306 Unitas

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306 Unitas
306Unitas (Lightcurve Inversion).png
A three-dimensional model of 306 Unitas based on its light curve.
Discovered by Elia Millosevich
Discovery date March 1, 1891
Main belt
Orbital characteristics
Epoch 30 January 2005 (JD 2453400.5)
Aphelion 405.786 Gm (2.713 AU)
Perihelion 299.81 Gm (2.004 AU)
352.798 Gm (2.358 AU)
Eccentricity 0.15
1322.79 d (3.62 a)
19.4 km/s
Inclination 7.267°
Physical characteristics
Dimensions 52.88 ± 3.48[1] km
Mass (5.33 ± 5.77) × 1017[1] kg
8.73875[2] h
Albedo 0.211[3]
Spectral type

306 Unitas is a typical main belt asteroid that was discovered by Elia Millosevich on March 1, 1891 in Rome. The asteroid was named by the director of the Modena Observatory in honor of the Italian astronomer Angelo Secchi.[4] It is classified as an S-type asteroid.

In the late 1990s, a network of astronomers worldwide gathered light curve data that was ultimately used to derive the spin states and shape models of 10 new asteroids, including (306) Unitas. The computed shape model for this asteroid is regular, while the light curve displays two maxima per rotation.[2][5] Lightcurve data has also been recorded by observers at the Antelope Hill Observatory, which has been designated as an official observatory by the Minor Planet Center.[6]

Measurements of the thermal inertia of 306 Unitas give an estimate range from 100 to 260 m−2 K−1 s−1/2, compared to 50 for lunar regolith and 400 for coarse sand in an atmosphere.[3]

Although 306 Unitas has an orbit similar to the Vesta family asteroids, it was found to be an unrelated interloper on the basis of its non-matching spectral type.[citation needed]


  1. ^ a b Carry, B. (December 2012), "Density of asteroids", Planetary and Space Science 73: 98–118, arXiv:1203.4336, Bibcode:2012P&SS...73...98C, doi:10.1016/j.pss.2012.03.009.  See Table 1.
  2. ^ a b Durech, J.; et al. (April 2007), "Physical models of ten asteroids from an observers' collaboration network", Astronomy and Astrophysics 465 (1): 331–337, Bibcode:2007A&A...465..331D, doi:10.1051/0004-6361:20066347. 
  3. ^ a b c Delbo', Marco; Tanga, Paolo (February 2009), "Thermal inertia of main belt asteroids smaller than 100 km from IRAS data", Planetary and Space Science 57 (2): 259–265, arXiv:0808.0869, Bibcode:2009P&SS...57..259D, doi:10.1016/j.pss.2008.06.015. 
  4. ^ Schmadel Lutz D. Dictionary of Minor Planet Names (fifth edition), Springer, 2003. ISBN 3-540-00238-3.
  5. ^ Durech, J.; Kaasalainen, M.; Marciniak, A.; Allen, W. H. et al. “Asteroid brightness and geometry,” Astronomy and Astrophysics, Volume 465, Issue 1, April I 2007, pp. 331-337.
  6. ^ Lightcurve Results