| Discovery[1] | |
|---|---|
| Discovered by | K. Reinmuth |
| Discovery site | Heidelberg Obs. |
| Discovery date | 31 May 1929 |
| Designations | |
| (1108) Demeter | |
| Pronunciation | /dɪˈmiːtər/[2] |
Named after | Demeter(Greek mythology)[3] |
| 1929 KA · 1963 MF | |
| main-belt · (inner) Phocaea[4] · background[5] | |
| Orbital characteristics[1] | |
| Epoch 23 March 2018 (JD 2458200.5) | |
| Uncertainty parameter 0 | |
| Observation arc | 88.65yr (32,378 d) |
| Aphelion | 3.0510AU |
| Perihelion | 1.8040 AU |
| 2.4275 AU | |
| Eccentricity | 0.2568 |
| 3.78 yr (1,381 d) | |
| 139.57° | |
| 0° 15m 38.16s / day | |
| Inclination | 24.916° |
| 234.25° | |
| 78.109° | |
| Physical characteristics | |
| 25.285±0.057 km[6] 25.35±6.72 km[7] 25.61±2.0 km[8] 27.316±0.221 km[9] 27.333±5.042 km[10] 31.06±0.58 km[11] 31.33±0.45 km[12] | |
| 9.70±0.01 h[13] 9.701±0.002 h[14] 9.846±0.008 h[15] 9.870±0.012 h[16] | |
| 0.0229±0.0202[10] 0.031±0.005[12] 0.032±0.001[11] 0.0408±0.0040[9] 0.0464±0.008[8] 0.05±0.02[7] | |
| Tholen =CX[1][4] B–V = 0.681[1] U–B = 0.308[1] | |
| 11.91[1][4][7][8][9][11][12] 12.51[10] · 12.51±0.38[17] | |
1108 Demeter, provisional designation1929 KA, is a darkasteroid from the inner regions of theasteroid belt, approximately 27 kilometers (17 miles) in diameter. It was discovered on 31 May 1929, by German astronomerKarl Reinmuth at theHeidelberg-Königstuhl State Observatory near Heidelberg, Germany.[18] The asteroid was named afterDemeter, the Greek goddess of fruitful soil and agriculture.[3] It has arotation period of 9.846 hours.
Demeter is a non-family asteroid of the main belt'sbackground population when applying thehierarchical clustering method to itsproper orbital elements.[5] Based on osculating Keplerianorbital elements, it has also been classified as a member of thePhocaea family (701), a large family ofstony asteroids, different toDemeter's spectral type(see below).[4]
It orbits the Sun in theinner main-belt at a distance of 1.8–3.1 AU once every 3 years and 9 months (1,381 days;semi-major axis of 2.43 AU). Its orbit has aneccentricity of 0.26 and aninclination of 25° with respect to theecliptic.[1] The asteroid was first observed at the ItalianObservatory of Turin, three days prior to its official discovery observation at Heidelberg. The body'sobservation arc begins atYerkes Observatory in December 1930.[18]
In theTholen classification,Demeter'sspectral type is ambiguous, closest to a carbonaceousC-type and somewhat similar to anX-type asteroid.[1][4]
In June 2016, a rotationallightcurve ofDemeter was obtained fromphotometric observations by American astronomers Tom Polakis andBrian Skiff at the Command Module Observatory (V02) in Tempe, Arizona. Lightcurve analysis gave arotation period of 9.846 hours with an amplitude of 0.12magnitude (U=3).[15] Observations by the Spanish OBAS group, also taken during the 2016-opposition, gave a concurring period of 9.870 hours and a brightness variation of 0.11 magnitude (U=3-).[16] The results supersede previous observations byRobert Stephens, Olivier Thizy,René Roy andStéphane Charbonnel from July 2001, which gave a period of 9.70 and 9.701 hours with an amplitude of 0.12 and 0.14 magnitude, respectively.[13][14]
According to the surveys carried out by the Infrared Astronomical SatelliteIRAS, the JapaneseAkari satellite and theNEOWISE mission of NASA'sWide-field Infrared Survey Explorer,Demeter measures between 25.285 and 31.33 kilometers in diameter and its surface has a lowalbedo between 0.0229 and 0.05.[6][7][8][9][10][11][12]
TheCollaborative Asteroid Lightcurve Link adopts the results obtained by IRAS, that is, an albedo of 0.0464 and a diameter of 25.61 kilometers based on anabsolute magnitude of 11.91.[4]
Thisminor planet was named fromGreek mythology afterDemeter, the goddess of fruitful soil and agriculture. The official naming citation was mentioned inThe Names of the Minor Planets byPaul Herget in 1955 (H 104).[3]
Demeter is the Greek equivalent of the Roman goddessCeres.[3] When main-belt asteroid and dwarf planet1 Ceres was named, the Greeks called it "Demeter" effectively translating the name into Greek, rather than using the LatinCeres or the original ItalianCerere. However, this created a problem when asteroidDemeter was named. The Greeks resolved this by using the classical form of the name, ΔημήτηρDēmêtēr, for the new asteroid, distinguishing it from theModern Greek form ΔήμητραDêmētra that had been used for 1 Ceres. This conflict did not occur inGreek-influenced Slavic languages such as Russian, which had adoptedCerera for 1 Ceres, and were thus free to use the modern Greek formDemetra for the asteroidDemeter.
