An Analysis of the Ion Tail of C/2004 Q2 (Machholz) Jeff van Kerkhove1, Zhong Yi Lin2, Wing-Huen Ip2 1University of Rochester (Rochester, NY, USA), 2National Central University (Jhongli City, Taiwan)

1
An Analysis of the Ion Tail of C/2004 Q2
(Machholz)Jeff van Kerkhove1, Zhong Yi Lin2,
Wing-Huen Ip21University of Rochester
(Rochester, NY, USA), 2National Central
University (Jhongli City, Taiwan)
Abstract
Analysis/Conclusions
Results
We observe the folding ray phenomenon (ion rays
folding in toward the comets antisolar axis) in
these images over time. Degroote 2007 suggests a
connection between these folding rays and solar
winds. They believe such changes are caused by
peaks in proton flux density, which is followed
by an increase in solar wind velocity. So, if the
solar wind velocity increases, shouldnt there be
a complimentary increase in the ion ray folding
rate? To test this, we consider the proton flux
spike on January 21, which imparts an increase in
wind velocity soon after. It takes about 3 days
for these winds to reach the comet. Thus, the
changes from the spike should be evident between
January 24 and 25. From the folding rate
calculation made, we did notice a distinct change
in the folding rates from January 24th to the
25th. However, it is difficult to draw definitive
conclusions due to the relatively large error of
such measurements. Thus, future work should be
devoted to improving the validity of folding rate
measurements.
We have reduced and processed CO and H2O filter
images of the comet C/2004 Q2 (Machholz) between
its perigee and perihelion in January 2005. Many
of these images display folding ray phenomena,
which are believed to be related to solar wind.
This poster discusses the determination of the
ray folding rates, speculating whether or not
there is a correlation to changes in the solar
wind velocity. The results suggest there very
well could be a correlation, though a more
thorough analysis must be carried out first to
improve the methods validity.
Coma-subtracted images (top row has CO filtered
images, bottom row has H2O images)
Background
SoHO data-the middle graph represents proton flux
density with respect to time, while the top graph
show solar wind velocities with respect to time.
Note the proton flux peaks (blue circles) are
followed by spikes in solar wind speed (red
circles).
Comets are a class of small Solar System bodies
that can generally be thought of as dusty
iceballs. That are composed of water, CO, CO2,
with trace quantities of organic molecules. For
much of its existence, the comet is a icy
nucleus. Though when it gets close enough to the
Sun, the volatile materials start to sublimate,
forming a diffuse coma around the nucleus.
Radiation pressure and solar winds are then
presumed to push the loose particles away,
forming streaming dust and ion tails. Our study
focuses on C/2004 Q2 (Machholz), a comet that
passed quite close (0.35AU) to the Earth in
January 2005.
Carroll, Bradley, and Dale Ostlie. An
Introduction to Modern Astrophysics. 2nd. New
York Pearson, 2007. DeGroote, P., Bodewits, D.,
Reyniers, M. 2008, AA 477, L41-L44.
Fernandez, Julio Angel. Comets Nature,
Dynamics, Origin, and their Cosmological
Relevance. Dordrecht, Netherlands Springer,
2004. Ip, W.-H. 2004, Comets II, 605. Lin, Zhong
Yi. "A Study of Cometary Comae of Split Comets."
Diss. National Central University, 2007. Lin, Z.
Y., Weiler, M., Rauer, H. Ip, W. H. 2007, AA
469, 771-776.
Data/Methods
Our images were taken using LOT (Lulin One-meter
Telescope) at Lulin Observatory in central
Taiwan. We then reduced the data by subtracting
zero and dark frames from raw images, and
dividing by flat fields in CO and H2O filters.
These filters were used, as they are the most
abundant ions found in the ion tail. The images
are then centered, rotated, and trimmed to a
standard size. We then subtract the comets coma
from each image using a ring masking method to
better view ion ray folding phenomena. The rates
of folding can be calculated by measuring the
change in the position of the rays edge between
frames.
Folding rate velocities (for H2O filtered
images) with respect to Julian date. (The
leftmost plot shows all 5 observation dates,
below are data from January 24, 25)
Acknowledgments
I would like to thank SUNY Oswego and National
Central University for organizing this program,
as well as the National Science Foundation
(Office of International Science and Engineering,
grant number 1065093), for funding my work.