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Possible nuclear splitting of Comet Halley in March 1986
Pergamon Journals. Printed in Great Britain 0275-1062/87$10.00+.00
Chin.Astron.Astrophys.11 (1987) 306 Act.Astrophys.Sin.2 119871 161
Research Note
POSSIBLE
CHEN
NUCLEAR
Dao-hanl
SPLITTING
OF COMET
LIU Zong-li2
ZHENG
HALLEY
IN MARCH
Jia-qingl
1986
YAN Lin-shan'
1 PurpZe Mountain Observatory, Academia Sinica ' Beijing Observatory, Academia Sinica 3 Shanghai Observatory, Academia Sinica Key words: Comet - Comet Halley - nuclear splitting
False color picture of Comet Halley (the nuclear region) on 1986 March 25, 16h13mSOs- 16h18mSOs UT. Kodak 2415 + RG610. Pixel size: 25 pm x 25 pm.
Between March 16 and April 22, 1986, we made photographic observations of Comet Halley at Mt. John Observatory, New Zealand. The telescope used was a 61-cm reflector (f/14.2), plate scale 23.8'/mm. Three types of plate; and filter combinations were used: Kodak IIaO, Kodak 2415 and Kodak 2415+ RG610. The IIaO plate was sensitized with nitrogen baking, and the 2415 film, with hydrogen baking. A total of 96 plates were obtained, and an abundance of activities in the nuclear region were recorded. On the night of March 25, the sky transperancy was good and the seeing was betwwer than 1'. A total of 10 plates were obtained: 1 IIaO, 2 2415 and 7 2415+RG610. Two nuclei can be seen on these plates, separated by a distance of about 500 km (projected on the plane of the sky). Even the fainter of the two showed its own jets. This is probably a result of a splitting of the nucleus of the comet.
With the aim of confirming the existence of two separate nuclei, we used a C-450011 Image Processor to effect a digitized image treatment and on the resulting false color picture, reproduced here, two separate density centres can clearly be seen. Thus, we are convinced that a splitting of the nucleus had taken place. From our data, our preliminary‘conclusion is that the splitting took place between the 22nd and 28th of March. Relating this to the results of photoelectric photometry carried out by CHEN Pei-sheng et al. at Yunnan Observatory between March 20 and April 3, when rapid increases in brightness in four optical ranges were noted, the largest being 2.5 mag, this splitting was probably caused by eruptive activities in the comet. Our final conclusion must await a more detailed analysis of the whole of our data and other observed results of the same time.
Chin.Astron.Astrophys.11 (1987) 306 Act.Astrophys.Sin.2 119871 161
Research Note
POSSIBLE
CHEN
NUCLEAR
Dao-hanl
SPLITTING
OF COMET
LIU Zong-li2
ZHENG
HALLEY
IN MARCH
Jia-qingl
1986
YAN Lin-shan'
1 PurpZe Mountain Observatory, Academia Sinica ' Beijing Observatory, Academia Sinica 3 Shanghai Observatory, Academia Sinica Key words: Comet - Comet Halley - nuclear splitting
False color picture of Comet Halley (the nuclear region) on 1986 March 25, 16h13mSOs- 16h18mSOs UT. Kodak 2415 + RG610. Pixel size: 25 pm x 25 pm.
Between March 16 and April 22, 1986, we made photographic observations of Comet Halley at Mt. John Observatory, New Zealand. The telescope used was a 61-cm reflector (f/14.2), plate scale 23.8'/mm. Three types of plate; and filter combinations were used: Kodak IIaO, Kodak 2415 and Kodak 2415+ RG610. The IIaO plate was sensitized with nitrogen baking, and the 2415 film, with hydrogen baking. A total of 96 plates were obtained, and an abundance of activities in the nuclear region were recorded. On the night of March 25, the sky transperancy was good and the seeing was betwwer than 1'. A total of 10 plates were obtained: 1 IIaO, 2 2415 and 7 2415+RG610. Two nuclei can be seen on these plates, separated by a distance of about 500 km (projected on the plane of the sky). Even the fainter of the two showed its own jets. This is probably a result of a splitting of the nucleus of the comet.
With the aim of confirming the existence of two separate nuclei, we used a C-450011 Image Processor to effect a digitized image treatment and on the resulting false color picture, reproduced here, two separate density centres can clearly be seen. Thus, we are convinced that a splitting of the nucleus had taken place. From our data, our preliminary‘conclusion is that the splitting took place between the 22nd and 28th of March. Relating this to the results of photoelectric photometry carried out by CHEN Pei-sheng et al. at Yunnan Observatory between March 20 and April 3, when rapid increases in brightness in four optical ranges were noted, the largest being 2.5 mag, this splitting was probably caused by eruptive activities in the comet. Our final conclusion must await a more detailed analysis of the whole of our data and other observed results of the same time.