On a Forgotten 1836 Explosion from Halley's Comet, Reminiscent of 17P/Holmes' Outburst

摘要

Although it is often affirmed that the outbursts displayed by comet 17P/Holmes, including the megaburstof 2007, have never been observed in any other comet, I find that about ten weeks after its 1835 perihelion, comet1P/Halley experienced a similarly massive explosion in late January 1836, at 1.44 AU from the sun, with a peak intrinsicmagnitude of at least +0.3, midway between the limits on the outbursts of 17P/Holmes. Predictably, this outburst ofHalley's comet accompanied the formation of a disk-shaped, sharply-bounded dust halo, which was steadily expanding ata rate of 0.575 km/s into a feature of nearly-parabolic outlines, very similar in appearance to the halos of 17P/Holmes in1892-1893 and 2007. The 1836 episode of Halley's comet and its aftermath thus compare favorably with the 17P/Holmesevents in all respects.