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5080 Oja, provisional designation 1976 EB, is a stony Florian asteroid from the inner regions of the asteroid belt, approximately 8 kilometers in diameter. It was discovered on 2 March 1976, by astronomer Claes-Ingvar Lagerkvist at the Kvistaberg Station of the Uppsala Observatory in Sweden. In 1992, it was named after Estonian–Swedish astronomer Tarmo Oja.[1] The S-type asteroid has a rotation period of 7.222 hours.[3]

5080 Oja
Discovery [1]
Discovered byC.-I. Lagerkvist
Discovery siteKvistaberg Stn.
Discovery date2 March 1976
MPC designation(5080) Oja
Named after
Tarmo Oja[1]
(Estonian–Swedish astronomer)
1976 EB · 1951 WO
1951 XA · 1988 XH
A924 SB
main-belt[1][2] · (inner)
Flora[3][4] · Matterania
Orbital characteristics[2]
Epoch 23 March 2018 (JD 2458200.5)
Uncertainty parameter 0
Observation arc92.68 yr (33,852 d)
Aphelion2.5215 AU
Perihelion1.9617 AU
2.2416 AU
3.36 yr (1,226 d)
0° 17m 37.32s / day
Physical characteristics
Mean diameter
6.94±1.26 km[5]
7.766±0.080 km[6]
8.377 km[7]
8.38 km (taken)[3]
8.399±0.049 km[8]
7.2220±0.0004 h[9]
7.2222±0.00003 h[a]
7.7 h[10]
S[11] · S (assumed)[3]
12.52±0.04 (R)[a] · 12.6[2]
12.9[8] · 12.97[5] · 13.01[3]


Orbit and classificationEdit

Oja is a member of the Flora family (402),[3][4] a giant asteroid family and the largest family of stony asteroids in the main-belt.[12] It orbits the Sun in the inner main-belt at a distance of 2.0–2.5 AU once every 3 years and 4 months (1,226 days; semi-major axis of 2.24 AU). Its orbit has an eccentricity of 0.12 and an inclination of 5° with respect to the ecliptic.[2]

On 29 September 1924, the asteroid was first observed as A924 SB at Heidelberg Observatory, where the body's observation arc begins two days later on 1 October 1924.[1]

Physical characteristicsEdit

Oja has been characterized as a common, stony S-type asteroid by Pan-STARRS' photometric survey, in line with the overall spectral type of the Flora family.[12]:23

Rotation periodEdit

In January 2006, a rotational lightcurve of Oja was obtained from photometric observations by an international collaboration of astronomers including Petr Pravec at Ondřejov Observatory and Donald Pray at Carbuncle Hill Observatory (912). The consolidated lightcurve analysis gave a rotation period of 7.222 hours and a brightness variation between 0.31 and 0.39 magnitude (U=3/3).[9][a] The result supersedes a period of 7.7 hours obtained by the discoverer (Claes-Ingvar Lagerkvist) in March 1976 (U=2).[10]

Diameter and albedoEdit

According to the survey carried out by the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer, Oja measures between 6.94 and 8.399 kilometers in diameter and its surface has an albedo between 0.1573 and 0.31.[5][6][7][8] The Collaborative Asteroid Lightcurve Link adopts an albedo of 0.1573 from Pravec's revised WISE data and uses a diameter of 8.38 kilometers based on an absolute magnitude of 13.01.[3]


This minor planet was named after the Swedish astronomer of Estonian descent Tarmo Oja (born 1934), who was a professor in astronomy at Uppsala University and the director of the discovering Kvistaberg Station during 1970–1999. His research included the structure of galaxies and variable stars. The official naming citation was published by the Minor Planet Center on 14 July 1992 (M.P.C. 20522).[13]


  1. ^ a b c Pravec (2006) web: rotation period 7.2222±0.00003 hours and a brightness amplitude of 0.39±0.01 mag in the R-band. Observation period from 31 December 2005 to 10 January 2006. Quality Code is 3. Summary figures at the LCDB and Pravec, P.; Wolf, M.; Sarounova, L. (2016) with data sheet


  1. ^ a b c d e "5080 Oja (1976 EB)". Minor Planet Center. Retrieved 20 March 2018.
  2. ^ a b c d "JPL Small-Body Database Browser: 5080 Oja (1976 EB)" (2017-06-05 last obs.). Jet Propulsion Laboratory. Retrieved 20 March 2018.
  3. ^ a b c d e f g "LCDB Data for (5080) Oja". Asteroid Lightcurve Database (LCDB). Retrieved 20 March 2018.
  4. ^ a b "Small Bodies Data Ferret". Nesvorny HCM Asteroid Families V3.0. Retrieved 20 March 2018.
  5. ^ a b c d 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. Retrieved 20 March 2018.
  6. ^ a b c 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" (PDF). The Astrophysical Journal. 791 (2): 11. arXiv:1406.6645. Bibcode:2014ApJ...791..121M. doi:10.1088/0004-637X/791/2/121. Retrieved 20 March 2018.
  7. ^ a b c d Pravec, Petr; Harris, Alan W.; Kusnirák, Peter; Galád, Adrián; Hornoch, Kamil (September 2012). "Absolute magnitudes of asteroids and a revision of asteroid albedo estimates from WISE thermal observations". Icarus. 221 (1): 365–387. Bibcode:2012Icar..221..365P. doi:10.1016/j.icarus.2012.07.026. Retrieved 20 March 2018.
  8. ^ a b c d Mainzer, A.; Grav, T.; Masiero, J.; Hand, E.; Bauer, J.; Tholen, D.; et al. (November 2011). "NEOWISE Studies of Spectrophotometrically Classified Asteroids: Preliminary Results" (PDF). The Astrophysical Journal. 741 (2): 25. arXiv:1109.6407. Bibcode:2011ApJ...741...90M. doi:10.1088/0004-637X/741/2/90. Retrieved 20 March 2018.
  9. ^ a b Pray, Donald P.; Galad, Adrian; Gajdos, Stefan; Vilagi, Jozef; Cooney, Walt; Gross, John; et al. (December 2006). "Lightcurve analysis of asteroids 53, 698, 1016, 1523, 1950, 4608, 5080 6170, 7760, 8213, 11271, 14257, 15350 and 17509". The Minor Planet Bulletin. 33 (4): 92–95. Bibcode:2006MPBu...33...92P. ISSN 1052-8091. Retrieved 20 March 2018.
  10. ^ a b Lagerkvist, C.-I. (March 1978). "Photographic photometry of 110 main-belt asteroids". Astronomy and Astrophysics Supplement Series: 361–381. Bibcode:1978A&AS...31..361L. Retrieved 20 March 2018.
  11. ^ a b 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 20 March 2018.
  12. ^ a b Nesvorný, D.; Broz, M.; Carruba, V. (December 2014). "Identification and Dynamical Properties of Asteroid Families" (PDF). Asteroids IV: 297–321. arXiv:1502.01628. doi:10.2458/azu_uapress_9780816532131-ch016. Retrieved 20 March 2018.
  13. ^ "MPC/MPO/MPS Archive". Minor Planet Center. Retrieved 20 March 2018.

External linksEdit