1150 Achaia

1150 Achaia (/əˈkaɪə/); prov. designation: 1929 RB) is a stony background asteroid from the inner regions of the asteroid belt. It was discovered by Karl Reinmuth at Heidelberg Observatory on 2 September 1929.[1] The S-type asteroid has a notably long rotation period of hours 61 hours and measures approximately 7.8 kilometers (4.8 miles) in diameter. It is named for the Greek region of Achaia.[4]

1150 Achaia
Shape model of Achaia from its lightcurve
Discovery[1]
Discovered byK. Reinmuth
Discovery siteHeidelberg Obs.
Discovery date2 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 arc86.78 yr (31,696 days)
Aphelion2.6392 AU
Perihelion1.7424 AU
2.1908 AU
Eccentricity0.2047
3.24 yr (1,184 days)
348.01°
0° 18m 14.04s / day
Inclination2.3929°
206.54°
139.58°
Earth MOID0.7366 AU
Physical characteristics
Mean diameter
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[lower-alpha 1]
  • (5.0°, −65.0°) (λ1/β1)[7]
  • (20.0°, −69.0°) (λ2/β2)[7]
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]

    Discovery

    Achaia was discovered on 2 September 1929, by German astronomer Karl Reinmuth at Heidelberg Observatory in southwest Germany.[1] Ten nights later, it was independently discovered by Friedrich Schwassmann and Arno Wachmann at Bergedorf.[4] The body's observation arc begins at Heidelberg, five days after its first and official discovery observation.<[1]

    Orbit and classification

    Located in the orbital region of the Flora family,[9] one of the largest, yet disputed families of the main-belt, Achaia is a non-family asteroid of the main belt's background population when applying the hierarchical clustering method to its proper 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 an eccentricity of 0.20 and an inclination of 2° with respect to the ecliptic.[5]

    Naming

    This minor planet is named for the region Achaea (or "Achaia") in Western Greece. It is located in the northern part of the Peloponnese peninsula and borders on the gulfs of Patras and Corinth.[4] Naming citation was first mentioned in The Names of the Minor Planets by Paul Herget in 1955 (H 107).[4]

    Physical characteristics

    In the Tholen-like taxonomy of the Small Solar System Objects Spectroscopic Survey (S3OS2), Achaia is a common, stony S-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 uncommon L-type asteroid.[7][13]

    Photometry

    A rotational lightcurve of Achaia was obtained from photometric observations by Czech astronomer Petr Pravec at Ondřejov Observatory in October 2007.[lower-alpha 2] It gave a well-defined rotation period of 60.99 hours with a brightness variation of 0.72 magnitude (U=3).[lower-alpha 1]

    Published in 2016, two additional lightcurves were derived from modeled photometric data using various sources. They gave a sidereal rotation period of 61.071±0.001 and 61.072±0.005 hours, as well as a spin axis of (5.0°, −65.0°) and (20.0°, −69.0°) in ecliptic coordinates, respectively.[14][15]

    While not being a slow 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.

    Diameter and albedo

    According to the surveys carried out by the Japanese Akari satellite and NASA's Wide-field Infrared Survey Explorer with its subsequent NEOWISE mission, Achaia measures between 7.689 and 8.16 kilometers in diameter, and its surface has an albedo between 0.234 and 0.251.[8][10][11][12] The Collaborative Asteroid Lightcurve Link assumes an albedo of 0.24 – taken from 8 Flora, the Flora family's principal body and namesake – and calculates a diameter of 7.82 kilometers based on an absolute magnitude of 12.7.[9]

    Notes
    1. Pravec (2007) web: rotation period 60.99±0.05 hours with a brightness amplitude of 0.72 mag. Quality code of 3. Summary figures at Collaborative Asteroid Lightcurve Link (CALL) for (1150) Achaia and Pravec, P.; Wolf, M.; Sarounova, L. (2007)
    2. (1150) Achaia: Lightcurve Plot analysis on 23 October 2007 by Pravec and Galad. ProjectID: Modra, Kharkiv. Comment: Error of 0.02 h is formal, real error perhaps a couple times greater.

