Comet Holmes

3488 · Nov 14, 2007

Hi ashish, The coma is growing in size & Holmes is looking larger, despite the fact, the distance between Earth & Holmes is increasing. No Holmes will not be a permanent naked eye object, it will fade back to its previous obscurity over time. I would be surprised now if Holmes will remain above naked eye visibilty in a couple of weeks. Already I am finding it hard to spot with the naked eye & I have no problems finding M31 in town & M33 under dark skies with the naked eye. As MeteorWayne says, Holmes hjas changed enormously only over a few days. UI was quite shocked last night & even tonight, Holmes looks slightly larger than yesterday, but is not easy to see with the eyes. Andrew Brown. <div class="Discussion_UserSignature"> "I suddenly noticed an anomaly to the left of Io, just off the rim of that world. It was extremely large with respect to the overall size of Io and crescent shaped. It seemed unbelievable that something that big had not been visible before". Linda Morabito on discovering that the Jupiter moon Io was volcanically active. Friday 9th March 1979.http://www.launchphotography.com/ http://anthmartian.googlepages.com/thisislandearthhttp://web.me.com/meridianijournal </div>

MeteorWayne · Nov 14, 2007

Yes it is growing in size (and becoming harder to see naked eye every day). No it will not be permenant. In the other 18 of it's 20 solar orbits (Excluding this one, and the discovery year of 1892), it was not even a telescopic object without long photographic exposures. Usually it's ~ +16 magnitude at it's brightest. That's VERY dim. And of course that usually occurs at perihelion. These outbursts seem to happen a few months after perihelion. Very hard to explain. In the discovery year though, the outbursts were not as bright as this one. There were two times it was naked eye visible in 1892, about 4 months apart IIRC. I'll check and edit for the time between outbursts in a few minutes. Certainly, within a week or two, it seems to be destined to fade below naked eye visibility, except under VERY dark skies, and within a few months below unaided telescopic brightness. If there's another ourburst, we might have to reset that clock. It's been 3 weeks since the day it increased in brightness a million times in 12 hours. Wowowowow. MW <div class="Discussion_UserSignature"> But the Krell forgot one thing John. Monsters. Monsters from the Id. I really, really, really, really miss the "first unread post" function </div>

3488 · Nov 14, 2007

I really hope we get to find out what actually happened. I agree with you that it might have been an impact. Regarding activity levels, I wonder if the warmest temperatures do occur just after perihelion, because it taks time for the surface to warm? I am thinking along the lines, that generally here in the Northern Hemisphere, June has the longest days, but August usually has the hottest days of the year. I wonder if comets behave in a similar way?? Andrew Brown. <div class="Discussion_UserSignature"> "I suddenly noticed an anomaly to the left of Io, just off the rim of that world. It was extremely large with respect to the overall size of Io and crescent shaped. It seemed unbelievable that something that big had not been visible before". Linda Morabito on discovering that the Jupiter moon Io was volcanically active. Friday 9th March 1979.http://www.launchphotography.com/ http://anthmartian.googlepages.com/thisislandearthhttp://web.me.com/meridianijournal </div>

adrenalynn · Nov 14, 2007

I still support the theory that it's porous and we're witnessing cell failure due to repeated heating and cooling. It does seem to fit the observations. I haven't observed it in several days, but I might just have to move the scope w/camera back to the other side of the house and start photographing its fade back into obscurity... <img src="/images/icons/wink.gif" /> <div class="Discussion_UserSignature"> .bipartisan (bī-pär'tĭ-zən, -sən) [Adj.] Maintaining the ability to blame republications when your stimulus plan proves to be a devastating failure.IMPEACH OBAMA! </div>

