_Achaia.png) Shape model ofAchaia from itslightcurve | |
| Discovery[1] | |
|---|---|
| Discovered by | K. Reinmuth |
| Discovery site | Heidelberg Obs. |
| Discovery date | 2 September 1929 |
| Designations | |
| (1150) Achaia | |
| Pronunciation | /əˈkaɪə/,[2]/əˈkeɪə/[3] |
Named after | Achaea(Greek region)[4] |
| 1929 RB · 1955 SZ1 | |
| Orbital characteristics[5] | |
| Epoch 16 February 2017 (JD 2457800.5) | |
| Uncertainty parameter 0 | |
| Observation arc | 86.78 yr (31,696 days) |
| Aphelion | 2.6392AU |
| Perihelion | 1.7424 AU |
| 2.1908 AU | |
| Eccentricity | 0.2047 |
| 3.24yr (1,184 days) | |
| 348.01° | |
| 0° 18m 14.04s / day | |
| Inclination | 2.3929° |
| 206.54° | |
| 139.58° | |
| Earth MOID | 0.7366 AU |
| Physical characteristics | |
| 7.689±0.020 km[8] 7.82 km(calculated)[9] 7.928±0.036 km[10] 7.96±0.25 km[11] 8.16±0.25 km[12] | |
| 60.99±0.05 h[a] | |
| 0.2343±0.0479[10] 0.239±0.017[11] 0.24(assumed)[9] 0.242±0.029[12] 0.251±0.017[8] | |
| 12.60[12] · 12.7[5][9][10][11] | |
1150 Achaia (/əˈkaɪə/);prov. designation:1929 RB) is a stonybackground asteroid from the inner regions of theasteroid belt. It was discovered byKarl Reinmuth atHeidelberg Observatory on 2 September 1929.[1] TheS-type asteroid has a notably longrotation period of hours 61 hours and measures approximately 7.8 kilometers (4.8 miles) in diameter. It is named for the Greek region ofAchaia.[4]
Achaia was discovered on 2 September 1929, by German astronomerKarl Reinmuth atHeidelberg Observatory in southwest Germany.[1] Ten nights later, it was independently discovered byFriedrich Schwassmann andArno Wachmann atBergedorf.[4] The body'sobservation arc begins at Heidelberg, five days after its first and official discovery observation.<[1]
Located in the orbital region of theFlora family,[9] one of the largest, yet disputed families of the main-belt,Achaia is a non-family asteroid of the main belt'sbackground population when applying thehierarchical clustering method to itsproper orbital elements.[6][7] It orbits the Sun at a distance of 1.7–2.6 AU once every 3 years and 3 months (1,184 days). Its orbit has aneccentricity of 0.20 and aninclination of 2° with respect to theecliptic.[5]
Thisminor planet is named for the regionAchaea (or "Achaia") inWestern Greece. It is located in the northern part of thePeloponnese peninsula and borders on the gulfs ofPatras andCorinth.[4] Naming citation was first mentioned inThe Names of the Minor Planets byPaul Herget in 1955 (H 107).[4]
In the Tholen-like taxonomy of theSmall Solar System Objects Spectroscopic Survey (S3OS2),Achaia is a common, stonyS-type asteroid, while in the survey's SMASS (Bus–Binzel)-like taxonomic variant, it is an Sl-subtype, which transitions from the S-type to the uncommonL-type asteroid.[7][13]
A rotationallightcurve ofAchaia was obtained fromphotometric observations by Czech astronomerPetr Pravec atOndřejov Observatory in October 2007.[b] It gave a well-definedrotation period of 60.99 hours with a brightness variation of 0.72magnitude (U=3).[a]
Published in 2016, two additional lightcurves were derived from modeled photometric data using various sources. They gave asidereal rotation period of61.071±0.001 and61.072±0.005 hours, as well as aspin axis of (5.0°, −65.0°) and (20.0°, −69.0°) inecliptic coordinates, respectively.[14][15]
While not being aslow rotator,Achaia has a notably longer period than the vast majority of asteroids, which typically rotate every 2 to 20 hours once around their axis. Also, the body's changes in brightness are relatively high and indicate that it has a non-spheroidal shape.
According to the surveys carried out by the JapaneseAkari satellite and NASA'sWide-field Infrared Survey Explorer with its subsequentNEOWISE mission,Achaia measures between 7.689 and 8.16 kilometers in diameter, and its surface has analbedo between 0.234 and 0.251.[8][10][11][12] TheCollaborative Asteroid Lightcurve Link assumes an albedo of 0.24 – taken from8 Flora, the Flora family's principal body and namesake – and calculates a diameter of 7.82 kilometers based on anabsolute magnitude of 12.7.[9]
