.png) A three-dimensional model of 115 Thyra based on its light curve. | |
| Discovery | |
|---|---|
| Discovered by | James Craig Watson |
| Discovery date | 6 August 1871 |
| Designations | |
| MPC designation | (115) Thyra |
| Pronunciation | /ˈθaɪərə/ |
| Named after | Thyra |
| Alternative designations | A871 PA |
| Minor planet category | Main belt |
| Orbital characteristics | |
| Epoch 31 July 2016 (JD 2457600.5) | |
| Uncertainty parameter 0 | |
| Observation arc | 143.31 yr (52344 d) |
| Aphelion | 2.8376 AU (424.50 Gm) |
| Perihelion | 1.92394 AU (287.817 Gm) |
| Semi-major axis | 2.38077 AU (356.158 Gm) |
| Eccentricity | 0.19188 |
| Orbital period (sidereal) | 3.67 yr (1341.8 d) |
| Average orbital speed | 19.13 km/s |
| Mean anomaly | 108.401° |
| Mean motion | 0° 16 5.88 / day |
| Inclination | 11.595° |
| Longitude of ascending node | 308.901° |
| Argument of perihelion | 96.946° |
| Earth MOID | 0.97246 AU (145.478 Gm) |
| Jupiter MOID | 2.63437 AU (394.096 Gm) |
| TJupiter | 3.486 |
| Physical characteristics | |
| Dimensions | 79.83±1.4 km 79.83 km |
| Mass | 5.3×10 kg |
| Equatorial surface gravity | 0.0223 m/s |
| Equatorial escape velocity | 0.0422 km/s |
| Synodic rotation period | 7.241 h (0.3017 d) |
| Geometric albedo | 0.2747±0.010 0.275 |
| Temperature | ~180 K |
| Spectral type | S |
| Absolute magnitude (H) | 7.51 |
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 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.
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.
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°). Measurements of the thermal inertia of 115 Thyra give a value of around 75 m K s, compared to 50 for lunar regolith and 400 for coarse sand in an atmosphere.
References
- From 'Tyra', a variant of the name.
- ^ Yeomans, Donald K., "115 Thyra", JPL Small-Body Database Browser, NASA Jet Propulsion Laboratory, retrieved 12 May 2016.
- ^ 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, S2CID 14517561.
- *JPL Small-Body Database Browser
- "Numbered Minor Planets 1–5000", Discovery Circumstances, IAU Minor Planet center, retrieved 7 April 2013.
- DeMeo, Francesca E.; et al. (July 2009), "An extension of the Bus asteroid taxonomy into the near-infrared" (PDF), Icarus, 202 (1): 160–180, Bibcode:2009Icar..202..160D, doi:10.1016/j.icarus.2009.02.005, archived from the original (PDF) on 17 March 2014, retrieved 8 April 2013. 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, 416: 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, 192 (1): 223–237, Bibcode:2007Icar..192..223K, doi:10.1016/j.icarus.2007.06.008.
External links
- 115 Thyra at AstDyS-2, Asteroids—Dynamic Site
- 115 Thyra at the JPL Small-Body Database
| Minor planets navigator | |
|---|---|
| Small Solar System bodies | |||||||
|---|---|---|---|---|---|---|---|
| Minor planets |
| ||||||
| Comets | |||||||
| Other | |||||||