C/2014 UN₂₇₁ (Bernardinelli–Bernstein)

C/2014 UN₂₇₁ (Bernardinelli–Bernstein), simply known as C/2014 UN₂₇₁ or Comet Bernardinelli–Bernstein (nicknamed BB),^[3] is a large Oort cloud comet discovered by astronomers Pedro Bernardinelli and Gary Bernstein in archival images from the Dark Energy Survey.^[11][2] When first imaged in October 2014, the object was 29 AU (4.3 billion km; 2.7 billion mi) from the Sun, almost as far as Neptune's orbit and the greatest distance at which a comet has been discovered.^[12] With a nucleus diameter of at least 120 km (75 mi), it is the largest Oort cloud comet known. It is approaching the Sun and will reach its perihelion of 10.9 AU (just outside of Saturn's orbit) in January 2031.^[7] It will not be visible to the naked eye because it will not enter the inner Solar System.^[g]

C/2014 UN₂₇₁
(Bernardinelli–Bernstein)

Color composite image of C/2014 UN271 by the Hubble Space Telescope on 28 March 2022
Discovery^[1]
Discovered by	Pedro Bernardinelli Gary Bernstein (Dark Energy Survey)
Discovery date	20 October 2014 (first discovery image)
Designations
Alternative designations	2014 UN271 Comet Bernardinelli–Bernstein^[2] "BB"^[3]
Orbital characteristics (barycentric)^[4]
Epoch	1 January 1600 (inbound)^[a] 1 January 2500 (outbound)^[b]
Observation arc	8.41 yr (3,070 days)
Earliest precovery date	15 November 2010^[3]
Orbit type	Oort cloud
Aphelion	≈ 39,600 AU (inbound) ≈ 55,000 AU (outbound)
Perihelion	10.9502 AU (1.64 billion km)^[6]^[c]
Semi-major axis	≈ 19,800 AU (inbound) ≈ 27,500 AU (outbound)
Eccentricity	0.99945 (inbound) 0.99960 (outbound)
Orbital period	≈ 2.79 million yr (inbound) ≈ 4.56 million yr (outbound)
Inclination	95.466° (inbound) 95.460° (outbound)
Longitude of ascending node	190.003° (inbound) 190.009° (outbound)
Argument of periapsis	326.280° (inbound) 326.246° (outbound)
Next perihelion	≈ 23 January 2031^[d]
TJupiter	–0.398^[7]
Jupiter MOID	6.173 AU^[7]
Physical characteristics
Dimensions	a/b = 1.26±0.11^[8]
Mean diameter	119±15^[e] to 137±17 km^[10]
Synodic rotation period	20.6±0.2 d^[8]
Geometric albedo	0.033±0.009 to 0.044±0.012^[f]
Comet total magnitude (M1)	6.2±0.9^[7]
Comet nuclear magnitude (M2)	8.63±0.11^[9]

Observational history

Discovery

 

Color composite image of C/2014 UN₂₇₁ from the Dark Energy Survey in October 2017

C/2014 UN₂₇₁ was discovered by astronomers Pedro Bernardinelli and Gary Bernstein in an algorithm-assisted search for slowly-moving trans-Neptunian objects, in archival images from the Dark Energy Survey (DES) at Cerro Tololo Inter-American Observatory.^[13] It was detected at the 22nd apparent magnitude in 42 DES images spanning 10 October 2014 to 26 November 2018.^[3] The long observation arc by the DES images revealed that the object was on a near-parabolic trajectory inbound towards the Solar System, implying a cometary origin from the Oort cloud, despite the object's apparently asteroidal (point-like) appearance in the images.^[14][15] When first imaged by the DES, the object was located in the southern constellation Sculptor, inside the orbit of Neptune at a distance of 29.0 AU (4.3 billion km; 2.7 billion mi) from the Sun.^[16][2] The object's relatively high brightness from its distance indicated that its diameter must be on the order of 100 km (62 mi)—an exceptionally large size for an object of cometary origin.^[3]

The discovery was announced by the Minor Planet Center on 19 June 2021, and the object was given the minor planet provisional designation 2014 UN₂₇₁.^[11][h] The object attracted significant attention from astronomers worldwide: astronomers made follow-up observations and found several precoveries within days of the announcement.^[1][14] The earliest precovery observations of 2014 UN₂₇₁ were obtained from Paranal Observatory's VISTA survey images taken on 15 November 2010, when the object was 34.1 AU (5.1 billion km; 3.2 billion mi) from the Sun.^[3]

Cometary activity

 

Comet Bernardinelli–Bernstein with a diffuse coma, imaged by Las Cumbres Observatory on 22 June 2021

 

Comet Bernardinelli–Bernstein imaged by the Hubble Space Telescope on 8 January 2022