MeteorWayne · Nov 14, 2007

It's awfully late after perihelion for that. Perihelion was May 6, the outburst was October 24. That's 5 1/2 months, and perihelion is at 2.053 AU, the outburst at 2.44 AU. Therefore even the max heating heating is much less than earth's. Of course, AFAIK, we don't know anything about the spin (axes or rates) of this tiny nucleus. Even so, there's no vast quantity of water to ****** the max temperature from the maximum heating. From what I can tell (and I've seen no definitive evidence either way) most of the "puffball" appears to have been dust, based on the color. There is also a gas ion tail, so some ice was involved, but the outrageous brightening looked like dust to me. Fun to think about. I sure am anxious for some spectrographic data on this event!!! <div class="Discussion_UserSignature"> But the Krell forgot one thing John. Monsters. Monsters from the Id. I really, really, really, really miss the "first unread post" function </div>

MeteorWayne · Nov 14, 2007

If it's been several days, you will be shocked at the difference naked aye and in binoculars. Have no idea what your photos will show. If you can, please take some!!!! <div class="Discussion_UserSignature"> But the Krell forgot one thing John. Monsters. Monsters from the Id. I really, really, really, really miss the "first unread post" function </div>

3488 · Nov 14, 2007

I second that request too <img src="/images/icons/laugh.gif" /> . I see your point MeteorWayne. The timescale is too long to allow for that. My woolly headed thinking again <img src="/images/icons/crazy.gif" /> . I just hope that the HST, Spitzer & maybe the MRO HiRISE from Mars orbit, looked. This is one weird comet. Andrew Brown. <div class="Discussion_UserSignature"> "I suddenly noticed an anomaly to the left of Io, just off the rim of that world. It was extremely large with respect to the overall size of Io and crescent shaped. It seemed unbelievable that something that big had not been visible before". Linda Morabito on discovering that the Jupiter moon Io was volcanically active. Friday 9th March 1979.http://www.launchphotography.com/ http://anthmartian.googlepages.com/thisislandearthhttp://web.me.com/meridianijournal </div>

adrenalynn · Nov 14, 2007

Absolutely will. I think I may just need to make a few upgrades in the near future. I think a fascinating project will be doing plate solutions and astrometrics against old photos (pre-erruption) and new photos post-fade-to-obscurity, and measuring the differences. I've been looking for an excuse to buy a nice "portable" 16-20" research-grade RC for awhile now... <img src="/images/icons/wink.gif" /> <div class="Discussion_UserSignature"> .bipartisan (bī-pär'tĭ-zən, -sən) [Adj.] Maintaining the ability to blame republications when your stimulus plan proves to be a devastating failure.IMPEACH OBAMA! </div>

adrenalynn · Nov 14, 2007

In earth-atmosphere-bound cycle failure, we can see it generally occurs in the cooling cycle, not the heating cycle. Metal fractures, for example. Repeated heating and cooling can fracture the honeycomb and we'll typically see it catastrophically fail during cooling. That final shrinkage causes things to start snapping. That's one of the reasons I support the theory proposed in my prior post. It just fits with my past observations and my knowledge of structural engineering. <div class="Discussion_UserSignature"> .bipartisan (bī-pär'tĭ-zən, -sən) [Adj.] Maintaining the ability to blame republications when your stimulus plan proves to be a devastating failure.IMPEACH OBAMA! </div>

MeteorWayne · Nov 14, 2007

I didn't say you were wrong <img src="/images/icons/smile.gif" /> I was just thinking out loud <img src="/images/icons/wink.gif" /> <div class="Discussion_UserSignature"> But the Krell forgot one thing John. Monsters. Monsters from the Id. I really, really, really, really miss the "first unread post" function </div>

MeteorWayne · Nov 14, 2007

That certainly could be correct as well. the wood stove makes noise heating up and cooling down <img src="/images/icons/smile.gif" /> <div class="Discussion_UserSignature"> But the Krell forgot one thing John. Monsters. Monsters from the Id. I really, really, really, really miss the "first unread post" function </div>

adrenalynn · Nov 14, 2007

Exactly. But I suspect that if you measure the tension on the grain structures, you'd find that the stress is higher under shrinkage than expansion. The concern I have with the under-developed theory is the period over which the brightening occured. Expansion at that rate sure seems more like explosion than leakage. So that would either mean dissimilar materials that were reactive, or a core under pressure - right? <div class="Discussion_UserSignature"> .bipartisan (bī-pär'tĭ-zən, -sən) [Adj.] Maintaining the ability to blame republications when your stimulus plan proves to be a devastating failure.IMPEACH OBAMA! </div>

