C/2022 E3 (ZTF)

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For other comets discovered by the Zwicky Transient Facility, see Comet ZTF.

C/2022 E3 (ZTF)
Synodic rotation period
8.5–8.7 hours
Comet total
magnitude (M1)		10.5±0.6
5.0
(2023 apparition)

C/2022 E3 (ZTF) is a

periodic comet, and "2022 E3" means that it was the third comet to be discovered in the first half of March 2022.[5]

The comet nucleus was estimated to be about a kilometer in size,[7] rotating every 8.5[8] to 8.7 hours.[9] Its tails of dust and gas extended for millions of kilometers and, during January 2023, an anti-tail was also visible.[10]

The comet reached its

perihelion on 12 January 2023, at a distance of 1.11 AU (166 million km; 103 million mi), and the closest approach to Earth was on 1 February 2023, at a distance of 0.28 AU (42 million km; 26 million mi). The comet reached magnitude 5 and was visible with the naked eye under moonless dark skies.[11][12][13][14]

Observational history

Discovery

Astronomers Bryce Bolin and Frank Masci discovered C/2022 E3 (ZTF) using the

solar elongation of 44 degrees.[16]

The object was initially identified as an

arcseconds across in stacked photos he obtained from the remote observatory in Mayhill, New Mexico, while K. Yoshimoto reported its coma was 15 arcseconds across and the comet had a small tail 25 arcseconds long.[1][15] The comet in stacked ZTF images appeared extended when compared to nearby stars and was flagged as a comet by the Tails neural network.[16]

The comet was

Pan-STARRS 1 in Haleakalā Observatory, Hawai'i on 10 July 2021, when the comet had an apparent magnitude of 23. The comet had also been photographed without being noticed by ZTF in October and November 2021.[18]

Near perihelion

The dust tail and the coma was gradually getting bigger as the comet was approaching the Sun between July and October 2022, and dust production rose from 241 ± 3 kg/s in July to 476 ± 9 kg/s.[19] By early November 2022, the comet had brightened to magnitude 10 and was appearing to move slowly in Corona Borealis and Serpens as it moved parallel to Earth.[20] The comet exhibited a green coma and a yellowish dust tail and a faint ion tail. The comet was visible in the early evening and started being visible in the morning sky by the end of November.[21] By 19 December, the comet had developed a greenish coma, a short, broad dust tail, and a long faint ion tail stretching across a 2.5-degree wide field of view.[22] After that, the comet started moving northward, passing through Boötes, Draco, and Ursa Minor, passing within about 10 degrees of Polaris by the end of January.[21][23]

The comet on 24 January 2023, with the antitail towards the left

The comet reached its perihelion on 12 January 2023, at a distance of 1.11 AU (166 million km; 103 million mi).

anti-tail became visible. This tail appears pointing toward the Sun and opposite the dust and ion tails. It is caused by particles lying on a disk on the orbital plane of the comet, and when Earth aligns with that plane, they look like a reverse tail.[28][29] XMM-Newton X-ray space telescope observed the comet on 23 January, but it was only faintly detected.[30][31]

The comet's closest approach to Earth was on 1 February 2023, at a distance of 0.28 AU (42 million km; 26 million mi). As of 31 January 2023, the comet had an apparent magnitude of about 5; its coma was reported to be about 20' across.[11] The central region of the coma measured bout 4 arcminutes across, which corresponds to diameter of 50,000 km, and featured two jets about 20 arcseconds long.[16] During its closest approach to Earth, it was near the north celestial pole[32] and located within the Camelopardalis constellation.[33] The moon was a waxing gibbous and the brightening moon hampered viewing the comet without optical aid.[34] On 5 February, at the full moon, the comet passed 1.5 degrees from the bright star Capella.[34] On 6 February, C/2022 E3 (ZTF) visually passed near comet C/2022 U2 (ATLAS).[35] On 10 to 11 February, the comet passed 1.5 degrees from Mars and, on 13 to 15 February, passed in front of the Hyades star cluster.[21]

