Comet 169P/NEAT

One of the stranger comets I've observed during all the years I've been
following these objects. Despite having the second-shortest orbital period
among all known periodic comets, it wasn't discovered until 2002, and its
cometary nature wasn't known until 2005. During that return I observed it as
a 15th-magnitude stellar object when it was passing 0.15 AU from Earth in
early August, and again as an 11 1/2 magnitude "ordinary" diffuse comet when
near perihelion in mid-September.

I wasn't sure if we would see a repeat of the 2005 activity this time
around. After seeing an image taken by Michael Jaeger in Austria early this
month (wherein it appeared very faint, but diffuse) I made an attempt for
it, unsuccessfully. More recently, after reading that it had just been
detected as a fairly bright object by the STEREO-B spacecraft (which was
then only 0.39 AU from the comet) I decided to try for it again, and despite
its low elevation and location in the rich Milky Way star fields of central
Sagittarius I managed to spot it on the evening of November 17. On November
18.06, m1=12.9 (extinction corrected), 0.7' coma. (Because of the
conditions, I suspect the comet may be a bit brighter than this.)

Since the comet is traveling southward and its elongation is decreasing, and
also since the moon is now entering the evening sky, I am probably already
close to being done with it. It is in inferior conjunction (35 degrees south
of the sun) in late December, reaches a peak southerly declination of -72
degrees in early January, and passes 0.19 AU from Earth on January 12. We
know very little of this comet's post-perihelion brightness behavior, but it
is certainly conceivable that southern hemisphere observers may get a
relatively decent view of it when it makes its passage by Earth early next
year.


Description at http://www.earthriseinstitute.org/coms46.html#466

Images and reports (including reports of outreach efforts) are welcome.


Sincerely,

Alan

Dear all:
    I have placed in my webpage the current secular light
curve of comet 107P using all the observations that I
was able to gather.   There is significant vertical
dispersion of the observations, but there is no definitive
evidence of activity up to now:

http://webdelprofesor.ula.ve/ciencias/ferrin

    However many images would benefit from a detailed
photometric analysis to confirm the astrometric
magnitudes which are usually of poor quality, and to
confirm some observations that depart from the mean.
    Please let me know if your images could be available
for such detailed analysis.
    As mentioned in this forum, the comet may exhibit
activity at any time.  The object is well placed for
observations 90° from the sun in the evening sky.
    Kind regards,

Ignacio Ferrin,
Center for Fundamental Physics,
University of the Andes,
Merida, Venezula
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++

I will take more pics today, this is the result of my shots yesterday evening.

http://astrosurf.com/nazaret/images/cometas/107/107-091119-J47.jpg

shows asteroidal aspect, with my obs. I cannot detect any activity.
best regards, gustavo.

Hello group.!
I did an observation with the 12" and st-8 yesterday afternoon.
the shoots was very low, 14º over the horizon, but the night was very good and
the pictures developed an coma in circular aperture 60" in 13.52. nuclear magn.
10" was 15.08, as we can see in the next multiaperture report from yesterday.
COD J47
OBS G. Muler
CATALOGO: USNO A2.0 / CMC-14 - BANDA: R

10x10 20x20 30x30 40x40 50x50 60x60 RSR FC COD
OBJETO FECHA HORA +/- +/- +/- +/- +/- +/- N FWHM CAT
------------ ---------- -------- ----- ----- ----- ----- ----- ----- ---- ----
---
169P 19/11/2009 19:12:45 15.08 14.20 13.74 13.53 13.48 13.52 5.9 16.8 J47
169P 19/11/2009 19:12:45* 0.19 0.09 0.10 0.16 0.21 0.24 3 5.5 CMC
FoCAs II - 13/10/2009
www.astrosurf.com/cometas-obs
es.groups.yahoo.com/group/Cometas_Obs

the result for me is a bright comet in the beginning of the night, with an
generous comma.

image of yesterday´s shots...
60 x 30 secs...
http://astrosurf.com/nazaret/images/cometas/169/169-091119-J47.jpg

always, best regards, gustavo.


