C/2019 U5 (PanSTARRS)

C/2019 U5 (PanSTARRS)
Discovery[1][2]
Discovered byPan-STARRS
Discovery siteHaleakalā Observatory
Discovery date22 October 2019
Designations
A/2019 U5[1]
Orbital characteristics[3]
Epoch27 September 2022 (JD 2459849.5)
Observation arc6.34 years
Earliest precovery date11 October 2019
Number of
observations		5,421
Perihelion3.624 AU
Eccentricity1.00143
Orbital period5.9 million years (inbound)[4]
Inclination113.52°
2.637°
Argument of
periapsis		181.51°
Mean anomaly–0.001°
Last perihelion29 March 2023
TJupiter–0.942
Earth MOID2.626 AU
Jupiter MOID1.834 AU
Physical characteristics[5]
Mean radius
30–47.5 km (18.6–29.5 mi)[6]
  • (B−V) = 0.70±0.05
  • (V−R) = 0.47±0.02
  • (B−R) = 1.18±0.05
Absolute
magnitude (H)		6.84±0.02
Comet total
magnitude (M1)		8.5[3]
10.3[7]
(2023 apparition)

Comet C/2019 U5 (PanSTARRS), formerly known by its provisional designation A/2019 U5, is a distant non-periodic comet moving in a retrograde trajectory around the Sun. It is one of several comets discovered by the Pan-STARRS survey.

Observational history

When it was first discovered in October 2019,[1] it was presumed to be a hyperbolic asteroid.[6] Later observations from September 2020 revealed that weak cometary activity was detected and increasing as it went closer to the Sun.[2] Further observations of a persistent coma seen from Hawaii, Japan, and other European nations confirmed its nature as a comet.[2]

Physical characteristics

Optical photometry obtained from the Sanglokh Observatory (193) between May and September 2022 reveal an absolute magnitude of 6.84±0.02, with color indices suggesting a quasi-steady activity within its coma.[5] Morphological observations while it was 4.63–4.03 AU (693–603 million km) from the Sun also show no signs of jet-like or other structural features within the coma.[5] The comet's nucleus is estimated to be about 60–95 km (37–59 mi) in diameter.[6]

Orbit

Barycentric osculating parameters from HORIZONS show that C/2019 U5 is a dynamically new comet from the Oort cloud.[5] It reached perihelion on 29 March 2023 at a distance of 3.624 AU (542.1 million km) from the Sun.[4] The comet is expected to leave the Solar System on its outbound trajectory.[4]

References

  1. 1 2 3 R. Wainscoat; C. Crowder; T. Burdullis; et al. (1 November 2019). "A/2019 U5". Minor Planet Electronic Circulars. 2019-V10. ISSN 1523-6714.
  2. 1 2 3 M. Micheli; K. J. Meech; J. Kleyna; et al. (April 2021). D. W. Green (ed.). "Comet C/2019 U5 (PanSTARRS)". Central Bureau Electronic Telegrams. 4953: 1. Bibcode:2021CBET.4953....1M.
  3. 1 2 "C/2019 U5 (PanSTARRS) – JPL Small-Body Database Lookup". ssd.jpl.nasa.gov. Jet Propulsion Laboratory. Retrieved 21 July 2026.
  4. 1 2 3 Horizons output. "Barycentric Osculating Orbital Elements for Comet PanSTARRS (C/2019 U5)". Retrieved 21 July 2026. (Solution using the Solar System's barycenter (Sun+Jupiter). Select Ephemeris Type:Elements and Center:@0)
    Inbound period (PR) = 2.15E+09 / 365.25 days = 5.9 million years
  5. 1 2 3 4 G. I. Kokhirova; E. S. Bakanas; V. V. Emel'yanenko; F. D. Rakhmatullaeva; A. P. Kartashova (2026). "Photometric characteristics of comet C/2019 U5 during the pre-perihelion period and its dynamical features". Planetary and Space Science. 278–279 106302. Bibcode:2026P&SS..27806302K. doi:10.1016/j.pss.2026.106302.
  6. 1 2 3 T. Hromakina; I. Belskaya; Y. Krugly; et al. (2021). "Small Solar System objects on highly inclined orbits. Surface colours and lifetimes" (PDF). Astronomy & Astrophysics. 647: 71–85. arXiv:2101.04541. doi:10.1051/0004-6361/202039737.
  7. ↑ "Observation list for C/2019 U5". COBS – Comet OBServation database. Retrieved 21 July 2026.
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