925 Alphonsina

925 Alphonsina, provisional designation 1920 GM, is a stony Hansian asteroid from the central region of the asteroid belt, approximately 58 kilometers (36 miles) in diameter. It was discovered on 13 January 1920, by Catalan astronomer Josep Comas i Solà at the Fabra Observatory in Barcelona, Spain.[1] The S-type asteroid has a rotation period of 7.88 hours.[9] It was named for the Spanish Kings Alfonso X and Alfonso XIII.[20]

925 Alphonsina
Discovery [1]
Discovered byJ. Comas Solà
Discovery siteFabra Obs.
Discovery date13 January 1920
Designations
(925) Alphonsina
Pronunciation/ælfɒnˈsaɪnə/
Named after
Alfonso X and Alfonso XIII
(Kings of Castile and Spain)
1920 GM · A902 ED
main-belt [1][2] · (middle)
Hansa [3][4]
Orbital characteristics [2]
Epoch 23 March 2018 (JD 2458200.5)
Uncertainty parameter 0
Observation arc115.98 yr (42,362 d)
Aphelion2.9130 AU
Perihelion2.4881 AU
2.7006 AU
Eccentricity0.0787
4.44 yr (1,621 d)
24.261°
0° 13m 19.56s / day
Inclination21.077°
299.59°
201.60°
Physical characteristics
Mean diameter
54.34±3.4 km[5]
57.505±0.443 km[6]
58.000±4.841 km[7]
58±16 km[8]
58.06 km (taken)[9]
58.062 km[10]
59.2 km[11]
62.57±0.64 km[12]
63.52±11.11 km[13]
7.876 h[14]
7.87754±0.00005 h[8][15]
7.8780±0.0004 h[14]
7.879±0.001 h[16]
7.880±0.001 h[17]
7.883±0.002 h[lower-alpha 1]
7.92 h[lower-alpha 2]
0.204±0.069[13]
0.214±0.006[12]
0.218[11]
0.2266[10]
0.248±0.036[6]
0.25±0.05[18]
0.2533±0.0534[7]
0.2786±0.038[5]
Tholen = S [2]
SMASS = S [2][9] · S [19]
B–V = 0.850[2]
U–B = 0.454[2]
8.33[2][5][7][12][13]
8.41[9][10][11][17]

    Orbit and classification

    Together with asteroid 480 Hansa, Alphonsina is the largest member of the stony Hansa family (803),[3] a high-inclination family with more than a thousand known members.[4][21]:23

    It orbits the Sun in the intermediate asteroid belt at a distance of 2.5–2.9 AU once every 4 years and 5 months (1,621 days; semi-major axis of 2.7 AU). Its orbit has an eccentricity of 0.08 and an inclination of 21° with respect to the ecliptic.[2] The asteroid was first observed as A902 ED at Heidelberg Observatory in March 1902. The body's observation arc begins ten days after its official discovery observation at Heidelberg.[1]

    Physical characteristics

    Alphonsina is a common, stony S-type asteroid in both the Tholen and SMASS classification.[2] Polarimetric observations in 2017 also characterized it as an S-type asteroid.[19]

    Rotation period and pole

    Since 1980, several rotational lightcurves of Alphonsina have been obtained from photometric observations with rotation periods between 7.876 and 7.92 hours (U=3/3/3/2/2).[14][16][17][lower-alpha 1][lower-alpha 2] The best-rated lightcurve by Alan Harris and James Whitney Young gave a period of 7.880 hours. The consolidated brightness amplitude is between 0.11 and 0.57 magnitude.[9][17]

    In 2011, two modeled lightcurves using data from the Uppsala Asteroid Photometric Catalogue (UAPC) and from asteroidal occultation silhouettes gave a concurring period 7.87754 hours. The studies also determined a spin axis at (296.0°, 41.0°) and (294.0°, 41.0°) in ecliptic coordinates (λ, β), respectively.[8][15]

    Diameter and albedo

    According to the surveys carried out by the Infrared Astronomical Satellite IRAS, the Japanese Akari satellite and the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer, Alphonsina measures between 54.34 and 63.52 kilometers in diameter and its surface has an albedo between 0.204 and 0.2786.[5][6][7][10][12][13][18]

    Combined Plot - Light Curve Inversion model (DAMIT 301) and Multi-chord Occultation.

    In 2003, stellar occultation measured a diameter of 59.2 kilometres and deduced an albedo of 0.218,[11] while the modelling of asteroid occultation silhouettes gave a diameter of 58 kilometres.[8] The asteroid has been observed in stellar occultations 8 times since 2003.[22]

    The Collaborative Asteroid Lightcurve Link adopts Petr Pravec's revised WISE data, that is, an albedo of 0.2266 and a diameter of 58.06 kilometers based on an absolute magnitude of 8.41.[9]

    Naming

    This minor planet was named in honor of the Iberian Kings, Alfonso X (1221–1284) and Alfonso XIII (1886–1941), King of Castile and Spain, respectively. The original citation from 1920, mentions, that the 13th century king inspired the field of astronomy in the Middle Ages, and, that the latter king was a great enthusiast of the scientific development in Spain. It also mentions that the King of Spain approved the naming of the asteroid (AN 211, 223).[20]

    Notes
    1. Hamanowa (2011) web: rotation period 7.883±0.002 hours with a brightness amplitude of 0.30 mag. Summary figures for (925) Alphonsina at the LCDB.
    2. Hanslmeier (1980): rotation period for (925) Alphonsina of 7.92 hours with a brightness amplitude of 0.18 mag. Quality Code of 2. Summary figures at the LCDB.