Cometary activity in 2014 UN₂₇₁ was first reported on 22 June 2021, by Tim Lister at Las Cumbres Observatory's telescope in Sutherland, South Africa and by Luca Buzzi at the SkyGems Remote Telescope in Namibia. The comet was found to be one magnitude brighter than predicted in their observations, with a slightly asymmetric coma up to 15 arcseconds in width.^[18][1] At that time, the comet's distance from the Sun was 20.2 AU (3.0 billion km; 1.9 billion mi).^[18] The detection of cometary activity was confirmed by the Minor Planet Center and the comet was formally named C/2014 UN₂₇₁ (Bernardinelli–Bernstein) on 24 June 2021.^[1][i]

Analysis of archival images from NASA's Transiting Exoplanet Survey Satellite (TESS) show that C/2014 UN₂₇₁ had an extensive, diffuse coma at least 43 arcseconds wide in observations as early as September 2018, when it was 23.8 AU (3.6 billion km) from the Sun.^[3][20] Between the 2018 and 2020 TESS observation epochs, the comet's brightness had significantly increased by 1.5 magnitudes, likely as a result of continuous activity rather than a spontaneous outburst.^[3][21]

Reexamination of other telescope datasets have also identified a diffuse and distinctly asymmetric coma in DES images beginning from 2017 (at 25.1 AU) and Pan-STARRS 1 images beginning from 2019 (at 22.6 AU). C/2014 UN₂₇₁'s coma brightness has been growing exponentially since 2017, while the comet's overall brightness had remained steady in 2014–2018, hinting that activity may have well begun prior to the comet's discovery at 29.0 AU.^[3][20] The observation of cometary activity from such large heliocentric distances is rare: only three other comets, Comet Hale–Bopp (27.2 AU outbound),^[22] C/2010 U3 (Boattini) (25.8 AU inbound), and C/2017 K2 (PanSTARRS) (24.0 AU inbound), have been observed to exhibit activity at heliocentric distances greater than 20 AU.^[3][21] As of 2022^[update], C/2014 UN₂₇₁ holds the record for the greatest distance at which a comet has been discovered in the Solar System.^[12]

C/2014 UN₂₇₁ was observed by the Hubble Space Telescope in January,^[23][9] March, July, August, and October 2022.^[24]

2021 outburst

On 9 September 2021, an apparent outburst of C/2014 UN₂₇₁ was detected at Las Cumbres Observatory, as reported on 14 September. It brightened by 0.65 magnitudes compared to images taken earlier that day, and reached an apparent magnitude of 18.9. Calculations based on this brightening indicate that 10 to 100 million kg (11 to 110 thousand short tons) of dust was ejected during the outburst.^[25] At the time, the comet was 19.9 AU (3.0 billion km; 1.8 billion mi) from the Sun.^[26] The comet's brightness has since faded back down to the 19th magnitude by December 2021.^[27]

Occultations

Rigorous computations of C/2014 UN₂₇₁'s orbit and ephemeris have identified few potential occultation events by the comet from 2021–2025, during which the comet would pass in front of a bright star and briefly block out the star's light.^[28] Observing these occultation events would allow for opportunities to make precise measurements of the comet's size and position, as well as search for surrounding dust and possible satellites.^[29] The first attempt at observing one of those occultations was made from Australia and New Zealand on 19 September 2021, but was unsuccessful due to poor weather conditions.^[28]

Visibility

 

Sky path of C/2014 UN₂₇₁ as seen from Earth. The comet is currently moving through the Southern hemisphere and will cross the celestial equator (yellow vertical line) in 2032. The apparent loops in the comet's path are caused by the annual motion of the Earth around the Sun.

With a current declination of −47° below the celestial equator, C/2014 UN₂₇₁ is best seen from the Southern hemisphere. The evolution of its cometary activity will soon be monitored by the upcoming Vera C. Rubin Observatory starting 2023.^[2][15][30] Once at perihelion, the comet is not expected to get brighter than Pluto (mag 13–16) and is more likely to reach the brightness of Pluto's moon Charon (mag 16.8) as the comet does not enter the inner Solar System where comets become notably more active.^[31][32][33] Even if it reaches the magnitude of Pluto, it will require about a 200 mm telescope to be visually seen.^[34]

Nucleus properties

Size and mass

 

Size and color comparison of the largest known comets, including dwarf planet Pluto and natural satellites Mimas and Phobos for scale. C/2014 UN₂₇₁ is the second-largest known comet, being only behind 95P/Chiron.

