37 Fides

Fides /ˈfaɪdiːz/ (minor planet designation: 37 Fides) is a large main-belt asteroid. It was discovered by German astronomer Karl Theodor Robert Luther on October 5, 1855,^[6] and named after Fides, the Roman goddess of loyalty. Fides was the last of the main-belt asteroids to be assigned an iconic symbol,^[7]aLatin cross U+271D ✝ ().^[8]^[9] 37 Fides is also a S-type asteroid in the Tholen classification system.^[2]

37 Fides
A three-dimensional model of 37 Fides based on its light curve
Discovery
Discovered by	R. Luther
Discovery date	October 5, 1855
Designations
Designation	(37) Fides
Pronunciation	/ˈfaɪdiːz/^[1]
Named after	Fides
Alternative names	1925 WH
Minor planet category	Main belt
Adjectives	Fidean /ˈfɪdiən/
Symbol	(historical)
Orbital characteristics^[2]
Epoch February 25, 2023 (JD 2460000.5)
Observation arc	167 yr
Aphelion	464.902 Gm (3.108 AU)
Perihelion	325.937 Gm (2.179 AU)
Semi-major axis	395.419 Gm (2.643 AU)
Eccentricity	0.176
Orbital period (sidereal)	1,569.628 d (4.30 a)
Mean anomaly	303.436°
Mean motion	0° 13^m 45.84^s / day
Inclination	3.071°
Longitude of ascending node	7.267°
Argument of perihelion	62.327°
Physical characteristics
Dimensions	108.35 ± 1.9 km^[2]
Mass	(1.674 ± 0.663/0.314)×10¹⁸kg^[3]
Mean density	2.906 ± 1.150/0.545 g/cm³^[3]^[a]
Surface gravity	0.0381 m/s²
Escape velocity	0.0642 km/s
Synodic rotation period	0.3055 d (7.334 h)^[4]
Albedo	0.183 ± 0.007^[5]
Temperature	~167 K
Spectral type	S
Absolute magnitude (H)	7.41^[2]

Photometric observations of this asteroid at multiple observatories during 1981–82 gave an unusual light curve with three minima and maxima. The curve changed with varying phase angle of the asteroid relative to the viewer and the position of the Sun, indicating the changing influence of shadows cast by surface features. The composite light curve has a best fit period estimate of 7.33 hours.^[10] Austrian astronomer Hans Josef Schober has suggested that the multiple minima and maxima during each period may be an indication of a binary nature.^[11]

^ Assuming a diameter of 103.23 ± 1.39 km.

^ Noah Webster (1884) A Practical Dictionary of the English Language

^ ^a ^b ^c ^d Jet Propulsion Laboratory, JPL Small-Body Database Browser: 37 Fides (A855 TB), NASA, retrieved 29 June 2023.

^ ^a ^b Fienga, A.; Avdellidou, C.; Hanuš, J. (February 2020). "Asteroid masses obtained with INPOP planetary ephemerides". Monthly Notices of the Royal Astronomical Society. 492 (1). doi:10.1093/mnras/stz3407.

^ Asteroid Lightcurve Parameters, Planetary Science Institute, archived from the original on 14 June 2006, retrieved 3 November 2008

^ Asteroid Data Archive, Planetary Science Institute, archived from the original on 23 May 2006, retrieved 3 November 2008.

^ "Numbered Minor Planets 1–5000", Discovery Circumstances, IAU Minor Planet center, retrieved 7 April 2013.

^ Gould, B. A. (1852), "On the Symbolic Notation of the Asteroids", Astronomical Journal, 2: 80, Bibcode:1852AJ......2...80G, doi:10.1086/100212.

^ Bala, Gavin Jared; Miller, Kirk (18 September 2023). "Unicode request for historical asteroid symbols" (PDF). unicode.org. Unicode. Retrieved 26 September 2023.

^ Unicode. "Proposed New Characters: The Pipeline". unicode.org. The Unicode Consortium. Retrieved 6 November 2023.

^ Zappla, V.; et al. (July 1983), "Remarkable modification of light curves for shadowing effects on irregular surfaces - The case of the asteroid 37 Fides", Astronomy and Astrophysics, 123 (2): 326–330, Bibcode:1983A&A...123..326Z.

^ Schober, H. J. (February 1984), "A comparison between binary star light curves and those of possible binary asteroids", Astrophysics and Space Science, 99 (1–2): 387–392, Bibcode:1984Ap&SS..99..387S, doi:10.1007/BF00650261, S2CID 189850465.

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