    References
    1. "925 Alphonsina (1920 GM)". Minor Planet Center. Retrieved 4 April 2018.
    2. "JPL Small-Body Database Browser: 925 Alphonsina (1920 GM)" (2018-02-27 last obs.). Jet Propulsion Laboratory. Retrieved 4 April 2018.
    3. "Asteroid 925 Alphonsina – Nesvorny HCM Asteroid Families V3.0". Small Bodies Data Ferret. Retrieved 24 October 2019.
    4. Hergenrother, C. W.; Larson, S. M.; Spahr, T. B. (September 1996). "The Hansa Family: A New High-Inclination Asteroid Family". American Astronomical Society. 28: 1097. Bibcode:1996DPS....28.1007H.
    5. Tedesco, E. F.; Noah, P. V.; Noah, M.; Price, S. D. (October 2004). "IRAS Minor Planet Survey V6.0". NASA Planetary Data System – IRAS-A-FPA-3-RDR-IMPS-V6.0. Bibcode:2004PDSS...12.....T. Retrieved 24 October 2019.
    6. 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. arXiv:1406.6645. Bibcode:2014ApJ...791..121M. doi:10.1088/0004-637X/791/2/121.
    7. Mainzer, A.; Grav, T.; Masiero, J.; Hand, E.; Bauer, J.; et al. (November 2011). "NEOWISE Studies of Spectrophotometrically Classified Asteroids: Preliminary Results". The Astrophysical Journal. 741 (2): 25. arXiv:1109.6407. Bibcode:2011ApJ...741...90M. doi:10.1088/0004-637X/741/2/90.
    8. Durech, Josef; Kaasalainen, Mikko; Herald, David; Dunham, David; Timerson, Brad; et al. (August 2011). "Combining asteroid models derived by lightcurve inversion with asteroidal occultation silhouettes". Icarus. 214 (2): 652–670. arXiv:1104.4227. Bibcode:2011Icar..214..652D. doi:10.1016/j.icarus.2011.03.016.
    9. "LCDB Data for (925) Alphonsina". Asteroid Lightcurve Database (LCDB). Retrieved 4 April 2018.
    10. 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.
    11. Shevchenko, Vasilij G.; Tedesco, Edward F. (September 2006). "Asteroid albedos deduced from stellar occultations". Icarus. 184 (1): 211–220. Bibcode:2006Icar..184..211S. doi:10.1016/j.icarus.2006.04.006.
    12. Usui, Fumihiko; Kuroda, Daisuke; Müller, Thomas G.; Hasegawa, Sunao; Ishiguro, Masateru; 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.
    13. Masiero, Joseph R.; Mainzer, A. K.; Grav, T.; Bauer, J. M.; Cutri, R. M.; 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.
    14. Behrend, Raoul. "Asteroids and comets rotation curves – (925) Alphonsina". Geneva Observatory. Retrieved 4 April 2018.
    15. Hanus, J.; Durech, J.; Broz, M.; Warner, B. D.; Pilcher, F.; 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 and Astrophysics. 530: 16. arXiv:1104.4114. Bibcode:2011A&A...530A.134H. doi:10.1051/0004-6361/201116738.
    16. Alton, Kevin B. (July 2017). "CCD Lightcurves for Main-belt Asteriods [sic] 423 Diotima and 925 Alphonsina". The Minor Planet Bulletin. 44 (3): 188–189. Bibcode:2017MPBu...44..188A. ISSN 1052-8091.
    17. Harris, A. W.; Young, J. W. (October 1989). "Asteroid lightcurve observations from 1979-1981". Icarus. 81 (2): 314–364. Bibcode:1989Icar...81..314H. doi:10.1016/0019-1035(89)90056-0. ISSN 0019-1035.
    18. Mainzer, A.; Grav, T.; Masiero, J.; Bauer, J.; Wright, E.; et al. (August 2011). "Thermal Model Calibration for Minor Planets Observed with Wide-field Infrared Survey Explorer/NEOWISE". The Astrophysical Journal. 736 (2): 9. Bibcode:2011ApJ...736..100M. CiteSeerX 10.1.1.472.4936. doi:10.1088/0004-637X/736/2/100.
    19. Belskaya, I. N.; Fornasier, S.; Tozzi, G. P.; Gil-Hutton, R.; Cellino, A.; Antonyuk, K.; et al. (March 2017). "Refining the asteroid taxonomy by polarimetric observations". Icarus. 284: 30–42. Bibcode:2017Icar..284...30B. doi:10.1016/j.icarus.2016.11.003.
    20. Schmadel, Lutz D. (2007). "(925) Alphonsina". Dictionary of Minor Planet Names – (925) Alphonsina. Springer Berlin Heidelberg. p. 82. doi:10.1007/978-3-540-29925-7_926. ISBN 978-3-540-00238-3.
    21. Nesvorný, D.; Broz, M.; Carruba, V. (December 2014). Identification and Dynamical Properties of Asteroid Families. Asteroids IV. pp. 297–321. arXiv:1502.01628. Bibcode:2015aste.book..297N. doi:10.2458/azu_uapress_9780816532131-ch016. ISBN 9780816532131.
    22. "Asteroid Data Sets". sbn.psi.edu. Retrieved 27 May 2018.

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