Radio thermal emission measurements by the Atacama Large Millimeter Array (ALMA) in 2021 estimate a maximum diameter of 137 ± 17 km (85 ± 11 mi) for C/2014 UN₂₇₁'s nucleus, assuming negligible contamination of the nucleus's thermal emission by an unseen dust coma.^[10] The ALMA measurements have not ruled out the possibility of a dust coma contaminating up to 24% of the nucleus's thermal emission, so the actual diameter may well be smaller.^[9] Hubble Space Telescope observations confirmed C/2014 UN₂₇₁'s large size in 2022, placing a lower limit diameter of 119 ± 15 km (74 ± 9 mi) for the maximum possible dust coma contamination.^[9]

Even at its minimum estimated diameter, C/2014 UN₂₇₁ is the largest Oort cloud comet discovered, being more than 50 times larger than a typical comet which is less than 2 km (1.2 mi) in diameter. The previous largest known long-period comet was C/2002 VQ₉₄ (LINEAR) with a diameter of 96 km (60 mi),^[35] followed by Comet Hale–Bopp at 74 km (46 mi).^[10][30][j] The only known comet larger than C/2014 UN₂₇₁ is the active centaur 95P/Chiron, which has a diameter of approximately 215 km (134 mi).^[10]

Media outlets have dubbed C/2014 UN₂₇₁ a "mega-comet",^[30][37] with some even purporting it to be a possible dwarf planet.^[32][38][39] However, C/2014 UN₂₇₁ lies far below the 400–1,000 km (250–620 mi) diameter threshold for hydrostatic equilibrium; it cannot be a dwarf planet as it is most likely not massive enough to have become spherical through its own gravity.^[40][41] Additionally, comet nuclei up to the size of C/2014 UN₂₇₁ typically have low bulk densities below 1 g/cm³, indicative of highly porous interior structures in contrast to the solid and differentiated interiors of dwarf planets.^[40]

While the mass and density C/2014 UN₂₇₁ have not yet been measured,^[3] a rough estimate by NASA places its mass at 450 quadrillion kg (500 trillion short tons), about 100,000 times greater than that of a typical comet.^[42]

Albedo and color

 

Artist's impression of Bernardinelli–Bernstein

Without its coma, the nucleus of C/2014 UN₂₇₁ has a visual (V-band) absolute magnitude of 8.63±0.11, which is calculated from its distance and apparent magnitude.^[9] Given the minimum estimated diameter (119 km) and absolute magnitude, the nucleus is calculated to have a very low visual geometric albedo up to 4.4%±1.2%, meaning that it reflects only 4.4%±1.2% of visible light—making its surface darker than coal.^[42] For the maximum estimated diameter (137 km), the minimum albedo of the nucleus would be 3.3%±0.9%.^[9] C/2014 UN₂₇₁'s low albedo is characteristic of small comet nuclei from both short- and long-period populations, suggesting a lack of correlation between albedo, nucleus size, and orbit type in Solar System comets.^[10] The low albedos of cometary nuclei are generally attributed to the deposition of carbon, organic compounds, and sulfides produced by cosmic rays dissociating molecules on the nucleus's surface.^[10][43]

Optical observations of C/2014 UN₂₇₁ during its inbound passage show that its nucleus appears more reflective at longer wavelengths, indicating a moderately red color similar to (albeit slightly less red than) most long-period comets.^[3][10] The albedo and color of C/2014 UN₂₇₁'s nucleus are expected to change over time due to cometary activity, especially after perihelion passage when temperatures decrease; its nucleus is massive enough to gravitationally recapture deposited icy ejecta back onto its surface, similar to what has been observed on Comet Hale–Bopp after its perihelion.^[10]

Rotation

The rotation period of 2014 UN₂₇₁'s nucleus is disputed, as some studies found no significant rotational periodicity in its light curve. Continuous observations by TESS in 2018 and 2020 did not detect any periodicity, placing an upper limit of 0.3 magnitudes for the nucleus's amplitude of variability.^[44][21] In 2021, Bernardinelli and collaborators from the DES analyzed various ground-based telescope datasets from 2018 and earlier, finding an apparent nucleus variability of 0.2 magnitudes, but no periodicity due to sparse data. Bernardinelli et al. do not rule out other factors such as small dust outbursts that may contribute to this apparent variability, leaving room for the possibility that the nucleus's true rotational variability may be even less than 0.2 magnitudes.^[3] In April 2022, astronomers Ignacio Ferrin and A. Ferrero reported a nucleus rotation period of 20.6±0.2 days, based on an analysis of 2014 UN₂₇₁'s long-term light curve behavior in observations from the Minor Planet Center's database.^[8] Ferrin and Ferrero found a nucleus light curve amplitude of 0.5±0.1 magnitudes, incongruous with findings by TESS and Bernardinelli et al.^[8]

Cometary properties

The exponential brightening of C/2014 UN₂₇₁'s coma at 20–25 AU is consistent with it being generated by sublimating carbon dioxide (CO₂) or ammonia (NH₃) ices from the nucleus's surface.^[3] Less abundant supervolatile substances such as carbon monoxide (CO) are likely present in C/2014 UN₂₇₁ and may additionally contribute to its distant activity, but their emissions remain yet to be detected.^[3] Infrared NEOWISE observations from November 2020 did not detect any CO gas emission from C/2014 UN₂₇₁ at 20.9 AU, placing an upper limit CO outgassing rate at about ten times that of Comet Hale–Bopp at the same heliocentric distance.^[21]

