3247 Di Martino

3247 Di Martino (prov. designation: 1981 YE) is a dark Nysa family asteroid from the inner regions of the asteroid belt. It was discovered on 30 December 1981, by American astronomer Edward Bowell at Lowell's Anderson Mesa Station near Flagstaff, Arizona, in the United States.^[1] The asteroid has a rotation period of 5.4 hours and measures approximately 13 kilometers (8 miles) in diameter.^[3] It was named for Italian astronomer Mario di Martino.^[1]

3247 Di Martino

Shape model of Di Martino from its lightcurve
Discovery[1]
Discovered by	E. Bowell
Discovery site	Anderson Mesa Stn.
Discovery date	30 December 1981
Designations
MPC designation	(3247) Di Martino
Named after	Mario di Martino[1] (Italian astronomer)
Alternative designations	1981 YE · 1968 HR 1979 HO1 · A909 BL
Minor planet category	main-belt[1][2] · (inner)[3] Nysa–Polana[4][5]
Orbital characteristics[2]
Epoch 23 March 2018 (JD 2458200.5)
Uncertainty parameter 0
Observation arc	109.09 yr (39,844 d)
Aphelion	2.6824 AU
Perihelion	2.0727 AU
Semi-major axis	2.3776 AU
Eccentricity	0.1282
Orbital period (sidereal)	3.67 yr (1,339 d)
Mean anomaly	229.54°
Mean motion	0° 16m 7.68s / day
Inclination	3.9342°
Longitude of ascending node	45.601°
Argument of perihelion	146.34°
Physical characteristics
Mean diameter	11.267±2.644 km[6] 11.74±3.06 km[7] 12.42±2.19 km[8] 13.60±5.23 km[9] 13.72 km (derived)[3] 13.75±1.0 km[10] 15.60±0.51 km[11]
Synodic rotation period	5.443±0.0014 h[12] 5.4446±0.0007 h[13] 5.445 h[14] 5.44517±0.00005 h[15]
Pole ecliptic latitude	(53.0°, −70.0°) (λ1/β1)[15] (231.0°, −75.0°) (λ2/β2)[15]
Geometric albedo	0.05±0.10[8] 0.053±0.004[11] 0.0540 (derived)[3] 0.060±0.060[9] 0.0647±0.011[10] 0.08±0.09[7] 0.0925±0.0544[6]
Spectral type	S (assumed)[3]
Absolute magnitude (H)	12.90[10][11] 13.00[7][9] 13.1[2][3] 13.116±0.003 (R)[12] 13.26[6] 13.51[8]

Orbit and classification

Di Martino is member of the Nysa–Polana complex (405),^[4][5] one of the largest asteroid families.^[16] Its low albedo (see below) it likely belongs to the Polana family within the larger Nysa–Polana complex. The asteroid orbits the Sun in the inner main-belt at a distance of 2.1–2.7 AU once every 3 years and 8 months (1,339 days; semi-major axis of 2.38 AU). Its orbit has an eccentricity of 0.13 and an inclination of 4° with respect to the ecliptic.^[2] The body's observation arc begins with its first observation as A909 BL at Heidelberg Observatory in January 1909, almost 73 years prior to its official discovery observation at Anderson Mesa.^[1]

Naming

This minor planet was named after Mario di Martino (born 1947), Italian astronomer and photometrist of lightcurves at the Turin Observatory. The official naming proposed by the discoverer. The citation was prepared by Alain Harris and published by the Minor Planet Center on 14 April 1987 (M.P.C. 11749).^[17]

Physical characteristics

Di Martino is an assumed S-type asteroid,^[3] while its low albedo indicates a carbonaceous composition.

Rotation period

Three rotational lightcurve of Di Martino have been obtained from photometric observations by French amateur astronomer Pierre Antonini and at the Palomar Transient Factory and Haute Provence Observatory (U=2/3/3).^[12][13][14] Lightcurve analysis gave a rotation period of 5.445 hours with a consolidated brightness amplitude between 0.32 and 0.51 magnitude (U=2/3/3), indicative of a somewhat elongated shape.^[3]

In 2016, a modeled lightcurve gave a concurring sidereal period of 5.44517 hours using photometric data from a large international collaboration of astronomers. The study also determined two spin axes of (53.0°, −70.0°) and (231.0°, −75.0°) in ecliptic coordinates (λ, β).^[15]

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, Di Martino measures between 11.267 and 15.60 kilometers in diameter and its surface has an albedo between 0.05 and 0.0925.^{[6][7][8][9][10][11]} The Collaborative Asteroid Lightcurve Link derives an albedo of 0.0540 and a diameter of 13.72 kilometers based on an absolute magnitude of 13.1.^[3]