Astronomy:1494 Savo

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1494 Savo
001494-asteroid shape model (1494) Savo.png
Shape of Savo modelled from its lightcurve
Discovery[1]
Discovered byY. Väisälä
Discovery siteTurku Obs.
Discovery date16 September 1938
Designations
(1494) Savo
Named afterSavonia[2]
(Finnish region)
1938 SJ · 1925 RL
1938 SG1 · 1948 VR
1951 SV · 1953 GD
1966 HB · 1976 HZ
Minor planet categorymain-belt · (inner)[3]
background[4]
Orbital characteristics[1]
Epoch 4 September 2017 (JD 2458000.5)
Uncertainty parameter 0
Observation arc78.50 yr (28,673 days)
|{{{apsis}}}|helion}}2.4777 AU
|{{{apsis}}}|helion}}1.9019 AU
2.1898 AU
Eccentricity0.1315
Orbital period3.24 yr (1,184 days)
Mean anomaly114.29°
Mean motion0° 18m 14.76s / day
Inclination2.4560°
Longitude of ascending node195.02°
184.32°
Physical characteristics
Dimensions7.80±0.22 km[5]
7.804±0.219 km[5]
9.23±0.43 km[6]
10.30 km (calculated)[3]
Rotation period5.35011±0.00028 h[lower-alpha 1]
5.35020±0.00005 h[7]
5.35031±0.00005 h[7]
5.35059±0.00001 h[8]
5.35059±0.00005 h[9]
5.35062±0.00005 h[7]
Geometric albedo0.173±0.017[6]
0.20 (assumed)[3]
0.349±0.061[5]
SMASS = Sa[1] · S[3]
Absolute magnitude (H)12.08±0.24[10] · 12.30[1][3][5] · 12.70[6]


1494 Savo, provisional designation 1938 SJ, is a stony background asteroid from the inner region of the asteroid belt, approximately 8 kilometers in diameter. Discovered by astronomer Yrjö Väisälä at the Turku Observatory in 1938, the asteroid was later named after the Finnish region of Savonia.[2]

Discovery

Savo was discovered on 16 September 1938, by Finnish astronomer Yrjö Väisälä at the Iso-Heikkilä Observatory near Turku, Finland.[11] Two nights later, it was independently discovered by German astronomer Arno Arthur Wachmann at the Bergedorf Observatory in Hamburg.[2] However, the Minor Planet Center only acknowledges the first discoverer. The asteroid was first identified as 1925 RL at the Crimean Simeiz Observatory in September 1929, or nine years before its official discovery observation.[11]

Orbit and classification

Savo is an asteroid of the main belt's background population that does not belong to any known asteroid family.[4] It orbits the Sun in the inner asteroid belt at a distance of 1.9–2.5 AU once every 3 years and 3 months (1,184 days). Its orbit has an eccentricity of 0.13 and an inclination of 2° with respect to the ecliptic.[1] The body's observation arc begins with its official discovery observation at Turku in September 1938.[11]

Physical characteristics

In the SMASS classification, Savo is an Sa-subtype that transitions from the stony S-type to the A-type asteroids.[1]

Rotation period

In August 2006, a rotational lightcurve of Savo was obtained from photometric observations by Czech astronomer Petr Pravec at Ondřejov Observatory. Lightcurve analysis gave a well-defined rotation period of 5.35011 hours with a brightness amplitude of 0.52 magnitude ({{{1}}}), indicative for a non-spherical shape.[lower-alpha 1] Follow up observations at the Calvin College Observatory (H62) in 2007 and 2008, gave three nearly identical periods of 5.35020, 5.35031 and 5.35062 hours with an amplitude between 0.44 and 0.63 ({{{1}}}).[7]

Poles

The asteroid's lightcurve has also been modeled twice. In 2011, the first modelling used photometric data from the AstDyS database and the Uppsala Asteroid Photometric Catalogue, and found two spin axis of (248.0°, −68.0°) and (83.0°, −66.0°) in ecliptic coordinates (λ, β).[9] A refined modeling in 2016, using the Lowell Photometric Database gave two poles of (50.0°, −65.0°) and (233.0°, −68.0°) in ecliptic coordinates.[8] Also, both studies found a concurring period of 5.35059 hours.[9][8]