Analysis of C/2014 UN₂₇₁'s coma shape in TESS images from 2018–2020 suggests that the coma is composed of submillimeter-sized dust grains ejected at low speeds around 10 m/s (33 ft/s), indicating that the comet had become active 2 to 10 years prior to 2018.^[21][9] Based on the coma's brightness in Hubble observations from January 2022, C/2014 UN₂₇₁ is losing mass at a rate of roughly 1,000 kg/s (1.1 short ton/s) at 20 AU, similar to Comet Hale–Bopp at this distance.^[9]

Orbit and origin

 

Orbit diagram of C/2014 UN₂₇₁'s near-parabolic trajectory passing perpendicularly through the outer Solar System

C/2014 UN₂₇₁ came from the Oort cloud and has been inside of the orbit of Neptune (29.9 AU) since March 2014 and passed inside the orbit of Uranus (18.3 AU) in September 2022.^[k][16][45] The time of perihelion has been well-known since June 2021.^[6] The current 3-sigma uncertainty in the comet's distance from the Sun is ±35,000 km.^[16]

The inbound and outbound orbital period of an Oort cloud comet are never exactly the same as the orbit changes as a result of planetary perturbations. For an Oort cloud comet an orbit defined while inside of the planetary region can produce results that are misleading. Therefore, the inbound and outbound orbits should be computed before entering the planetary region and after leaving the planetary region. With an observation arc of several years using dozens of observations, the orbit of C/2014 UN₂₇₁ is securely known.^[l] Its incoming orbit in 1600, as calculated by JPL Horizons, has a semimajor axis of 20,000 AU (0.3 ly).^[4] This indicates that C/2014 UN₂₇₁ was at its furthest distance, or aphelion, of 40,000 AU (0.6 ly) in the Oort cloud around 1.4 million years ago.^[4][a][m] It will come to perihelion (closest approach to the Sun) around 23 January 2031 at a distance of 10.95 AU (1.6 billion km; 1.0 billion mi),^[6] just outside the aphelion of Saturn's orbit (10.1 AU).^[6][45] It will make its closest approach to Earth around 5 April 2031 at a distance of 10.1 AU (1.5 billion km; 0.94 billion mi).^[46] It will cross the ecliptic plane on 8 August 2033 when it is outbound 12.0 AU from the Sun.^[47] Its outbound orbital period will be approximately 4.6 million years with an aphelion distance of about 55,000 AU (0.9 ly).^[4] The object is only very loosely bound to the Sun and subject to perturbations by the galactic tide while in the Oort cloud.^[48]

Large, long-period comets such as C/2014 UN₂₇₁ are rarely found due to a phenomenon known as fading: comets on bound orbits around the Sun periodically lose mass and volatile content to activity in each perihelion passage, resulting in a gradual diminishing in size, brightness, and activity as they age.^[49][30] This adds further evidence to C/2014 UN₂₇₁ being a dynamically new comet.^[49]

Comets from the outer Oort Cloud

Comet	Inbound Epoch 1600 Barycentric Aphelion (AU)	Outbound Epoch 2500 Barycentric Aphelion (AU)	Reference
C/1980 E1 (Bowell)	74,000	hyperbolic	Horizons
C/1999 F1 (Catalina)	55,000	66,000	Horizons
C/2000 W1 (Utsunomiya–Jones)	69,000	1,700	Horizons
C/2003 A2 (Gleason)	47,000	15,000	Horizons
C/2006 P1 (McNaught)	67,000	4,100	Horizons
C/2010 U3 (Boattini)	34,000	9,900	Horizons
C/2011 L4 (PanSTARRS)	68,000	4,500	Horizons
Comet ISON	hyperbolic	hyperbolic	Horizons
C/2013 A1 (Siding Spring)	52,000	13,000	Horizons
C/2013 US10 (Catalina)	38,000	hyperbolic	Horizons
C/2014 UN271 (Bernardinelli–Bernstein)	40,000	55,000	Horizons
C/2017 K2 (PanSTARRS)	46,000	1,400	Horizons
C/2017 T2 (PanSTARRS)	74,000	2,900	Horizons
C/2019 E3 (ATLAS)	67,000	34,000	Horizons

Exploration

As of 2022^[update] there are no mission proposals to C/2014 UN₂₇₁, nor are there any upcoming missions that can be retargeted to the comet. The European Space Agency's upcoming Comet Interceptor mission, which will launch in 2029 and make a flyby of a long-period comet within Earth's orbit, will not be able to reach C/2014 UN₂₇₁ due to its large perihelion distance.^[50]

