C/2018 Y1 (Iwamoto)

For the 2013 and 2020 comets of the same name, see C/2013 E2 (Iwamoto) and C/2020 A2 (Iwamoto).
C/2018 Y1 (Iwamoto)
Comet Iwamoto photographed by Brandon Ghany on 26 February 2019
Discovery[1][2]
Discovered byMasayuki Iwamoto
Discovery siteAwa, Tokushima, Japan
Discovery date18 December 2018
Designations
CK18Y010
Orbital characteristics[3]
Epoch3 March 2019 (JD 2458545.5)
Observation arc348 days
Number of
observations		2,771
Aphelion287.25 AU
Perihelion1.287 AU
Semi-major axis144.27 AU
Eccentricity0.9911
Orbital period1,733 years
Inclination160.40°
147.48°
Argument of
periapsis		358.06°
Last perihelion7 February 2019
TJupiter–1.286
Earth MOID0.299 AU
Jupiter MOID1.507 AU
Physical characteristics
Comet total
magnitude (M1)		13.6
5.5[4]
(2019 apparition)

C/2018 Y1 (Iwamoto) is a non-periodic comet with a retrograde orbit discovered on 18 December 2018, by Japanese amateur astronomer Masayuki Iwamoto.[5] Its orbital period is estimated to be 1,733 years, and it passed closest to Earth on 13 February 2019.[6]

Observational history

Nearly a month after co-discovering C/2018 V1 (Machholz–Fujikawa–Iwamoto), Masayuki Iwamoto spotted another comet on 18 December 2018, which was moving north on the constellation Hydra.[a] Shuichi Nakano noted that the 13th-magnitude object has a blue coma, where he also provided initial orbital calculations using Iwamoto's images two days later.[1]

It was expected to reach a magnitude of between 6.5 and 7.5, visible in binoculars or a small telescope.[6][7] On 13 February 2019, Juan Jose Gonzalez reported that it had reached a peak magnitude of 5.5,[4] before fading to 7.6 two weeks later.[8]

Physical characteristics

The comet was observed by iSHELL spectrograph at the NASA Infrared Telescope Facility (IRTF). Overall, the measured spatial distributions for polar molecules (in particular, H
2O and CH
3OH) were broader, exhibiting more complex structure compared with nonpolar or weakly polar species (CH4, C2H6, and CO). Compositionally, compared to their respective mean abundances among comets from the Oort cloud, C2H6 and CH3OH were enriched, CH4 and HCN were near normal, and all other species were depleted. The abundance ratio CH3OH/C2H6 was higher by 45±8% on January 13 versus February 5, whereas CH4/C2H6 was unchanged within the uncertainty, suggesting nonhomogeneous composition among regions of the nucleus dominating activity on these dates.[9]

Orbit


  • Comet C/2018 Y1 (Iwamoto) with M44, 13. February 2019, 23:04 Uhr
  • Comet C/2018 Y1 (Iwamoto) with the spiral galaxy NGC 2903, 13 February 2019, 23:19 Uhr
  • Comet C/2018 Y1 (Iwamoto) with nebulae IC 410 and IC 405
  • C/2018 Y1 (Iwamoto) as seen from the infrared telescope NEOWISE on 25 February 2019

See also

References

Notes

  1. ^ Reported initial position upon discovery was: α = 14h 17m 45.33s, δ = –24° 44′ 13.4″[2]

Citations

  1. ^ a b M. Iwamoto; I. Enoh; S. Nakano; et al. (December 2018). D. W. Green (ed.). "Comet C/2020 A2 (Iwamoto)". Central Bureau for Astronomical Telegrams. 4588 (1). Bibcode:2018CBET.4588....1E.
  2. ^ a b M. Iwamoto; I. Enoh; K. Kadota; et al. (20 December 2018). "Comet C/2018 Y1 (Iwamoto)". Minor Planet Electronic Circulars. 2018-Y52. Bibcode:2018MPEC....Y...52E. ISSN 1523-6714.
  3. ^ "C/2018 Y1 (Iwamoto) – JPL Small-Body Database Lookup". ssd.jpl.nasa.gov. Jet Propulsion Laboratory. Retrieved 15 October 2022.
  4. ^ a b "Observation list for C/2018 Y1". COBS – Comet OBServation database. Retrieved 2 October 2025.
  5. ^ N. James (29 December 2018). "C/2018 Y1 (Iwamoto) - A New Comet for the New Year". britastro.org. British Astronomical Association. Retrieved 18 February 2019.
  6. ^ a b E. Irizarry (11 February 2019). "Speedy comet approaching Earth's vicinity". EarthSky.org. Retrieved 12 February 2019.
  7. ^ H. Weitering (12 February 2019). "How to See Comet Iwamoto Fly Past Earth This Week". Space.com. Retrieved 15 October 2022.
  8. ^ S. Yoshida. "Weekly Information about Bright Comets (2019 Mar. 2: North)". www.aerith.net. Retrieved 15 October 2022.
  9. ^ M. A. DiSanti; B. P. Bonev; N. Dello Russo; A. J. McKay; N. X. Roth; et al. (2021). "Volatile Composition and Outgassing in C/2018 Y1 (Iwamoto): Extending Limits for High-resolution Infrared Cometary Spectroscopy between 2.8 and 5.0 μm" (PDF). The Planetary Science Journal. 2 (6): 225–244. Bibcode:2021PSJ.....2..225D. doi:10.3847/psj/ac07ae. ISSN 2632-3338. S2CID 229008642. This article contains quotations from this source, which is available under the Creative Commons Attribution 4.0 Unported (CC BY 4.0) license.
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