a few days apart, suggest that the chunks are pushed down the tail by outgassing from the icy, sunward-facing surfaces of the chunks, much like space-walking astronauts are propelled by their jetpacks. The smaller chunks have the lowest mass, and so are accelerated away from the parent nucleus faster than the larger chunks. Some of the chunks seem to dissipate completely over the course of several days.
Deep-freeze relics of the early solar system, cometary nuclei are porous and fragile mixes of dust and ices. They can be broken apart by gravitational tidal forces when they pass near large bodies (for example, Comet Shoemaker-Levy 9 was torn to pieces when it skirted near Jupiter in 1992, prior to plunging into Jupiter’s atmosphere two years later). They can also fly apart from rapid rotation of the nucleus, break apart because of thermal stresses as they pass near the Sun, or explosively pop apart like corks from champagne bottles due to the outburst of trapped volatile gases.
73P/Schwassmann-Wachmann 3 fragment B on April 20, 2006.
“Catastrophic breakups may be the ultimate fate of most comets,” says planetary astronomer Hal Weaver of the Johns Hopkins University Applied Physics Laboratory, who led the team that made the recent Hubble observations and who used Hubble previously to study the fragmentations of comets Shoemaker-Levy 9 in 1993-1994, Hyakutake in 1996, and 1999 S4 (LINEAR) in 2000. Analysis of the new Hubble data, and data taken by other observatories as the comet approaches the Earth and Sun, may reveal which of these breakup mechanisms are contributing to the disintegration of 73P/Schwassmann-Wachmann 3.
The full set of Hubble imagery from these latest observations is available here, along with shots taken from the ground. I look forward to seeing more from additional facilities (including the Spitzer Space Telescope) which will seize the opportunity to observe a comet in its death throes. It’s a fantastic (and rare) chance for astronomers to study the processes at work.
And, despite some ridiculous rumors which have permeated the Internet as well as the fringe radio airwaves, 73P’s fragments do not pose any danger to the Earth (more here).
For further reading, see the Bad Astronomy Blog.
rss
entries
comments
Search
faves
Hi Wolverine, so glad to see you alive and well here. ‘Hope all the electrical problems have subsided, though we’re do for some more storms, grrr, this weekend. BTW, last weekend I printed out 84 pages from the NOAA site, including these cute lesson plans and coloring books for teachers and kids (”Billy, Maria & The Thunderstorm”) for each of my family members. Apparently they are clueless about lightning, and two of them live in the most concentrated area of the USA for strikes!) Remember the storm last Friday morning? At least here is was brutal enough that it delayed and messed up their flight plans. On top of that, both batteries in their CT cars were dead when they got home. Nifty VWs like mine have those solar panels you stick on your windshield and plug in the front or trunk to keep one’s battery alive when gone for long periods. My father didn’t seem to take my word about lightning facts–grrr–so this is what they get: lightning coloring books and crossword puzzles! Seriously, the NOAA’s lightning section is quite good.
[I decided not get a convertible next time, because I need at least one hardtop, umm, because of lightning.
Are you going to get rid of your truck? My car of choice would be a Mercedes, and actually a 1970s one, because one can never mistake the sound–it was my first car, though I killed it. My BIL drives an Audi, and likes it. My only problem with my car is the plastic parts–all the stereo parts, the little bass, treble, etc, buttons are all falling off, or the spring catches…plastic sucks in cars.VW had to relent on the plastic window clips because they failed in extreme heat or cold, so the windows would drop, which happened to me. So, they went back to metal clips–duh.]
Watch, I finally get and open my PST and it will be a cruddy weekend. (BTW, what do you think is the best way to keep sand away from a scope–I mean the best way to protect and cover it? My 17-year old deceased Konica always had sand grit on the lens et al, being that I’m a little rough with my cameras, but I don’t think I can get away with that with my new stuff. Really, the new cameras like my Pentax have so much computer stuff they seem so fragile. I’m going to take my PST to the beach, not the observatory, as I left something behind there two weeks ago. Maybe this time I’ll actually depress the shutter….)
Anyway this was about comets:
Now I tend to think of David Levy’s quote:
“Comets are like cats. They have tails and do precisely what they want.”
But I would add:
The Cat only grinned when it saw Alice. It looked good-natured she thought, still it had very long claws and a great many teeth, so she felt that it ought to be treated with respect.
However, in interstellar-speak, this comet’s breakup is a long, slowww one. What is nine lives in space time?
Cats don’t like change without their consent. – Roger A. Caras
[I could go on and on with cat analogies, lol. Babbling over.]
:-)
the comets images are very fine, the shading is also looking quite amazing, how this shading appear in the camera? wolverine.
really awesome images here, I have never seen before such a close view of comets though it has only dust and ice. are there any toxic gasses in the comets founds?
Good morning, Wolve. Last night I was reading Spaceweather.com to get the solar report since I planned on using my PST today at the beach, but right now it’s storming, yes 100%, and all the non-factory car alarms are going off (I hate non-factory-installed alarms; mine never goes off until it’s supposed to.) It may clear up later, so I have a chance to drive down tonight, and tomorrow should be a sunny day.
Anyway, Tony Phillips* wrote on the main-page:
Forget seeing anything in this neck of the woods, but your area is looking better than mine. (BTW, I am well acquainted with Wimberly…love the town.)
On the SW homepage, too, is this little anecdote, which I have to admit gives me some guilty pleasure:
Sometimes it’s nice when it’s a bit peaceful and quiet.
*Tony Phillips seems like a cool guy.
Shoot, the picture posted in the preview, but not after submitting…guess I’m used to how my board works the HTML business.
It looked better against a black background.
:-(