According to a 2021 study by the Initiative for Interstellar Studies, a future flyby mission with a direct, low-energy trajectory to C/2014 UN₂₇₁ can have yearly optimal launch windows between September and October throughout 2022–2029, for a maximum delta-v of 12 km/s at Earth. In all scenarios, the spacecraft would optimally arrive to C/2014 UN₂₇₁ at a relative velocity of 12–14 km/s by August 2033, when the comet crosses the ecliptic plane at 11.9 AU from the Sun.^[51][52] For instance a mission similar to New Horizons (with the same launch vehicle but no Jupiter encounter) could reach C/2014 UN₂₇₁ by August 2033 if launched in October 2029. Alternatively, a flyby trajectory to C/2014 UN₂₇₁ using a combined gravity assist and Oberth maneuver at Jupiter can have feasible launch dates from 2020–2027 and 2034–2037. A launch within the latter window could utilize an Earth flyby to Jupiter after completing a 1:1 Earth resonant orbit, which would significantly reduce the characteristic energy at Earth launch and allow for target arrival above the ecliptic.^[51] A flyby trajectory using consecutive gravity assists and orbital resonances from the inner planets is also possible, but the most optimal encounter combinations provide launch dates up to 2028, for a late 2033 arrival time.^[51]

A rendezvous trajectory to C/2014 UN₂₇₁ has been considered, although the comet's nearly-perpendicular orbit renders any direct rendezvous trajectory from the ecliptic unfeasible.^[52] Nonetheless, a rendezvous with C/2014 UN₂₇₁ can be performed with a Jupiter gravity assist after the comet has crossed the ecliptic, with optimal launch dates in 2030–2034 and flight durations around 14–15 years.^[51]

See also

• List of Solar System objects by greatest aphelion

Notes

1. For epoch 1600-Jan-01 orbit period is "PR = 1.02E+09 / 365.25 days" = ~2.79 million years.^[4] In 1600 the comet was still 310 AU from the Sun and had not entered the planetary region of the Solar System.^[5]
2. For epoch 2500-Jan-01 orbit period is "PR = 1.66E+09 / 365.25 days" = ~4.54 million years.^[4] In 2500 the comet will be 328 AU from the Sun and will have exited the planetary region of the Solar System.^[5]
3. The 3-sigma uncertainty in the perihelion distance is ±50,000 km.^[6]
4. Perihelion passage: Since perihelion has not yet occurred and the orbit is highly eccentric, an epoch closer to 2031 will give a more accurate estimated perihelion date that better accounts for continuing planetary perturbations. The JPL SBDB's epoch 2016 unperturbed two-body solution (Sun+comet) gives a date of 2031-Jan-21. But properly integrating the orbit with JPL Horizons to perihelion passage accounts for all planetary perturbations and gives a date of 2031-Jan-23.^[6]
5. The uncertainty in C/2014 UN₂₇₁'s thermal emission-derived diameter largely comes from the unknown level of thermal contamination by cometary dust surrounding the nucleus. The lower-limit estimate 119±15 km assumes maximal dust contamination, whereas the upper-limit estimate 137±17 km assumes negligible dust contamination.^[9]
6. As with the case of C/2014 UN₂₇₁'s thermal-derived diameter, the uncertainty in C/2014 UN₂₇₁'s visual (V-band) geometric albedo largely comes from the unknown level of thermal contamination by cometary dust surrounding the nucleus. The lower-limit albedo 0.033±0.009 is calculated from the upper-limit diameter assuming negligible dust contamination, whereas the upper-limit albedo 0.044±0.012 is calculated from the lower-limit diameter assuming maximal dust contamination.^[9]
7. Even though they have a large nucleus, comets such as C/2014 UN₂₇₁ (137 km) at 11 AU, 95P/Chiron (215 km) at 8 AU, and C/2002 VQ₉₄ (96 km) at 7 AU do not become visible to the naked eye because they stay outside of the inner Solar System. Comet Hale-Bopp (74 km) was visible to the naked eye as it passed within 1 AU of the Sun.
8. The provisional designation of a minor planet indicates its discovery date and order.^[17] For 2014 UN₂₇₁, 2014 is when the first discovery image was taken, U is the discovery half-month (second half of October), and N₂₇₁ is the discovery counter in that half-month.
9. In official comet naming convention, the C/ prefix indicates a non-periodic orbit and the attached surnames credit the discoverers of the comet.^[19]
10. The Comet of 1729 (C/1729 P1) may be also a large comet with a diameter potentially up to 100 km (62 mi), but this estimate is highly uncertain.^[36]
11. The planets have eccentric orbits, so heliocentric distances inside a planet's orbit are less than its perihelion, while distances outside a planet's orbit are greater than its aphelion.
12. (4 year arc) defined at epoch 2021-Jul-01 had aphelion (Q) = ~14,300 AU and period = ~604,000 years. The current orbit (6 year arc) defined at epoch 2021-Jul-01 also has aphelion (AD) = 14,200 AU and period = ~600,000 years. The solutions are basically the same.
13. While a loosely bound long-period comet such as C/2014 UN₂₇₁ is in the planetary region of the Solar System at an epoch defined near the present year, the JPL Small-Body Database can show a misleading heliocentric orbit solution that does not display the true inbound or outbound orbital period or true aphelion distances.^[7] The orbit of a long-period comet is properly obtained when the osculating orbit is computed using the Solar System barycenter as its reference frame, at an epoch before and/or after leaving the planetary region. Using an epoch of 1600 (inbound) and 2500 (outbound) will generate much more meaningful results.^[4]

