Astronomy:950 Ahrensa
_Ahrensa.png) Modelled shape of Ahrensa from its lightcurve | |
| Discovery [1] | |
|---|---|
| Discovered by | K. Reinmuth |
| Discovery site | Heidelberg Obs. |
| Discovery date | 1 April 1921 |
| Designations | |
| (950) Ahrensa | |
| Named after | Ahrens family (friends of discoverer)[2] |
| 1921 JP · 1955 SU2 1974 VG3 · A904 RF | |
| Minor planet category | main-belt · Phocaea [3] |
| Orbital characteristics [1] | |
| Epoch 31 July 2016 (JD 2457600.5) | |
| Uncertainty parameter 0 | |
| Observation arc | 111.60 yr (40761 days) |
| |{{{apsis}}}|helion}} | 2.7477 astronomical unit|AU (411.05 Gm) |
| |{{{apsis}}}|helion}} | 1.9958 AU (298.57 Gm) |
| 2.3717 AU (354.80 Gm) | |
| Eccentricity | 0.15851 |
| Orbital period | 3.65 yr (1334.1 d) |
| Mean anomaly | 53.005° |
| Mean motion | 0° 16m 11.424s / day |
| Inclination | 23.477° |
| Longitude of ascending node | 181.81° |
| 348.19° | |
| Physical characteristics | |
| Mean diameter | 15.03±1.8 (IRAS:15) km[4] 16.21±0.53 km[5] 14.299±0.070 km[6] 16.66±0.41 km[7] 15.34 km (derived)[3] |
| Rotation period | 202±1 h,[8] 202 h (8.4 d)[1] |
| Geometric albedo | 0.1793±0.054 (IRAS:15)[1][4] 0.158±0.011[5] 0.1988±0.0203[6] 0.231±0.031[7] 0.2727 (derived)[3] |
| SMASS = Sa S [3] | |
| Absolute magnitude (H) | 11.2[1] |
950 Ahrensa, provisional designation 1921 JP, is a stony Phocaea asteroid and slow rotator from the inner regions of the asteroid belt, approximately 15 kilometers in diameter. It was discovered on 1 April 1921, by German astronomer Karl Reinmuth at Heidelberg Observatory in southern Germany.[9]
Description
The S-type asteroid, classified as a Sa-subtype in the SMASS taxonomic scheme, is a member of the Phocaea family, a group of asteroids with similar orbital characteristics. It orbits the Sun at a distance of 2.0–2.7 AU once every 3 years and 8 months (1,334 days). Its orbit shows an eccentricity of 0.16 and is tilted by 23 degrees to the plane of the ecliptic.
A photometric lightcurve analysis at the U.S. Palmer Divide Observatory in 2009, showed that the body has an exceptionally long rotation period of 202 hours.[8] According to the surveys carried out by the Infrared Astronomical Satellite, IRAS, the Japanese Akari satellite, and the U.S. Wide-field Infrared Survey Explorer with its subsequent NEOWISE mission, the surface of the asteroid has an albedo in the range of 0.16 to 0.23, while the Collaborative Asteroid Lightcurve Link derives an even higher value of 0.27 for the stony body.[3][4][5][6][7]
The minor planet was named in honor of friends of the discoverer Karl Reinmuth, the Ahrens family, who helped him financially at the Heidelberg Observatory. Reinmuth also named the minor planet 909 Ulla after Ulla Ahrens, a member of this family.[2]
References
- ↑ 1.0 1.1 1.2 1.3 1.4 "JPL Small-Body Database Browser: 950 Ahrensa (1921 JP)". Jet Propulsion Laboratory. https://ssd.jpl.nasa.gov/sbdb.cgi?sstr=2000950.
- ↑ 2.0 2.1 Schmadel, Lutz D. (2003). "(950) Ahrensa". Dictionary of Minor Planet Names – (950) Ahrensa. Springer Berlin Heidelberg. p. 84. doi:10.1007/978-3-540-29925-7_951. ISBN 978-3-540-29925-7.
- ↑ 3.0 3.1 3.2 3.3 3.4 "LCDB Data for (950) Ahrensa". Asteroid Lightcurve Database (LCDB). http://www.minorplanet.info/PHP/generateOneAsteroidInfo.php?AstInfo=950%7CAhrensa.
- ↑ 4.0 4.1 4.2 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. https://sbnarchive.psi.edu/pds3/iras/IRAS_A_FPA_3_RDR_IMPS_V6_0/data/diamalb.tab. Retrieved 22 October 2019.
- ↑ 5.0 5.1 5.2 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)
- ↑ 6.0 6.1 6.2 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. http://adsabs.harvard.edu/cgi-bin/bib_query?bibcode=2011ApJ...741...90M. Retrieved 4 January 2016.
- ↑ 7.0 7.1 7.2 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 4 January 2016.
- ↑ 8.0 8.1 Warner, Brian D. (January 2010). "Asteroid Lightcurve Analysis at the Palmer Divide Observatory: 2009 June-September". The Minor Planet Bulletin 37 (1): 24–27. ISSN 1052-8091. Bibcode: 2010MPBu...37...24W. http://adsabs.harvard.edu/cgi-bin/bib_query?bibcode=2010MPBu...37...24W. Retrieved 4 January 2016.
- ↑ "950 Ahrensa (1921 JP)". Minor Planet Center. https://www.minorplanetcenter.net/db_search/show_object?object_id=950.
External links
- Lightcurve plot of 950 Ahrensa, Palmer Divide Observatory, B. D. Warner (2009)
- Asteroid Lightcurve Database (LCDB), query form (info )
- Dictionary of Minor Planet Names, Google books
- Asteroids and comets rotation curves, CdR – Observatoire de Genève, Raoul Behrend
- Discovery Circumstances: Numbered Minor Planets (1)-(5000) – Minor Planet Center
- 950 Ahrensa at AstDyS-2, Asteroids—Dynamic Site
- 950 Ahrensa at the JPL Small-Body Database
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