For other comets discovered by Donald E. Machholz, see Comet Machholz.
96P/Machholz
DiscovererDonald E. Machholz
Discovery siteLoma Prieta, California
Discovery date12 May 1986
Mpc nameP/1986 J2
Designations
  • Machholz 1
  • 1986 VII, 1991 XII, 1986e
Epoch21 November 2025 (JD 2461000.5)
Observation arc38.17 years
Obs1,559
Perihelion0.116 AU[a]
Aphelion5.946 AU
Semimajor3.031 AU
Eccentricity0.96173
Period5.277 years
Max speed122 km/s (440,000 km/h)[1]
Inclination57.586°
Asc node93.963°
Arg peri14.739°
Mean191.35°
Tjup1.942
Earth moid0.333 AU
Jupiter moid0.613 AU
Mean radius3.2 km (2.0 mi)[2]
M 113.7
M 216.9
Last p31 January 2023
Next p12 May 2028[1]

Comet 96P/Machholz, also known as Machholz 1[3] is a periodic sunskirting comet[a] discovered on 12 May 1986, by amateur astronomer Donald Machholz on Loma Prieta peak, in central California using 130 mm (5.1 in) binoculars.[3][4] On 6 June 1986, 96P/Machholz passed 0.404 astronomical units from the Earth.[5] 96P/Machholz last came to perihelion on January 31, 2023.[6] The comet has an estimated diameter of around 6.4 km (4.0 mi).[2]

This comet is the parent body of both the Kracht and Marsden sungrazer families.[7]

96P/Machholz is unusual among comets in several respects. Other than small SOHO comets, its highly eccentric 5.29 year orbit has the smallest perihelion distance known among numbered/regular short-period comets, bringing it considerably closer to the Sun than the orbit of Mercury. It is also the only known short-period comet with both high orbital inclination and high eccentricity.[8] In 2007, 96P/Machholz was found to be both carbon-depleted and cyanogen-depleted, a chemical composition nearly unique among comets with known compositions.[9][10] The chemical composition implies a different and possible extrasolar origin.[11][12]

Orbit

The orbit of 96P/Machholz corresponds to the Arietids and the Marsden and Kracht comet groups.[13][7] Its Tisserand parameter with respect to Jupiter, TJ, is 1.94 and comets are generally classified as Jupiter family if TJ > 2.[8] Orbital integrations indicate that TJ was greater than 2 about 2500 years ago.[8] 96P/Machholz is currently in a 9:4 orbital resonance with Jupiter.[8] It will not make another close approach to the Earth until 2028, when it will pass at a distance of 0.3197 astronomical units.[5] It may eventually be ejected from the Solar System.[14]

96P/Machholz closest Earth approach around 2139-Jun-13[5]
Date & time of
closest approach		Earth distance
(AU)		Sun distance
(AU)		Velocity
wrt Earth
(km/s)		Velocity
wrt Sun
(km/s)		Uncertainty
region
(3-sigma)		Reference
2139-Jun-13 23:28 ± 13 hours0.179 astronomical units1.06 astronomical units41.437.1± 500 thousand kmHorizons

Perihelion

Perihelion distance
at different epochs[15]
EpochPerihelion
(AU)
18970.169
19280.152
19390.145
19750.133
19860.127
20230.116
20380.109
20810.095
21020.093

96P/Machholz has a perihelion (closest approach to the Sun) of 0.116 astronomical units for 2028.[6] At perihelion Comet Machholz passes the Sun at 122 km/s (440,000 km/h).[1] It comes closer to the Sun than any numbered comet less than 321P/SOHO. Between 1897 and 2102 perihelion gradually drops from 0.17 astronomical units to 0.09 astronomical units.[15] 2081 will be the first perihelion below 0.1 AU.[15]

Observations

Machholz 1 entered the field of view of the orbiting Solar and Heliospheric Observatory (SOHO) in 1996, 2002, 2007, 2012, and 2017, where it was seen by the corona-observing LASCO instrument in its C2 and C3 coronagraphs.[3][16]

2001/02 perihelion

During the 2001/2002 passage the comet brightened to magnitude −2,[17] and was very impressive as seen by SOHO.[18]

2007 perihelion

In 2007, it appeared in SOHO's LASCO C3's field of view from April 2 to 6, peaking in brightness on April 4, 2007,[19] around magnitude +2.[20] In these observations, its coma was substantially smaller than the Sun in volume,[citation needed] but the forward scattering of light made the comet appear significantly brighter.[21]

The comet SOHO 2333 is believed to be a fragment of Machholz that came off during the 2007 perihelion. It was discovered by Indian amateur astronomer Prafull Sharma in August 2012 by analyzing data from the Solar and Heliospheric Observatory, specifically the Large Angle and Spectrometric Coronagraph.[22] Data analysis of this sort has become commonplace based on public availability of SOHO images. Sharma became the third Indian to have discovered a comet in this manner.[23]

