49 Pales

49 Pales (/ˈpeɪliːz/) is a large, dark main-belt asteroid. It was discovered by German-French astronomer Hermann Goldschmidt on 19 September 1857 from his balcony in Paris.^[11] The asteroid is named after Pales, the goddess of shepherds in Roman mythology. Since it was discovered on the same night as 48 Doris, geologist Élie de Beaumont suggested naming the two "The Twins".^[12]

49 Pales

Orbital diagram
Discovery[1]
Discovered by	Hermann Goldschmidt
Discovery site	Paris Observatory
Discovery date	19 September 1857
Designations
Designation	(49) Pales
Pronunciation	/ˈpeɪliːz/[2]
Named after	Pales
Minor planet category	Main belt[1]
Adjectives	Palian /ˈpeɪliən/; Palilian /pəˈlɪliən/ (adj. only)
Orbital characteristics[3]
Epoch 23 March 2018 (JD 2458200.5)
Aphelion	3.7989 AU
Perihelion	2.4030 AU
Semi-major axis	3.10093 AU
Eccentricity	0.22507
Orbital period (sidereal)	1994.51 days (5.46 years)
Mean anomaly	169.53°
Inclination	3.17°
Longitude of ascending node	285.646°
Argument of perihelion	111.146°
Physical characteristics
Dimensions	149.80±3.8 km Mean diameter[4]
Mass	2.69×1018 kg[5]
Synodic rotation period	20.7057±0.0002 h[6] 20.705±0.002 h[7] 20.704±0.001 h[8]
Albedo	0.0597±0.003[4]
Spectral type	C[9]
Absolute magnitude (H)	7.8[10]

The orbit of this asteroid has close to a 2:1 commensurability with the orbit of Jupiter.^[13] On 17 January 2000, this minor planet was observed occulting a 9th magnitude star from seven locations. These timed chords across the silhouette allowed an estimate to be made of the object's dimensions,^[14] yielding a cross-section of 251 km × 160 km.^[15]

Pales has been studied by radar.^[16] It has a rotation period of 20.705±0.002 h and a lightcurve with an amplitude of 0.18 mag. The lightcurve shows 4 maxima and 4 minima per cycle, suggesting an irregular shape.^[7] The previously accepted period of 10.42 hours with 2 maxima and minima per cycle^[17] was proven to be wrong by Pilcher in 2016, showing that correct rotation periods still have not been found for all low-numbered asteroids.^[8]

References

1. "49 Pales". JPL Small-Body Database. Jet Propulsion Laboratory. Retrieved 26 June 2018.
2. Noah Webster (1884) A Practical Dictionary of the English Language
3. "(49) Pales". AstDyS. Italy: University of Pisa. Archived from the original on 27 February 2012. Retrieved 29 December 2008.
4. Tedesco; et al. (2004). "Supplemental IRAS Minor Planet Survey (SIMPS)". IRAS-A-FPA-3-RDR-IMPS-V6.0. Planetary Data System. Archived from the original on 17 August 2009. Retrieved 29 December 2008.
5. Jim Baer (2008). "Recent Asteroid Mass Determinations". Personal Website. Archived from the original on 29 January 2009. Retrieved 29 December 2008.
6. Romeuf, David; Behrend, Raoul (7 January 2016). "Courbes de rotation d'astéroïdes et de comètes" (in French). Retrieved 26 June 2018.
7. Pilcher, Frederick (2017). "Rotation Period Determinations for 49 Pales, 96 Aegle, 106 Dione 375 Ursula, and 576 Emanuela". Minor Planet Bulletin. Retrieved 26 June 2018.
8. Pilcher, Frederick; Benishek, Vladimir; Klinglesmith, Daniel A. (2016). "Rotation Period, Color Indices, and H-G parameters for 49 Pales". Minor Planet Bulletin. Retrieved 26 June 2018.
9. Neese (2005). "Asteroid Taxonomy". EAR-A-5-DDR-TAXONOMY-V5.0. Planetary Data System. Archived from the original on 5 August 2009. Retrieved 27 December 2008.
10. Tholen (2007). "Asteroid Absolute Magnitudes". EAR-A-5-DDR-ASTERMAG-V11.0. Planetary Data System. Archived from the original on 16 August 2009. Retrieved 29 December 2008.
11. "Discovery Circumstances: Numbered Minor Planets (1)–(5000)". IAU: Minor Planet Center. Archived from the original on 2 February 2009. Retrieved 29 December 2008.
12. Schmadel, Lutz (2003), Dictionary of minor planet names (fifth ed.), Germany: Springer, p. 19, ISBN 3-540-00238-3.
13. Fernández, S.; Beaugé, C. (1988). "Asteroids in the 1:3:2 Commensurability". In Valtonen, Mauri (ed.). The Few Body Problem: Proceedings of the 96th Colloquium of the International Astronomical Union Held in Turku, Finland, June 14–19, 1987. Astrophysics and Space Science Library. Vol. 140. Springer Science & Business Media. pp. 131–133. ISBN 9789027726803.
14. Mizon, R. (April 2000). "'Your friendly local street light'". Journal of the British Astronomical Association. 110 (2): 62–63. Bibcode:2000JBAA..110R..62M.
15. Dunham, D. W.; et al. (September 2002). "Asteroidal occultation results multiply helped by Hipparcos". Memorie della Società' Astronomica Italiana. 73 (3): 662. Bibcode:2002MmSAI..73..662D.
16. "Radar-Detected Asteroids and Comets". NASA/JPL Asteroid Radar Research. Retrieved 30 October 2011.
17. Schober, H. J.; et al. (April 1979), "Photoelectric photometry and rotation periods of three large and dark asteroids – 49 Pales, 88 Thisbe and 92 Undina", Astronomy and Astrophysics Supplement Series, vol. 36, pp. 1–8, Bibcode:1979A&AS...36....1S.

External links

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