1101 Clematis

1101 Clematis /ˈklɛmətɪs/ is an Alauda asteroid from the outermost regions of the asteroid belt, approximately 37 kilometers in diameter. It was discovered on 22 September 1928, by German astronomer Karl Reinmuth at the Heidelberg-Königstuhl State Observatory in southwest Germany, and assigned the provisional designation 1928 SJ.^[13] It was named for the flowering plant Clematis. The presumably carbonaceous asteroid has a relatively long rotation period of 34.3 hours.

1101 Clematis

Discovery[1]
Discovered by	K. Reinmuth
Discovery site	Heidelberg Obs.
Discovery date	22 September 1928
Designations
MPC designation	(1101) Clematis
Pronunciation	/ˈklɛmətɪs/[2]
Named after	κληματίς clēmatis (flowering plant)[3]
Alternative designations	1928 SJ · 1928 WB 1963 TG1 · 1969 TG1
Minor planet category	main-belt · (outer)[1][4] Alauda[5]
Adjectives	Clematidian
Orbital characteristics[1]
Epoch 4 September 2017 (JD 2458000.5)
Uncertainty parameter 0
Observation arc	89.17 yr (32,571 days)
Aphelion	3.4833 AU
Perihelion	2.9770 AU
Semi-major axis	3.2302 AU
Eccentricity	0.0784
Orbital period (sidereal)	5.81 yr (2,120 days)
Mean anomaly	151.11°
Mean motion	0° 10m 11.28s / day
Inclination	21.424°
Longitude of ascending node	201.98°
Argument of perihelion	107.54°
Physical characteristics
Dimensions	29.13±1.62 km[6] 29.65±1.21 km[7] 33.765±0.809 km[7] 37.60 km (derived)[4] 37.86±1.4 km[8]
Synodic rotation period	6 h[9] 8.5994±0.0006 h[9] 8.61±0.02 h[9] 12.68±0.01 h[10] 34.3±0.1 h[11][a]
Geometric albedo	0.0788 (derived)[4] 0.1124±0.009[8] 0.127±0.019[7] 0.190±0.023[6]
Spectral type	C (assumed)[4]
Absolute magnitude (H)	10.10[6][8] · 10.50[4][7] · 10.6[1] · 10.64±0.28[12]

Orbit and classification

Clematis is a member of the Alauda family (902),^[5] a large family of typically "bright" carbonaceous asteroids and named after its parent body, 702 Alauda.^[14]: 23 According to a different study, this object is also the namesake of the Clematis family, a small family of 5–16 asteroids hence they may have arisen from the same collisional event. All members have a relatively high orbital inclination.^[15]

It orbits the Sun in the outermost asteroid belt at a distance of 3.0–3.5 AU once every 5 years and 10 months (2,120 days; semi-major axis of 3.23 AU). Its orbit has an eccentricity of 0.08 and an inclination of 21° with respect to the ecliptic.^[1]

The body's observation arc begins with its observation as 1963 TG₁ at Goethe Link Observatory in October 1963, more than 35 years after its official discovery observation at Heidelberg.^[13]

Physical characteristics

Clematis is an assumed carbonaceous C-type asteroids,^[4] while the overall spectral type for members of the Alauda family is that of a somewhat brighter B-type.^[14]: 23

Rotation period

In September 2009, a rotational lightcurve^[a] of Clematis was obtained from photometric observations by American astronomers Brian Warner at the Palmer Divide Observatory, Colorado, and by Robert Stephens at GMARS (G79, California. Lightcurve analysis gave a synodic rotation period of 34.3 hours with a brightness amplitude of 0.16 magnitude (U=2),^[11] which significantly differs from previously reported periods of 6 to 12.68 hours (U=1/2/2/2).^[9][10] While not being a slow rotator, Clematis has a much longer period than that known for most other asteroids, and its small amplitude is indicative for a rather spheroidal shape.

Diameter and albedo

According to the surveys carried out by the Infrared Astronomical Satellite IRAS, the Japanese Akari satellite and the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer, Clematis measures between 29.13 and 37.86 kilometers in diameter and its surface has an albedo between 0.1124 and 0.190.^[6][7][8]

The Collaborative Asteroid Lightcurve Link derives an albedo of 0.0788 and a diameter of 37.60 kilometers based on an absolute magnitude of 10.5.^[4]

Naming

This minor planet was named after the flowering plant Clematis, a genus within the Ranunculaceae (buttercup or crowfoot family). The official naming citation was mentioned in The Names of the Minor Planets by Paul Herget in 1955 (H n.a.).^[3]

Reinmuth's flowers

Due to his many discoveries, 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).^[16]

Notes

1. Lightcurve plot of 1101 Clematis, Palmer Divide Observatory, B. D. Warner (2009): rotation period 34.3±0.1 hours with a brightness amplitude of 0.16±0.02 mag. Quality code of 2. Summary figures at the LCDB