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Some questions about C/2011 W3 (Lovejoy)

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  • Rob
    Linked below please find images of Lovejoy taken by Lester Barnes on 22 & 23 Feb 2012: http://i727.photobucket.com/albums/ww271/Rob_Kau/LesterW322Feb2012a.jpg
    Message 1 of 3 , Feb 24, 2012
      Linked below please find images of Lovejoy taken by Lester Barnes on 22 & 23 Feb 2012:

      http://i727.photobucket.com/albums/ww271/Rob_Kau/LesterW322Feb2012a.jpg
      http://i727.photobucket.com/albums/ww271/Rob_Kau/LesterW323Feb2011.jpg

      The images don't seem to pick up anything within at least 9 arcmins of the ephemeris position. I can't imagine that the orbit was so poor that it would be that far out already (even with the difficulties of assigning a 'head' position) given that there were a few weeks of observations after perihelion. So what is happening? Not new really, the last bit into the 'head' has been considerably fainter for 6 weeks or so.

      Just looking at the tail which, while very faint, nonetheless seems quite well defined and 'strong'. There hasn't been any recent discussion about W3 on comets_ml but after this length of time, is it an indication that there is still some level of activity going on, or not? Is there an intact nucleus there or not? To me it doesn't seem to be like a remnant waft of dust drifting off into space, but I certainly don't have a lot to back that up!

      I'd really appreciate hearing some expert comments or opinions on this. The last discussions I saw (ages ago) were ambivalent, some saying it's broken up & finished and others (such as NASA) saying it will return intact in several hundred years! Thanks.

      Cheers -

      Rob Kaufman
      Bright, Victoria, Australia
    • jbortle@aol.com
      Rob, the exact same sort of situation seems to have occurred in conjunction with Comet 1887 B1, The Headless Wonder , observed under very similar
      Message 2 of 3 , Feb 24, 2012
        Rob, the exact same sort of situation seems to have occurred in conjunction
        with Comet 1887 B1, "The Headless Wonder", observed under very similar
        circumstances to Comet Lovejoy. According to a study by Z. Sekanina, the
        measured positions of the tail's sunward terminus during the short interval that
        the 1887 comet was under observation did not quite correspond to the
        anticipated ephemeris positions for a Kreutz sungrazing comet. In fact, the
        tail's sunward terminus lay essential "outside" such an orbit, or
        progressively anti-solar, of the path the comet's head should have tracked.

        Rather likely, in both cases the comets' nuclei had totally disrupted at,
        or shortly following perihelion passage, with the resulting rubble field
        from the original small nuclei progressively differentiating itself into size
        order vs solar distance with the passage of time forming the huge dust
        tail. Since there was/is no indication of any physical object at the expected
        ephemeris position of either comet, it seems reasonably safe to conclude no
        mass of any very significant size and activity level survived. That there
        currently exists a fairly clear sunward terminus to the tail of Comet
        Lovejoy on the images implies that that region probably includes virtually all
        the remaining "larger" mass debris that survived the disruption event. That
        this feature seems located well anti-solar of the anticipated location of
        the nucleus would also tend to suggest that even the largest of the
        surviving solid debris is so fine that it has been pushed significantly outward
        from the orbit by the solar wind and must have very little mass indeed.

        My suggestion at this time would be to attempt to determine the position of
        the sunward terminus of the tail on as many sequential images as possible
        from say January 1st onward to see when and if clear evidence of a
        progressive increase in the separation between the ephemeris position and the
        tail's sunward terminus starts and if/how it evolves. If found and shown to
        progressively increase with time, this would confirm the situation beyond
        question in my mind.

        J.Bortle



        In a message dated 2/24/2012 7:33:22 P.M. Eastern Standard Time,
        Rob.Kau@... writes:




        Linked below please find images of Lovejoy taken by Lester Barnes on 22 &
        23 Feb 2012:

        _http://i727.photobucket.com/albums/ww271/Rob_Kau/LesterW322Feb2012a.jpg_
        (http://i727.photobucket.com/albums/ww271/Rob_Kau/LesterW322Feb2012a.jpg)
        _http://i727.photobucket.com/albums/ww271/Rob_Kau/LesterW323Feb2011.jpg_
        (http://i727.photobucket.com/albums/ww271/Rob_Kau/LesterW323Feb2011.jpg)

        The images don't seem to pick up anything within at least 9 arcmins of the
        ephemeris position. I can't imagine that the orbit was so poor that it
        would be that far out already (even with the difficulties of assigning a
        'head' position) given that there were a few weeks of observations after
        perihelion. So what is happening? Not new really, the last bit into the 'head' has
        been considerably fainter for 6 weeks or so.

        Just looking at the tail which, while very faint, nonetheless seems quite
        well defined and 'strong'. There hasn't been any recent discussion about W3
        on comets_ml but after this length of time, is it an indication that there
        is still some level of activity going on, or not? Is there an intact
        nucleus there or not? To me it doesn't seem to be like a remnant waft of dust
        drifting off into space, but I certainly don't have a lot to back that up!

