115 Thyra
Main-belt asteroid
From Wikipedia, the free encyclopedia
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[5] 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.[6]
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A three-dimensional model of 115 Thyra based on its light curve. | |
| Discovery | |
|---|---|
| Discovered by | James Craig Watson |
| Discovery date | 6 August 1871 |
| Designations | |
| (115) Thyra | |
| Pronunciation | /ˈθaɪərə/[1] |
Named after | Thyra |
| A871 PA | |
| Main belt | |
| Orbital characteristics[2] | |
| 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) |
| 2.38077 AU (356.158 Gm) | |
| Eccentricity | 0.19188 |
| 3.67 yr (1341.8 d) | |
Average orbital speed | 19.13 km/s |
| 108.401° | |
| 0° 16m 5.88s / day | |
| Inclination | 11.595° |
| 308.901° | |
| 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[2] 79.83 km[3] |
| Mass | 5.3×1017 kg |
Equatorial surface gravity | 0.0223 m/s2 |
Equatorial escape velocity | 0.0422 km/s |
| 7.241 h (0.3017 d) | |
| 0.2747±0.010[2] 0.275[3] | |
| Temperature | ~180 K |
| S[4] | |
| 7.51[2][3] | |
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.[7]
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°).[8] 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.[3]