--- In comets-ml@yahoogroups.com, Juan José González Suárez <jjgonzalez@...>
wrote:
>
> 169P/NEAT:
> 2009 Nov. 18.77 UT: m1=9.2, Dia.=4', DC=2/, 20 cm SCT (100x).
> [ Significantly brighter than expected. Elongated wide coma with faint
> outer region. Mountain location, very clear sky. End of astronomical
> twilight. Altitude: 9 deg ].
>
> ( Pico Cueto - Busfrío - Cudillero, alt. 770 m, Asturias, N. Spain )
>
> ---------------------------------------
> ICQ Format:
>
> 169        2009 11 18.77  S  9.2 TK 20.3T10 100   4    2/           ICQ
> XX GON05
> -------------------------------
>
> J. J. Gonzalez
>

Hi all,

> I have imaged this comet on Nov. 17.52 UT remotely from D25 Tzec Maun
Observatory. I also had some doubt about its magnitude - certainly brighter than
17.6m, but maybe not as bright as 9m.

this is typical for comets close to earth: they exhibit a (very) large and faint
outer coma which is much more easily visible visually with SMALL apertures. In
such
suc cases the difference between CCD images and visual means can easily amount
to
much more than 5 magnitudes.

This is also why visual observing and brightness estimates of comets is such
important. Of course, a very dark sky is needed to detect the faint coma, and,
to a
certain amount, the an experienced and trained eye.

Cheers, Maik
--
If they give you ruled paper, write the other way.  * Juan Ramon Jimenez
________________________________________________________________________
         maik@...          http://www.comethunter.de
         German Comet Section         http://www.fg-kometen.de
              http://groups.yahoo.com/group/comets-ml

I have imaged this comet on Nov. 17.52 UT remotely from D25 Tzec Maun
Observatory. I also had some doubt about its magnitude - certainly brighter than
17.6m, but maybe not as bright as 9m.

Here is the image (100% size, cropped):
http://www.astronomy.ru/forum/index.php?action=dlattach;topic=47951.0;attach=209\
436;image

(comet altitude 17deg, north is left, east is down)
The brightest star to the left is TYC 6857-1650-1 (10.8m).

Regards,
Roman Kostenko
mailto:poltava-astro@...

--- On Thu, 19/11/09, Juan José González Suárez <jjgonzalez@...> wrote:
169P/NEAT:
2009 Nov. 18.77 UT: m1=9.2, Dia.=4', DC=2/, 20 cm SCT (100x).
[ Significantly brighter than expected. Elongated wide coma with faint
outer region. Mountain location, very clear sky. End of astronomical
twilight. Altitude: 9 deg ].
( Pico Cueto - Busfrío - Cudillero, alt. 770 m, Asturias, N. Spain )
J. J. Gonzalez

Rob,

     Sincere thanks for your image and kind words. 169P is now
approaching perihelion ( T 2009 Nov. 30, q=0.608 AU ), developing a wide
faint coma. A very dark sky is needed for the observation of  the outer
region.

     I've observed 169P ( under similar circumstances ) in the previous
aparition in the morning twilight:

- 2005 Sep. 14.19 UT: m1=10.3, Dia.=3', DC=2/ , 20 cm SCT (100x).
[ Mountain location, very clear sky. Zodiacal light. Altitude: 12 deg. ].

Yesterday 169P was clearly brighter ...

Best regards and clear skies,


J. J. Gonzalez

P.S.: For this kind of observations I routinely check the field stars in
the DSS images.

--------------------------------------------------------------------------------\
------

Rob Kaufman wrote:

> Hi Juan!  I managed to get a rough widefield image of the field tonight in
fairly poor sky conditions (dust).  169P shows (just), but it appears to be
considerably dimmer than mag 9.2.  In the image, the small star immediately to
the right of the comet is mag 12.7 while the fainter one below that is mag 13.1.
Comet mag is indicative of high 12s perhaps, although I'd never attempt any real
estimate on poor data like this!
>
> http://i727.photobucket.com/albums/ww271/Rob_Kau/169P19Nov09textsm.jpg
>
> At the time of your obs there were two small globular clusters, NGCs 6642 mag
9.1 & 6638 mag 9.0, within a degree or so of the comet position.  They are
marked on the image.  Do you think it might be possible that it was a case of
mistaken identity?
>
> Anyway, look forward to more obs from you, and congratulations on all the good
work you do in comet observation!
>
> Cheers -
>
> Rob Kaufman
> Bright, Victoria, Australia (36.7 deg S, 147.0 deg E)
>
> --- In comets-ml@yahoogroups.com, Juan José González Suárez <jjgonzalez@...>
wrote:
>
>> 169P/NEAT:
>> 2009 Nov. 18.77 UT: m1=9.2, Dia.=4', DC=2/, 20 cm SCT (100x).
>> [ Significantly brighter than expected. Elongated wide coma with faint
>> outer region. Mountain location, very clear sky. End of astronomical
>> twilight. Altitude: 9 deg ].
>>
>> ( Pico Cueto - Busfrío - Cudillero, alt. 770 m, Asturias, N. Spain )
>>
>> ---------------------------------------
>> ICQ Format:
>>
>> 169        2009 11 18.77  S  9.2 TK 20.3T10 100   4    2/           ICQ
>> XX GON05
>> -------------------------------
>>
>> J. J. Gonzalez
>>
>>

