(1089) Tama

1089 Tama
1089Tama (Lightcurve Inversion).png
Lightcurve-based 3D-model of Tama
Discovered byO. Oikawa
Discovery siteTokyo Astronomical Obs.
Discovery date17 November 1927
(1089) Tama
PronunciationJapanese: [tama]
Named after
Tama River[2]
(Japanese river)
1927 WB · 1930 ST
1952 HE4 · A894 VA
A904 VD · A919 HA
main-belt · (inner)
Flora[3] · background[4]
Orbital characteristics[1]
Epoch 4 September 2017 (JD 2458000.5)
Uncertainty parameter 0
Observation arc122.40 yr (44,708 days)
Aphelion2.4951 AU
Perihelion1.9327 AU
2.2139 AU
3.29 yr (1,203 days)
0° 17m 57.12s / day
Known satellites[3][5][6]
Physical characteristics
Dimensions11.33±2.00 km[7]
12.2±1.6 km[8]
12.82 km (derived)[3]
12.92±0.6 km[9]
13.08±0.37 km[10]
13.082±0.373 km[10]
13.32±0.19 km[11]
4 (dated)h[12]
16.4±0.1 h[13]
16.44 h[8]
16.444±0.001 h[14]
16.4442±0.0004 h[6][13]
16.445±0.005 h[13]
16.45±0.05 h[13]
16.4530±0.0004 h[13]
16.464±0.004 h[15]
16.4655 h[16]
0.2048 (derived)[3]
S (assumed)[3]
11.60[9][11] · 11.63±0.0[8] · 11.70[7][10] · 11.8[1][3] · 11.86±0.85[17]

1089 Tama, provisional designation 1927 WB, is an elongated Florian asteroid and synchronous binary system from the inner regions of the asteroid belt, approximately 12 kilometers in diameter.

It was discovered by Japanese astronomer Okuro Oikawa at the old Tokyo Astronomical Observatory (389) on 17 November 1927.[18] The asteroid was named after the Tama River in Japan.[2] Its minor-planet moon was discovered in December 2003 and measures approximately 9 kilometers.[6]

Orbit and classification[]

Tama is a member of the Flora family (402), a giant asteroid family and the largest family of stony asteroids in the main-belt.[3] It is, however, a non-family asteroid from the main belt's background population when applying the Hierarchical Clustering Method to its proper orbital elements.[4]

The asteroid orbits the Sun in the inner main-belt at a distance of 1.9–2.5 AU once every 3 years and 3 months (1,203 days). Its orbit has an eccentricity of 0.13 and an inclination of 4° with respect to the ecliptic.[1] Tama was first identified as A894 VA at Heidelberg Observatory in November 1894. The body's observation arc begins with its identification as A904 VD at Heidelberg in November 1904, or 23 years prior to its official discovery observation at Tokyo.[18]

Physical characteristics[]

Tama is an assumed stony S-type asteroid.[3]

Rotation period[]

A large number of rotational lightcurves of Tama were obtained from photometric observations since it has been identified as a binary asteroid (see below). Lightcurve analysis gave a rotation period between 16.4 and 16.464 hours with a brightness variation between 0.08 and 0.41 magnitude (U=2-/2-3-/3), superseding a period of 4 hours from a fragmentary lightcurve obtained in the 1990s (U=1).[6][8][12][13][15]

Tama appears to be somewhat elongated in shape.[6] LCDB's consolidated result gives a period of 16.44 hours and an amplitude of 0.41 magnitude (U=3).[3]

Diameter and albedo[]

According to the surveys carried out by the Infrared Astronomical Satellite IRAS, the Japanese Akari satellite, the Spitzer Space Telescope and the NEOWISE mission of the Wide-field Infrared Survey Explorer, Tama measures between 11.33 and 13.32 kilometers in diameter and its surface has an albedo between 0.216 and 0.32.[7][8][9][10][11]

The Collaborative Asteroid Lightcurve Link derives an albedo of 0.2048 and a diameter of 12.82 kilometers based on an absolute magnitude of 11.8.[3]


In 2004, it was announced that Tama has a minor-planet moon, provisionally designated S/2003 (1089) 1. The satellite was identified based on lightcurve observations with mutual occultation and eclipsing events from 24 December 2003 to 5 January 2004 by Raoul Behrend, René Roy, Claudine Rinner, Pierre Antonini, Petr Pravec, Alan Harris, Stefano Sposetti, Russell Durkee, and Alain Klotz.[6][13] The moon measures approximately 9 kilometers in diameter. It may orbits 20 km away in a period of 16.4442 hours (synchronously).[3][5][6]

Spin axis[]

Tamas lightcurve has also been modeled. In 2013, modelling by an international study using photometric data from the US Naval Observatory, the Uppsala Asteroid Photometric Catalogue (UAPC) and the Palmer Divide Observatory, gave a concurring rotation period of 16.4655 hours.[16] Another modeled lightcurve using data from UAPC, the Palomar Transient Factory survey, and individual observers, gave a period of 16.4461 hours as well as two spin axes of (193.0°, 32.0°) and (9.0°, 28.0°) in ecliptic coordinates (λ, β).[19]


