2026-06-02 中国科学院（CAS）
＜関連情報＞
- https://english.cas.cn/newsroom/research-news/202606/t20260602_1160332.shtml
- https://iopscience.iop.org/article/10.3847/1538-4357/ae6649
長周期彗星C/2023 A3（津津山-ATLAS）の遠方における活動 The Distant Activity of Long-period Comet C/2023 A3 (Tsuchinshan-ATLAS)
Yingqi Wu, Jianchun Shi, Man-to Hui, Xian Shi, F. Li, and Y. Yuan
The Astrophysical Journal Published: 2026 May 25
DOI:10.3847/1538-4357/ae6649
Abstract
We present broadband CCD observations of the long-period comet C/2023 A3 (Tsuchinshan–ATLAS) obtained between 2023 March and July, when its heliocentric distance decreased from 7.25 to 5.91 au. Photometric measurements in the B-, V-, and R bands were used to investigate the comet’s distant activity using morphological features, Afρ, effective scattering cross section, activity index n, and color indices. A faint coma became detectable during the observing period, and a visible dust tail developed by late June, accompanied by rapid increases in Afρ and scattering cross section. The activity index n exhibits distinct values at different epochs. In the early epoch (7.25–6.64 au), n is close to 10, while in the later epoch (6.56–5.91 au), it decreases to values near 5 but remains significantly greater than 2, indicating enhanced and persistent activity at large heliocentric distances. The coma color shows a predominantly red trend, with occasional blueward excursions. At heliocentric distances beyond 5 au, the colors of C/2023 A3 (Tsuchinshan–ATLAS) are comparable to those of other distant long-period comets, while its activity level lies toward the higher end of the observed range.