I imaged it on  Nov. 10.00 in remote from San Pedro de Atacama :

0169P         C2009 11 10.00035 18 06 24.84 -21 36 40.3          17.0 N      I10

Francois Kugel


terryjlovejoy a écrit :
>
>
> Interesting. I imaged the comet's position on Nov 11.4 and nothing was
> visible brighter than mag 13. So this looks like a very recent development.
>
> Terry
>
> --- In comets-ml@yahoogroups.com <mailto:comets-ml%40yahoogroups.com>,
> Juan José González Suárez <jjgonzalez@...> wrote:
>  >
>  > 169P/NEAT:
>  > 2009 Nov. 18.77 UT: m1=9.2, Dia.=4', DC=2/, 20 cm SCT (100x).
>  > [ Significantly brighter than expected. Elongated wide coma with faint
>  > outer region. Mountain location, very clear sky. End of astronomical
>  > twilight. Altitude: 9 deg ].
>  >
>  > ( Pico Cueto - Busfrío - Cudillero, alt. 770 m, Asturias, N. Spain )
>  >
>  > ---------------------------------------
>  > ICQ Format:
>  >
>  > 169 2009 11 18.77 S 9.2 TK 20.3T10 100 4 2/ ICQ
>  > XX GON05
>  > -------------------------------
>  >
>  > J. J. Gonzalez
>  >
>
>

Interesting.  I imaged the comet's position on Nov 11.4 and nothing was visible
brighter than mag 13.  So this looks like a very recent development.

Terry

--- In comets-ml@yahoogroups.com, Juan José González Suárez <jjgonzalez@...>
wrote:
>
> 169P/NEAT:
> 2009 Nov. 18.77 UT: m1=9.2, Dia.=4', DC=2/, 20 cm SCT (100x).
> [ Significantly brighter than expected. Elongated wide coma with faint
> outer region. Mountain location, very clear sky. End of astronomical
> twilight. Altitude: 9 deg ].
>
> ( Pico Cueto - Busfrío - Cudillero, alt. 770 m, Asturias, N. Spain )
>
> ---------------------------------------
> ICQ Format:
>
> 169        2009 11 18.77  S  9.2 TK 20.3T10 100   4    2/           ICQ
> XX GON05
> -------------------------------
>
> J. J. Gonzalez
>

Hi Juan!  I managed to get a rough widefield image of the field tonight in
fairly poor sky conditions (dust).  169P shows (just), but it appears to be
considerably dimmer than mag 9.2.  In the image, the small star immediately to
the right of the comet is mag 12.7 while the fainter one below that is mag 13.1.
Comet mag is indicative of high 12s perhaps, although I'd never attempt any real
estimate on poor data like this!

http://i727.photobucket.com/albums/ww271/Rob_Kau/169P19Nov09textsm.jpg

At the time of your obs there were two small globular clusters, NGCs 6642 mag
9.1 & 6638 mag 9.0, within a degree or so of the comet position.  They are
marked on the image.  Do you think it might be possible that it was a case of
mistaken identity?

Anyway, look forward to more obs from you, and congratulations on all the good
work you do in comet observation!

