The Unusual Apparition of Comet 252P/2000 G1 (LINEAR) and Comparison with Comet P/2016 BA₁₄ (PanSTARRS)

Abstract

Abstract:We imaged Comet 252P/2000 G1 (LINEAR) (hereafter 252P) with the Hubble Space Telescope and both 252P and P/2016 BA 14 shows a bright and narrow jet of a few hundred kilometers long in the sunward direction, changing its projected position angle in the sky with a periodicity consistent with 7.24 hours. However, its photometric lightcurve is consistent with a periodicity of 5.41 hours. We suggest that the nucleus of 252P is likely in a non-principal axis rotation. The nucleus radius of 252P is estimated to be about 0.3±0.03 km, indicating an active fraction of 40% to >100% in its 2016 apparition. Evidence implies a possible cloud of slow-moving grains surrounding the nucleus. The activity level of 252P in the 2016 apparition increased by two orders of magnitude from its previous apparitions, making this apparition unusual. On the other hand, the activity level of BA 14 appears to be at least three orders of magnitude lower than that of 252P, despite its ten times or larger surface area.

A Deep Search for Emission From "Rock Comet" (3200) Phaethon At 1 AU

“…The derived upper limit for CN, presented in § 3.2.1, is nearly an order of magnitude improvement over the previous best result by Chamberlin et al (1996), and is on par with the lowest numbers ever measured/constrained for comets (133P/Elst-Pizarro had Q(CN ) < 1.3 × 10 21 molecule s −1 , and P/2016 BA14 (PANSTARRS) had Q(CN ) = 1.4 × 10 22 molecule s −1 , c.f. Licandro et al 2011;Li et al 2017). The derived upper limit for dust emission is on par with the best limits derived previously (Hsieh & Jewitt 2005;Tabeshian et al 2019).…”

Near-UV and optical spectroscopy of comets using the ISIS spectrograph on theWHT

“…We also corrected these measurements to a phase angle of 0 • using the composite phase function published by Schleicher (2010). The exception to this procedure was P/2016 BA14, where imaging at this time revealed an extremely weak dust coma (Li et al 2017). Hence for this comet we assumed the contribution from the nucleus was non-negligible, and we did not attempt to measure A f ρ for this object.…”

Mid-infrared observations of the nucleus of Comet P/2016 BA14 (PANSTARRS)

“…There are several plausible end states for comets including dormancy, extinction (plausibly connected to primitive asteroids such as P-or D-type asteroids), fragmentation (e.g., C/1999 S4 (LINEAR) and C/2012 S1 (ISON); Farnham et al 2001;Sekanina & Kracht 2014), collision with a planet or the Sun (e.g., D/1993 F2 (Shoemaker-Levy 9; Levy 1998)), and removal from the inner solar system due to gravitational perturbation by giant planets (Fernandez 2005). Because cometary dormancy and extinction are considered gradual processes (Li et al 2017), comparing the physical properties of cometary nuclei with possible dormant/exhausted comet candidates, such as D-type asteroids, is important for verifying the proposed links between comets and primitive asteroids (Campins et al 2018).…”