Imaging polarimetry and photometry of comet 21P/Giacobini-Zinner

What Does It Mean to be a "Depleted" Comet? High Spectral Resolution Observations of the Prototypical Depleted Comet 21P/Giacobini-Zinner from McDonald Observatory

We present high spectral resolution optical observations of comet 21P/Giacobini-Zinner from six nights in 2018. The observations were obtained with the Tull coude spectrograph on the 2.7m Harlan J. Smith Telescope of McDonald Observatory. This comet's spectrum shows strong depletions in C$_2$, C$_3$, CH, and NH$_2$ relative to CN. We explore what it means for a comet to be depleted and show that all of the species are present in the spectrum at similar relative line intensities within a a molecular band compared with a typical comet. The depletions represent a much lower abundance of the speci…

Comet 21P/Giacobini-Zinner: Narrowband Photometry of the Prototype of Carbon-Chain Depleted Comets at Multiple Apparitions

We obtained extensive narrowband photoelectric photometry of Comet 21P/Giacobini-Zinner with observations spanning 33 years. The original data from 1985 (Schleicher et al. 1987) were re-reduced and are presented along with data from three additional apparitions including 2018/19. The original conclusion regarding Giacobini-Zinner's chemical composition remains unchanged, with it having a 4-6x depletion in the carbon-chain molecules C2 and C3, and in NH, as compared with both OH and CN. The comet continues to exhibit a large asymmetry in production rates as a function of time and heliocentric d…

High-resolution optical spectroscopic observations of comet 21P/Giacobini-Zinner in Its 2018 apparition

Comet 21P/Giacobini-Zinner is a peculiar comet from the viewpoints of the chemical and physical properties of its dust grains. We conduct optical high-resolution spectroscopic observations of the comet. The intensity ratios of forbidden oxygen lines (at 557.7, 630.0, and 636.4 nm) and ortho-to-para abundance ratios (OPRs) of water cations (H$_2$O$^+$) and amidogen radicals (NH$_2$) are obtained while only the upper limit for $^{14}$N/$^{15}$N in the amidogen radical is restricted. The OPRs of H$_2$O$^+$ and NH$_2$ are similar to those of other comets, although the real meaning of these OPRs is…

Analysis of CN Coma Morphology Features of Comet 21P/Giacobini-Zinner

We analyze jet features found in the coma of Comet 21P/Giacobini-Zinner (21P/GZ) during its 2018 perihelion passage using narrowband CN photometric imaging in order to determine the comet's rotational period, and constrain the CN gas outflow velocity and rotational state through the analysis of azimuthally enhanced morphological features. We find that 21P/GZ has a period of either 7.39 $\pm$ 0.01 or 10.66 $\pm$ 0.01 hours. We measure a lower limit to the outflow velocity for the Northern Jet of 730 $\pm$ 30 m s$^{-1}$ and for the Southern Jet of 740 $\pm$ 30 m s$^{-1}$. We analyze the morpholo…

起源于彗星21P/Giacobini-Zinner的流星体与水星、金星和火星碰撞的预测

Prediction of the collisions of meteoroids originating in comet 21P/Giacobini-Zinner with the Mercury, Venus, and Mars

本文基于彗星21P/Giacobini-Zinner的理论流星流建模，预测了其粒子在水星、金星和火星上引发的陨石或流星雨，并揭示了流星流细丝结构源于近日点幅角和升交点黄经的特定分布。

Dust Production of Comet 21P/Giacobini-Zinner Throughout its 2018 Apparition

We present the results of a long term telescopic observation campaign of comet 21P/Giacobini-Zinner, parent body of the Draconid meteor shower, spanning $\sim 240$ days during its 2018 apparition. Determinations of comet 21P's dust production rate through the $Afρ$ parameter derived from these images show that the comet had a highly asymmetric dust production rate that peaked $\sim 10-30$ days before perihelion, when the comet was at a heliocentric distance of $\sim 1.02 - 1.08 \thinspace \mathrm{AU}$. The single highest $Afρ$ measurement occurred on 2018-Aug-14 (27 days before perihelion), an…