References

1. "MPEC 2021-M83 : COMET C/2014 UN271 (Bernardinelli–Bernstein)". Minor Planet Electronic Circulars. Minor Planet Center. 24 June 2021. Retrieved 24 June 2021.
2. Kocz, Amanda (25 June 2021). "Giant Comet Found in Outer Solar System by Dark Energy Survey". NOIRLab. Retrieved 25 June 2021.
3. Bernardinelli, Pedro H.; Bernstein, Gary M.; Montet, Benjamin T.; Weryk, Robert; Wainscoat, Richard; et al. (November 2021). "C/2014 UN271 (Bernardinelli–Bernstein): The Nearly Spherical Cow of Comets". The Astrophysical Journal Letters. 921 (2): 14. arXiv:2109.09852. Bibcode:2021ApJ...921L..37B. doi:10.3847/2041-8213/ac32d3. OSTI 1829535. S2CID 237581632. L37.
4. "JPL Horizons On-Line Ephemeris for 2014 UN271 at epoch 1600 and 2500". JPL Horizons On-Line Ephemeris System. Jet Propulsion Laboratory. Retrieved 20 February 2022. Solution using the Solar System Barycenter. Ephemeris Type: Elements and Center: @0 (To be outside planetary region, inbound epoch 1600 and outbound epoch 2500. Aphelia/orbital periods defined while in the planetary-region are misleading for knowing the long-term inbound/outbound solutions.)
5. "Distance from Sun in 1600 and 2500". JPL Horizons On-Line Ephemeris System (Range, radial velocity/range rate, and range 3-sigma uncertainties). Jet Propulsion Laboratory. Retrieved 20 February 2022.
6. "Perihelion in January 2031 (1 minute interval)". JPL Horizons On-Line Ephemeris System (Perihelion occurs when rdot flips from negative to positive at 00:32 UT). Jet Propulsion Laboratory. from the original on 20 February 2022. Retrieved 20 February 2022.
7. "JPL Small-Body Database Browser: C/2014 UN271 (Bernardinelli–Bernstein)" (2022-02-13 last obs.). Jet Propulsion Laboratory. Retrieved 14 February 2022.
8. Ferrin, I.; Herrero, A. (29 April 2022). "Diameter and rotational period of Comet C/2014 UN271 (Bernardinelli-Bernstein)". The Astronomer's Telegram. 15356 (15356): 1. Bibcode:2022ATel15356....1F. Retrieved 24 May 2022.
9. Hui, Man-To; Jewitt, David; Yu, Liang-Liang; Mutchler, Max J. (April 2022). "Hubble Space Telescope Detection of the Nucleus of Comet C/2014 UN271 (Bernardinelli–Bernstein)". The Astrophysical Journal Letters. 929 (1): 7. arXiv:2202.13168. Bibcode:2022ApJ...929L..12H. doi:10.3847/2041-8213/ac626a. S2CID 247158849. L12.
10. Lellouch, E.; Moreno, R.; Bockelée-Morvan, D.; Biver, N.; Santos-Sanz, P. (March 2022). "Size and albedo of the largest detected Oort-cloud object: comet C/2014 UN271 (Bernardinelli–Bernstein)" (PDF). Astronomy & Astrophysics. 659: 8. arXiv:2201.13188. Bibcode:2022A&A...659L...1L. doi:10.1051/0004-6361/202243090. S2CID 246430382. L1.
11. Bernardinelli, Pedro; Bernstein, Gary (19 June 2021). "MPEC 2021-M53 : 2014 UN271". Minor Planet Electronic Circulars. 2021-M53. Minor Planet Center. Bibcode:2021MPEC....M...53B. Retrieved 19 June 2021.
12. "Illustration of Comet Bernardinelli–Bernstein". NOIRLab. 25 June 2021. Retrieved 14 July 2021.
13. Bernardinelli, Pedro H.; Bernstein, Gary M.; Sako, Masao; Yanny, Brian; et al. (February 2022). "A search of the full six years of the Dark Energy Survey for outer Solar System objects". The Astrophysical Journal Supplement Series. 258 (2): 20. arXiv:2109.03758. Bibcode:2022ApJS..258...41B. doi:10.3847/1538-4365/ac3914. OSTI 1833281. S2CID 237440391. 41.
14. Green, Daniel W. E. (21 June 2021). "CBET 4983: 2014 UN_271". Central Bureau Electronic Telegram. Central Bureau for Astronomical Telegrams. from the original on 14 June 2022. Retrieved 14 June 2022.
15. Gater, Will (24 June 2021). "Huge Oort Cloud object has been spotted entering the solar system". PhysicsWorld. Retrieved 24 June 2021.
16. "Distance from Sun from 2010 to 2023 (1 month interval)". JPL Horizons On-Line Ephemeris System (Range, radial velocity/range rate, Constellation, and range 3-sigma uncertainties). Jet Propulsion Laboratory. Retrieved 20 February 2022.
17. "New- And Old-Style Minor Planet Designations". Minor Planet Center. Retrieved 20 February 2022.
