115 Thyra
.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 |
| 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) | |
Average orbital speed | 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
- ^ Yeomans, Donald K., "115 Thyra", JPL Small-Body Database Browser, NASA Jet Propulsion Laboratory, retrieved 2013-03-25.
- ^ 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, vol. 57, no. 2, pp. 259–265, arXiv:0808.0869, Bibcode:2009P&SS...57..259D, doi:10.1016/j.pss.2008.06.015.
- ^ *JPL Small-Body Database Browser
- ^ "Numbered Minor Planets 1–5000", Discovery Circumstances, IAU Minor Planet center, retrieved 2013-04-07.
- ^ DeMeo, Francesca E.; et al. (July 2009), "An extension of the Bus asteroid taxonomy into the near-infrared" (PDF), Icarus, vol. 202, no. 1, pp. 160–180, Bibcode:2009Icar..202..160D, doi:10.1016/j.icarus.2009.02.005, retrieved 2013-04-08. See appendix A.
- ^ 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, vol. 416, pp. 353–366, Bibcode:2004A&A...416..353M, doi:10.1051/0004-6361:20031706.
- ^ Kryszczyńska, A.; et al. (December 2007), "New findings on asteroid spin-vector distributions", Icarus, vol. 192, pp. 223–237, Bibcode:2007Icar..192..223K, doi:10.1016/j.icarus.2007.06.008.
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