This minor planet was named after Tama River near the discovering Tokyo Astronomical Observatory (389) in Japan. The official naming citation was mentioned in The Names of the Minor Planets by Paul Herget in 1955 (H 103).[2]


  1. ^ a b c d "JPL Small-Body Database Browser: 1089 Tama (1927 WB)" (2017-03-29 last obs.). Jet Propulsion Laboratory. Archived from the original on 19 August 2020. Retrieved 26 September 2017.
  2. ^ a b c Schmadel, Lutz D. (2007). "(1089) Tama". Dictionary of Minor Planet Names – (1089) Tama. Springer Berlin Heidelberg. p. 93. doi:10.1007/978-3-540-29925-7_1090. ISBN 978-3-540-00238-3.
  3. ^ a b c d e f g h i j k "LCDB Data for (1089) Tama". Asteroid Lightcurve Database (LCDB). Retrieved 26 September 2017.
  4. ^ a b "Asteroid 1089 Tama – Nesvorny HCM Asteroid Families V3.0". Small Bodies Data Ferret. Retrieved 26 October 2019.
  5. ^ a b "(1089) Tama". Asteroids with Satellites Database – Johnston's Archive. Retrieved 26 September 2017.
  6. ^ a b c d e f g Behrend, R.; Roy, R.; Rinner, C.; Antonini, P.; Pravec, P.; Harris, A. W.; et al. (January 2004). "(1089) Tama". IAU Circ. 8265 (8265): 2. Bibcode:2004IAUC.8265....2B. Retrieved 26 September 2017.
  7. ^ a b c d 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 26 September 2017.
  8. ^ a b c d e f Marchis, F.; Enriquez, J. E.; Emery, J. P.; Mueller, M.; Baek, M.; Pollock, J.; et al. (November 2012). "Multiple asteroid systems: Dimensions and thermal properties from Spitzer Space Telescope and ground-based observations". Icarus. 221 (2): 1130–1161. arXiv:1604.05384. Bibcode:2012Icar..221.1130M. doi:10.1016/j.icarus.2012.09.013. Retrieved 26 September 2017.
  9. ^ a b c d 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.
  10. ^ a b c d e 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 26 September 2017.
  11. ^ a b c d 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. ^ a b Sárneczky, K.; Szabó, Gy.; Kiss, L. L. (June 1999). "CCD observations of 11 faint asteroids". Astronomy and Astrophysics Supplement. 137 (2): 363–368. Bibcode:1999A&AS..137..363S. doi:10.1051/aas:1999251. Retrieved 26 September 2017.
  13. ^ a b c d e f g Behrend, Raoul. "Asteroids and comets rotation curves – (1089) Tama". Geneva Observatory. Retrieved 26 September 2017.
  14. ^ Behrend, R.; Bernasconi, L.; Roy, R.; Klotz, A.; Colas, F.; Antonini, P.; et al. (February 2006). "Four new binary minor planets: (854) Frostia, (1089) Tama, (1313) Berna, (4492) Debussy". Astronomy and Astrophysics. 446 (3): 1177–1184. Bibcode:2006A&A...446.1177B. doi:10.1051/0004-6361:20053709. Retrieved 26 September 2017.
  15. ^ a b Polishook, David (October 2012). "Lightcurves for Shape Modeling: 852 Wladilena, 1089 Tama, and 1180 Rita". The Minor Planet Bulletin. 39 (4): 242–244. Bibcode:2012MPBu...39..242P. ISSN 1052-8091. Retrieved 26 September 2017.
  16. ^ a b Durech, J.; Kaasalainen, M.; Warner, B. D.; Fauerbach, M.; Marks, S. A.; Fauvaud, S.; et al. (January 2009). "Asteroid models from combined sparse and dense photometric data". Astronomy and Astrophysics. 493 (1): 291–297. Bibcode:2009A&A...493..291D. doi:10.1051/0004-6361:200810393. Retrieved 24 August 2017.
  17. ^ Veres, Peter; Jedicke, Robert; Fitzsimmons, Alan; Denneau, Larry; Granvik, Mikael; Bolin, Bryce; et al. (November 2015). "Absolute magnitudes and slope parameters for 250,000 asteroids observed by Pan-STARRS PS1 - Preliminary results". Icarus. 261: 34–47. arXiv:1506.00762. Bibcode:2015Icar..261...34V. doi:10.1016/j.icarus.2015.08.007. Retrieved 26 September 2017.
  18. ^ a b "1089 Tama (1927 WB)". Minor Planet Center. Retrieved 26 September 2017.
  19. ^ Hanus, J.; Durech, J.; Broz, M.; Marciniak, A.; Warner, B. D.; Pilcher, F.; et al. (March 2013). "Asteroids' physical models from combined dense and sparse photometry and scaling of the YORP effect by the observed obliquity distribution". Astronomy and Astrophysics. 551: 16. arXiv:1301.6943. Bibcode:2013A&A...551A..67H. doi:10.1051/0004-6361/201220701.

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