Diameter and albedo

According to the surveys carried out by the Japanese Akari satellite and the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer, Savo measures between 7.80 and 9.23 kilometers in diameter and its surface has an albedo between 0.173 and 0.349.[5][6] The Collaborative Asteroid Lightcurve Link assumes a standard albedo for stony asteroids of 0.20 and calculates a diameter of 10.30 kilometers based on an absolute magnitude of 12.3.[3]

Naming

This minor planet was named after Finnish historical province of Savonia.[2] The official naming citation was published by the Minor Planet Center in January 1956 (M.P.C. 1350).[12]

Notes

  1. ↑ 1.0 1.1 Pravec (2006) web: Lightcurve plot of (1494) Savo with a rotation period 5.35011±0.00028 hours with a brightness amplitude of 0.52 mag. Quality Code of 3. Summary figures for (1494) Savo at LCDB and data sheet at Ondrejov Asteroid Photometry Project

References

  1. ↑ 1.0 1.1 1.2 1.3 1.4 1.5 "JPL Small-Body Database Browser: 1494 Savo (1938 SJ)". Jet Propulsion Laboratory. https://ssd.jpl.nasa.gov/sbdb.cgi?sstr=2001494. Retrieved 28 September 2017. 
  2. ↑ 2.0 2.1 2.2 2.3 Schmadel, Lutz D. (2007). "(1494) Savo". Dictionary of Minor Planet Names – (1494) Savo. Springer Berlin Heidelberg. p. 119. doi:10.1007/978-3-540-29925-7_1495. ISBN 978-3-540-00238-3. 
  3. ↑ 3.0 3.1 3.2 3.3 3.4 3.5 "LCDB Data for (1494) Savo". Asteroid Lightcurve Database (LCDB). http://www.minorplanet.info/PHP/generateOneAsteroidInfo.php?AstInfo=1494%7CSavo. Retrieved 28 September 2017. 
  4. ↑ 4.0 4.1 "Asteroid 1494 Savo – Proper Elements". AstDyS-2, Asteroids – Dynamic Site. https://newton.spacedys.com/astdys/index.php?pc=1.1.6&n=1494. 
  5. ↑ 5.0 5.1 5.2 5.3 5.4 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. doi:10.1088/2041-8205/759/1/L8. Bibcode: 2012ApJ...759L...8M. http://adsabs.harvard.edu/cgi-bin/bib_query?bibcode=2012ApJ...759L...8M. Retrieved 28 September 2017. 
  6. ↑ 6.0 6.1 6.2 6.3 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. doi:10.1093/pasj/63.5.1117. Bibcode: 2011PASJ...63.1117U.  (online, AcuA catalog p. 153)
  7. ↑ 7.0 7.1 7.2 7.3 Dykhuis, Melissa J.; Molnar, Lawrence A.; Gates, Christopher J.; Gonzales, Joshua A.; Huffman, Jared J.; Maat, Aaron R. et al. (March 2016). "Efficient spin sense determination of Flora-region asteroids via the epoch method". Icarus 267: 174–203. doi:10.1016/j.icarus.2015.12.021. Bibcode: 2016Icar..267..174D. http://adsabs.harvard.edu/cgi-bin/bib_query?bibcode=2016Icar..267..174D. Retrieved 28 September 2017. 
  8. ↑ 8.0 8.1 8.2 Durech, J.; Hanus, J.; Oszkiewicz, D.; Vanco, R. (March 2016). "Asteroid models from the Lowell photometric database". Astronomy and Astrophysics 587: 6. doi:10.1051/0004-6361/201527573. Bibcode: 2016A&A...587A..48D. 
  9. ↑ 9.0 9.1 9.2 Hanus, J.; Durech, J.; Broz, M.; Warner, B. D.; Pilcher, F.; Stephens, R. et al. (June 2011). "A study of asteroid pole-latitude distribution based on an extended set of shape models derived by the lightcurve inversion method". Astronomy & Astrophysics 530: 16. doi:10.1051/0004-6361/201116738. Bibcode: 2011A&A...530A.134H. 
  10. ↑ 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 28 September 2017. 
  11. ↑ 11.0 11.1 11.2 "1494 Savo (1938 SJ)". Minor Planet Center. https://www.minorplanetcenter.net/db_search/show_object?object_id=1494. Retrieved 28 September 2017. 
  12. ↑ Schmadel, Lutz D.. "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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