2012 perihelion

Between July 12–17, 2012,[11] 96P/Machholz was visible in the SOHO LASCO/C3 field of view and expected to brighten to about magnitude +2.[24] Two small faint fragments of 96P/Machholz were detected in the SOHO C2 images.[25] The fragments were five hours ahead of 96P/Machholz, and probably fragmented from the comet during the 2007 perihelion passage.[25]

2017 perihelion

The 2017 perihelion was on October 27, 2017. At closest approach, it passed 0.12395 AU (18,543,000 km; 11,522,000 mi) from the Sun. Coronagraphs on SOHO were monitoring the flyby for a fifth time. Its peak brightness was expected to be about 2.0, when it was closest to the Sun.[26]

2023 perihelion

The January 31, 2023 perihelion passage was the sixth passage observed by SOHO.[27] On February 4, 2023, the comet was recovered in the morning sky 2 degrees above the horizon at around magnitude 7.[28]

Using observations through October 2022, which is three months before the 2023 perihelion passage, the comet will next come to perihelion around 12 May 2028.[1]

Unusual composition

Spectrographic analysis of the coma of 96P/Machholz was made during its 2007 apparition, as part of the Lowell Observatory comet composition long-term observing program.[29] When compared with the measured abundances of five molecular species in the comae of the other 150 comets in their database, these measurements showed 96P/Machholz to have far fewer carbon molecules.[8] These other comets had on average 72 times as much cyanogen as 96P/Machholz.

The only two comets previously seen with similar depletion both in carbon-chain molecules and cyanogens were C/1988 Y1 (Yanaka) and C/2025 K1 (ATLAS), but they both have substantially different orbits.[30]

There are currently three hypotheses to explain the chemical composition of 96P/Machholz. One hypothesis for the difference is that 96P/Machholz was an interstellar comet from outside the Solar System and was captured by the Sun.[31] Other possibilities are that it formed in an extremely cold region of the Solar System (such that most carbon gets trapped in other molecules). Given how close it approaches the Sun at perihelion, repeated baking by the Sun may have stripped most of its cyanogen.

The following table represents future orbital elements for 96P keeping in mind that results hundreds of years in the future are highly speculative given the uncertain behavior of nongravitational forces over long time intervals and divergent solutions. By the year 2235, the uncertainty in the comets position is more than 1 e9km.[1]

Osculating elements as of January 1[1]
Year1600170018001900200021002200230024002500
Periapsis (au)0.340.270.230.170.120.090.070.040.030.03
Apoapsis (au)5.735.775.855.885.905.976.016.016.016.02
Inclination (degrees)70.8769.6566.3563.6260.1153.2044.0032.3615.0816.82
Eccentricity0.890.910.930.940.960.970.980.990.990.99

Notes

  1. ^ Sunskirters are comets passing perihelion between 3.45 to 33 solar radii from Sun's centre.