Cheers -

Rob Kaufman
Bright, Victoria, Australia (36.7 deg S, 147.0 deg E)

--- In comets-ml@yahoogroups.com, Juan José González Suárez <jjgonzalez@...>
wrote:
>
> 169P/NEAT:
> 2009 Nov. 18.77 UT: m1=9.2, Dia.=4', DC=2/, 20 cm SCT (100x).
> [ Significantly brighter than expected. Elongated wide coma with faint
> outer region. Mountain location, very clear sky. End of astronomical
> twilight. Altitude: 9 deg ].
>
> ( Pico Cueto - Busfrío - Cudillero, alt. 770 m, Asturias, N. Spain )
>
> ---------------------------------------
> ICQ Format:
>
> 169        2009 11 18.77  S  9.2 TK 20.3T10 100   4    2/           ICQ
> XX GON05
> -------------------------------
>
> J. J. Gonzalez
>

169P/NEAT:
2009 Nov. 18.77 UT: m1=9.2, Dia.=4', DC=2/, 20 cm SCT (100x).
[ Significantly brighter than expected. Elongated wide coma with faint
outer region. Mountain location, very clear sky. End of astronomical
twilight. Altitude: 9 deg ].

( Pico Cueto - Busfrío - Cudillero, alt. 770 m, Asturias, N. Spain )

---------------------------------------
ICQ Format:

169        2009 11 18.77  S  9.2 TK 20.3T10 100   4    2/           ICQ
XX GON05
-------------------------------

J. J. Gonzalez

Dear all:
    Concerning comet 107P we need high precision photometry
to detect even minute changes in its brightness.  In that
regard there is a nice calibration field just 15° away from
the comet for the period November 20th to December 10th.
It is called 3C454.3 and it is located at

RA 22h 53m 57.7 s, DEC +16° 08' 54"

It has BVRIJHK photometry and you can read the paper at
An.J., Vol. 122, p. 2055-2098.  It is a paper by
Gonzalez, Kidger and Martin-Luis.  It is specially
useful if you are doing B photometry.

Kind regards,

Ignacio Ferrin
Center for Fundamental Physics,
Unversity of the Andes,
Merida, Venezuela
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

Hi all,
I first tried to spot C/2009 Q4 Boattini on October 21 in my 37cm reflector
but was unable to see it. This Sunday morning Nov. 15 I was surprised to
find the comet easily visible even at modest magnification in the same
telescope. My observation follows:

Nov. 15.3 UT
37cm reflector at 142x, 286x
Coma diameter = ~1'
DC=5, well-condensed
Mag. = ~12.3

Wishing everyone clear skies for Comet Tempel-Tuttle's Leonids tomorrow.
Bob


[Non-text portions of this message have been removed]

Giovanni is correct, of course.

Ignacio

--- In comets-ml@yahoogroups.com, "gvnn64\@...\.it" <gvnn64@...> wrote:
>
> Dear Ignacio and all.
>
> > I agree with Richard Miles that this is how science works.
>
> Science works on data and experimental facts, and here we have only *one*
observational evidence about a certain occurence.
> Then, anyone can propose nearly any theory to explain such unique event, and
it would be very difficult to accept or refuse it, just relying over one
sporadic observation.
>
> I agree that more observations are needed.
>
> Giovanni
>

Hi all,

I have updated my analysis of the currently observable comets. You can find them
at

http://kometen.fg-vds.de/aktause.htm

Regards,

Andreas


PS: third(!) try, hoping that the link will work now...

Hi all,

I have updated my analysis of the currently observable comets. You can find them
at

http://kometen. fg-vds.de/aktause.htm

Regards,

Andreas


PS: second try, now without the final point incorporated in the link...

Hi all,

I have updated my analysis of the currently observable comets. You can find them
at http://kometen.fg-vds.de/aktause.htm.

Regards,

Andreas

Comet 81P has developed a nice tail on images this morning
  Twitter:  http://twitter.com/cbellh47
Flickr: http://www.flickr.com/photos/cbellh47/
Facebook: http://www.facebook.com/cbellh47

Thank you Dimitry and Charles very much! Those will both work.
Gratefully yours,
Bob

On Sun, Nov 15, 2009 at 1:58 PM, Dimitry Chestnov <chestd@...> wrote:

>
>
> --- In comets-ml@yahoogroups.com <comets-ml%40yahoogroups.com>, Bob King
> <nightsky55@...> wrote:
> >
> > Does anyone have orbital elements for 107P?
>
> Bob,
>
> You can find comet-style orbital elements for 107P with dates of perihelion
> and info about close approaches at Kazuo Kinoshita home page:
>
> http://jcometobs.web.fc2.com/pcmtn/0107p.htm
>
>
>


[Non-text portions of this message have been removed]

--- In comets-ml@yahoogroups.com, Bob King <nightsky55@...> wrote:
>
> Does anyone have orbital elements for 107P?

