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Newswise Stony Brook, NY March 6, 2015 A team of astronomy researchers from Stony Brook University, the National Astronomical Observatory of Japan, and Tsuru University are the first to reveal clear details about the rapidly changing plasma tail of the comet C/2013 R1 (Lovejoy). The observation and details behind the discovery are published in a paper in the March 2015 edition of the Astronomical Journal.

The team, Led by Jin Koda, PhD, Assistant Professor in the Department of Physics and Astronomy at Stony Brook University, captured the images by using the Subaru Telescopes wide-field prime-focus camera, called Suprime-Cam, which resulted in gaining new knowledge regarding the extreme activity in that tail as the comet neared the Sun.

My research is on galaxies and cosmology, but I always want to explore beyond these boundaries. Lovejoy was up in the sky after my targets were gone, and we started taking other images for educational and outreach purposes, and for curiosity, said Dr. Koda. The single image from one night revealed such delicate details along the tail that it inspired us further to take a series of images on the following night. When we analyzed these additional images, we realized that the tail was displaying rapid motion in a matter of only a few minutes. This was an incredible discovery.

In the paper, titled Initial Speed of Knots in the Plasma Tail of C/213 R1 (Lovejoy), the researchers report short-time variations in the plasma tail of Lovejoy.

They write: A series of short (2-3 minutes) exposure images with the 8.2 m Subaru telescope shows faint details of filaments and their motions over a 24 minutes observing duration. We identified rapid movements of two knots in the plasma tail near the nucleus. Their speeds are 20 and 25 kms along the tail and 2.8 and 2.2 kms across it respectively. These set a constraint on an acceleration model of plasma tail and knots as they set the initial speed just after their formation. We also found a rapid narrowing of the tail.

They suggest that these rapid motions suggest the need for high time-resolution studies of comet plasma tails with a large telescope.

Dr. Koda explained that the plasma tail of a comet forms when gas molecules and atoms coming out from the comet encounter the solar wind. Changes and disturbances in the solar wind can affect the behavior and appearance of this plasma tail, causing it to form clumps of ionized material. The material in the plasma tail departed from the comets coma and floats away on the solar wind. At these times, the plasma tail can take on a kinked or twisted look.

In 2013, the team reported highly resolved fine details of this comet captured in B-band filter in Subaru Telescopes Image Captures the Intricacy of Comet Lovejoys Tail. They used I-band filter which includes H2O+ line emissions and V-band filter which includes CO+ and H2O+ line emissions. During the observations, the comet exhibited very rapid changes in its tail in the course of only 20 minutes (Figure 1). Such extreme short-term changes are the result of the comets interactions with the solar wind where charged particles constantly sweeping out from the Sun. They explain that the reason for the rapidity of these changes is not well understood.

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Rapid Changes in Lovejoy Comet's Tail Observed