References

  1. ^ "Horizons Batch for 96P/Machholz (90000922) on 2028-May-12" (Perihelion occurs when rdot flips from negative to positive). JPL Horizons. Retrieved 2023-07-06. (JPL#K233/7/Soln.date: 2023-Jul-05)
  2. ^ P. L. Lamy; I. Toth; Y. R. Fernández; H. A. Weaver (2004). "The Sizes, Shapes, Albedos, and Colors of Cometary Nuclei". Comets II. University of Arizona Press. pp. 223–264. Bibcode:2004come.book..223L. doi:10.2307/j.ctv1v7zdq5.22. ISBN 978-0-8165-2450-1. JSTOR j.ctv1v7zdq5.22
  3. ^ Kronk, Gary W. "96P/Machholz 1". Cometography. Archived July 5, 2008 at the Wayback Machine. Retrieved August 6, 2008.
  4. ^ "Don Machholz and Comet 96P". Astronomy.com. March 29, 2007. Retrieved August 6, 2008.
  5. ^ "96P/Machholz 1 – JPL Small-Body Database Lookup". ssd.jpl.nasa.gov. Jet Propulsion Laboratory. Retrieved 2014-12-06.
  6. ^ "96P/Machholz Orbit". Minor Planet Center. Retrieved 2017-12-11.
  7. ^ Z. Sekanina & P. W. Chodas (2005). "Origin of the Marsden and Kracht Groups of Sunskirting Comets. I. Association with Comet 96P/Machholz and Its Interplanetary Complex". The Astrophysical Journal Supplement Series. 161 (2): 551–586. Bibcode:2005ApJS..161..551S. doi:10.1086/497374
  8. ^ D. G. Schleicher (2008). "The Extremely Anomalous Molecular Abundances of Comet 96P/MACHHOLZ 1 from Narrowband Photometry". The Astronomical Journal. 136 (5): 2204–2213. Bibcode:2008AJ....136.2204S. doi:10.1088/0004-6256/136/5/2204
  9. ^ "IAU Circular 8842". International Astronomical Union. June 6, 2007. Retrieved July 5, 2011.
  10. ^ L. E. Langland-Shula & G. H. Smith (2007). "The Unusual Spectrum of Comet 96P/Machholz". The Astrophysical Journal Letters. 664 (2): L119–L122. arXiv:0706.2022. Bibcode:2007ApJ...664L.119L. doi:10.1086/520839. S2CID 119134664
  11. ^ MacRobert, Alan (December 2, 2008). "A Very Oddball Comet". Sky & Telescope. Archived from the original on 2013-02-24. Retrieved December 5, 2008.
  12. ^ Ferreira, Becky (3 February 2023). "We May Have Had an Interstellar Visitor for Eons and Scientists Are Stumped - "I think it's going to be inconclusive, if not impossible to demonstrate conclusively," one physicist said of the possible interstellar comet.". Vice. Retrieved 4 February 2023.
  13. ^ K. Ohtsuka; S. Nakano; M. Yohikawa (February 2003). "On the Association among Periodic Comet 96P/Machholz, Arietids, the Marsden Comet Group, and the Kracht Comet Group". Publications of the Astronomical Society of Japan. 55 (1): 321–324. Bibcode:2003PASJ...55..321O. doi:10.1093/pasj/55.1.321
  14. ^ C. de la Fuente Marcos; R. de la Fuente Marcos; S. J. Aarseth (2015). "Flipping minor bodies: what comet 96P/Machholz 1 can tell us about the orbital evolution of extreme trans-Neptunian objects and the production of near-Earth objects on retrograde orbits". Monthly Notices of the Royal Astronomical Society. 446 (2): 1867–1873. arXiv:1410.6307. Bibcode:2015MNRAS.446.1867D. doi:10.1093/mnras/stu2230
  15. ^ Kinoshita, Kazuo (2017-06-24). "96P/Machholz past, present and future orbital elements". Comet Orbit. Archived 2012-04-22 at the Wayback Machine. Retrieved 2023-07-19.
  16. ^ Boschat, Mike (January 7, 2002). "Comet 96P/Machholz now in the SOHO C3 images". Meteorobs.org. Archived from the original on July 6, 2008. Retrieved August 6, 2008.
  17. ^ Yoshida, Seiichi (May 29, 2007). "96P/Machholz 1 (2002)". Aerith.net. Retrieved February 3, 2012.
  18. ^ "Exclusive Views of Comet 96P/Machholz". Solar and Heliospheric Observatory. NASA. January 6–10, 2002. Retrieved February 3, 2012.
  19. ^ "SOHO Movie Theater". Archived from the original on February 6, 2012. Retrieved February 2, 2012.
  20. ^ Yoshida, Seiichi (September 20, 2007). "96P/Machholz 1 (2007)". Aerith.net. Archived August 29, 2008 at the Wayback Machine. Retrieved August 6, 2008.
  21. ^ Marcus, Joseph C. (April 2007). "Forward-Scattering Enhancement of Comet Brightness. I. Background and Model". International Comet Quarterly. 29 (2): 39–66. Bibcode:2007ICQ....29...39M
  22. ^ "Delhi boy discovers a new comet". ZeeNews. August 11, 2012.
  23. ^ "SOHO Comet Discoverers' Totals". Archived from the original on October 16, 2011. Retrieved 18 October 2012.
  24. ^ M. Kusiak. "Transits of Objects through the LASCO/C3 field of view (FOV) in 2012". The Sungrazer Project. United States Navy. Archived 2023-03-27 at the Wayback Machine. Retrieved 2012-02-01.
  25. ^ Battams, Karl (July 16, 2012). "Breaking News: Comet Machholz had babies!!". Sungrazer Project. United States Navy. Archived February 3, 2023 at the Wayback Machine. Retrieved July 16, 2012.
  26. ^ "SOHO Pick of the Week". NASA. October 20, 2017.
  27. ^ Karl Battams (3 Feb 2023)
  28. ^ Qicheng Zhang (4 Feb 2023) // Michael Jäger (5 Feb 2023)
  29. ^ "A New Compositional Class of Comets: from Fire, Ice, or Beyond? Lowell Observatory Astronomer Confirms New Class of Comets". Lowell Observatory. 2008-12-02. Retrieved 2008-12-05.
  30. ^ U. Fink (1992). "Comet Yanaka (1988r): A New Class of Carbon-Poor Comet". Science. 257 (5078): 1926–1929. Bibcode:1992Sci...257.1926F. doi:10.1126/science.257.5078.1926. PMID 17753496. S2CID 7644921
  31. ^ Bryner, Jeanna (December 2, 2008). "Odd Comet Possibly from Another Star System". Space.com