1921 Pala

1921 Pala, provisional designation 1973 SE is a background asteroid in an unstable orbit located in the outer region of asteroid belt, approximately 8.2 kilometers in diameter. It is one of very few bodies located in the 2 : 1 mean motion resonance with Jupiter.[4] It was discovered by Dutch–American astronomer Tom Gehrels at Palomar Observatory on 20 September 1973.[6]

1921 Pala
Discovery [1]
Discovered byT. Gehrels
Discovery sitePalomar Obs.
Discovery date20 September 1973
Designations
(1921) Pala
Named after
Pala (Indian reservation)[2]
1973 SE
main-belt · (outer) [1]
background [3]
Orbital characteristics [1]
Epoch 4 September 2017 (JD 2458000.5)
Uncertainty parameter 0
Observation arc43.52 yr (15,895 days)
Aphelion4.5807 AU
Perihelion2.0148 AU
3.2978 AU
Eccentricity0.3890
5.99 yr (2,187 days)
165.04°
0° 9m 52.56s / day
Inclination19.192°
352.31°
20.092°
Physical characteristics
Dimensions8.2 km[4]:422
14.3[5] · 14.6[1]

    Orbit and characterization

    Pala is a non-family background asteroid from the main belt's background population.[3] It orbits the Sun in the outer asteroid belt at a distance of 2.0–4.6 AU once every 5 years and 12 months (2,187 days; semi-major axis of 3.30 AU). Its orbit has an eccentricity of 0.39 and an inclination of 19° with respect to the ecliptic.[1] The body's observation arc begins at Palomar with its official discovery observation.[6]

    It has a strongly unstable orbit near the 2:1 orbital resonance with Jupiter. The asteroid's orbit is expected to persist for another 18 million years though.[4]

    Pala measures approximately 8.2 kilometers in diameter, while the albedo of its surface has not been estimated.[4] As of 2017, the body's spectral type as well as its rotation period and shape remain unknown.[1][7]

    Naming

    This minor planet is named after the Indian reservation, Pala, located at the base of Palomar Mountain, believed to apply to an Indian tribe whose members have lived in the area for many centuries.[2] The official naming citation was published by the Minor Planet Center on 20 February 1976 (M.P.C. 3938).[8]

    See also

    References
    1. "JPL Small-Body Database Browser: 1921 Pala (1973 SE)" (2017-03-28 last obs.). Jet Propulsion Laboratory. Retrieved 14 June 2017.
    2. Schmadel, Lutz D. (2007). "(1921) Pala". Dictionary of Minor Planet Names – (1921) Pala. Springer Berlin Heidelberg. p. 154. doi:10.1007/978-3-540-29925-7_1922. ISBN 978-3-540-00238-3.
    3. "Asteroid 1921 Pala – Proper Elements". AstDyS-2, Asteroids – Dynamic Site. Retrieved 29 October 2019.
    4. Roig, F.; Nesvorný, D.; Ferraz-Mello, S. (September 2002). "Asteroids in the 2 : 1 resonance with Jupiter: dynamics and size distribution [ Erratum: 2002MNRAS.336.1391R ]". Monthly Notices of the Royal Astronomical Society. 335 (2): 417–431. Bibcode:2002MNRAS.335..417R. doi:10.1046/j.1365-8711.2002.05635.x. Retrieved 14 June 2017.
    5. Tholen (2007). "Asteroid Absolute Magnitudes". EAR-A-5-DDR-ASTERMAG-V11.0. Planetary Data System. Archived from the original on 17 June 2012. Retrieved 1 January 2009.
    6. "1921 Pala (1973 SE)". Minor Planet Center. Retrieved 14 June 2017.
    7. "LCDB Data for (1921) Pala". Asteroid Lightcurve Database (LCDB). Retrieved 14 June 2017.
    8. Schmadel, Lutz D. "Appendix – Publication Dates of the MPCs". Dictionary of Minor Planet Names – Addendum to Fifth Edition (2006–2008). Springer Berlin Heidelberg. p. 221. doi:10.1007/978-3-642-01965-4. ISBN 978-3-642-01964-7.

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