1484 Postrema

1484 Postrema, provisional designation 1938 HC, is a carbonaceous Postremian asteroid and namesake of the Postrema family from the central regions of the asteroid belt, approximately 41 kilometers in diameter. It was discovered on 29 April 1938, by Soviet astronomer Grigory Neujmin at the Simeiz Observatory on the Crimean peninsula.[16] The name "Postrema" celebrates the astronomer's last minor planet discovery.[2]

1484 Postrema
Shape model of Postrema from its lightcurve
Discovery[1]
Discovered byG. Neujmin
Discovery siteSimeiz Obs.
Discovery date29 April 1938
Designations
(1484) Postrema
Pronunciation/pɒˈstriːmə/
Named after
postrēma[2]
("the last of a group")
1938 HC · 1933 DH
A911 KC
main-belt · (middle)
Postrema[3]
AdjectivesPostremian
Orbital characteristics[1]
Epoch 4 September 2017 (JD 2458000.5)
Uncertainty parameter 0
Observation arc84.61 yr (30,903 days)
Aphelion3.2973 AU
Perihelion2.1816 AU
2.7394 AU
Eccentricity0.2036
4.53 yr (1,656 days)
194.22°
0° 13m 2.64s / day
Inclination17.300°
72.767°
126.82°
Physical characteristics
Dimensions34.696±1.954 km[4]
38.82±6.78 km[5]
40.871±0.279 km[6]
41±4 km[7]
41.1±8.2 km[8]
41.73±12.60 km[9]
43.18±1.0 km[10]
43.42 km (derived)[11]
47.00±0.62 km[12]
12.18978±0.00001 h[13]
12.19±0.02 h[14]
12.1923±0.0005 h[15]
0.0137±0.001[10]
0.015±0.009[6]
0.035±0.001[12]
0.0367±0.0074[4]
0.0409 (derived)[11]
0.05±0.01[7]
0.05±0.02[8][5]
0.05±0.04[9]
SMASS = B[1][11]
10.80[7][8][9] · 10.88[5] · 10.90[1][11][12] · 12.10[4][10]

    Orbit and classification

    Postrema is the parent body and namesake of the Postrema family (541),[3] a mid-sized central asteroid family of little more than 100 members.[17]: 23 

    It orbits the Sun in the central main-belt at a distance of 2.2–3.3 AU once every 4 years and 6 months (1,656 days). Its orbit has an eccentricity of 0.20 and an inclination of 17° with respect to the ecliptic.[1]

    The asteroid was first identified as A911 KC at Johannesburg Observatory in May 1911. The body's observation arc begins with its identification as 1933 DH at Lowell Observatory in February 1933, more than 5 years prior to its official discovery observation at Simeiz.[16]

    Physical characteristics

    Spectral type

    In the SMASS classification, Postrema is a bright carbonaceous B-type asteroid,[1] while the overall spectral type of the Postrema family has been described as that of C- and X-type.[17]: 23 

    Rotation period

    In May 2006, two rotational lightcurves of Postrema were independently obtained from photometric observations. Lightcurve analysis gave a rotation period of 12.19 and 12.1923 hours with a brightness amplitude of 0.23 and 0.22 magnitude, respectively (U=2+/3-).[14][15]

    Spin axis

    The asteroids lightcurve has also been modeled, using photometric data from the Lowell Photometric Database and other sources. Modelling gave a concurring period of 12.18978 hours, as well as two spin axis of (19.0°, 44°) and (250.0°, 64°) in ecliptic coordinates (λ, β).[13]

    Diameter and albedo

    According to the surveys carried out by the Infrared Astronomical Satellite IRAS, the Japanese Akari satellite and the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer, Postrema measures between 34.696 and 47.00 kilometers in diameter and its surface has a notably low albedo between 0.0137 and 0.05.[4][5][6][7][8][9][10][12]

    The Collaborative Asteroid Lightcurve Link derives an albedo of 0.0409 and a diameter of 43.42 kilometers based on an absolute magnitude of 10.9.[11]

    Naming

    This minor planet was named "Postrema", which means "the last of a group". It celebrates Grigory Neujmin's last numbered minor planet discovery. The official naming citation was published by the Minor Planet Center in June 1955 (M.P.C. 1252).[18]

