Discovery [1] | |
---|---|
Discovered by | Pan-STARRS |
Discovery site | Haleakala Observatory |
Discovery date | 17 March 2018 |
Designations | |
C/2018 F4 | |
hyperbolic comet [2] | |
Orbital characteristics [2] | |
Epoch 23 March 2018 (JD 2458200.5) | |
Observation arc | 27 days |
Perihelion | 3.44584±0.0029 AU |
Eccentricity | 1.00385±0.0072 [a] (JPL) 1.0130±0.0046 (MPC) |
Inclination | 78.2971±0.19° |
Jupiter MOID | 0.60 AU (90 million km) |
Physical characteristics | |
Dimensions | 10–20 km (assumed) [3] |
11.8±0.5 | |
C/2018 F4 (PanSTARRS) is a hyperbolic comet (previously classified as A/2018 F4, a hyperbolic asteroid). [2] It was discovered on 17 March 2018 when it was beyond the orbit of Jupiter, 6.4 AU (960 million km ) from the Sun. [1] It was quite far from the Sun and turned out to simply be an asteroidal object that was discovered before cometary activity was noticeable. As perihelion (closest approach to the Sun) is inside the orbit of Jupiter, this object should become more active. In April 2018 it was determined to be a hyperbolic comet. [4] Given that the incoming velocity was similar to that of an Oort cloud object, we can very confidently say that it is not of interstellar origin. [5] [6] C/2018 F4 fragmented around August 2020. [7]
It would be no problem to fit a parabolic orbit to the C/2018 F4 data, [2] [a] as used to be done for most short arc comets. The orbital eccentricity is decently constrained at 1.0038±0.0072, [a] so it could even be a closed orbit with an eccentricity below 1. [2] The velocity of the object currently has an uncertainty of ±0.2 km/s. With a common Oort cloud velocity of roughly 3 km/s (6,700 mph) when inbound 200 AU from the Sun, there is no reason to think 2018 F4 is of interstellar origin. [5]
It will come to perihelion around 3 December 2019 when it will be 3.4 AU from the Sun. [2]
Further observations will be necessary to determine if the orbit is hyperbolic. As a comet this object became known as C/2018 F4 (PANSTARRS).
The somewhat short observation arc of 35 days suggests that before entering the planetary region of the Solar System (epoch 1950), the comet had an orbital period on the order of a hundred thousand years. The heliocentric eccentricity became greater than 1 in November 2016 when the comet was 9.6 AU (1.44 billion km ) from the Sun.
Object | Year | Velocity km/s | # of observations and obs arc |
---|---|---|---|
90377 Sedna | 1746 | 1.99±0.00 | 196 in 9240 days |
C/1980 E1 (Bowell) | 1765 | 2.95±0.00 | 179 in 2514 days |
C/1997 P2 (Spacewatch) | 1779 | 2.96±0.01 | 94 in 49 days |
C/2010 X1 (Elenin) | 1798 | 2.96±0.00 | 2,222 in 235 days |
C/2012 S1 (ISON) | 1801 | 2.99±0.00 | 6,514 in 784 days |
C/2008 J4 (McNaught) | 1855 | 4.88±5.44 | 22 in 15 days |
C/2018 F4 | 1792 | 2.74±0.03 | 402 in 967 days |
C/1999 U2 (SOHO) | 1947 | 17±447 | 41 in 1 day |
1I/2017 U1 (ʻOumuamua) | 1982 | 26.49±0.03 | 121 in 34 days |
At 200 AU from the Sun, the escape velocity from the Sun is 2.98 km/s. In the above table, the only outlier is ʻOumuamua with a confident 34-day observation arc. Comet C/2008 J4 (McNaught) has a short observation arc with large uncertainties. Comet C/1999 U2 (SOHO) has a meaningless 1-day observation arc. Comet C/2018 F4 has a common Oort cloud velocity when 200 AU from the Sun. [5]
An interstellar object is an astronomical object in interstellar space that is not gravitationally bound to a star. This term can also be applied to an object that is on an interstellar trajectory but is temporarily passing close to a star, such as certain asteroids and comets. In the latter case, the object may be called an interstellar interloper.
