Английская Википедия:C/2021 A1 (Leonard)

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Шаблон:Short description Шаблон:Infobox comet

C/2021 A1 (Leonard) was a long period comet[1] that was discovered by G. J. Leonard at the Mount Lemmon Observatory on 3 January 2021 (a year before perihelion) when the comet was Шаблон:Convert from the Sun.[2] It had a retrograde orbit. The nucleus was about Шаблон:Convert across. It came within Шаблон:Convert of Venus, the closest-known cometary approach to Venus.[3]

Observational history

The comet was discovered by G. J. Leonard at the Mount Lemmon Observatory on 3 January 2021 (a year before perihelion) when the comet was Шаблон:Convert from the Sun. The comet appeared to have a 10" coma and a 5" broad tail in the photographs taken as part of the Mt. Lemmon Survey and its magnitude was estimated to be 19.0. Precovery images dated back to April 11, 2020.[2]

On 10 October the comet showed a short but dense dust tail.[4] In late November the comet appeared to stop brightening as expected and to fade instead, indicating a possible disintegration of the nucleus.[5] In early December the comet had an apparent magnitude (coma+nucleus) of around 6.[6] The first reports of naked-eye observations by experienced observers started coming in on 5 December 2021.[7] Much like observing Messier 33, the low surface brightness of the comet can make it difficult to observe near urban areas. On 3 December 2021 many emission lines of NH2, C2, and [OI] were detected in the spectrum of the comet in the wavelength range between 5000 and 7000 Å.[8][9] On the morning of 6 December 2021 the comet was about 5 degrees from the star Arcturus. On 14 December 2021 the comet was 14.7 degrees from the Sun[10] and quickly became better seen from the southern hemisphere.

The forward scattering of light helped the comet to briefly brighten to as much as magnitude 2.5,[6][11][12] but was also enhanced by a modest outburst.[13] The comet experienced outbursts on December 15, 20 and 23, thus reaching third magnitude before dimming back to 4th magnitude. The ion tail of the comet appeared complex, with knots and steamers.[14] The comet's discoverer called the tails "some of the best ever observed".[15] In stacked photos the tail could be traced for 60 degrees in the sky.[16] While the comet was lower in the sky, atmospheric extinction offset much of the brightening.Шаблон:Citation needed As of 22 December 2021, the comet was around apparent magnitude 4, making it a good binocular comet for the Southern hemisphere.[6][14] It was the brightest comet of 2021.[15] One more outburst took place after perihelion, on 6–8 January 2022, when the comet brightened by 1.5 magnitudes.[17]

On 23 February 2022 the comet was observed with the SLOOH telescope in Chile, operated by Martin Masek. The comet lacked a central concentration, which indicates that the nucleus of the comet disintegrated or evaporated completely. Further observations confirmed the lack of concentration.[15] In April 2022, the disintegrating comet was observed using the Hubble Space Telescope, with further observations planned for June 2022.[18] No surviving fragments were found by the Hubble Space Telescope, while the Swan Hill observatory imaged an extensive debris cloud. The disintegration of the comet probably started in mid December 2021.[19]

Orbit

Файл:Animation of C／2021 A1's orbit around Sun - 2021 close approach.gif
Animation of C／2021 A1's orbit around Sun – 2021 close approach
Шаблон:Legend2Шаблон:·Шаблон:Legend2Шаблон:·Шаблон:Legend2Шаблон:·Шаблон:Legend2Шаблон:·Шаблон:Legend2Шаблон:·Шаблон:Legend2

C/2021 A1 has been inside of the orbit of Neptune since May 2009.[20] Using an epoch of 1950 which is well before the comet entered the planetary region of the Solar System, a barycentric orbit solution suggests the comet had an approximately 80,000-year orbital period.[21] Thus, the comet has spent the last 40,000 years inbound from approximately Шаблон:Convert (0.06 light year). After perihelion, the comet will be ejected from the Solar System. The barycentric orbit will remain hyperbolic after September 2022.[21]

On 12 December 2021 the comet was Шаблон:Convert from Earth and on 18 December 2021 it was Шаблон:Convert from Venus.[22] The latter distance is smaller than any known close encounter of Earth with a long period comet, and one of the closest recorded for any planet in recent history. The minimum orbit intersection distance of Venus with the comet is about 50,000 kilometers, with Venus passing from that point two days after the comet, so it is possible that dust from the comet could create a meteor shower in Venus.[23]

It made its closest approach to the Sun on 3 January 2022.

Gallery

See also

References

Шаблон:Reflist

Шаблон:Comets Шаблон:2021 in space Шаблон:Authority control

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  1. ↑ Ошибка цитирования Неверный тег <ref>; для сносок CBET4907 не указан текст
  2. ↑ 2,0 2,1 Ошибка цитирования Неверный тег <ref>; для сносок MPEC2021-A99 не указан текст
  3. ↑ Шаблон:Cite web
  4. ↑ Шаблон:Cite news
  5. ↑ Шаблон:Cite web
  6. ↑ 6,0 6,1 6,2 Ошибка цитирования Неверный тег <ref>; для сносок vanbuitenen не указан текст
  7. ↑ Шаблон:Cite tweet
  8. ↑ Шаблон:Cite web
  9. ↑ Шаблон:Cite web
  10. ↑ Ошибка цитирования Неверный тег <ref>; для сносок sol-elong не указан текст
  11. ↑ Ошибка цитирования Неверный тег <ref>; для сносок Yoshida не указан текст
  12. ↑ Шаблон:Cite tweet
  13. ↑ Шаблон:Cite web
  14. ↑ 14,0 14,1 Шаблон:Cite news
  15. ↑ 15,0 15,1 15,2 Шаблон:Cite web
  16. ↑ Шаблон:Cite web
  17. ↑ Шаблон:Cite web
  18. ↑ Шаблон:Cite web
  19. ↑ Шаблон:Cite journal
  20. ↑ Ошибка цитирования Неверный тег <ref>; для сносок Neptune не указан текст
  21. ↑ 21,0 21,1 Ошибка цитирования Неверный тег <ref>; для сносок barycenter не указан текст
  22. ↑ Ошибка цитирования Неверный тег <ref>; для сносок jpldata не указан текст
  23. ↑ Шаблон:Cite journal
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