18. Kokotanekova, Rosita; Lister, Tim; Bannister, Michele; Snodgrass, Colin; Opitom, Cyrielle; Schwamb, Meg; Kelley, Michael S. P. (22 June 2021). "Newly discovered object 2014 UN271 observed as active at 20.18 au". The Astronomer's Telegram. 14733 (14733): 1. Bibcode:2021ATel14733....1K. Retrieved 22 June 2021.
19. "Naming of Astronomical Objects". International Astronomical Union. Retrieved 20 February 2022.
20. Farnham, Tony (6 July 2021). "Comet C/2014 UN271 (Bernardinelli–Bernstein) exhibited activity at 23.8 au". The Astronomer's Telegram. 14759 (14759): 1. Bibcode:2021ATel14759....1F. Retrieved 6 July 2021.
21. Farnham, Tony L.; Kelley, Michael S. P.; Bauer, James M. (December 2021). "Early Activity in Comet C/2014 UN271 Bernardinelli–Bernstein as Observed by TESS". The Planetary Science Journal. 2 (6): 8. Bibcode:2021PSJ.....2..236F. doi:10.3847/PSJ/ac323d. S2CID 244727277. 236.
22. Kramer, Emily A.; Fernandez, Yanga R.; Lisse, Carey M.; Kelley, Michael S. P.; Woodney, Laura M. (July 2014). "A dynamical analysis of the dust tail of Comet C/1995 O1 (Hale–Bopp) at high heliocentric distances". Icarus. 236: 136–145. arXiv:1404.2562. Bibcode:2014Icar..236..136K. doi:10.1016/j.icarus.2014.03.033. S2CID 119201510.
23. Hui, Man-To (November 2021). "A Remarkable Inbound Long-Period Comet at Record Heliocentric Distances". Mikulski Archive for Space Telescopes (HST Proposal 16886). Space Telescope Science Institute: 16886. Bibcode:2021hst..prop16886H. Retrieved 14 February 2022.
24. Bolin, Bryce (November 2021). "Determining the coma contents of the incoming Oort Cloud comet C/2014 UN271". Mikulski Archive for Space Telescopes (HST Proposal 16878). Space Telescope Science Institute: 16878. Bibcode:2021hst..prop16878B. Retrieved 14 February 2022.
25. Marcin, Wesołowski (March 2022). "Dust mass loss during the recent outburst of comet C/2014 UN271 Bernardinelli–Bernstein". Monthly Notices of the Royal Astronomical Society. 512 (4): 4683–4688. Bibcode:2022MNRAS.512.4683W. doi:10.1093/mnras/stac682.
26. Kelley, Michael S. P.; Lister, Tim; Holt, Carrie E. (14 September 2021). "Apparent Outburst of Comet C/2014 UN271 (Bernardinelli–Bernstein)". The Astronomer's Telegram. 14917 (14917): 1. Bibcode:2021ATel14917....1K. Retrieved 15 September 2021.
27. "C/2014 UN271 (Bernardinelli–Bernstein)". Minor Planet Center. Retrieved 19 June 2021.
28. Eubanks, Marshall (22 September 2021). "C/2014 UN271 a bust". International Occultation Timing Association Group. Retrieved 13 February 2022.
29. Barry, Tony (8 February 2021). "Occultation by the Big Comet C/2014 UN271 from the Oort Cloud predicted for Sun 19th September at 2:45am AEST Sydney time" (PDF). Western Sydney Amateur Astronomy Group. Retrieved 13 February 2022.
30. Meghan, Bartels (7 September 2021). "The 'megacomet' Bernardinelli–Bernstein is the find of a decade. Here's the discovery explained". Space.com. Retrieved 15 February 2022.
31. Yoshida, Seiichi. "C/2014 UN271 (Bernardinelli–Bernstein)". aerith.net. Retrieved 12 February 2022.
32. Irving, Michael (20 June 2021). "Extremely eccentric minor planet to visit inner solar system this decade". New Atlas. Retrieved 21 June 2021.
33. Williams, David R. (23 December 2021). "Pluto Fact Sheet". NASA Space Science Data Coordinated Archive. NASA. Retrieved 20 February 2022.
34. Johnson-Roehr (4 July 2021). "See Pluto in 2015". Sky & Telescope. Retrieved 4 July 2021.
35. Korsun, Pavlo P.; Rousselot, Philippe; Kulyk, Irina V.; Afanasiev, Viktor L.; Ivanova, Oleksandra V. (April 2014). "Distant activity of Comet C/2002 VQ94 (LINEAR): Optical spectrophotometric monitoring between 8.4 and 16.8 au from the Sun". Icarus. 232: 88–96. arXiv:1401.3137. Bibcode:2014Icar..232...88K. doi:10.1016/j.icarus.2014.01.006. S2CID 118462955.
36. Hecht, Jeff (22 June 2021). "Giant Oort Cloud Comet Lights Up in the Outer Solar System". Sky & Telescope. Retrieved 14 April 2022.
