C∕2022 E3 (ZTF) Comet
| Polish version is here |
C/2022 E3 (ZTF) is a long-period comet discovered on March 2, 2022, during the sky survey carried out by the Zwicky Transient Facility. Its orbital period is estimated at roughly 50,000 years, although it may actually be a single-apparition comet that will never return to the inner Solar System.
The object was initially classified as an asteroid, but follow-up observations revealed a condensed coma, conclusively confirming its cometary nature. At peak brightness the comet reached about magnitude 5, allowing it to be seen through binoculars and — under favorable dark-sky conditions — even with the naked eye.
Observations
February 2, 2023, around 8:00 PM – Jaworzno, Poland
Conditions: urban area, high level of light pollution
During that session the comet passed near Iota Aurigae ι Aur, a K-type giant better known by its traditional names Hassaleh or Al Kab.
The nucleus is estimated to be about 1 kilometer (0.62 mi) in diameter and rotates once every 8.5–8.7 hours. Its dust and gas tails stretched across millions of kilometers (millions of miles).
The green color — not visible in the photograph above — is most likely produced by diatomic carbon concentrated around the comet’s head. When C2 molecules are excited by solar ultraviolet radiation, they emit primarily in the infrared, but their triplet state radiates at a wavelength of 518 nm. These molecules form through photolysis of organic compounds that sublimate from the nucleus and then undergo further decomposition, so the green glow appears in the comet’s head but not in its tail.
The comet reached perihelion on January 12, 2023, approaching the Sun to within 1.11 astronomical units — about 166 million km (103 million mi). Its closest approach to Earth occurred on February 1, 2023, at a distance of 0.28 AU, roughly 42 million km (26 million mi).
Apart from the comet, the photograph also features several other noteworthy objects. The open cluster M38, containing several hundred young stars, lies about 4,200 light-years from Earth. With a longer exposure time, the faint reflection nebula IC 1778 would be visible slightly higher in the frame, while the emission–reflection nebula IC 405 — illuminated by the runaway star AE Aurigae — occupies the central region. Near the bottom of the image sits the open cluster NGC 1893.
Photo 1 Parameters:
- Canon EOS 60D
- Total exposure time: 60 seconds
- ISO: 1000
- Lens: zoom
- Aperture: f/4
Further readings:
- Bolin B. T., Masci F. J., Duev D. A., Milburn J. W., Neill J. D., Purdum J. N., Avdellidou C., Saki M., Cheng Y.-C., Delbo M., Fremling C., Ghosal M., Lin Z.-Y., Lisse C. M., Mahabal A., Palomar discovery and initial characterization of naked-eye long-period comet C/2022 E3 (ZTF), Monthly Notices of the Royal Astronomical Society: Letters, 527(1), 2023, pp. L42–L46
- Liu B., Liu X., Unraveling the dust activity of naked-eye comet C/2022 E3 (ZTF), Astronomy & Astrophysics, 683, 2024, p. A51
- Biver N., Bockelée-Morvan D., Handzlik B., Sandqvist Aa., Boissier J., Drozdovskaya M. N., Moreno R., Crovisier J., Lis D. C., Cordiner M., Milam S., Roth N. X., Bonev B. P., Dello Russo N., Vervack R., Opitom C., Kawakita H., Chemical composition of comets C/2021 A1 (Leonard) and C/2022 E3 (ZTF) from radio spectroscopy and the abundance of HCOOH and HNCO in comets, Astronomy & Astrophysics, 690, 2024, p. A271
Marek Ples