    References
    1. "1150 Achaia (1929 RB)". Minor Planet Center. Retrieved 2 February 2017.
    2. "Achaia". Oxford English Dictionary (Online ed.). Oxford University Press. (Subscription or participating institution membership required.)
    3. "Achaia". Merriam-Webster.com Dictionary.
    4. Schmadel, Lutz D. (2007). "(1150) Achaia". Dictionary of Minor Planet Names. Springer Berlin Heidelberg. p. 97. doi:10.1007/978-3-540-29925-7_1151. ISBN 978-3-540-00238-3.
    5. "JPL Small-Body Database Browser: 1150 Achaia (1929 RB)" (2016-06-13 last obs.). Jet Propulsion Laboratory. Retrieved 2 February 2017.
    6. "Asteroid 1150 Achaia – Proper Elements". AstDyS-2, Asteroids – Dynamic Site. Retrieved 14 March 2020.
    7. "Asteroid 1150 Achaia". Small Bodies Data Ferret. Retrieved 14 March 2020.
    8. Masiero, Joseph R.; Grav, T.; Mainzer, A. K.; Nugent, C. R.; Bauer, J. M.; Stevenson, R.; et al. (August 2014). "Main-belt Asteroids with WISE/NEOWISE: Near-infrared Albedos". The Astrophysical Journal. 791 (2): 11. arXiv:1406.6645. Bibcode:2014ApJ...791..121M. doi:10.1088/0004-637X/791/2/121. Retrieved 2 February 2017.
    9. "LCDB Data for (1150) Achaia". Asteroid Lightcurve Database (LCDB). Retrieved 2 February 2017.
    10. Mainzer, A.; Grav, T.; Masiero, J.; Hand, E.; Bauer, J.; Tholen, D.; et al. (November 2011). "NEOWISE Studies of Spectrophotometrically Classified Asteroids: Preliminary Results". The Astrophysical Journal. 741 (2): 25. arXiv:1109.6407. Bibcode:2011ApJ...741...90M. doi:10.1088/0004-637X/741/2/90.
    11. Usui, Fumihiko; Kuroda, Daisuke; Müller, Thomas G.; Hasegawa, Sunao; Ishiguro, Masateru; Ootsubo, Takafumi; et al. (October 2011). "Asteroid Catalog Using Akari: AKARI/IRC Mid-Infrared Asteroid Survey". Publications of the Astronomical Society of Japan. 63 (5): 1117–1138. Bibcode:2011PASJ...63.1117U. doi:10.1093/pasj/63.5.1117. (online, AcuA catalog p. 153)
    12. Masiero, Joseph R.; Mainzer, A. K.; Grav, T.; Bauer, J. M.; Cutri, R. M.; Nugent, C.; et al. (November 2012). "Preliminary Analysis of WISE/NEOWISE 3-Band Cryogenic and Post-cryogenic Observations of Main Belt Asteroids". The Astrophysical Journal Letters. 759 (1): 5. arXiv:1209.5794. Bibcode:2012ApJ...759L...8M. doi:10.1088/2041-8205/759/1/L8. Retrieved 2 February 2017.
    13. Lazzaro, D.; Angeli, C. A.; Carvano, J. M.; Mothé-Diniz, T.; Duffard, R.; Florczak, M. (November 2004). "S3OS2: the visible spectroscopic survey of 820 asteroids" (PDF). Icarus. 172 (1): 179–220. Bibcode:2004Icar..172..179L. doi:10.1016/j.icarus.2004.06.006. Retrieved 14 March 2020.
    14. Durech, J.; Hanus, J.; Oszkiewicz, D.; Vanco, R. (March 2016). "Asteroid models from the Lowell photometric database". Astronomy and Astrophysics. 587: 6. arXiv:1601.02909. Bibcode:2016A&A...587A..48D. doi:10.1051/0004-6361/201527573. Retrieved 2 February 2017.
    15. Hanuš, J.; Ďurech, J.; Oszkiewicz, D. A.; Behrend, R.; Carry, B.; Delbo, M.; et al. (February 2016). "New and updated convex shape models of asteroids based on optical data from a large collaboration network". Astronomy and Astrophysics. 586: A108. arXiv:1510.07422. Bibcode:2016A&A...586A.108H. doi:10.1051/0004-6361/201527441. ISSN 0004-6361.
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