Bob,

You can find comet-style orbital elements for 107P with dates of perihelion and
info about close approaches at Kazuo Kinoshita home page:

http://jcometobs.web.fc2.com/pcmtn/0107p.htm

Hi everyone,
Does anyone have orbital elements for 107P? I found an incomplete set online
but none that list the perihelion date and distance for this apparition. I
use MegaStar to plot comets. Seiichi's entry for 107P lists everything but
those details. Thanks for your help.
Best wishes,
Bob


[Non-text portions of this message have been removed]

Dear Rob McNaught,

> > I heard that P/2009 U4 (McNaught) was discovered in the course of
> > follow-up observations of C/2009 R1.
>
> No, it was found in general surveying.

Thank you for your information.

I read IAUC 9087 again, and I see that you discovered P/2009 U4 on
Oct. 23, and then you found the pre-discovery image of this new comet
in the images of C/2009 R1 on the previous day.

So, it seems to be another case like C/2009 U6 near by 29P and 81P.

Best regards,

--
Seiichi Yoshida
comet@...
http://www.aerith.net/

Dear Rob Matson,

Thank you for your comments. I guess the next return of P/2009 Q1 (Hill)
can prove the linkage of your data in 1996 and 1998.

Best regards,

> They were reported right away. Brian Marsden and I exchanged a
> number of e-mails on the linkage, and ultimately came to the
> conclusion that the residuals were too high to link BOTH the
> 1996 obs and 1998 obs. The 1996 obs are definitely real, but
> the 1998 obs were right at the noise limit, so could easily
> have been false (or another object). Of course, with only the
> single night from 1996, the linkage (while certainly real)
> could not be proven.  We really needed a second night.
>
> I may revisit the 1998 data to see if anything can be done
> to pull the comet out of the noise, but I suspect it was
> just too dim.
>
> --Rob

--
Seiichi Yoshida
comet@...
http://www.aerith.net/

Hello Francois and all.
this morning 29P measures bring the same result as your observations.
nuclear mag. 13.71 nuclear magn. 10"
coma diameter = 9.6"
multiaperture obs;
COD J47
OBS G. Muler
CATALOGO: USNO A2.0 / CMC-14 - BANDA: R

                                    10x10  20x20  30x30  40x40  50x50  60x60  
RSR   FC   COD
OBJETO        FECHA      HORA        +/-    +/-    +/-    +/-    +/-    +/-    
N  FWHM  CAT
------------  ---------- --------  -----  -----  -----  -----  -----  ----- 
----  ----  ---
29P           12/11/2009 06:29:05  13.71  13.27  13.14  13.02  12.89  12.75 
14.3  16.8  J47
29P           12/11/2009 06:29:05*  0.01   0.01   0.01   0.01   0.04   0.04    
5   3.5  CMC

FoCAs II - 13/10/2009
www.astrosurf.com/cometas-obs
es.groups.yahoo.com/group/Cometas_Obs
--- In comets-ml@yahoogroups.com, francois kugel <fkugel@...> wrote:
>
> Hello,
>
> 29P in outburst again :
>
> Nov. 09.22 mag.16.3 (dia=20")
> Nov. 12.22 mag.13.3 (dia=20")
>
> Francois Kugel
> #A77
>

Hello,

29P in outburst again :

Nov. 09.22 mag.16.3 (dia=20")
Nov. 12.22 mag.13.3 (dia=20")

Francois Kugel
#A77

(4015) Wilson-Harrington was an object of study by the Midcourse Space
Experiment (MSX) mission

Mission images are available in the Planetary Data System MSX Small Bodies
Images data set:

"Kraemer, K., Lisse, C.M., Price, S., Mizuno, D., Walker, R.G., Farnham, T.L.,
and Makinen, T., MSX Small Bodies Images. MSX-C-SPIRIT3-3-MSXSB-V1.0. NASA
Planetary Data System, 2005."

http://www.psi.edu/pds/resource/msxsb.html

in this directory:
http://www.psi.edu/pds/asteroid/MSX_C_SPIRIT3_3_MSXSB_V1_0/data/wilsonh/


