astro.wikisort.org - Comet

12P/Pons–Brooks is a periodic comet with an orbital period of 71 years. It fits the classical definition of a Halley-type comet with (20 years < period < 200 years).[1] The next perihelion passage is 21 April 2024,[7][lower-alpha 1] with closest approach to Earth being 1.54 AU (230 million km) on 2 June 2024.[8] The comet nucleus is estimated to be around 30 km in diameter assuming it was not producing too much dust and gas during the 2020 photometry.[5]

12P/Pons–Brooks

Discovery
Discovered by	Jean-Louis Pons William Robert Brooks
Discovery date	July 12, 1812
Alternative designations	1812; 1884 I; 1954 VII;[1] C/1457 A1; C/1385 U1[2][3]
Orbital characteristics A
Epoch	2024-05-10[4]
Aphelion	33.616 AU
Perihelion	0.78078 AU
Semi-major axis	17.199 AU
Eccentricity	0.95460
Orbital period	71.32 yr
Inclination	74.191°
Earth MOID	0.176 AU (26.3 million km)
Dimensions	34±12 km[5]
Last perihelion	May 22, 1954[6][4] January 25, 1884 September 15, 1812
Next perihelion	April 21, 2024[7][lower-alpha 1]

12P/Pons–Brooks may be the parent body of the December κ-Draconids meteor shower.[9]

Comet Pons-Brooks was discovered at Marseilles Observatory in July 1812, and then later recovered in 1883.[10]

On 10 June 2020 Pons–Brooks was recovered at apparent magnitude 23 by the Lowell Discovery Telescope when the comet was beyond the orbit of Saturn at 11.9 AU (1.78 billion km) from the Sun.[11][5] The uncertainty in the comet's heliocentric distance is roughly ±10000 km.[12]

Discovery

This section needs to be updated. (August 2020)

Comet 12P/Pons–Brooks was discovered on July 12, 1812, by Jean-Louis Pons. Independently, this comet was later found by Vincent Wisniewski on August 1, and Alexis Bouvard on August 2 the same year. At the time no-one had brought these observations together.

In 1883 a (faint) comet was accidentally discovered by William Robert Brooks and later identified with the comet of 1812. Shortly after its initial discovery it was found to have an orbital period of about 70 years with an error of about 5 years. Johann Franz Encke determined a definitive orbit with a period of 70.68 years. This orbit was used to generate an ephemeris for the 1883-4 return, but searches were unsuccessful, until it was rediscovered by Brooks. This year it traveled from Scheat and Markab in western Pegasus, 13 January 1884; southward (through Pisces) to reach perihelion below Iota and Beta Ceti (~RA 0h, Dec. -10°) around 24 January.[13]

Orbit

Earth close approach

Date	Distance (AU)	Solar elongation
1884-Jan-09[14]	0.63 AU (94 million km)	58°
1954-Jun-29	1.6 AU (240 million km)	38°
2024-Jun-02[8]	1.5 AU (220 million km)	45°
2095-Aug-27	1.5 AU (220 million km)	31°

Libration is locked at a 6:1 resonance with Jupiter.[15] The Tisserand invariant with respect to Jupiter (J) is 0.60.[16] Aphelion (furthest point from the Sun) is just beyond the orbit of Neptune at 33 AU (4.9 billion km).

With a steep orbital inclination of 74.2° this comet does not spend a lot of time near the ecliptic. The Jet Propulsion Laboratory's (JPL) website shows that between the years 1900 and 2200, that the comet was and will be most significantly perturbed by Saturn on July 29, 1957. At that point it passed within 1.6AU of the giant planet's influence; even this approach had negligible effect.[1] The comet's orbit appears to be stable between 1740 and 2167, with no strong perturbations by any of the planets.[14][17]

Kirkwood in 1884 noticed that Pons-Brooks shares elements with De Vico's comet of 1846. He suggested that the latter had calved off Pons-Brooks some centuries prior.[18] Later he identified the two comets' capture into their elliptical orbits (or their parent body's capture) with their shared aphelion close to Neptune 991 CE.[19]

Speculations

Bonilla's comet

On August 12-13th of 1883, Mexican astronomer José Bonilla observed 447 bodies cross the solar disc, from an observatory in Zacatecas. Mexican astronomers in 2011 suggested that a comet may have split into several pieces. These objects were estimated to have had a size of between 46 and 1022 meters, and to have passed only 538 to 8062 km from the Earth. They raised Pons-Brooks as one possibility, in which case Earth barely avoided multiple Tunguska events or even a mass extinction.[20] This was reported in the media October 2011.[21][22]

But the source of these objects could also have been comet C/1883 D1 (Brooks-Swift) or even a third, unknown comet that year. The event also coincided with the annual Perseids meteor shower. Even migrating birds cannot be ruled out.[20]

Ancient times

Chinese historiography records, although long after the fact, its first comet around 1500 BCE. This "broom-star" is said to have heralded the sweeping-away of the as tyrannically described Xia dynasty (and its replacement with the Shang dynasty).[23]

1954

Pons–Brooks came to perihelion on May 22, 1954[6] when it was 1.7 AU from Earth. On 10 December 1954, the meteor stream of comet Pons–Brooks passed about 0.12 AU (18 million km) from Earth, resulting in potential meteors impacting Earth`s atmosphere at relative velocity 45 km/s.[24] The comet was recovered in June 2020, and perihelion passage is in April 2024.[5]

Other comets with a similar orbital period include 13P/Olbers, 23P/Brorsen-Metcalf, 122P/de Vico and 1P/Halley.

Notes

References

Sources

• Carusi A, Kresak L, Perozzi E, Valsecchi GB (1987). "High-order librations of Halley-type comets". Astronomy and Astrophysics. 187: 899–905. Bibcode:1987A&A...187..899C.
• Park, So-Yeon; Chae, Jong-Chul (2007). "Analysis of Korean Historical Comet Records". Publications of the Korean Astronomical Society (in Korean). 22 (4): 151–68. Bibcode:2007PKAS...22..151P. doi:10.5303/pkas.2007.22.4.151.
• Peng-Yoke H (1964). "Natural Phenomena Recorded in the Đai-Viêt Su'-ky Toan-Thu', an Early Annamese Historical Source". Journal of the American Oriental Society. 84 (2): 127–149. doi:10.2307/597100. JSTOR 597100.

External links

• 1954 apparition lightcurve – Maik Meyer
• Comet 12P/Pons-Brooks light curve (Dmitry Chestnov)
• 12P/Pons-Brooks at the JPL Small-Body Database
  • Close approach · Discovery · Ephemeris · Orbit diagram · Orbital elements · Physical parameters

Numbered comets
Previous 11P/Tempel–Swift–LINEAR	12P/Pons–Brooks	Next 13P/Olbers

На других языках

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- [en] 12P/Pons–Brooks

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[ru] 12P/Понса — Брукса

Комета Понса — Брукса (12P/Pons-Brooks) — короткопериодическая комета из семейства Галлея, которая была открыта 12 июля 1812 года французским астрономом Жан-Луи Понсом в Марсельской обсерватории[4], когда комета медленно двигалась по созвездию Рыси. Он описал её как маленькую, плохо различимую туманность, без хвоста. Чуть позднее, 1 августа комета была независимо открыта российским астрономом Винсентом Вишневским, а ещё днём позже французским астрономом Алексисом Буваром. В 2016 году было опубликовано исследование, в котором утверждалось, что данная комета может быть родоначальницей метеорного потока[5]. Комета обладает длительным периодом обращения вокруг Солнца — чуть более 70,0 лет.

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