115 Thyra

115 Thyra
	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/[1]
Named after	Thyra
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)
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	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°
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[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]
Temperature	~180 K
Spectral type	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.
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), 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 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), pp. 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, 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, 192, pp. 223–237, Bibcode:2007Icar..192..223K, doi:10.1016/j.icarus.2007.06.008.

External links

115 Thyra at AstDyS-2, Asteroids—Dynamic Site
- Ephemeris · Observation prediction · Orbital info · Proper elements · Observational info
115 Thyra at the JPL Small-Body Database
- Close approach · Discovery · Ephemeris · Orbit diagram · Orbital elements · Physical parameters

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[1] From 'Tyra', a variant of the name.

[JPL-2] Yeomans, Donald K., "115 Thyra", JPL Small-Body Database Browser, NASA Jet Propulsion Laboratory, retrieved 12 May 2016.

[Delbo2009-3] 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), pp. 259–265, arXiv:0808.0869, Bibcode:2009P&SS...57..259D, doi:10.1016/j.pss.2008.06.015.

[4] JPL Small-Body Database Browser

[5] JPL Small-Body Database Browser

[IAU_MPC-5] "Numbered Minor Planets 1–5000", Discovery Circumstances, IAU Minor Planet center, retrieved 7 April 2013.

[DeMeo2009-6] DeMeo, Francesca E.; et al. (July 2009), "An extension of the Bus asteroid taxonomy into the near-infrared" (PDF), Icarus, 202 (1), pp. 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.

[Michalowski2004-7] 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, pp. 353–366, Bibcode:2004A&A...416..353M, doi:10.1051/0004-6361:20031706.

[Kryszczynska2007-8] Kryszczyńska, A.; et al. (December 2007), "New findings on asteroid spin-vector distributions", Icarus, 192, pp. 223–237, Bibcode:2007Icar..192..223K, doi:10.1016/j.icarus.2007.06.008.