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.[5] It was discovered photographically, when the comet was in outburst and the magnitude was about 13.[5] Precovery images of the comet from March 4, 1902, were found in 1931 and showed the comet at 12th magnitude.[5]

29P/Schwassmann–Wachmann
The comet Schwassmann–Wachmann 1
(Spitzer infrared image in false colours)
Nasa
Discovery
Discovered byArnold Schwassmann
Arno Arthur Wachmann
Discovery dateNovember 15, 1927
Alternative
designations		1908 IV; 1927 II; 1941 VI;
1957 IV; 1974 II; 1989 XV;
Orbital characteristics A
EpochMarch 6, 2006
Aphelion6.25 AU
Perihelion5.722 AU
Semi-major axis5.986 AU
Eccentricity0.0441
Orbital period14.65 a
Inclination9.3903°
Dimensions60.4 ± 7.4 km[1]
Last perihelionMarch 7, 2019[2]
Next perihelionOctober 31, 2033[3][4]

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.[6] This happens with a frequency of 7.3 outbursts per year,[6] 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. 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.[7]

The comet is a member of a relatively new class of objects called "Centaurs", of which at least 400 are known.[8] These are small icy bodies with orbits between those of Jupiter and Neptune. Astronomers believe that 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 Jupiter[9] will likely accumulate and cause the comet to migrate either inward or outward by the year 4000.[10]

The dust and gas comprising the comet's nucleus is part of the same primordial materials from which the Sun and planets were formed billions of years ago. The complex carbon-rich molecules they contain may have provided some of the raw materials from which life originated on Earth.

The comet nucleus is estimated to be 60.4±7.4 kilometers[1] in diameter.[9]

29P reached perihelion on March 7, 2019 and opposition on October 9, 2019.

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.[11][12]
Comet 29P photographed at Ka-Dar Observatory
The quasi-circular orbit of 29P/Schwassmann–Wachmann compared to Jupiter and Saturn

References
  1. Schambeau, C.; Fernández, Y.; Lisse, C.; Samarasinha, N.; Woodney, L. (2015). "A new analysis of Spitzer observations of Comet 29P/Schwassmann-Wachmann 1". Icarus. 260: 60–72. arXiv:1506.07037. Bibcode:2015Icar..260...60S. doi:10.1016/j.icarus.2015.06.038.
  2. 29P past, present and future orbital elements
  3. Syuichi Nakano (January 29, 2012). "29P/Schwassmann-Wachman 1 (NK 2189)". OAA Computing and Minor Planet Sections. Retrieved February 18, 2012.
  4. Patrick Rocher (February 4, 2012). "Note number : 0015 P/Schwassmann-Wachmann 1 : 29P". Institut de mécanique céleste et de calcul des éphémérides. Retrieved February 18, 2012.
  5. Kronk, Gary W. (2001–2005). "29P/Schwassmann-Wachmann 1". Archived from the original on October 22, 2008. Retrieved October 13, 2008. (Cometography Home Page)
  6. Trigo-Rodríguez; Melendo; García-Hernández; Davidsson; Sánchez (2008). "A continuous follow-up of Centaurs, and dormant comets: looking for cometary activity" (PDF). European Planetary Science Congress. Retrieved October 13, 2008.
  7. Miles, Richard (July 1, 2016). "Discrete sources of cryovolcanism on the nucleus of Comet 29P/Schwassmann–Wachmann and their origin". Icarus. 272: 387–413. doi:10.1016/j.icarus.2015.11.011.
  8. "JPL Small-Body Database Search". Jet Propulsion Laboratory. Retrieved August 13, 2018.
  9. "JPL Close-Approach Data: 29P/Schwassmann-Wachmann 1" (last observation: April 10, 2009). Retrieved May 5, 2009.
  10. "Twelve clones of 29P/Schwassmann-Wachmann diverging by the year 4000". Archived from the original on June 23, 2015. Retrieved April 30, 2009. (Solex 10) Archived December 20, 2008, at the Wayback Machine
  11. Trigo-Rodriguez et al., Outburst activity in comets, I. Continuous monitoring of comet 29P/Schwassmann-Wachmann 1
  12. Trigo-Rodriguez et al., Outburst activity in comets , II. A multi-band photometric monitoring of comet 29P/Schwassmann-Wachmann 1 arXiv:1009.2381
Numbered comets
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