There is an on line article about this mission:

MIDCOURSE SPACE EXPERIMENT OBSERVATIONS OF SMALL SOLAR SYSTEM BODIES by KATHLEEN
E. KRAEMER, C. M. LISSE, STEPHAN D. PRICE,D. MIZUNO, R. G. WALKER,T. L.
FARNHAM,5 AND T. MÄKINEN, 2005

http://www.iop.org/EJ/article/1538-3881/130/5/2363/204596.text.html

Figure 15 text gives a summary

MSX images of the asteroid-comet transition object (4015) P/Wilson-Harrington
taken on 1997 January 6 (left) and 10 (right). The target was detected at 8.3 m
on both days, at 14.7 m on January 10, but not at the other wavelengths on
either day. There is no apparent extension of the image due to an extended dust
atmosphere.
http://www.iop.org/EJ/article/1538-3881/130/5/2363/204596.fg15.html

Dear Ignacio and all.

> I agree with Richard Miles that this is how science works.

Science works on data and experimental facts, and here we have only *one*
observational evidence about a certain occurence.
Then, anyone can propose nearly any theory to explain such unique event, and it
would be very difficult to accept or refuse it, just relying over one sporadic
observation.

I agree that more observations are needed.

Giovanni

Hi everyone,

I am happy to see this worthwhile discussion on this most interesting
object, and like the other posters I would encourage physical observation
attempts of all kinds while it is currently well-placed and near Earth.

There is one point I tried to make which, upon re-reading my earlier post,
may not have been as clear as I had thought:

The comet was discovered on photographs taken November 19, 1949. We do not
know, however, what its activity level was prior to that date; it
conceivably could have been active days, perhaps even weeks or months, prior
to that date, and we simply didn't know that since the comet's existence
wasn't yet known. We should probably keep this in mind now, both when
planning observing strategies as well as in formulating explantions for the
activity.

For what it's worth, I made another unsuccessful visual attempt last night.
My sky conditions probably weren't the greatest, but on the other hand I now
have a very clean optical system. Assuming a stellar object, the "comet" is
certainly no brighter than "m1" ~15.3, and probably a few tenths fainter
than that. This is, of course, consistent with the DOU MPECs as well as with
the photometry that has been reported in this forum.


Sincerely,

Alan

I agree with Richard Miles that this is how science works.
So it is fascinating to see so many hypothesis poping up.
In this regard I would like to point out two things:

(1) The activity may have been triggered by a) the thermal
wave penetrating inside the nucleus and activating a deep
layer of ice.  This hypothesis finds support from the
fact that the activity was observed +42 days *after*
perihelion.  Or b) the pole of the comet is pointing to the sun
at +42 days after perihelion.  Then there is no night and
the amount of solar energy received is maximum.

(2) The critical observing period starts next december 4th.
So please try to make an effort to observe from that day
onward.   In a previous posting Clay Sherrod and Alan Hale
suggested that the activity may take place at any time.
They may be correct.  We really do not know.  The pole
position may have shifted, the deep layer may have
been exhausted, etc.   So we should be observing for as long
as possible.

      I am already plotting the secular light curve of this
object in 2009 and I will have it available soon.  Please
let me know of your magnitudes to place them in the plot.
Robert Mason and all, go ahead with your observations.  The
object deserved all our attention.  In the Atlas of Secular
Light Curves this comet has a photometric age of 760 comet
years, so it is a methuselah comet.  The question is if it
is dead or alive.

Kind Regards,

Ignacio
Center for Fundamental Physics,
University of the Andes,
Merida, Venezuela

