Secular light curves of comets 60P/Tsuchinshan 2 and 62P/Tsuchinshan 1

Abstract

ABSTRACT The activity of Jupiter family comets, 60P/Tsuchinshan 2 and 62P/Tsuchinshan 1, is analysed by creating their Secular light curves (SLCs). We collected 850 observations in apparitions 1995, 2005, 2012, and 2018 for 60P/Tsuchinshan 2 and 471 observations in apparitions 1998, 2004, and 2017 for 62P/Tsuchinshan 1. We obtained the main activity parameters: turn-on distance (RON) and time (TON), turn-off distance (ROFF) and time (TOFF), photometric age (P-AGE), and time age (T-AGE). The results show that both comets could be classified as middle-age comets in early apparitions, due to P-AGE ≳30 comet yr, and their activity lasting for more than 300 d similar to those of comets 32P/Comas-Sola and 67P/Churyumov–Gerasimenko. The orbital changes (decrease of perihelion distance) of comets 60P/Tsuchinshan 2 and 62P/Tsuchinshan 1 in recent apparitions enhanced their activity with different characteristics, which was proved by the increased brightness amplitude or space range of activity and the decreased P-AGE; meanwhile, they are entering the range of young comets, and are classified as Lazarus comets.