        I'd really appreciate hearing some expert comments or opinions on this.
        The last discussions I saw (ages ago) were ambivalent, some saying it's
        broken up & finished and others (such as NASA) saying it will return intact in
        several hundred years! Thanks.

        Cheers -

        Rob Kaufman
        Bright, Victoria, Australia






        [Non-text portions of this message have been removed]
      • Rob
        Thanks John for your analysis, much appreciated. Yes it would be interesting to go back over the images, and while there s a bit of night-to-night variation
        Message 3 of 3 , Feb 25, 2012
          Thanks John for your analysis, much appreciated. Yes it would be interesting to go back over the images, and while there's a bit of night-to-night variation in what cameras are picking up with slight sky variations (especially now that it's extremely faint), there may be a trend to be found. For me it would be a very prolonged task & I don't have a lot of time, but maybe it would suit someone with suitable astrometry software. Lester's log of images might be a useful starting point:
          http://oortcloud.org/index.php?topic=17617.0
          Mine aren't so good, but are available here:
          https://sites.google.com/site/robsastropics/comets/comet-c-2011-w3-lovejoy

          Cheers -

          Rob


          --- In comets-ml@yahoogroups.com, jbortle@... wrote:
          >
          > Rob, the exact same sort of situation seems to have occurred in conjunction
          > with Comet 1887 B1, "The Headless Wonder", observed under very similar
          > circumstances to Comet Lovejoy. According to a study by Z. Sekanina, the
          > measured positions of the tail's sunward terminus during the short interval that
          > the 1887 comet was under observation did not quite correspond to the
          > anticipated ephemeris positions for a Kreutz sungrazing comet. In fact, the
          > tail's sunward terminus lay essential "outside" such an orbit, or
          > progressively anti-solar, of the path the comet's head should have tracked.
          >
          > Rather likely, in both cases the comets' nuclei had totally disrupted at,
          > or shortly following perihelion passage, with the resulting rubble field
          > from the original small nuclei progressively differentiating itself into size
          > order vs solar distance with the passage of time forming the huge dust
          > tail. Since there was/is no indication of any physical object at the expected
          > ephemeris position of either comet, it seems reasonably safe to conclude no
          > mass of any very significant size and activity level survived. That there
          > currently exists a fairly clear sunward terminus to the tail of Comet
          > Lovejoy on the images implies that that region probably includes virtually all
          > the remaining "larger" mass debris that survived the disruption event. That
          > this feature seems located well anti-solar of the anticipated location of
          > the nucleus would also tend to suggest that even the largest of the
          > surviving solid debris is so fine that it has been pushed significantly outward
          > from the orbit by the solar wind and must have very little mass indeed.
          >
          > My suggestion at this time would be to attempt to determine the position of
          > the sunward terminus of the tail on as many sequential images as possible
          > from say January 1st onward to see when and if clear evidence of a
          > progressive increase in the separation between the ephemeris position and the
          > tail's sunward terminus starts and if/how it evolves. If found and shown to
          > progressively increase with time, this would confirm the situation beyond
          > question in my mind.
          >
          > J.Bortle
          >
          >
          >
          > In a message dated 2/24/2012 7:33:22 P.M. Eastern Standard Time,
          > Rob.Kau@... writes:
          >
          >
          >
          >
          > Linked below please find images of Lovejoy taken by Lester Barnes on 22 &
          > 23 Feb 2012:
          >
          > _http://i727.photobucket.com/albums/ww271/Rob_Kau/LesterW322Feb2012a.jpg_
          > (http://i727.photobucket.com/albums/ww271/Rob_Kau/LesterW322Feb2012a.jpg)
          > _http://i727.photobucket.com/albums/ww271/Rob_Kau/LesterW323Feb2011.jpg_
          > (http://i727.photobucket.com/albums/ww271/Rob_Kau/LesterW323Feb2011.jpg)
          >
          > The images don't seem to pick up anything within at least 9 arcmins of the
          > ephemeris position. I can't imagine that the orbit was so poor that it
          > would be that far out already (even with the difficulties of assigning a
          > 'head' position) given that there were a few weeks of observations after
          > perihelion. So what is happening? Not new really, the last bit into the 'head' has
          > been considerably fainter for 6 weeks or so.
          >
          > Just looking at the tail which, while very faint, nonetheless seems quite
          > well defined and 'strong'. There hasn't been any recent discussion about W3
          > on comets_ml but after this length of time, is it an indication that there
          > is still some level of activity going on, or not? Is there an intact
          > nucleus there or not? To me it doesn't seem to be like a remnant waft of dust
          > drifting off into space, but I certainly don't have a lot to back that up!
          >
          > I'd really appreciate hearing some expert comments or opinions on this.
          > The last discussions I saw (ages ago) were ambivalent, some saying it's
          > broken up & finished and others (such as NASA) saying it will return intact in
          > several hundred years! Thanks.
          >
          > Cheers -
          >
          > Rob Kaufman
          > Bright, Victoria, Australia
          >
          >
          >
          >
          >
          >
          > [Non-text portions of this message have been removed]
          >
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