| Discovery[1] | |
|---|---|
| Discovered by | J. Palisa |
| Discovery site | Vienna Obs. |
| Discovery date | 18 March 1914 |
| Designations | |
| (783) Nora | |
Named after | Character ofNora Helmer in the playA Doll's House (By poetHenrik Ibsen)[2] |
| A914 FB · A911 QG 1914 UL | |
| Orbital characteristics[3] | |
| Epoch 31 May 2020 (JD 2459000.5) | |
| Uncertainty parameter 0 | |
| Observation arc | 108.44yr (39,607 d) |
| Aphelion | 2.8811AU |
| Perihelion | 1.8046 AU |
| 2.3429 AU | |
| Eccentricity | 0.2297 |
| 3.59 yr (1,310 d) | |
| 136.94° | |
| 0° 16m 29.28s / day | |
| Inclination | 9.3410° |
| 142.09° | |
| 154.70° | |
| Physical characteristics | |
| 55.53±0.08 h[10] | |
| SMASS =C[3] | |
783 Nora (prov. designation:A914 FBor1914 UL) is a darkbackground asteroid from the inner regions of theasteroid belt. It was discovered by Austrian astronomerJohann Palisa at theVienna Observatory on 18 March 1914.[1] The carbonaceousC-type asteroid has a longer-than averagerotation period of 55.5 hours and measures approximately 40 kilometers (25 miles) in diameter. It was likely named afterNora Helmer, principal character in the playA Doll's House by Norwegian poetHenrik Ibsen.[2]
Nora is a non-family asteroid of the main belt'sbackground population when applying thehierarchical clustering method to itsproper orbital elements.[4][5][6] It orbits the Sun in theinner asteroid belt at a distance of 1.8–2.9 AU once every 3 years and 7 months (1,310 days;semi-major axis of 2.34 AU). Its orbit has aneccentricity of 0.23 and aninclination of 9° with respect to theecliptic.[3] The body'sobservation arc begins with its first observation asA911 QG atHeidelberg Observatory on 28 August 1911, more than two years prior to its official discovery observation atVienna Observatory.[1]
Thisminor planet was likely named afterNora Helmer, the heroine in the playA Doll's House (1879) by Norwegian poetHenrik Ibsen (1828–1906). The name was given by the discoverer's friends. Thenaming was also mentioned inThe Names of the Minor Planets byPaul Herget in 1955 (H 78).[2]
In the Bus–BinzelSMASS classification,Nora is a common, carbonaceousC-type asteroid.[3][5] In theTholen classification it is one of few asteroids consideredunclassifiable.
In March 2018, a rotationallightcurve ofNora was obtained fromphotometric observations byTom Polakis at the Command Module Observatory (V02) in Arizona. Lightcurve analysis gave arotation period of55.53±0.08 hours with a low brightness variation of0.08±0.02magnitude (U=2).[10] The result supersedes previous observations by European astronomers at theLa Silla,Haute Provence andHoher List observatories during the 1990s which gave two periods of24 h and34.4±0.5 h with an amplitude of0.2 and0.08±0.02 magnitude, respectively (U=1/2−).[12][13] In April 2007, French astronomer Arnaud Leroy determined a period of9.6 h and a brightness variation of 0.01 magnitude (U=1).[14]
According to the surveys carried out by theNEOWISE mission of NASA'sWide-field Infrared Survey Explorer (WISE), the JapaneseAkari satellite, and the Infrared Astronomical SatelliteIRAS,Nora measures (38.719±0.105), (39.58±0.62) and (40.02±0.8) kilometers in diameter and its surface has analbedo of (0.068±0.012), (0.065±0.002) and (0.0635±0.003), respectively.[7][8][9] TheCollaborative Asteroid Lightcurve Link derives an albedo of 0.0404 and a diameter of 39.84 kilometers based on anabsolute magnitude of 11.1.[11] Alternative mean-diameter measurements published by the WISE team include (41.712±11.25 km), (42.407±0.229 km), (43.41±12.97 km), (43.43±5.49 km) and (46.96±11.00 km) with corresponding albedos of (0.0299±0.0194), (0.0565±0.0056), (0.028±0.017), (0.034±0.009) and (0.025±0.011).[5][11] On 4 May 2004, anasteroid occultation ofNora gave a best-fit ellipse dimension of (40.0 km × 40.0 km), with a poor quality rating of 1. These timed observations are taken when the asteroid passes in front of a distant star.[5]
