Astronomy:1473 Ounas

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1473 Ounas
Discovery[1]
Discovered byY. Väisälä
Discovery siteTurku Obs.
Discovery date22 October 1938
Designations
(1473) Ounas
Named afterOunasjoki River
(in Finland)[2]
1938 UT · 1950 NZ
1950 PB1
Minor planet categorymain-belt · (middle)[3]
Orbital characteristics[1]
Epoch 16 February 2017 (JD 2457800.5)
Uncertainty parameter 0
Observation arc77.90 yr (28,452 days)
|{{{apsis}}}|helion}}3.1862 AU
|{{{apsis}}}|helion}}1.9623 AU
2.5743 AU
Eccentricity0.2377
Orbital period4.13 yr (1,509 days)
Mean anomaly19.843°
Mean motion0° 14m 18.96s / day
Inclination13.651°
Longitude of ascending node216.52°
129.42°
Physical characteristics
Dimensions17.62 km (derived)[3]
18.164±0.109[4]
20.032 km (dated)[5]
Rotation period16 h (dated)[3]
139.1±0.1 h[6]
139.1±0.5 h[7]
Geometric albedo0.0841 (dated)[5]
0.110±0.018[4]
0.1189 (derived)[3]
S[3]
Absolute magnitude (H)11.67±0.32[8] · 11.7[1][3] · 11.8[5]


1473 Ounas, provisional designation 1938 UT, is a stony asteroid, suspected tumbler and a slow rotator from the middle region of the asteroid belt, approximately 18 kilometers in diameter. It was discovered on 22 October 1938, by Finnish astronomer Yrjö Väisälä at Turku Observatory in Southwest Finland.[9] The asteroid was named after the Finnish Ounas river.[2]

Classification and orbit

Ounas is a S-type asteroid that orbits the Sun in the central main-belt at a distance of 2.0–3.2 AU once every 4 years and 2 months (1,509 days). Its orbit has an eccentricity of 0.24 and an inclination of 14° with respect to the ecliptic.[1] As no precoveries were taken, and no previous identifications were made, the body's observation arc begins with its official discovery observation at Turku in 1938.[9]

Physical characteristics

In October 2012/13, a rotational lightcurve of Ounas was obtained from photometric observations by astronomers René Roy, Vladimir Benishek, Andrea Ferrero, Daniel Klinglesmith, Frederick Pilcher, Raoul Behrend and Petr Pravec. It gave a well-defined rotation period of 139.1 hours with a brightness variation of 0.6 magnitude ({{{1}}}).[6][7] Ounas is a suspected "tumbler", which have a non-principal axis rotation (NPAR).[6]

According to the survey carried out by NASA's Wide-field Infrared Survey Explorer with its subsequent NEOWISE mission, the asteroid measures 18.16 kilometers in diameter and its surface has an albedo of 0.11.[4][5] The Collaborative Asteroid Lightcurve Link derives an albedo of 0.1189 and a diameter of 17.62 kilometers with an absolute magnitude of 11.7.[3]

Naming

This minor planet was named after the Ounas river, one of the principal rivers in Finland.[2] The official naming citation was published by the Minor Planet Center on 20 February 1976 (M.P.C. 3928).[10]

References

  1. ↑ 1.0 1.1 1.2 1.3 "JPL Small-Body Database Browser: 1473 Ounas (1938 UT)". Jet Propulsion Laboratory. https://ssd.jpl.nasa.gov/sbdb.cgi?sstr=2001473. 
  2. ↑ 2.0 2.1 2.2 Schmadel, Lutz D. (2007). "(1473) Ounas". Dictionary of Minor Planet Names – (1473) Ounas. Springer Berlin Heidelberg. p. 118. doi:10.1007/978-3-540-29925-7_1474. ISBN 978-3-540-00238-3. 
  3. ↑ 3.0 3.1 3.2 3.3 3.4 3.5 3.6 "LCDB Data for (1473) Ounas". Asteroid Lightcurve Database (LCDB). http://www.minorplanet.info/PHP/generateOneAsteroidInfo.php?AstInfo=1473%7COunas. 
  4. ↑ 4.0 4.1 4.2 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. doi:10.1088/0004-637X/791/2/121. Bibcode: 2014ApJ...791..121M. http://adsabs.harvard.edu/cgi-bin/bib_query?bibcode=2014ApJ...791..121M. Retrieved 16 December 2016. 
  5. ↑ 5.0 5.1 5.2 5.3 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. doi:10.1088/0004-637X/741/2/90. Bibcode: 2011ApJ...741...90M. 
  6. ↑ 6.0 6.1 6.2 Pilcher, Frederick; Benishek, Vladimir; Ferrero, Andrea; Klinglesmith, Daniel A. III; Pravec, Petr; Roy, Rene et al. (July 2013). "New Photometry of 1473 Ounas". The Minor Planet Bulletin 40 (3): 126–129. ISSN 1052-8091. Bibcode: 2013MPBu...40..126P. http://adsabs.harvard.edu/cgi-bin/bib_query?bibcode=2013MPBu...40..126P. Retrieved 16 December 2016. 
  7. ↑ 7.0 7.1 Behrend, Raoul. "Asteroids and comets rotation curves – (1473) Ounas". Geneva Observatory. http://obswww.unige.ch/~behrend/page4cou.html#001473. 
  8. ↑ 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. doi:10.1016/j.icarus.2015.08.007. Bibcode: 2015Icar..261...34V. http://adsabs.harvard.edu/cgi-bin/bib_query?bibcode=2015Icar..261...34V. Retrieved 16 December 2016. 
  9. ↑ 9.0 9.1 "1473 Ounas (1938 UT)". Minor Planet Center. https://www.minorplanetcenter.net/db_search/show_object?object_id=1473. 
  10. ↑ 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. https://archive.org/details/dictionaryminorp2008schm. 

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