C/1980 E1 is a non-periodic comet discovered by Edward L. G. Bowell on 11 February 1980 and which came closest to the Sun (perihelion) in March 1982. It is leaving the Solar System on a hyperbolic trajectory due to a close approach to Jupiter. In the 43 years since its discovery only two objects with higher eccentricities have been identified, 1I/ʻOumuamua (1.2) and 2I/Borisov (3.35).
Comet C/2010 X1 (Elenin) is an Oort cloud comet discovered by Russian amateur astronomer Leonid Elenin on December 10, 2010, through remote control of the International Scientific Optical Network's robotic observatory near Mayhill in the U.S. state of New Mexico. The discovery was made using the automated asteroids discovery program CoLiTec. At the time of discovery, the comet had an apparent magnitude of 19.5, which made it about 150,000 times fainter than can be seen with the naked eye. The discoverer, Leonid Elenin, originally estimated that the comet nucleus was 3–4 km in diameter, but more recent estimates place the pre-breakup size of the comet at 2 km. Comet Elenin started disintegrating in August 2011, and as of mid-October 2011 was not visible even using large ground-based telescopes.
(709487) 2013 BL76 is a trans-Neptunian object and centaur from the scattered disk and Inner Oort cloud approximately 30 kilometers in diameter.
In observational astronomy, the observation arc of a Solar System body is the time period between its earliest and latest observations, used for tracing the body's path. It is usually given in days or years. The term is mostly used in the discovery and tracking of asteroids and comets. Arc length has the greatest influence on the accuracy of an orbit. The number, spacing of intermediate observations, and timestamps have a lesser effect.
2005 HC4 is the asteroid with the smallest known perihelion of any known object orbiting the Sun (except sungrazing comets). Its extreme orbital eccentricity brings it to within 0.071 AU of the Sun (23% of Mercury's perihelion) and takes it as far as 3.562 AU from the Sun (well beyond the orbit of Mars). Due to its very small perihelion and comparably large aphelion, 2005 HC4 achieves the fastest speed of any known asteroid bound to the Solar System with a velocity of 157 km/s (565,000 km/h; 351,000 mi/h) at perihelion (there are comets, however, which obtain much higher speeds).
2012 VP113 is a trans-Neptunian object of the sednoid population, located in the outermost reaches of the Solar System. It was first observed on 5 November 2012 by American astronomers Scott Sheppard and Chad Trujillo at the Cerro Tololo Inter-American Observatory in Chile. The discovery was announced on 26 March 2014. The object probably measures somewhere between 300 and 1000 km in diameter, possibly large enough to be a dwarf planet.
C/2013 US10 (Catalina) is an Oort cloud comet discovered on 31 October 2013 by the Catalina Sky Survey at an apparent magnitude of 19 using a 0.68-meter (27 in) Schmidt–Cassegrain telescope. From September 2015 to February 2016 the comet was around apparent magnitude 6. The comet took around a million years to complete half an orbit from its furthest distance in the Oort cloud and should be ejected from the Solar System over many millions of years.
C/2015 ER61 (PanSTARRS) is a comet and inner Oort cloud object. When classified as a minor planet, it had the fourth-largest aphelion of any known minor planet in the Solar System, after 2005 VX3, 2012 DR30, and 2013 BL76. It additionally had the most eccentric orbit of any known minor planet, with its distance from the Sun varying by about 99.9% during the course of its orbit, followed by 2005 VX3 with an eccentricity of 0.9973. On 30 January 2016, it was classified as a comet when it was 5.7 AU from the Sun. It comes close to Jupiter, and a close approach in the past threw it on the distant orbit it is on now.
2014 FE72 is a trans-Neptunian object first observed on 26 March 2014, at Cerro Tololo Inter-American Observatory in La Serena, Chile. It is a possible dwarf planet, a member of the scattered disc, whose orbit extends into the inner Oort cloud. Discovered by Scott Sheppard and Chad Trujillo, the object's existence was revealed on 29 August 2016. Both the orbital period and aphelion distance of this object are well constrained. 2014 FE72 had the largest barycentric aphelion until 2018. However, the heliocentric aphelion of 2014 FE72 is second among trans-Neptunian objects (after the damocloid 2017 MB7). As of 2023, it is about 66 AU (9.9 billion km) from the Sun.