Mee_n_Mac · Nov 14, 2007

... or a core under pressure ... Well call me wooly headed ( <img src="/images/icons/smile.gif" /> ) but that's my best guess right now too. Imagine Holmes approaching the Sun and heating up. The surface is already depleted of volatiles due to previous passes but they still exist under the surface. Perhaps a a vein of snowy dirt conducts heat to a pocket. It vaporises and builds pressure but can't find a way out until sometime in the cooling cycle a fissure is formed and the gas can escape. So can we rule out the above ? Can we estimate how much gas and how dense it must be to account for the growth in brightness ? Could this amount be outgassed and still fit into the observed size of the coma ? Is there an estimate for Holmes' surface temperature vs orbital position ? Let the games begin !! <div class="Discussion_UserSignature"> -----------------------------------------------------Ask not what your Forum Software can do do on you,Ask it to, please for the love of all that's Holy, STOP ! </div>

adrenalynn · Nov 14, 2007

Those are exactly the kind of questions I'd personally like to explore. I think Holmes is giving off a lot of data that the serious amateur can play with nearly as well as the BigGuys. For that, I'm kinda appreciative of the big fuzzball. <img src="/images/icons/wink.gif" /> <div class="Discussion_UserSignature"> .bipartisan (bī-pär'tĭ-zən, -sən) [Adj.] Maintaining the ability to blame republications when your stimulus plan proves to be a devastating failure.IMPEACH OBAMA! </div>

adrenalynn · Nov 15, 2007

Wow. In the last week it's gone from naked-eye visible double coma to no longer naked-eye visible from my observing location. It's gone from brilliant, apparent triple coma layers in the 5" scope to "The RA/Dec is right, but I'm not really sure I have it..." in direct vision, only viewable through averted vision. (NE is under a streetlight from here. I can't see that sky from the home observatory which is several magnitudes darker...) It completely fills the view of the 1250mm *0.6 crop of the camera view. It will be interesting to do a mosaic of its growth. I'm stacking 18min 55sec worth of light frames [45sec exposures @3200 ISO] (+ 9min 30sec of dark frames) right now... I'll post the results when they're ready. The Quad is happily munching data as we speak. <div class="Discussion_UserSignature"> .bipartisan (bī-pär'tĭ-zən, -sən) [Adj.] Maintaining the ability to blame republications when your stimulus plan proves to be a devastating failure.IMPEACH OBAMA! </div>

adrenalynn · Nov 15, 2007

http://uplink.space.com/showflat.php?Cat=&Board=amazingimg&Number=813891&page=0&view=collapsed&sb=5&o=0&fpart=2 Comet Holmes photo tonight in Amazing Images... <div class="Discussion_UserSignature"> .bipartisan (bī-pär'tĭ-zən, -sən) [Adj.] Maintaining the ability to blame republications when your stimulus plan proves to be a devastating failure.IMPEACH OBAMA! </div>

adrenalynn · Nov 15, 2007

Plate solution for Holmes this evening: http://www.jlrdesigns.com/astrophotography/Holmes-plate-nov-14-07.jpg The "apparent core" (bright spot on the outter edge, about 8 o'clock) lines-up with predicted location down to 0.2" (beyond the expected limit of my scope and camera) (I've labled it as "Holmes (17P)" in this image) The coma currently measures 0 deg 24' 11" high by 0deg 35' 39" wide (both at longest points obvious in this photo. What I don't expose could be wider/taller). From a photometric perspective, the "apparent core" is Mag 8.79, the dimmest star seen in this photo appears to be Mag 14.64. More than you ever wanted to know, huh? <div class="Discussion_UserSignature"> .bipartisan (bī-pär'tĭ-zən, -sən) [Adj.] Maintaining the ability to blame republications when your stimulus plan proves to be a devastating failure.IMPEACH OBAMA! </div>

