_Sphinx.png) Modelled shape ofSphinx from itslightcurve | |
| Discovery[1] | |
|---|---|
| Discovered by | M. F. Wolf |
| Discovery site | Heidelberg Obs. |
| Discovery date | 1 August 1918 |
| Designations | |
| (896) Sphinx | |
| Pronunciation | /ˈsfɪŋks/ |
Named after | |
| A918 PE · 1918 DV | |
| Adjectives | Sphinxian/ˈsfɪŋksiən/[6] |
| Orbital characteristics[3] | |
| Epoch 31 May 2020 (JD 2459000.5) | |
| Uncertainty parameter 0 | |
| Observation arc | 101.50yr (37,074 d) |
| Aphelion | 2.6588AU |
| Perihelion | 1.9128 AU |
| 2.2858 AU | |
| Eccentricity | 0.1632 |
| 3.46 yr (1,262 d) | |
| 211.73° | |
| 0° 17m 6.72s / day | |
| Inclination | 8.1903° |
| 254.18° | |
| 1.9628° | |
| Physical characteristics | |
| 21.038±0.008 h[10] | |
| n.a. | |
| 11.6[1][3] | |
896 Sphinx/ˈsfɪŋks/ is abackground asteroid from the inner regions of theasteroid belt, that measures approximately 13 kilometers (8 miles) in diameter. It was discovered on 1 August 1918, by astronomerMax Wolf at theHeidelberg-Königstuhl State Observatory in southwest Germany.[1] The asteroid has arotation period of 21.0 hours and is one of few low-numbered objects for which nospectral type has been determined. It was named after theSphinx, a creature from Greek and Egyptian mythology.[2]
Sphinx is a non-family asteroid of the main belt'sbackground population when applying thehierarchical clustering method to itsproper orbital elements.[4][5] It orbits the Sun in theinner asteroid belt at a distance of 1.9–2.7 AU once every 3 years and 6 months (1,262 days;semi-major axis of 2.29 AU). Its orbit has aneccentricity of 0.16 and aninclination of 8° with respect to theecliptic.[3] The body'sobservation arc begins atHeidelberg Observatory on 9 October 1918, two months after its official discovery observation.[1]
Thisminor planet was named after theSphinx, alegendary creature fromGreek andEgyptian mythology. The female monster has the head of a woman, the haunches of a lion, and the wings of a bird. It has the habit of killing anyone who cannot answer her riddle. Thenaming citation was mentioned inThe Names of the Minor Planets byPaul Herget in 1955 (H 87).[2]
Contrary to most other low-numbered asteroids, nospectral type has been determined.[5][11] Based on its relatively high albedo(see below) and its location within the inner parts of the main-belt,Sphinx may possibly be a common, stonyS-type asteroid.
In June 2018, a rotationallightcurve ofSphinx was obtained fromphotometric observations byTom Polakis at the Command Module Observatory (V02) in Arizona. Lightcurve analysis gave arotation period of21.038±0.008 hours with a brightness variation of0.16±0.02magnitude (U=2+). However, an alternative period solution of10.541±0.003 hours with an amplitude of0.17±0.02 magnitude is also possible.[10] Both results supersede a tentative period determination byLaurent Bernasconi from September 2001 (U=1).[12]
A modeled lightcurve using photometric data from theLowell Photometric Database and from theWide-field Infrared Survey Explorer (WISE) was published in 2018. It gave a divergent sidereal period of12.95209±0.00002 hours and includes twospin axes at (172.0°, 20.0°) and (352.0°, 42.0°) inecliptic coordinates (λ, β).[13]
According to the surveys carried out by theNEOWISE mission of NASA'sWISE telescope, the Infrared Astronomical SatelliteIRAS, and the JapaneseAkari satellite,Sphinx measures (11.974±0.071), (13.07±0.5) and (14.45±0.35) kilometers in diameter and its surface has analbedo of (0.242±0.045), (0.1971±0.017) and (0.163±0.009), respectively.[7][8][9] TheCollaborative Asteroid Lightcurve Link derives an albedo of 0.2332 and a diameter of 13.17 kilometers based on anabsolute magnitude of 11.6.[11] Alternativemean diameter measurements published by the WISE team include (12.59±2.11 km), (13.320±0.122 km) and (13.658±3.101 km) with corresponding albedos of (0.25±0.11), (0.1924±0.0127) and (0.241±0.080).[5][11]
