C/2025 D1 (Gröller)

C/2025 D1 (Gröller)
Discovery[1][2]
Discovered byHannes Gröller
Discovery siteKitt Peak, Arizona
(Bok Telescope)
Discovery date20 February 2025
Orbital characteristics[3]
Epoch24 June 2024 (JD 2460485.5)
Observation arc6.90 years (2,522 days)
Earliest precovery date6 June 2018
Number of
observations		66
Perihelion14.123 AU
Eccentricity1.00302
Orbital period~6 million years (inbound)
Inclination84.491°
312.89°
Argument of
periapsis		185.85°
Mean anomaly–0.004°
Next perihelion18 May 2028
Earth MOID13.143 AU
Jupiter MOID8.826 AU
Physical characteristics[4]
Mean radius
≥ 0.4 km (0.25 mi)
Comet total
magnitude (M1)		6.6

Comet Gröller, also known as C/2025 D1 (Gröller), is a very distant non-periodic comet discovered by Hannes Gröller of the Catalina Sky Survey on 20 February 2025. It is the comet with the most distant perihelion ever known,[5] which will approach the Sun no closer than 14.12 AU (2.112 billion km) by May 2028,[3] surpassing the record previously held by C/2003 A2 (Gleason) by 2.7 AU.[5][6]

It was Hannes Gröller's fourth comet discovery since 2019.[a]

Observational history

The comet was discovered by Hannes Gröller using the 2.25 m (7.4 ft) Bok Telescope of the Kitt Peak Observatory in Arizona.[2] Images obtained through stacking of 30-second exposures show a magnitude 20.6 object with a condensed coma measuring 3 arcseconds across.[1][7] Amateur astronomer Sam Deen found several precovery observations of C/2025 D1 from 2018, when the comet was more than 21 AU (3.1 billion km) from the Sun (beyond the orbit of Uranus).[5] This makes C/2025 D1 one of the few known "ultradistant comets" that have been observed beyond 20 AU (3.0 billion km) from the Sun.[5] The ultradistant comets, which include the giant Oort cloud comet C/2014 UN271 (Bernardinelli–Bernstein), are believed to contain supervolatile compounds such as carbon monoxide and carbon dioxide, which are known to easily vaporize at low temperatures far from the Sun.[5]

Orbit

Astrometric measurements and orbital calculations reveal that C/2025 D1 is a dynamically new comet from the Oort cloud, with its previous perihelion distance approximately 6 million years ago were estimated to be greater than or equal to 60 AU (9.0 billion km).[4] It will reach its next perihelion on 18 May 2028,[3] and is expected to be ejected from the Solar System on its outbound flight.[4]

See also

Other ultradistant comets:

Notes

  1. ^ Hannes Gröller previously discovered the following three comets between 2019 and 2021. These were P/2019 B2, P/2019 V2, and P/2021 R6

References

  1. ^ a b H. Gröller; S. Deen; M. Jaeger; et al. (24 February 2025). D. W. Green (ed.). "Comet C/2025 D1 (Groeller)". Central Bureau Electronic Telegrams. 5509. Bibcode:2025CBET.5509....1G.
  2. ^ a b C. E. Woodward; D. Rankin; H. Gröller; et al. (22 February 2025). "Comet C/2025 D1 (Groeller)". Minor Planet Electronic Circulars. 2025-D83. Bibcode:2025MPEC....D...83W. doi:10.48377/MPEC/2025-D83. ISSN 1523-6714.
  3. ^ a b c "C/2025 D1 (Gröller) – JPL Small-Body Database Lookup". ssd.jpl.nasa.gov. Jet Propulsion Laboratory. Retrieved 13 March 2025.
  4. ^ a b c M. T. Hui; R. Weryk; M. Micheli; et al. (2025). "Dynamically New Comet C/2025 D1 (Groeller) with Record Perihelion Distance". arXiv:2509.09829 [astro-ph.EP].
  5. ^ a b c d e D. L. Chandler (11 March 2025). "Astronomers have spotted the most distant comet ever discovered". Astronomy.com. Retrieved 13 March 2025.
  6. ^ "C/2003 A2 (Gleason) – JPL Small-Body Database Lookup". ssd.jpl.nasa.gov. Jet Propulsion Laboratory. Retrieved 13 March 2025.
  7. ^ S. Yoshida (24 February 2025). "Comet C/2025 D1 (Groeller)". www.aerith.net. Retrieved 13 March 2025.
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