astro.wikisort.org - Asteroid

731 Sorga (prov. designation: A912 GH or 1912 OQ) is a highly elongated background asteroid from the outer regions of the asteroid belt, approximately 38 kilometers (24 miles) in diameter. It was discovered on 15 April 1912, by German astronomer Adam Massinger at the Heidelberg-Königstuhl State Observatory in southwest Germany.[1] The C-type (CD) and X-type asteroid (Xe) has a rotation period of 8.2 hours. It was named Sorga, meaning "the heavens" in the Indonesian language.[2]

731 Sorga

Modelled shape of Sorga from its lightcurve
Discovery [1]
Discovered by	A. Massinger
Discovery site	Heidelberg Obs.
Discovery date	15 April 1912
Designations
MPC designation	(731) Sorga
Named after	"the heavens" [2] (Indonesian language)
Alternative designations	A912 GH · 1940 WP 1912 OQ
Minor planet category	main-belt [1][3] · (outer) background [4][5][6]
Orbital characteristics [3]
Epoch 31 May 2020 (JD 2459000.5)
Uncertainty parameter 0
Observation arc	104.24 yr (38,075 d)
Aphelion	3.4090 AU
Perihelion	2.5656 AU
Semi-major axis	2.9873 AU
Eccentricity	0.1412
Orbital period (sidereal)	5.16 yr (1,886 d)
Mean anomaly	201.03°
Mean motion	0° 11m 27.24s / day
Inclination	10.689°
Longitude of ascending node	46.136°
Argument of perihelion	288.62°
Physical characteristics
Mean diameter	34.597±0.409 km[7][8] 38.93±0.44 km[9] 41.78±2.0 km[10]
Synodic rotation period	8.184±0.005 h[11]
Pole ecliptic latitude	(83.0°, 40.0°) (λ1/β1)[5] (275.0°, 21.0°) (λ2/β2)[5]
Geometric albedo	0.1436±0.015[10] 0.173±0.005[9] 0.209±0.042[7][8]
Spectral type	Tholen = CD [3] SMASS = Xe [3] B–V = 0.691±0.030[3] U–B = 0.312±0.028[3]
Absolute magnitude (H)	9.62[7][9][10] 9.7[1][3]

Orbit and classification

Sorga is a non-family asteroid of the main belt's background population when applying the hierarchical clustering method to its proper orbital elements.[4][5][6] It orbits the Sun in the outer asteroid belt at a distance of 2.6–3.4 AU once every 5 years and 2 months (1,886 days; semi-major axis of 2.99 AU). Its orbit has an eccentricity of 0.14 and an inclination of 11° with respect to the ecliptic.[3] The body's observation arc begins at Heidelberg Observatory on 21 October 1919, more than seven years after its official discovery observation.[1]

Naming

This minor planet was named Sorga, the word for "the heavens" in the Indonesian language, also transliterated as "surga". The naming was not mentioned in The Names of the Minor Planets by Paul Herget.[2]

Physical characteristics

In the Tholen classification, Sorga is closest to a common, carbonaceous C-type asteroid and somewhat similar to a dark D-type asteroid (CD), while in the Bus–Binzel SMASS classification, it is an Xe-subtype which transitions from the X-type to the bright E-type.[3][5] Sorga has also been classified as a metallic M-type asteroid.[12]

Rotation period and poles

In April 2005, a rotational lightcurve of Sorga was obtained from photometric observations by Brian Warner at his Palmer Divide Observatory (716) in Colorado. Analysis gave a classically shaped bimodal lightcurve with a well-defined rotation period of (8.184±0.005) hours and a high brightness variation of (0.52±0.02) magnitude, indicative of its elongated shape (U=3).[11] In February 2009, Warner revisited Sorga and determined a very similar period of (8.192±0.002) hours though with a much lower amplitude of (0.19±0.02) magnitude (U=3).[13][lower-alpha 1]

In January 2010, astronomers at the Palomar Transient Factory measured a period of 8.188±0.0023 hours with an amplitude of 0.72 magnitude (U=2).[12][14] Additional observations by Christophe Demeautis in September 2017, and by Bruno Christmann in April 2020, gave a period of (8.186±0.003) and (8.1865±0.0003) hours with an amplitude of 0.54±0.02 and 0.57±0.02 magnitude, respectively (U=3–/3).[15]

In 2016, a modeled lightcurve rendered a concurring sidereal period of 8.18633±0.00002 hours using data from the Uppsala Asteroid Photometric Catalogue, the Palomar Transient Factory survey, and individual observers, as well as sparse-in-time photometry from the NOFS, the Catalina Sky Survey, and the La Palma surveys (950). The study also determined two spin axes of (83.0°, 40.0°) and (275.0°, 21.0°) in ecliptic coordinates (λ, β).[16]

Diameter and albedo

According to the surveys carried out by the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer (WISE), the Japanese Akari satellite, and the Infrared Astronomical Satellite IRAS, Sorga measures (34.597±0.409), (38.93±0.44) and (41.78±2.0) kilometers in diameter and its surface has an albedo of (0.209±0.042), (0.173±0.005) and (0.1436±0.015), respectively.[7][8][9][10] The Collaborative Asteroid Lightcurve Link derives an albedo of 0.1339 and a diameter of 41.70 kilometers based on an absolute magnitude of 9.7.[12] The WISE team also published an alternative mean-diameter of (31.955±0.293 km) with an albedo of (0.2605±0.0759).[12]

Two asteroid occultations on 24 October 2007, and on 31 October 2012, gave a best-fit ellipse dimension of (45.7 km × 45.7 km) and (38.0 km × 38.0 km), with an intermediate and low quality rating of 2 and 1, respectively.[5] These timed observations are taken when the asteroid passes in front of a distant star.[5]

Notes

References

External links

• Lightcurve Database Query (LCDB), at www.minorplanet.info
• Dictionary of Minor Planet Names, Google books
• Asteroids and comets rotation curves, CdR – Geneva Observatory, Raoul Behrend
• Discovery Circumstances: Numbered Minor Planets (1)-(5000) – Minor Planet Center
• 731 Sorga at AstDyS-2, Asteroids—Dynamic Site
  • Ephemeris · Observation prediction · Orbital info · Proper elements · Observational info
• 731 Sorga at the JPL Small-Body Database
  • Close approach · Discovery · Ephemeris · Orbit diagram · Orbital elements · Physical parameters

На других языках

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[de] (731) Sorga

(731) Sorga ist ein Asteroid des Hauptgürtels, der am 15. April 1912 vom deutschen Astronomen Adam Massinger in Heidelberg entdeckt wurde.

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- [en] 731 Sorga

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[es] (731) Sorga

(731) Sorga es un asteroide perteneciente al cinturón de asteroides descubierto el 15 de abril de 1912 por Adam Massinger desde el observatorio de Heidelberg-Königstuhl, Alemania. Está nombrado por la palabra indonesia para cielo.[2]

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[ru] (731) Сорга

(731) Сорга (лат. Sorga) — астероид главного пояса, который принадлежит к тёмному спектральному классу D. Он был открыт 11 февраля 1912 года немецким астрономом Адамом Массингером в обсерватории Хайдельберг и назван в честь индонезийской богини небес[1].

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