C/2017 K2 (PanSTARRS) is an Oort cloud comet with an inbound hyperbolic orbit, discovered in May 2017 at a distance beyond the orbit of Saturn when it was 16 AU (2.4 billion km) from the Sun. Precovery images from 2013 were located by July. It had been in the constellation of Draco from July 2007 until August 2020. As of June 2022, the 3-sigma uncertainty in the current distance of the comet from the Sun is ±6000 km.
A hyperbolic asteroid is any sort of asteroid or non-cometary astronomical object observed to have an orbit not bound to the Sun and will have an orbital eccentricity greater than 1 when near perihelion. Unlike hyperbolic comets, they have not been seen out-gassing light elements, and therefore have no cometary coma. Most of these objects will only be weakly hyperbolic and will not be of interstellar origin.
C/2017 U7 (PanSTARRS) is a hyperbolic comet, first observed on 29 October 2017 by astronomers of the Pan-STARRS facility at Haleakala Observatory, Hawaii, United States when the object was 7.8 AU (1.2 billion km) from the Sun. Despite being discovered only 10 days after interstellar asteroid 1I/'Oumuamua, it was not announced until March 2018 as its orbit is not strongly hyperbolic beyond most Oort Cloud comets. Based on the absolute magnitude of 10.6, it may measure tens of kilometers in diameter. As of August 2018, there is only 1 hyperbolic asteroid known, ʻOumuamua, but hundreds of hyperbolic comets are known.
C/2018 C2 (Lemmon) is a hyperbolic comet. It was first observed on 5 February 2018 by the Mount Lemmon Survey conducted at the Mount Lemmon Observatory near Tucson, Arizona, in the United States. The discovery was announced on 4 March 2018 along with another hyperbolic object, A/2017 U7. Based on the absolute magnitude of 15.1, it may measure several kilometers in diameter. On 22 March 2018 it was determined to be a hyperbolic comet.
Comet C/2018 V1 (Machholz–Fujikawa–Iwamoto) is a minor body that follows a slightly hyperbolic orbit. It was visually discovered on 7 November 2018 by Donald Machholz using an 18.5-inch reflecting telescope and it reached perihelion on 3 December 2018.
2I/Borisov, originally designated C/2019 Q4 (Borisov), is the first observed rogue comet and the second observed interstellar interloper after ʻOumuamua. It was discovered by the Crimean amateur astronomer and telescope maker Gennadiy Borisov on 29 August 2019 UTC.
C/2021 O3 (PanSTARRS) is perhaps an Oort cloud comet, discovered on 26 July 2021 by the Pan-STARRS sky survey. It came to perihelion on 21 April 2022 at 0.287 AU (42.9 million km). from the Sun.
2022 NX1 is a near-Earth object roughly 10 meters (33 ft) in diameter discovered by Grzegorz Duszanowicz and Jordi Camarasa. The object orbits the Sun but makes slow close approaches to the Earth–Moon system. Between 11 June 2022 and 3 July 2022 (a period of 22 days) it passed within Earth's Hill sphere (roughly 0.01 AU (1.5 million km; 0.93 million mi)) at a low relative velocity and became temporarily captured by Earth's gravity, with a geocentric orbital eccentricity of less than 1 and negative geocentric orbital energy. Due to its Earth-like orbit, the object might be of artificial origin or lunar ejecta. However, visible spectroscopy obtained with the Gran Telescopio Canarias shows that it is an asteroid. The closest approach to Earth in 2022 was 26 June 2022 at roughly 812,200 km (504,700 mi) when it had a relative velocity of 0.96 km/s (2,100 mph). It was last near Earth around 16 January 1981 when it passed about 600,000 km (370,000 mi) from Earth. It will return as a temporary satellite in December 2051.