29P/Schwassmann–Wachmann

Comet 29P/Schwassmann–Wachmann, also known as Schwassmann–Wachmann 1, was discovered on November 15, 1927, by Arnold Schwassmann and Arno Arthur Wachmann at the Hamburg Observatory in Bergedorf, Germany.<ref name=kronk/> The comet will next come to opposition on 12 March 2026, and then come to aphelion on 30 September 2026.<ref name="Horizons2026"/>

Discovery

It was discovered photographically, when the comet was in outburst and the magnitude was about 13.<ref name=kronk/> Precovery images of the comet from March 4, 1902, were found in 1931 and showed the comet at 12th magnitude.<ref name=kronk/>

Orbit and physical properties

The comet reached its most recent perihelion on March 7, 2019.Template:R It also came to its last opposition in late December 2022.<ref name="opposition">Template:Cite web</ref>

The comet is a member of a class of objects called "Centaurs", of which at least 500 are known.<ref name="Centaurs"/> These are small icy bodies with orbits between those of Jupiter and Neptune. The Centaurs have been recently perturbed inward from the Kuiper belt, a disk of trans-Neptunian objects occupying a region extending from the orbit of Neptune to approximately 50 AU from the Sun. Frequent perturbations by JupiterTemplate:R will likely accumulate and cause the comet to migrate either inward or outward by the year 4000.<ref name=29P4000/> A number of Centaurs appear to be dynamically and perhaps even physically related to 29P; such objects may traverse the coma of 29P when in outburst.<ref name="Marcos2021"/>

The comet nucleus is estimated to be Template:Val in diameter.Template:R

Outbursts

The comet is unusual in that while normally hovering at around 16th magnitude, it suddenly undergoes an outburst. This causes the comet to brighten by 1 to 5 magnitudes.<ref name=cometary/> This happens with a frequency of 7.3 outbursts per year,<ref name=cometary/> fading within a week or two. The magnitude of the comet has been known to vary from 18th magnitude to 10th magnitude, a more than thousand-fold increase in brightness, during its brightest outbursts. On 14 January 2021, an outburst was observed with brightness from 16.6 to 15.0 magnitude, and consistent with the 7.3 outbursts per year noted earlier.<ref name="AT-20210115">Template:Cite news</ref> Outbursts are very sudden, rising to maximum in about 2 hours, which is indicative of their cryovolcanic origin; and with the times of outburst modulated by an underlying 57-day periodicity possibly suggesting that its large nucleus is an extremely slow rotator.<ref name=cryovolcano>Template:Cite journal</ref>

Comet 29P after outburst, this is a stack of 20 images centered on the comet's movement, frames taken with a 0.40m telescope F10 + CCD at La Cañada Observatory (MPC-J87) 04-Oct-2008 02:24 UT the stacked images have been Larson–Sekanina filtered to enhance the details, on the left a radial process with delta = −1 px to better show the expanding shells of gas and dust, on the right a rotational gradient with alpha=15 degrees displaying various jets.<ref>Trigo-Rodriguez et al., Outburst activity in comets, I. Continuous monitoring of comet 29P/Schwassmann–Wachmann 1 [1]</ref><ref>Trigo-Rodriguez et al., Outburst activity in comets, II. A multi-band photometric monitoring of comet 29P/Schwassmann–Wachmann 1 Template:ArXiv</ref>

External links

• Template:JPL Small Body
• 29P/Schwassmann–Wachmann 1 – Seiichi Yoshida @ aerith.net
• 29P monitoring campaign – British Astronomical Association COMET MISSION 29P website
• 29P at CometBase
• 29P at Las Cumbres Observatory (8 Feb 2010 12:23, 60 seconds)
• 29P (Joseph Brimacombe April 18, 2013)