1:45 PM - 3:15 PM
[O05-P49] The Component Change of Three Comets by Spectroscopic Observation
Keywords:Comet, Coma, Spectroscopic observation, Emission line
1. Introduction
Two years ago, the students of Seisho High School launched a research group to study comets. The group conducted spectroscopic observations on a number of comets including Comet PanSTARRS. Unfortunately, due to limited observational data and other experimental issues, the original research group could not make ample progress on the study. That is why our team took over their research project. Here, we focused on observing only one comet by tracing its spectrum change. The number of appearances of comets suitable for our research this year was very limited. Therefore, we made use of data from spectroscopic observations of three comets in the past, C/2012K1, Comet Lovejoy(C/2014Q2) and Comet Catalina(C/2013US10). The data for those three comets was collected by researchers working at the Bisei Astronomical Observatory in Okayama prefecture and volunteers who participated in the public offering observation program.
2. Purpose
The purpose of our research is to study two changes. The first is the change of the emission line in the comet spectrum during or before and after the comet passes through perihelion. The second change is the change of gas releasing velocity.
3. Method
We conducted the data analysis with the following steps.
(1) We performed a primary treatment on the picture of the comets’ spectrum using “Makali'i” (National Astronomical Observatory of Japan and Astro Arts Company). The picture was obtained by a telescope at the Bisei Astronomical Observatory in Okayama. The mirror was 101 cm in diameter.
(2) We made a spectrum diagram using “Be Spec” (Tetsuya Kawabata).
(3) We specified the chemical composition for the main emission line in the spectrum diagram. Furthermore, after reading the whole width of the CN emission line, the maximum value of the releasing velocity of the gas in coma was calculated using a function of the Doppler Effect.
4. Result
The strength of each emission line (CN, C2, C3 and NH2) and the releasing velocity of the gas from coma, as read from the spectrum diagram is shown in the chart below.
5. Discussion
(1) According to our results, CN emission line appears for quite a long period of time. On the other hand, CN emission line was found to become clear just before it passed through the perihelion. The emission line gets the clearest soon after it passes the perihelion.
(2) It was also found that the releasing velocity of the gas from coma becomes the greatest at the point of perihelion.
6. Conclusion
One of the remaining problems could be solved by analyzing more spectroscopic data of the comets. However, we think it is necessary for us to continue researching the principle that dictates the order of appearance of emission lines.
Acknowledgement
We would like to express our deepest appreciations to Professor Fukue and Associate Professor Matsumoto at Osaka University of Education for advising us. Furthermore, we thank Principal Ayani and Mr. Maeno of the Bisei Astronomical Observatory, and Mr. Uno and Mr. Matsushita for giving us permission to use their observational data.
Two years ago, the students of Seisho High School launched a research group to study comets. The group conducted spectroscopic observations on a number of comets including Comet PanSTARRS. Unfortunately, due to limited observational data and other experimental issues, the original research group could not make ample progress on the study. That is why our team took over their research project. Here, we focused on observing only one comet by tracing its spectrum change. The number of appearances of comets suitable for our research this year was very limited. Therefore, we made use of data from spectroscopic observations of three comets in the past, C/2012K1, Comet Lovejoy(C/2014Q2) and Comet Catalina(C/2013US10). The data for those three comets was collected by researchers working at the Bisei Astronomical Observatory in Okayama prefecture and volunteers who participated in the public offering observation program.
2. Purpose
The purpose of our research is to study two changes. The first is the change of the emission line in the comet spectrum during or before and after the comet passes through perihelion. The second change is the change of gas releasing velocity.
3. Method
We conducted the data analysis with the following steps.
(1) We performed a primary treatment on the picture of the comets’ spectrum using “Makali'i” (National Astronomical Observatory of Japan and Astro Arts Company). The picture was obtained by a telescope at the Bisei Astronomical Observatory in Okayama. The mirror was 101 cm in diameter.
(2) We made a spectrum diagram using “Be Spec” (Tetsuya Kawabata).
(3) We specified the chemical composition for the main emission line in the spectrum diagram. Furthermore, after reading the whole width of the CN emission line, the maximum value of the releasing velocity of the gas in coma was calculated using a function of the Doppler Effect.
4. Result
The strength of each emission line (CN, C2, C3 and NH2) and the releasing velocity of the gas from coma, as read from the spectrum diagram is shown in the chart below.
5. Discussion
(1) According to our results, CN emission line appears for quite a long period of time. On the other hand, CN emission line was found to become clear just before it passed through the perihelion. The emission line gets the clearest soon after it passes the perihelion.
(2) It was also found that the releasing velocity of the gas from coma becomes the greatest at the point of perihelion.
6. Conclusion
One of the remaining problems could be solved by analyzing more spectroscopic data of the comets. However, we think it is necessary for us to continue researching the principle that dictates the order of appearance of emission lines.
Acknowledgement
We would like to express our deepest appreciations to Professor Fukue and Associate Professor Matsumoto at Osaka University of Education for advising us. Furthermore, we thank Principal Ayani and Mr. Maeno of the Bisei Astronomical Observatory, and Mr. Uno and Mr. Matsushita for giving us permission to use their observational data.