32532 Thereus

32532 Thereus /θɪˈriːəs/, provisional designation: 2001 PT13, is a centaur from the outer Solar System, approximately 80 kilometers (50 miles) in diameter. It was discovered on 9 August 2001, by astronomers of the Near-Earth Asteroid Tracking program at the Palomar Observatory in California, United States.[5] This minor planet was named for the phrase thēreios bia 'beastly strength', used to describe centaurs in Greek mythology.[2][3]

32532 Thereus
Discovery [1]
Discovered byNEAT
Discovery sitePalomar Obs.
Discovery date9 August 2001
Designations
(32532) Thereus
Pronunciation/θɪˈriːəs/
Named after
θήρειος βία thēreios bia[2][3]
2001 PT13 · 1995 MM6
1999 NE2
centaur [1][4] · distant [5]
Orbital characteristics [1]
Epoch 4 September 2017 (JD 2458000.5)
Uncertainty parameter 1
Observation arc21.57 yr (7,879 days)
Aphelion12.745 AU
Perihelion8.5345 AU
10.640 AU
Eccentricity0.1979
34.70 yr (12,676 days)
192.91°
0° 1m 42.24s / day
Inclination20.353°
205.33°
86.322°
Physical characteristics
Mean diameter
62±3 km[6]
77.19 km (derived)[4]
80±5 km[7]
86.500±1.900 km[8]
8.30 h[9]
8.3091 h[10]
8.335 h[11]
8.338±0.002 h[12]
8.3386±0.0006 h[13]
0.057 (assumed)[4]
0.059±0.013[8]
0.083±0.016[6]
0.0975±0.0125[7]
BR [14]
B–V = 0.770±0.020[14]
B–V = 0.810±0.050[15]
B–V = 0.763±0.072[16]
V–R = 0.490±0.010[14]
V–R = 0.501±0.016[16]
V–I = 0.940±0.010[14]
V–I = 0.900±0.130[15]
V–I = 0.917±0.035[16]
9.1[1] · 9.29[11][4] · 9.32[17] · 9.36[10] · 9.365±0.038 (R)[18] · 9.40±0.16[6] · 9.42±0.01[13]

    Orbit and classification

    Thereus orbits the Sun at a distance of 8.5–12.7 AU once every 34 years and 8 months (12,676 days). Its orbit has an eccentricity of 0.20 and an inclination of 20° with respect to the ecliptic.[1]

    The body's observation arc begins with a precovery taken by Spacewatch at Kitt Peak Observatory in June 1995, more than 6 years prior to its official discovery observation by NEAT at Palomar.[5]

    Naming

    This minor planet was named after Thereus, a centaur from Greek mythology. He is described as a hunter who captured bears and carried them home, alive and struggling.[2] The official naming citation was published by the Minor Planet Center on 14 June 2003 (M.P.C. 49102).[19]

    Physical characteristics

    Rotation period

    Since the early 2000s, several rotational lightcurves of Thereus were obtained from photometric observations with a period between 8.30 and 8.3386 hours.[9][10][11][12][13] Analysis of the consolidated, best-rated lightcurve gave a rotation period of 8.335 hours and a brightness amplitude of 0.38 magnitude (U=3).[4]

    Diameter and albedo

    According to observations made by the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer, ESA's Herschel Space Observatory with its PACS instrument, and the Spitzer Space Telescope, Thereus measures between 62 and 86.5 kilometers in diameter and its surface has an albedo between 0.059 and 0.0975.[6][7][8]

    The Collaborative Asteroid Lightcurve Link assumes a standard albedo for carbonaceous minor planets of 0.057 and derives a diameter of 77.19 kilometers based on an absolute magnitude of 9.29.[4]

