375 Ursula

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375 Ursula
Ursula imaged at amag 11.4 near the star TYC 581-36-1 (magnitude 11.9). The two galaxies are about magnitude 15.
Discovery [1]
Discovered byA. Charlois
Discovery siteNice Obs.
Discovery date18 September 1893
(375) Ursula
Named after
1893 AL
main-belt · (outer)[3]
AdjectivesUrsulian /ɜːrˈsjliən/
Orbital characteristics[1]
Epoch 4 September 2017 (JD 2458000.5)
Uncertainty parameter 0
Observation arc124.06 yr (45,314 days)
Aphelion3.4544 AU
Perihelion2.7928 AU
3.1236 AU
5.52 yr (2,016 days)
0° 10m 42.6s / day
Physical characteristics
Dimensions189.45±54.76 km[5]
191.65±4.01 km[6]
193.63±2.52 km[7]
215.67±54.80 km[8]
216±10 km[9]
216.10 km (taken)[3]
Mass(8.45±5.26)×1018 kg[6]
Mean density
2.29±1.43 g/cm3[6]
16.78±0.01 h[3]
16.83 h[10][11]
16.899±0.001 h[12]
16.900±0.003 h[13]
0.0494 (derived)[3]
Tholen = C[1]
SMASS = Xc [1]
B–V = 0.683[1]
U–B = 0.341[1]
7.21[3] · 7.21±0.02[13][14] · 7.45[8] · 7.47[1][5][7] · 7.58±0.31[15]

Ursula (minor planet designation: 375 Ursula), provisional designation 1893 AL, is a dark asteroid and parent body of the Ursula family from the outer regions of the asteroid belt. It is one of the largest asteroids with a diameter of approximately 200 kilometers. It was discovered on 18 September 1893, by French astronomer Auguste Charlois at Nice Observatory in France.[16] The referent of the asteroids's name is unknown.[2]

Orbit and classification[edit]

Ursula is the parent body of the Ursula family (631),[4] a large family of C- and X-type asteroids.[17]: 23  It orbits the Sun in the outer asteroid belt at a distance of 2.8–3.5 AU once every 5 years and 6 months (2,016 days; semi-major axis of 3.12 AU). Its orbit has an eccentricity of 0.11 and an inclination of 16° with respect to the ecliptic.[1] The body's observation arc begins at Vienna Observatory in October 1893, three weeks after its official discovery observation at Nice.[16]

Physical characteristics[edit]

In the Tholen classification, Ursula is a carbonaceous C-type asteroid, while in the SMASS taxonomy, it is a Xc-subtype that transitions to the X-type asteroids.[1]

Rotation period[edit]

In January 2017, the so-far best-rated rotational lightcurve of Ursula was obtained from photometric observations by American astronomer Frederick Pilcher at the Organ Mesa Observatory (G50), New Mexico. Lightcurve analysis gave a rotation period of 16.899 hours with a brightness amplitude of 0.11 magnitude (U=3).[12]

Diameter and albedo[edit]

According to the surveys carried out by the Japanese Akari satellite and the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer, Ursula measures between 189.45 and 215.67 kilometers in diameter and its surface has an albedo between 0.04 and 0.049.[5][7][8]

Observations of an occultation on 15 November 1984, produced six chords indicating an estimated diameter of 216±10 km.[9] The Collaborative Asteroid Lightcurve Link derives an albedo of 0.0494 and adopts a diameter of 216.1 kilometers based on an absolute magnitude of 7.21.[3]


Any reference of this minor planet's name to a person or occurrence is unknown.[2]

Unknown referent[edit]

Among the many thousands of named minor planets, Ursula is one of only 120 for which no official naming citation has been published. All of these asteroids have low numbers between 164 Eva and 1514 Ricouxa and were discovered between 1876 and the 1930s, predominantly by astronomers Auguste Charlois, Johann Palisa, Max Wolf and Karl Reinmuth.[18]