37. Dvorsky, George (8 February 2021). "Mega Comet Arriving From the Oort Cloud Is 85 Miles Wide". Gizmodo. Retrieved 12 February 2022.
38. Whitt, Kelly Kizer (24 June 2021). "Mega comet inbound from Oort Cloud". EarthSky. Retrieved 12 February 2022.
39. Tomaswick, Andy (24 June 2021). "A Newly-Discovered (Almost) Dwarf Planet Will Come Surprisingly Close in 2031". Universe Today. Retrieved 12 February 2022.
40. Grundy, W. M.; Noll, K. S.; Buie, M. W.; Benecchi, S. D.; Ragozzine, D.; Roe, H. G. (December 2019). "The mutual orbit, mass, and density of transneptunian binary Gǃkúnǁʼhòmdímà ((229762) 2007 UK₁₂₆)" (PDF). Icarus. 334: 30–38. Bibcode:2019Icar..334...30G. doi:10.1016/j.icarus.2018.12.037. S2CID 126574999. (PDF) from the original on 7 April 2019.
41. O'Callaghan, Jonathan (30 June 2021). "Astronomers Thrill at Giant Comet Flying into Our Solar System". Scientific American. Retrieved 12 February 2022.
42. Gianopoulos, Andrea (12 April 2022). "Hubble Confirms Largest Comet Nucleus Ever Seen". NASA. Retrieved 12 April 2022.
43. Andrews, Robin George (14 April 2022). "Hubble Telescope Zooms In on the Biggest Comet Ever Spotted". The New York Times. Retrieved 14 April 2022.
44. Ridden-Harper, Ryan; Bannister, Michele T.; Kokotanekova, Rosita (July 2021). "No Rotational Variability in C/2014 UN271 (Bernardinelli–Bernstein) at 23.8 au and 21.1 au as Seen by TESS". Research Notes of the AAS. 5 (7): 161. Bibcode:2021RNAAS...5..161R. doi:10.3847/2515-5172/ac1512. S2CID 236166621.
45. Williams, David R. (27 December 2021). "Planetary Fact Sheet - Metric". NASA Space Science Data Coordinated Archive. NASA. Retrieved 20 February 2022.
46. "Closest Approach to Earth in 2031 (3 hour interval)". JPL Horizons On-Line Ephemeris System (Closest Earth approach occurs when deldot flips from negative to positive). Jet Propulsion Laboratory. Retrieved 25 June 2021.
47. "Ecliptic crossing in August 2033 (1 hour interval)". JPL Horizons On-Line Ephemeris System (Ecliptic crossing occurs when Z flips from negative to positive). Jet Propulsion Laboratory. Retrieved 20 February 2022.
48. Dybczyński, Piotr A.; Królikowska, Małgorzata (February 2022). "The influence of individual stars on the long-term dynamics of comets C/2014 UN271 and C/2017 K2" (PDF). Astronomy & Astrophysics. 660: A100. arXiv:2112.15353. Bibcode:2022A&A...660A.100D. doi:10.1051/0004-6361/202143018. S2CID 245634341.
49. Vokrouhlický, David; Nesvorný, David; Dones, Luke (May 2019). "Origin and Evolution of Long-period Comets". The Astronomical Journal. 157 (5): 10. arXiv:1904.00728. Bibcode:2019AJ....157..181V. doi:10.3847/1538-3881/ab13aa. S2CID 90261947. 181.
50. @CometIntercept (23 June 2021). "There's understandably a _lot_ of excitement about the newly-discovered, apparently huge comet, 2014 UN271. Many people are asking whether our mission could reach it. After all, encountering a long-period comet is Comet Interceptor's main aim. Unfortunately,..." (Tweet). Retrieved 12 February 2022 – via Twitter.
51. Hibberd, Adam (24 August 2021). "2014 UN₂₇₁ Spacecraft Missions" (PDF). Principium (34). Initiative for Interstellar Studies: 42–48. Retrieved 12 February 2022.
52. Davies, John I. (24 August 2021). "News Feature: Mission to 2014 UN271 using OITS" (PDF). Principium (34). Initiative for Interstellar Studies: 38–41. Retrieved 12 February 2022.

External links

 

Wikimedia Commons has media related to C/2014 UN271 (Bernardinelli-Bernstein).

• C/2014 UN271 (Bernardinelli–Bernstein) – comet catalog page by Seiichi Yoshida, updated 5 February 2022
• Giant Comet Found in Outer Solar System by Dark Energy Survey – NOIRLab press release, 25 June 2021
• C/2014 UN271 (Bernardinelli–Bernstein) at AstDyS-2, Asteroids—Dynamic Site
  • Ephemeris · Observation prediction · Orbital info · Proper elements · Observational info
• C/2014 UN271 at the JPL Small-Body Database
  • Close approach · Discovery · Ephemeris · Orbit diagram · Orbital elements · Physical parameters