C/1980 E1 (Bowell)

Hyperbolic path with annual motion
Discovery
Discovered by	Edward L. G. Bowell
Discovery date	11 February 1980
Designations
Alternative designations	C/1980 E1
Orbital characteristics[2]
Epoch	JD 2444972.5 (3 January 1982)
Observation arc	6.88 years
Number of observations	187
Aphelion	~75000 AU (inbound)[1]
Perihelion	3.3639 AU[2]
Eccentricity	1.057[2] (hyperbolic trajectory) 1.053 (epoch 1984+)[1]
Orbital period	~7.1 million years (epoch 1950)[1] Ejection (epoch 1977+)[1]
Inclination	1.6617°
Longitude of ascending node	114.558°
Argument of periapsis	135.083°
Last perihelion	12 March 1982[2]
Physical characteristics
Dimensions	> 1 km

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).^[3][4]

Overview

Before entering the inner Solar System for a 1982 perihelion passage, C/1980 E1 had a barycentric (epoch 1950-Jan-01) orbit with an aphelion of 75,000 AU (1.2 ly), and a period of approximately 7.1 million years.^[1]

As the comet was approaching on 9 December 1980, it passed within 0.228 AU of Jupiter,^[2] which accelerated the comet briefly giving an (epoch 1981-Jan-09) eccentricity of 1.066.^[1] The comet came to perihelion on 12 March 1982,^[2] when it had a velocity of 23.3 km/s (52,000 mph) with respect to the Sun. Since the epoch of 1977-Mar-04, C/1980 E1 has had a barycentric eccentricity greater than 1,^[1] keeping it on a hyperbolic trajectory that will eject it from the Solar System. Objects in hyperbolic orbits have a negative semimajor axis, giving them a positive orbital energy. After leaving the Solar System, C/1980 E1 will have an interstellar velocity (${\displaystyle v_{\infty ))$) of 3.77 km/s.^[a] The Minor Planet Center does not directly list a semimajor axis for this comet.^[5]

The escape velocity from the Sun at Neptune's orbit is 7.7 km/s. By June 1995, the comet was passing Neptune's orbit at 30.1 AU from the Sun continuing its ejection trajectory at 8.6 km/s.^[6] Since February 2008, the comet has been more than 50 AU from the Sun.^[7]

Emission of OH (hydroxide) was observed pre-perihelion while the comet was nearly 5 AU from the Sun.^[9] CN (cyanide) was not detected until the comet was near perihelion. The comet nucleus was estimated to have a radius of several kilometers. The surface crust was probably a few meters thick.