docm · Nov 15, 2007

Page by one of the University of Hawaii Institute for Astronomy guys working on Holmes with a fantastic to-scale pic showing its dust cloud is now larger than the sun. http://www.ifa.hawaii.edu/faculty/jewitt/holmes.html Wow..... <div class="Discussion_UserSignature"> </div>

adrenalynn · Nov 15, 2007

That's awesome, thanks - I hadn't seen that! I'm independantly arriving at my own astrometrics at the moment - my own photos, my own image processing, my own astro- and photo-metrics -- because I find it an amusing challenge. <img src="/images/icons/wink.gif" /> <div class="Discussion_UserSignature"> .bipartisan (bī-pär'tĭ-zən, -sən) [Adj.] Maintaining the ability to blame republications when your stimulus plan proves to be a devastating failure.IMPEACH OBAMA! </div>

alokmohan · Nov 15, 2007

Larger means?

adrenalynn · Nov 15, 2007

Bigger. The apparent diameter of the cloud (coma) is greater than the diameter of the sun. <div class="Discussion_UserSignature"> .bipartisan (bī-pär'tĭ-zən, -sən) [Adj.] Maintaining the ability to blame republications when your stimulus plan proves to be a devastating failure.IMPEACH OBAMA! </div>

3488 · Nov 15, 2007

I agree Adrenalynn. The coma is looking very huge now. Not only does it look bigger than the Sun, the coma is now physically larger than the Sun. It must be so tenous now, that its density is probably as good as a good laboratory vacuum. I will look again tonight. Andrew Brown. <div class="Discussion_UserSignature"> "I suddenly noticed an anomaly to the left of Io, just off the rim of that world. It was extremely large with respect to the overall size of Io and crescent shaped. It seemed unbelievable that something that big had not been visible before". Linda Morabito on discovering that the Jupiter moon Io was volcanically active. Friday 9th March 1979.http://www.launchphotography.com/ http://anthmartian.googlepages.com/thisislandearthhttp://web.me.com/meridianijournal </div>

Mee_n_Mac · Nov 15, 2007

Has anyone made an estimate on the density ? Also what shape (roughly) do we guess the coma to be ? Are we seeing a sphere of the bottom of a cylinder or ??? Where I'm headed is trying to get a guesstimate of the amount of material involved. <div class="Discussion_UserSignature"> -----------------------------------------------------Ask not what your Forum Software can do do on you,Ask it to, please for the love of all that's Holy, STOP ! </div>

MeteorWayne · Nov 15, 2007

The nucleus is far too small to have any idea about a shape. In fact, the only comets that we know that about have been visited close up (Halley, Borelly, Wild 2 and Tempel. I think that's all) It's apparently a very small (2 mile diameter) nucleus so shape is almost irrelevent. <div class="Discussion_UserSignature"> But the Krell forgot one thing John. Monsters. Monsters from the Id. I really, really, really, really miss the "first unread post" function </div>

3488 · Nov 15, 2007

BREAKING NEWS. HUBBLE SPACE TELESCOPE observes Comet 17/P Holmes. Great stuff <img src="/images/icons/laugh.gif" /> . Andrew Brown. <div class="Discussion_UserSignature"> "I suddenly noticed an anomaly to the left of Io, just off the rim of that world. It was extremely large with respect to the overall size of Io and crescent shaped. It seemed unbelievable that something that big had not been visible before". Linda Morabito on discovering that the Jupiter moon Io was volcanically active. Friday 9th March 1979.http://www.launchphotography.com/ http://anthmartian.googlepages.com/thisislandearthhttp://web.me.com/meridianijournal </div>

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