+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
--- In comets-ml@yahoogroups.com, "RICHARD MILES" <rmiles.btee@...> wrote:
>
> Giovanni,
>
> I guess this is how science works, people come forward with options for
> working hypotheses and these are then compared with experimental
> observation.  In this case, I am flagging the possibility that some
> asteroids in comet-like orbits when struck by energetic particles
> originating from a major solar flare will have water molecules ejected from
> otherwise stable hydrated minerals.  It might be a worthwhile exercise to
> test this in an ultrahigh vacuum chamber in the laboratory.  Certainly the
> energy of some particles emitted from the Sun is sufficient to sputter and
> erode the surface on the molecular scale.
>
> If the hypothesis is valid then we would expect other low-albedo asteroidal
> objects in comet-like orbits, which spend only a small fraction of their
> life close to the Sun, to exhibit similar behaviour when exposed to
> highly-energetic particles arising from solar flares.  So, for observers
> like ourselves, we should consider monitoring those few comet-like objects
> as they make their perihelion passage around the time of the next solar
> maximum since one might then discover another 'comet' of this type.  One
> requirement for success is that the object would need to be relatively close
> to the Earth for the emitted material to be detected.  In the case of 107P
> at the time of discovery, it was really quite close at about 0.22 AU.
>
> btw: A definitive study of the case of 107P was published in:
>
> Icarus, Volume 128, Issue 1, July 1997, Pages 114-126
> Analysis of POSS Images of Comet-Asteroid Transition Object 107P/1949 W1
> (Wilson-Harrington)
> Yanga R. Fernández, Lucy A. McFadden, Carey M. Lisse, Eleanor F. Helin and
> Alan B. Chamberlin
> http://adsabs.harvard.edu/abs/1997Icar..128..114F
>
> I have only been able to read the abstract online.  I would imagine that in
> their discussion they would have mooted a similar hypothesis to the one I am
> suggesting.
>
> Cheers,
> Richard
>
> P.S.  It's a pity that the Sun is so inactive at present.
>
> ----- Original Message -----
> From: <gvnn64@...>
> To: "comets-ml" <comets-ml@yahoogroups.com>
> Cc: "comets-ml" <comets-ml@yahoogroups.com>; "mpml" <mpml@egroups.com>
> Sent: Wednesday, November 11, 2009 9:56 AM
> Subject: Re: [comets-ml] Incoming Activity of comet 107P/Wilson-Harrington?
>
>
> > Dear Richard
> > yours is a fascinating working hypothesis (as there are many others).
> > Obviously, without a robust experimental support, I'm afraid it will
> > remain as such.
> > With kind regards,
> > Giovanni
>

Giovanni,

I guess this is how science works, people come forward with options for
working hypotheses and these are then compared with experimental
observation.  In this case, I am flagging the possibility that some
asteroids in comet-like orbits when struck by energetic particles
originating from a major solar flare will have water molecules ejected from
otherwise stable hydrated minerals.  It might be a worthwhile exercise to
test this in an ultrahigh vacuum chamber in the laboratory.  Certainly the
energy of some particles emitted from the Sun is sufficient to sputter and
erode the surface on the molecular scale.

If the hypothesis is valid then we would expect other low-albedo asteroidal
objects in comet-like orbits, which spend only a small fraction of their
life close to the Sun, to exhibit similar behaviour when exposed to
highly-energetic particles arising from solar flares.  So, for observers
like ourselves, we should consider monitoring those few comet-like objects
as they make their perihelion passage around the time of the next solar
maximum since one might then discover another 'comet' of this type.  One
requirement for success is that the object would need to be relatively close
to the Earth for the emitted material to be detected.  In the case of 107P
at the time of discovery, it was really quite close at about 0.22 AU.

btw: A definitive study of the case of 107P was published in:

Icarus, Volume 128, Issue 1, July 1997, Pages 114-126
Analysis of POSS Images of Comet-Asteroid Transition Object 107P/1949 W1
(Wilson-Harrington)
Yanga R. Fernández, Lucy A. McFadden, Carey M. Lisse, Eleanor F. Helin and
Alan B. Chamberlin
http://adsabs.harvard.edu/abs/1997Icar..128..114F

I have only been able to read the abstract online.  I would imagine that in
their discussion they would have mooted a similar hypothesis to the one I am
suggesting.

Cheers,
Richard

P.S.  It's a pity that the Sun is so inactive at present.

----- Original Message -----
From: <gvnn64@...>
To: "comets-ml" <comets-ml@yahoogroups.com>
Cc: "comets-ml" <comets-ml@yahoogroups.com>; "mpml" <mpml@egroups.com>
Sent: Wednesday, November 11, 2009 9:56 AM
Subject: Re: [comets-ml] Incoming Activity of comet 107P/Wilson-Harrington?


> Dear Richard
> yours is a fascinating working hypothesis (as there are many others).
> Obviously, without a robust experimental support, I'm afraid it will
> remain as such.
> With kind regards,
> Giovanni