Speaker
Description
C/2017 K2 (PanSTARRS), hereafter K2, is a dynamically new comet, discovered by the Pan-STARRS survey in May 2017, when it was at a heliocentric distance of rh=16.1 au. Further investigations enabled to find a pre-discovery images of comet K2 exhibiting activity at a very large distance of 23.8 au in May 2013. K2 is the second most distant active comet ever discovered, with CO detected in significant abundance at 6.72 au by Yang et al. (2021), potentially accounting for its activity at such a large heliocentric distance.
I will present a detailed study of the comet activity and composition while crossing the water sublimation line using various instruments, including broad and narrow band photometry with TRAPPIST and optical and NIR high-resolution spectroscopy with UVES and CRIRES+ at the 8-m ESO/VLT.
We used both TRAPPIST-North (TN) and –South (TS), to monitor comet K2 for almost eight years. Our observations started with the TN on October 25, 2017, using broadband filters. At that time, the comet was 15.18 au from the Sun and had a visual magnitude of 19,7.
To thoroughly investigate the composition of K2 in the optical range and its evolution while getting closer to perihelion, and compare it to other long-period comets. We conducted a program with the high-resolution Ultraviolet Visual Echelle Spectrograph (UVES) at the VLT, at three different epochs before and after the water sublimation line (≈3.5 au).
Observations were conducted with CRIRES+ over three nights, simultaneously with UVES. The settings were chosen to capture major primary volatiles (e.g., H2O, CO, C2H6, CH4, HCN, NH3) and monitor their evolution as the comet approached the Sun.
This combined observational approach underscores the value of integrating high-resolution spectroscopic data of both optical and IR with photometric measurements to achieve a comprehensive understanding of cometary activity and composition.
| Stream | Science or Engineering |
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