    See also

    References
    1. "JPL Small-Body Database Browser: 32532 Thereus (2001 PT13)" (2016-12-30 last obs.). Jet Propulsion Laboratory. Retrieved 21 September 2017.
    2. Schmadel, Lutz D. (2006). "(32532) Thereus [10.6, 0.20, 20.4]". Dictionary of Minor Planet Names – Addendum to Fifth Edition: 2003–2005. Springer Berlin Heidelberg. p. 199. doi:10.1007/978-3-540-34361-5_2336. ISBN 978-3-540-34361-5.
    3. θήρειος. Liddell, Henry George; Scott, Robert; A Greek–English Lexicon at the Perseus Project
    4. "LCDB Data for (32532) Thereus". Asteroid Lightcurve Database (LCDB). Retrieved 21 September 2017.
    5. "32532 Thereus (2001 PT13)". Minor Planet Center. Retrieved 21 September 2017.
    6. Duffard, R.; Pinilla-Alonso, N.; Santos-Sanz, P.; Vilenius, E.; Ortiz, J. L.; Mueller, T.; et al. (April 2014). ""TNOs are Cool": A survey of the trans-Neptunian region. XI. A Herschel-PACS view of 16 Centaurs". Astronomy and Astrophysics. 564: 17. arXiv:1309.0946. Bibcode:2014A&A...564A..92D. doi:10.1051/0004-6361/201322377. S2CID 119177446.
    7. Stansberry, J. A.; Cruikshank, D. P.; Grundy, W. G.; Margot, J. L.; Emery, J. P.; Fernandez, Y. R.; et al. (August 2005). "Albedos, Diameters (and a Density) of Kuiper Belt and Centaur Objects". American Astronomical Society. 37: 737. Bibcode:2005DPS....37.5205S. Retrieved 21 September 2017.
    8. Bauer, James M.; Grav, Tommy; Blauvelt, Erin; Mainzer, A. K.; Masiero, Joseph R.; Stevenson, Rachel; et al. (August 2013). "Centaurs and Scattered Disk Objects in the Thermal Infrared: Analysis of WISE/NEOWISE Observations". The Astrophysical Journal. 773 (1): 11. arXiv:1306.1862. Bibcode:2013ApJ...773...22B. doi:10.1088/0004-637X/773/1/22. S2CID 51139703.
    9. Ortiz, J. L.; Baumont, S.; Gutiérrez, P. J.; Roos-Serote, M. (June 2002). "Lightcurves of Centaurs 2000 QC243 and 2001 PT13". Astronomy and Astrophysics. 388 (2): 661–666. Bibcode:2002A&A...388..661O. doi:10.1051/0004-6361:20020487.
    10. Ortiz, J. L.; Gutiérrez, P. J.; Casanova, V.; Sota, A. (September 2003). "A study of short term rotational variability in TNOs and Centaurs from Sierra Nevada Observatory". Astronomy and Astrophysics. 407 (3): 1149–1155. Bibcode:2003A&A...407.1149O. doi:10.1051/0004-6361:20030972.
    11. Farnham, Tony L.; Davies, John K. (August 2003). "The rotational and physical properties of the Centaur (32532) 2001 PT 13". Icarus. 164 (2): 418–427. Bibcode:2003Icar..164..418F. doi:10.1016/S0019-1035(03)00141-6. Retrieved 21 September 2017.
    12. Brucker, Melissa; Romanishin, W. J.; Tegler, S. C.; Consolmagno, G. J.; J., S.; Grundy, W. M. (September 2008). "Rotational Properties of Centaurs (32532) Thereus and (8405) Asbolus". American Astronomical Society. 40: 483. Bibcode:2008DPS....40.4709B. Retrieved 21 September 2017.
    13. Rabinowitz, David L.; Schaefer, Bradley E.; Tourtellotte, Suzanne W. (January 2007). "The Diverse Solar Phase Curves of Distant Icy Bodies. I. Photometric Observations of 18 Trans-Neptunian Objects, 7 Centaurs, and Nereid". The Astronomical Journal. 133 (1): 26–43. arXiv:astro-ph/0605745. Bibcode:2007AJ....133...26R. doi:10.1086/508931. S2CID 119406900. Retrieved 21 September 2017.
    14. Lowry, Stephen C.; Weissman, Paul R. (May 2007). "Rotation and color properties of the nucleus of Comet 2P/Encke". Icarus. 188 (1): 212–223. arXiv:astro-ph/0612380. Bibcode:2007Icar..188..212L. doi:10.1016/j.icarus.2006.11.014. S2CID 119024049.
    15. DeMeo, Francesca E.; Fornasier, S.; Barucci, M. A.; Perna, D.; Protopapa, S.; Alvarez-Candal, A.; et al. (September 2008). "Visible and Near-infrared Colors of TNOs from the Second ESO Large Program". American Astronomical Society. 40: 482. Bibcode:2008DPS....40.4705D. Retrieved 21 September 2017.
    16. Hainaut, O. R.; Boehnhardt, H.; Protopapa, S. (October 2012). "Colours of minor bodies in the outer solar system. II. A statistical analysis revisited". Astronomy and Astrophysics. 546: 20. arXiv:1209.1896. Bibcode:2012A&A...546A.115H. doi:10.1051/0004-6361/201219566. S2CID 54776793.
    17. Romanishin, W.; Tegler, S. C. (December 2005). "Accurate absolute magnitudes for Kuiper belt objects and Centaurs". Icarus. 179 (2): 523–526. Bibcode:2005Icar..179..523R. doi:10.1016/j.icarus.2005.06.016. Retrieved 21 September 2017.
    18. Peixinho, N.; Delsanti, A.; Guilbert-Lepoutre, A.; Gafeira, R.; Lacerda, P. (October 2012). "The bimodal colors of Centaurs and small Kuiper belt objects". Astronomy and Astrophysics. 546: 12. arXiv:1206.3153. Bibcode:2012A&A...546A..86P. doi:10.1051/0004-6361/201219057. S2CID 55876118. Retrieved 21 September 2017.
    19. "MPC/MPO/MPS Archive". Minor Planet Center. Retrieved 21 September 2017.
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