  1. ^ a b c d e f g h i "JPL Small-Body Database Browser: 375 Ursula (1893 AL)" (2017-10-30 last obs.). Jet Propulsion Laboratory. Archived from the original on 1 May 2021. Retrieved 6 December 2017.
  2. ^ a b c Schmadel, Lutz D. (2007). Dictionary of Minor Planet Names – (375) Ursula. Springer Berlin Heidelberg. p. 46. doi:10.1007/978-3-540-29925-7_376. ISBN 978-3-540-00238-3.
  3. ^ a b c d e f "LCDB Data for (375) Ursula". Asteroid Lightcurve Database (LCDB). Retrieved 6 December 2017.
  4. ^ a b "Asteroid 375 Ursula – Nesvorny HCM Asteroid Families V3.0". Small Bodies Data Ferret. Retrieved 24 October 2019.
  5. ^ a b c d Nugent, C. R.; Mainzer, A.; Masiero, J.; Bauer, J.; Cutri, R. M.; Grav, T.; et al. (December 2015). "NEOWISE Reactivation Mission Year One: Preliminary Asteroid Diameters and Albedos". The Astrophysical Journal. 814 (2): 13. arXiv:1509.02522. Bibcode:2015ApJ...814..117N. doi:10.1088/0004-637X/814/2/117.
  6. ^ a b c Carry, B. (December 2012), "Density of asteroids", Planetary and Space Science, 73 (1): 98–118, arXiv:1203.4336, Bibcode:2012P&SS...73...98C, doi:10.1016/j.pss.2012.03.009. See Table 1.
  7. ^ a b c d 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. Bibcode:2011PASJ...63.1117U. doi:10.1093/pasj/63.5.1117. (online, AcuA catalog p. 153)
  8. ^ 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.
  9. ^ a b Millis, R. L.; Wasserman, L. H.; Bowell, E.; Franz, O. G.; Klemola, A.; Dunham, D. W. (April 1984). "The diameter of 375 URSULA from its occultation of AG + 39 deg 303". Astronomical Journal. 89: 592–596. Bibcode:1984AJ.....89..592M. doi:10.1086/113553. ISSN 0004-6256.
  10. ^ Schober, H. J. (December 1982). "Rotations of all asteroids larger than 200 KM". IN: Asteroids: 21–26.ResearchsupportedbytheSteiermaerkischerWissenschafts–undForschungslandesfonds, FondszurFoerderungderWissenschaftlichenForschung. Bibcode:1983acm..proc...21S.
  11. ^ Schober, H. J. (September 1987). "Rotation and variability of the large C-type asteroid 375 URSULA". Astronomy and Astrophysics. 183 (1): 151–155. Bibcode:1987A&A...183..151S. ISSN 0004-6361.
  12. ^ a b Pilcher, Frederick (July 2017). "Rotation Period Determinations for 49 Pales, 96 Aegle, 106 Dione 375 Ursula, and 576 Emanuela". The Minor Planet Bulletin. 44 (3): 249–251. Bibcode:2017MPBu...44..249P. ISSN 1052-8091.
  13. ^ a b Harris, A. W.; Young, J. W.; Bowell, E.; Tholen, D. J. (November 1999). "Asteroid Lightcurve Observations from 1981 to 1983". Icarus. 142 (1): 173–201. Bibcode:1999Icar..142..173H. doi:10.1006/icar.1999.6181.
  14. ^ 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.
  15. ^ 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.
  16. ^ a b "375 Ursula (1893 AL)". Minor Planet Center. Retrieved 6 December 2017.
  17. ^ 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.
  18. ^ Schmadel, Lutz D. (2007). "Appendix 11 – Minor Planet Names with Unknown Meaning". Dictionary of Minor Planet Names – Fifth Revised and Enlarged revision. Springer Berlin Heidelberg. pp. 927–929. ISBN 978-3-540-00238-3.

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