115 Thyra

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115 Thyra
115Thyra (Lightcurve Inversion).png
A three-dimensional model of 115 Thyra based on its light curve.
Discovery
Discovered by James Craig Watson
Discovery date August 6, 1871
Designations
Named after
Thyra
Minor planet category Main belt
Orbital characteristics[1]
Epoch December 31, 2006 (JD 2454100.5)
Aphelion 424.287 Gm (2.836 AU)
Perihelion 287.821 Gm (1.924 AU)
356.054 Gm (2.380 AU)
Eccentricity 0.192
1341.169 d (3.67 a)
19.13 km/s
248.748°
Inclination 11.600°
308.982°
96.825°
Physical characteristics
Dimensions 79.83[2] km
Mass 5.3×1017 kg
0.0223 m/s²
0.0422 km/s
Albedo 0.275[2]
Temperature ~180 K
Spectral type
S[3]
7.51[2]

115 Thyra is a fairly large and bright inner main-belt asteroid that was discovered by Canadian-American astronomer J. C. Watson on August 6, 1871[4] and was named for Thyra, the consort of King Gorm the Old of Denmark. Based upon its spectrum, it is categorized as a stony S-type asteroid.[5]

Observations made between 1978 and 1981 produced a composite light curve with two minima and maxima. However, a subsequent study in 1983 only found a single minima and maxima. A synodical rotation period of 7.241 hours was determined. This was confirmed by observations between 1995 and 2000. The changes in brightness and color indicate a surface with an uneven composition.[6]

The asteroid has a slightly elongated shape, with a ratio of 1.20 between the lengths of the major and minor axes. The orbital longitude and latitude of the asteroid pole in degrees is estimated to be (λ0, β0) = (68°, 23°).[7] Measurements of the thermal inertia of 115 Thyra give a value of around 75 m–2 K–1 s–1/2, compared to 50 for lunar regolith and 400 for coarse sand in an atmosphere.[2]

References[edit]

  1. ^ Yeomans, Donald K., "115 Thyra", JPL Small-Body Database Browser (NASA Jet Propulsion Laboratory), retrieved 2013-03-25. 
  2. ^ a b c d 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. 
  3. ^ *JPL Small-Body Database Browser
  4. ^ "Numbered Minor Planets 1–5000", Discovery Circumstances (IAU Minor Planet center), retrieved 2013-04-07. 
  5. ^ DeMeo, Francesca E. et al. (July 2009), "An extension of the Bus asteroid taxonomy into the near-infrared", Icarus 202 (1): 160–180, Bibcode:2009Icar..202..160D, doi:10.1016/j.icarus.2009.02.005, retrieved 2013-04-08.  See appendix A.
  6. ^ Michałowski, T. et al. (March 2004), "Photometry and models of selected main belt asteroids I. 52 Europa, 115 Thyra, and 382 Dodona", Astronomy and Astrophysics 416: 353–366, Bibcode:2004A&A...416..353M, doi:10.1051/0004-6361:20031706. 
  7. ^ Kryszczyńska, A. et al. (December 2007), "New findings on asteroid spin-vector distributions", Icarus 192: 223–237, Bibcode:2007Icar..192..223K, doi:10.1016/j.icarus.2007.06.008.