1082 Pirola

1082 Pirola /ˈpɪrələ/ is a dark Themistian asteroid from the outer regions of the asteroid belt. It was discovered on 28 October 1927, by German astronomer Karl Reinmuth at the Heidelberg-Königstuhl State Observatory in Germany, and assigned the provisional designation 1927 UC.^[1] The carbonaceous C-type asteroid has a rotation period of 15.9 hours and measures approximately 41 kilometers (25 miles) in diameter. It was named after the herbaceous plant Pyrola (wintergreen).^[3]

1082 Pirola

Modelled shape of Pirola from its lightcurve
Discovery[1]
Discovered by	K. Reinmuth
Discovery site	Heidelberg Obs.
Discovery date	28 October 1927
Designations
MPC designation	(1082) Pirola
Pronunciation	/ˈpɪrələ/[2]
Named after	Pyrola (wintergreen) (herbaceous plant)[3]
Alternative designations	1927 UC · 1931 JQ 1951 AH · 1952 DS 1971 YJ · A916 UP
Minor planet category	main-belt[1][4] · (outer) Themis[5][6][7]
Orbital characteristics[4]
Epoch 4 September 2017 (JD 2458000.5)
Uncertainty parameter 0
Observation arc	90.01 yr (32,875 days)
Aphelion	3.6858 AU
Perihelion	2.5553 AU
Semi-major axis	3.1205 AU
Eccentricity	0.1811
Orbital period (sidereal)	5.51 yr (2,013 days)
Mean anomaly	130.74°
Mean motion	0° 10m 43.68s / day
Inclination	1.8524°
Longitude of ascending node	148.01°
Argument of perihelion	187.23°
Physical characteristics
Mean diameter	37.363±1.036 km[8] 39.14±13.91 km[9] 41.47±12.07 km[10] 42.607±0.476 km[11] 42.61±0.48 km[11] 44.67±0.71 km[12]
Synodic rotation period	15.85±0.01 h[13] 15.851±0.0140 h[14] 15.8525±0.0005 h[15] 15.8540±0.0001 h[16]
Pole ecliptic latitude	(123.0°, −42.0°) (λ1/β1)[6] (300.0°, −38.0°) (λ2/β2)[6]
Geometric albedo	0.052±0.006[17] 0.06±0.05[9][10] 0.061±0.002[12] 0.067±0.008[11] 0.0867±0.0105[8]
Spectral type	Tholen = C[4][5] B–V = 0.705[4] U–B = 0.315[4]
Absolute magnitude (H)	10.4[1][4][8][9][11][12] · 10.450±0.002 (R)[14] · 10.507±0.014[15] · 10.51[5] · 10.53[10]

Orbit and classification

When applying the hierarchical clustering method to its proper orbital elements, Pirola is a Themistian asteroid that belongs to the Themis family (602),^[18][6][7] a large family of nearly 6,000 known carbonaceous asteroids, named after 24 Themis.^[19]: 23 It orbits the Sun in the outer main belt at a distance of 2.6–3.7 AU once every 5 years and 6 months (2,013 days; semi-major axis of 3.12 AU). Its orbit has an eccentricity of 0.18 and an inclination of 2° with respect to the ecliptic.^[4] The asteroid was first identified as A916 UP at Simeiz Observatory in October 1916. The body's observation arc begins with its official discovery observation at Heidelberg in October 1927.^[1]

Naming

This minor planet was named after Pyrola, also known as wintergreen, a herbaceous plant (mostly evergreen), that belongs to the flowering herbs. The official naming citation was mentioned in The Names of the Minor Planets by Paul Herget in 1955 (H 102).^[3]

Reinmuth's flowers

Karl Reinmuth submitted a large list of 66 newly named asteroids in the early 1930s. The list covered his discoveries with numbers between (1009) and (1200). This list also contained a sequence of 28 asteroids, starting with 1054 Forsytia, that were all named after plants, in particular flowering plants (also see list of minor planets named after animals and plants).^[20] (Unusually the Pirola has lent its name to a COVID-19 variant: BA.2.86.^[21])

Physical characteristics

In the Tholen classification, Pirola is a carbonaceous C-type asteroid,^[4][5] which matches the overall spectral type of the Themis family.^[19]: 23

Rotation period

In 2010, three rotational lightcurves of Pirola were obtained from photometric observations. Lightcurve analysis gave a rotation period of 15.85, 15.851 and 15.8525 hours with a brightness amplitude between 0.53 and 0.62 magnitude (U=3-/2/3).^[13][14][15]

A 2016-published lightcurve, using modeled photometric data from the Lowell Photometric Database, gave a concurring period of 15.8540 hours, as well as two spin axis of (123.0°, −42.0°) and (300.0°, −38.0°) in ecliptic coordinates (λ, β).^[16]

Diameter and albedo

According to the surveys carried out by the Japanese Akari satellite and the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer, Pirola measures between 37.363 and 44.67 kilometers in diameter and its surface has an albedo between 0.052 and 0.0867.^{[8][9][10][11][12][17]} The Collaborative Asteroid Lightcurve Link derives an albedo of 0.0655 and a diameter of 41.06 kilometers based on an absolute magnitude of 10.51.^[5]