Positions of the comet C/2022 E3 (ZTF) in the starry sky between 14 January and 16 February 2023

C/2022 E3 closest Earth approach on 1 February 2023 17:55 UT[4]
Date and time of
closest approach 		Earth distance
(AU) 		Sun distance
(AU) 		Velocity
relative to Earth
(km/s) 		Velocity
relative to Sun
(km/s) 		Uncertainty
region
(
3-sigma
) 		Lunar
elongation 		Lunar
phase 		Reference
2023-02-01 17:55 0.2839 
LD
)		 1.159 AU (173.4 million km; 107.7 million mi; 451 LD) 57.4 39.1 ± 500 km 44° 86% Horizons

Scientific results

The nucleus of the comet was found to rotate every 8.5

H2S, carbon monosulfide, carbonyl sulfide, ethanol and aGg’-(CH2OH)2. The comet was depleted in hypervolatiles (low CO and H2S abundances relative to water) and had a relatively low methanol abundance relative to water (1.8%) compared to the mean of other comets.[38]

Color

The green color is likely due to the presence of

organic materials evaporated from the nucleus. It then undergoes further photolysis, with a lifetime of about two days, at which time the green glow appears in the comet's head but not the tail.[41][42] The comet researcher Matthew Knight opined that the green color of this comet is not unusual for comets with a higher gas content, but they only rarely approach the Earth as close so it provides for very good observation of the greenish hue.[43] Similar colors were seen with observations of comet C/2021 A1 (Leonard).[44]

Outbound trajectory

Before perihelion passage

barycentric outbound orbit to be bound to the Sun+Jupiter system at an epoch in the year 2050, but with an unrealistic maximum distance of 270,000 AU (4.3 ly) which is beyond the Oort cloud.[2] Post perihelion, the outbound orbit solution is only weakly bound to the Sun.[3] Using a heliocentric orbit at epoch 2495 with just the Sun's mass shows the comet unbound to the Solar System.[45] The Sun's escape velocity at 200 AU is 2.98 km/s[46] and the comet will be going 2.97 km/s at 200 AU from the Sun.[47] The comet will either leave the Solar System altogether or return in many millions of years depending on perturbations from outgassing (non-gravitational forces) or perturbations while in the Oort cloud by the galactic tide and passing stars.[48]

Comparable objects

Diffuse objects visible to the naked eye
Object
apmag
Andromeda Galaxy (M31) 3.4
Orion Nebula (M42) 4
C/2022 E3 (ZTF) 5
Triangulum Galaxy (M33) 5.7
  • The comet in December 2022, from the Asiago Astrophysical Observatory
    The comet in December 2022, from the Asiago Astrophysical Observatory
  • The comet on 10 January 2023 by Andrea Reguitti of the University of Padua
    The comet on 10 January 2023 by Andrea Reguitti of the University of Padua
  • The comet on 20 January 2023, showing a broad dust tail and a thin ion tail
    The comet on 20 January 2023, showing a broad dust tail and a thin ion tail
  • The comet on 22 January 2023, with the antitail visible
    The comet on 22 January 2023, with the
    antitail
    visible
  • C/2022 E3 (ZTF) observed from Vancouver, Canada on 28 January by Jaden Choi
    C/2022 E3 (ZTF) observed from Vancouver, Canada on 28 January by Jaden Choi
  • The comet on 28 January 2023, with star trails due to its relative motion in the sky
    The comet on 28 January 2023, with star trails due to its relative motion in the sky
  • The comet on 30 January 2023
    The comet on 30 January 2023
  • The comet in conjunction with Mars on 11 February
    The comet in conjunction with Mars on 11 February
  • The comet on February 13, 2023, with its dust tail and ion tail visible.
    The comet on February 13, 2023, with its dust tail and ion tail visible.

References

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    Minor Planet Electronic Circular. Minor Planet Center. Archived
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  2. ^
    barycenter
    (Sun+Jupiter). Select Ephemeris Type:Elements and Center:@0) Epoch 1950 has PR= 1.883E+07 / 365.25 = 51500 years
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