32P/Comas Solà

32P/Comas Solà is a periodic comet with a current orbital period of 9.7 years around the Sun. It is the second of two comets discovered by Spanish astronomer, Josep Comas Solà.^[a]

32P/Comas Solà

Infrared image of Comet Comas Solà taken by NEOWISE on 4 December 2014
Discovery[1]
Discovered by	Josep Comas i Solà
Discovery site	Fabra Observatory
Discovery date	4 November 1926
Designations
MPC designation	P/1926 V1, P/1935 P1
Alternative designations	1927 III, 1935 IV, 1944 II 1961 III, 1969 VIII 1978 XVII, 1987 XVIII
Orbital characteristics[2][3]
Epoch	5 May 2025 (JD 2460800.5)
Observation arc	98.49 years
Number of observations	5,507
Aphelion	7.082 AU
Perihelion	2.025 AU
Semi-major axis	4.554 AU
Eccentricity	0.55529
Orbital period	9.718 years
Inclination	9.920°
Longitude of ascending node	54.532°
Argument of periapsis	54.703°
Mean anomaly	38.473°
Last perihelion	20 April 2024
Next perihelion	15 January 2034[4]
TJupiter	2.678
Earth MOID	1.029 AU
Jupiter MOID	0.247 AU
Physical characteristics[2]
Mean radius	2.52 km (1.57 mi)[5]
Synodic rotation period	7.3 hours[6]
Comet total magnitude (M1)	10.3
Comet nuclear magnitude (M2)	13.5

Observational history

The comet was discovered on 4 November 1926, by Josep Comas Solà. As part of his work on asteroids for the Fabra Observatory (Barcelona), he was taking photographs with a 6-inch (150 mm) telescope. At the time, its position was located within the constellation Cetus.^[b] The comet's past orbital evolution became a point of interest as several astronomers suggested early on that the comet might be a return of the then lost periodic comet 113P/Spitaler. In 1935, additional positions had been obtained, and P. Ramensky investigated the orbital motion back to 1911. He noted the comet passed very close to Jupiter during May 1912 and that, prior to this approach, the comet had a perihelion distance of 2.15 AU (322 million km) and an orbital period of 9.43 years. The identity with Comet Spitaler was thus disproven.

In 1933, the Danish astronomer Julie Vinter Hansen undertook significant new research which calculated the orbit of the comet up to 1980, predicting when it would return to the Earth's orbit.^[7]

While searching for 32P/Comas Solà in 1969, two Soviet astronomers Klim Churyumov and Svetlana Gerasimenko accidentally discovered a new comet in photographic plates they took, which is now known as 67P/Churyumov–Gerasimenko.^[8]

Physical characteristics

Nucleus size

In 1985, precession models of the comet's nucleus derived an equatorial radius somewhere between 0.99–1.15 km (0.62–0.71 mi).^[9] CCD photometry of the comet taken while it was 3.1 AU (460 million km) from the Sun in 1999 obtained a larger upper limit about 3.2 km (2.0 mi).^[10] Further studies in 2006 revised the size estimate to be about 2.52 km (1.57 mi).^[5]

Rotation period

Initial estimates of the rotation period indicated that the comet spins around its axis once every 1.5 to 2.3 days.^[9] However, based on the 1999 estimate of the size of its nucleus, forced precession models obtained in 2001 indicated a shorter rotation period of around 7.3 hours.^[6]

Notes

1. Josep Comas Solà independently co-discovered C/1925 F1 (Shajn–Comas Solá) over a year earlier with Grigory Shajn.
2. Reported initial position upon discovery was: α = 2^h 56^m 36^s, δ = –6° 31′^[1]