    The citation only holds true at the time of publication. In retrospect, Postrema is not Neujmin's last discovery, neither by number nor by its discovery date. These would be the asteroids 4420 Alandreev (highest numbered) and 2536 Kozyrev, officially discovered on 15 August 1939, more than a year after Postrema.[2]

    References
    1. "JPL Small-Body Database Browser: 1484 Postrema (1938 HC)" (2017-09-28 last obs.). Jet Propulsion Laboratory. Retrieved 19 October 2017.
    2. Schmadel, Lutz D. (2007). "(1484) Postrema". Dictionary of Minor Planet Names. Springer Berlin Heidelberg. p. 118. doi:10.1007/978-3-540-29925-7_1485. ISBN 978-3-540-00238-3.
    3. "Asteroid 1484 Postrema – Nesvorny HCM Asteroid Families V3.0". Small Bodies Data Ferret. Retrieved 26 October 2019.
    4. 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.
    5. Nugent, C. R.; Mainzer, A.; Bauer, J.; Cutri, R. M.; Kramer, E. A.; Grav, T.; et al. (September 2016). "NEOWISE Reactivation Mission Year Two: Asteroid Diameters and Albedos". The Astronomical Journal. 152 (3): 12. arXiv:1606.08923. Bibcode:2016AJ....152...63N. doi:10.3847/0004-6256/152/3/63.
    6. 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 19 October 2017.
    7. Alí-Lagoa, V.; de León, J.; Licandro, J.; Delbó, M.; Campins, H.; Pinilla-Alonso, N.; et al. (June 2013). "Physical properties of B-type asteroids from WISE data". Astronomy and Astrophysics. 554: 16. arXiv:1303.5487. Bibcode:2013A&A...554A..71A. doi:10.1051/0004-6361/201220680. Retrieved 19 October 2017.
    8. Alí-Lagoa, V.; Licandro, J.; Gil-Hutton, R.; Cañ; ada-Assandri, M.; Delbo', M.; et al. (June 2016). "Differences between the Pallas collisional family and similarly sized B-type asteroids". Astronomy and Astrophysics. 591: 11. Bibcode:2016A&A...591A..14A. doi:10.1051/0004-6361/201527660.
    9. Nugent, C. R.; Mainzer, A.; Masiero, J.; Bauer, J.; Cutri, R. M.; Grav, T.; et al. (December 2015). "NEOWISE Reactivation Mission Year One: Preliminary Asteroid Diameters and Albedos". The Astrophysical Journal. 814 (2): 13. arXiv:1509.02522. Bibcode:2015ApJ...814..117N. doi:10.1088/0004-637X/814/2/117. Retrieved 19 October 2017.
    10. Tedesco, E. F.; Noah, P. V.; Noah, M.; Price, S. D. (October 2004). "IRAS Minor Planet Survey V6.0". NASA Planetary Data System. 12: IRAS-A-FPA-3-RDR-IMPS-V6.0. Bibcode:2004PDSS...12.....T. Retrieved 22 October 2019.
    11. "LCDB Data for (1484) Postrema". Asteroid Lightcurve Database (LCDB). Retrieved 19 October 2017.
    12. 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)
    13. 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 19 October 2017.
    14. Behrend, Raoul. "Asteroids and comets rotation curves – (1484) Postrema". Geneva Observatory. Retrieved 19 October 2017.
    15. Julian, William M., II (December 2006). "Period determination for 1484 Postrema". The Minor Planet Bulletin. 33 (4): 103–104. Bibcode:2006MPBu...33..103J. ISSN 1052-8091. Retrieved 19 October 2017.
    16. "1484 Postrema (1938 HC)". Minor Planet Center. Retrieved 19 October 2017.
    17. Nesvorný, D.; Broz, M.; Carruba, V. (December 2014). "Identification and Dynamical Properties of Asteroid Families". Asteroids IV. pp. 297–321. arXiv:1502.01628. Bibcode:2015aste.book..297N. doi:10.2458/azu_uapress_9780816532131-ch016. ISBN 9780816532131.
    18. Schmadel, Lutz D. (2009). "Appendix – Publication Dates of the MPCs". Dictionary of Minor Planet Names – Addendum to Fifth Edition (2006–2008). Springer Berlin Heidelberg. p. 221. doi:10.1007/978-3-642-01965-4. ISBN 978-3-642-01964-7.

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