1056 Azalea

1056 Azalea, provisional designation 1924 QD, is a stony Florian asteroid from the inner regions of the asteroid belt, approximately 12 kilometers in diameter. It was discovered on 31 January 1924, by astronomer Karl Reinmuth at the Heidelberg-Königstuhl State Observatory in southwest Germany.^[15] The asteroid is named after the Azalea flower.^[3]

1056 Azalea

Light curve-based 3D-model of 1056 Azalea
Discovery[1]
Discovered by	K. Reinmuth
Discovery site	Heidelberg Obs.
Discovery date	31 January 1924
Designations
MPC designation	(1056) Azalea
Pronunciation	/əˈzeɪliə/ ə-ZAY-lee-ə[2]
Named after	Azalea (flower)[3]
Alternative designations	1924 QD · 1925 NA 1929 WX
Minor planet category	main-belt · (inner) Flora[4][5]
Orbital characteristics[1]
Epoch 4 September 2017 (JD 2458000.5)
Uncertainty parameter 0
Observation arc	93.24 yr (34,057 days)
Aphelion	2.6277 AU
Perihelion	1.8321 AU
Semi-major axis	2.2299 AU
Eccentricity	0.1784
Orbital period (sidereal)	3.33 yr (1,216 days)
Mean anomaly	226.32°
Mean motion	0° 17m 45.6s / day
Inclination	5.4267°
Longitude of ascending node	104.17°
Argument of perihelion	212.39°
Physical characteristics
Dimensions	10.66±1.99 km[6] 11.76±0.54 km[7] 11.869±0.136 km[8] 12.40 km (calculated)[4] 12.984±0.069 km[9] 13.07±0.64 km[10]
Synodic rotation period	15.0276 h[11] 15.03±0.05 h[12] 15.15±0.03 h[13]
Geometric albedo	0.223±0.024[10] 0.24 (assumed)[4] 0.2457±0.0401[9] 0.292±0.040[7] 0.34±0.16[6]
Spectral type	SMASS = S[1] · S[4]
Absolute magnitude (H)	11.60[7][9] · 11.70[1][4][10] · 11.73±0.28[14] · 11.83[6]

Orbit and classification

Azalea is a member of the Flora family (402), a giant asteroid family and the largest family of stony asteroids in the main belt.^{[4][5][16]: 23} It orbits the Sun in the inner main belt at a distance of 1.8–2.6 AU once every 3 years and 4 months (1,216 days). Its orbit has an eccentricity of 0.18 and an inclination of 5° with respect to the ecliptic.^[1] The body's observation arc begins at Heidelberg in April 1928, more than 4 years after its official discovery observation.^[15]

Physical characteristics

In the SMASS classification, Azalea is a common stony S-type asteroid.^[1]

Rotation period

In 2004, two rotational lightcurves of Azalea were obtained from photometric observations by a group of predominately Polish astronomers including Agnieszka Kryszczyńska, as well as by astronomers Alain Klotz and Raoul Behrend. Lightcurve analysis gave a rotation period of 15.03 and 15.15 hours with a high brightness variation of 0.70 and 0.79 magnitude, respectively (U=2/2).^[12][13] The high brightness amplitude is typically indicative for a non-spheroidal shape.

Spin axis

In 2013, an international study modeled a lightcurve with a concurring period of 15.0276 hours and found two spin axis of (252.0°, 51.0°) and (64.0°, 41.0°) in ecliptic coordinates (λ, β) (U=n.a.).^[11]

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, Azalea measures between 10.66 and 13.07 kilometers in diameter and its surface has an albedo between 0.223 and 0.34.^{[6][7][8][9][10]}

The Collaborative Asteroid Lightcurve Link assumes an albedo of 0.24 – derived from 8 Flora, the largest member and namesake of the Flora family – and calculates a diameter of 12.40 kilometers based on an absolute magnitude of 11.7.^[4]

Naming

This minor planet was named after the genus of flowering shrubs, Azalea, which are rhododendrons with funnel-shaped corollas.^[3] The official naming citation was mentioned in The Names of the Minor Planets by Paul Herget in 1955 (H 100).^[3]