Astronomy:115 Thyra
.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 | |
| (115) Thyra | |
| Pronunciation | /ˈθaɪərə/[1] |
| Named after | Thyra |
| A871 PA | |
| Minor planet category | Main belt |
| Orbital characteristics[2] | |
| Epoch 31 July 2016 (JD 2457600.5) | |
| Uncertainty parameter 0 | |
| Observation arc | 143.31 yr (52344 d) |
| |{{{apsis}}}|helion}} | 2.8376 astronomical unit|AU (424.50 Gm) |
| |{{{apsis}}}|helion}} | 1.92394 AU (287.817 Gm) |
| 2.38077 AU (356.158 Gm) | |
| Eccentricity | 0.19188 |
| Orbital period | 3.67 yr (1341.8 d) |
| Average Orbital speed | 19.13 km/s |
| Mean anomaly | 108.401° |
| Mean motion | 0° 16m 5.88s / day |
| Inclination | 11.595° |
| Longitude of ascending node | 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 |
| Rotation period | 7.241 h (0.3017 d) |
| Geometric albedo | 0.2747±0.010[2] 0.275[3] |
| Physics | ~180 K |
| S[4] | |
| Absolute magnitude (H) | 7.51[2][3] |
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]
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]
References
- ↑ From 'Tyra', a variant of the name.
- ↑ 2.0 2.1 2.2 2.3 Yeomans, Donald K., "115 Thyra", JPL Small-Body Database Browser (NASA Jet Propulsion Laboratory), https://ssd.jpl.nasa.gov/sbdb.cgi?sstr=115, retrieved 12 May 2016.
- ↑ 3.0 3.1 3.2 3.3 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, doi:10.1016/j.pss.2008.06.015, Bibcode: 2009P&SS...57..259D.
- ↑ *JPL Small-Body Database Browser
- ↑ "Numbered Minor Planets 1–5000", Discovery Circumstances (IAU Minor Planet center), https://www.minorplanetcenter.net/iau/lists/NumberedMPs000001.html, retrieved 2013-04-07.
- ↑ DeMeo, Francesca E. et al. (July 2009), "An extension of the Bus asteroid taxonomy into the near-infrared", Icarus 202 (1): 160–180, doi:10.1016/j.icarus.2009.02.005, Bibcode: 2009Icar..202..160D, archived from the original on 2014-03-17, https://web.archive.org/web/20140317200310/https://www.tara.tcd.ie/bitstream/2262/43276/1/PEER_stage2_10.1016/j.icarus.2009.02.005.pdf, 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 416: 353–366, doi:10.1051/0004-6361:20031706, Bibcode: 2004A&A...416..353M.
- ↑ Kryszczyńska, A. et al. (December 2007), "New findings on asteroid spin-vector distributions", Icarus 192 (1): 223–237, doi:10.1016/j.icarus.2007.06.008, Bibcode: 2007Icar..192..223K.
External links
- 115 Thyra at AstDyS-2, Asteroids—Dynamic Site
- 115 Thyra at the JPL Small-Body Database
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