1016 Anitra

1016 Anitra, provisional designation 1924 QG, is a stony Florian asteroid and suspected asynchronous binary system from the inner regions of the asteroid belt, approximately 10 kilometers in diameter.

1016 Anitra

Discovery[1]
Discovered by	K. Reinmuth
Discovery site	Heidelberg Obs.
Discovery date	31 January 1924
Designations
MPC designation	(1016) Anitra
Pronunciation	/əˈniːtrə/
Named after	fictional character in drama Peer Gynt[2]
Alternative designations	1924 QG · 1929 TE1
Minor planet category	main-belt · (inner)[3] Flora[4]
Orbital characteristics[1]
Epoch 4 September 2017 (JD 2458000.5)
Uncertainty parameter 0
Observation arc	93.42 yr (34,123 days)
Aphelion	2.5035 AU
Perihelion	1.9356 AU
Semi-major axis	2.2196 AU
Eccentricity	0.1279
Orbital period (sidereal)	3.31 yr (1,208 days)
Mean anomaly	176.01°
Mean motion	0° 17m 53.16s / day
Inclination	6.0352°
Longitude of ascending node	8.8588°
Argument of perihelion	53.320°
Known satellites	1[5][6]
Physical characteristics
Dimensions	9.539±0.078 km[7] 10.302±0.068 km[8] 12.97 km (calculated)[3]
Synodic rotation period	5.928±0.001 h[9] 5.9288±0.0005 h[10] 5.929±0.001 h[11] 5.9295±0.0005 h[12] 5.92951 h[3] 5.9294±0.0001 h[6] 5.9300±0.0001 h[6] 5.930 h[13] 5.93 h[a] 5.9301±0.0003 h[14]
Geometric albedo	0.20 (assumed)[3] 0.2728±0.0572[8] 0.308±0.048[7]
Spectral type	SMASS = S[1] · S[3]
Absolute magnitude (H)	11.8[3] · 11.9[1] · 12.0[8]

It was discovered on 31 January 1924, by German astronomer Karl Reinmuth at the Heidelberg-Königstuhl State Observatory in southwest Germany.^[15] The asteroid was likely named after the fictional character Anitra from Henrik Ibsen's drama Peer Gynt.^[2]

Orbit and classification

Anitra is a member of the Flora family (402), a giant asteroid family and the largest family of stony asteroids in the main-belt.^{[4][16]: 23}

It orbits the Sun in the inner main-belt at a distance of 1.9–2.5 AU once every 3 years and 4 months (1,208 days). Its orbit has an eccentricity of 0.13 and an inclination of 6° with respect to the ecliptic.^[1] The asteroid's observation arc begins at Heidelberg, 12 days after to its official discovery observation.^[15]

Physical characteristics

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

Rotation period

In November 2015, a rotational lightcurve of Anitra was obtained from photometric observations by an international collaborations of astronomers who combined their observational results. Lightcurve analysis gave a rotation period of 5.92951 hours with a brightness amplitude of 0.30 magnitude (U=3).^[6]

Binary system

Anitra is a suspected asynchronous binary asteroid, a system with a fairly large separation, for which tidal forces have been insufficient to synchronize the periods within the system's lifetime.^[5][6] The likely minor-planet moon has a rotation period of 2.609 hours and is thought to orbit its primary every 240 hours. The results, however, are still tentative.^[3] More than 100 known binaries from the asteroid belt have already been discovered.

Diameter and albedo

According to the survey carried out by the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer, Anitra measures 9.539 and 10.302 kilometers in diameter and its surface has an albedo of 0.2728 and 0.308, respectively.^[7][8]

The Collaborative Asteroid Lightcurve Link assumes a standard albedo for stony S-type asteroids of 0.20 and calculates a diameter of 12.97 kilometers based on an absolute magnitude of 11.8.^[3]

Naming

This minor planet was probably named after the Arabian dancer Anitra, daughter of a Bedouin chief in Henrik Ibsen's drama Peer Gynt, a five-act play in verse. The music was composed by Edvard Grieg who named one piece "Anitra's Dance".^[2] The minor planets (4872) and (5696) are named after Grieg and Ibsen, respectively.^[2]

The official naming citation is based on research by Lutz Schmadel and feedback from astronomers R. Bremer and I. van Houten-Groeneveld.^[2]

Notes

1. Menke (2011) web: rotation period 5.93 hours with a brightness amplitude of 0.50 magnitude and a quality code of 2. Summary figures at Collaborative Asteroid Lightcurve Link (CALL)