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(Top)
 


1 Mars resonance  





2 References  





3 External links  














142 Polana






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142 Polana
Polana is in a 1:2 resonance with Mars
Discovery[1]
Discovered byJ. Palisa
Discovery siteAustrian Naval Obs.
Discovery date28 January 1875
Designations

MPC designation

(142) Polana
Pronunciation[citation needed]

Named after

Pula

Alternative designations

A875 BA; 1923 WA;
1954 BH; 1956 XZ;
1963 SA

Minor planet category

Asteroid belt
Orbital characteristics[1]
Epoch 31 July 2016 (JD 2457600.5)
Uncertainty parameter 0
Observation arc117.65 yr (42971 d)
Aphelion2.7444 AU (410.56 Gm)
Perihelion2.0934 AU (313.17 Gm)

Semi-major axis

2.4189 AU (361.86 Gm)
Eccentricity0.13457

Orbital period (sidereal)

3.76 yr (1374.1 d)

Average orbital speed

19.07 km/s

Mean anomaly

140.92°

Mean motion

0° 15m 43.128s / day
Inclination2.2379°

Longitude of ascending node

291.27°

Argument of perihelion

292.00°
Physical characteristics
Dimensions55.29±1.6 km[1]
55.3 ± 1.6[2]

Synodic rotation period

9.764 h (0.4068 d)

Geometric albedo

0.0451±0.003[1]
0.045 ± 0.003[2]

Spectral type

F/B[1]
B−V=0.621±0.022[1]
U−B=0.236±0.035[1]

Absolute magnitude (H)

10.27[1]

Polana (minor planet designation: 142 Polana) is a very dark asteroid from the asteroid belt. It was discovered by Johann Palisa on January 28, 1875, and named after the city of Pola (now Pula, Croatia), home of the Austrian Naval Observatory where he made the discovery.[1]

It is a major member of the eponymously named Polana family, which is a subgroup of the Nysa family.[3] The asteroid has an estimated diameter of about 55.3 km and a low albedo of 0.045.[2] It is orbiting at a distance of 2.419 times the separation of the Earth from the Sun, with an orbital period of 3.76 years and an eccentricity of 0.14.

In the Tholen classification scheme, Polana is a primitive carbonaceous asteroid of type F, which is a subdivision of more common C-type.[1] Under the SMASS classification taxonomy, Polana is listed as a B-type asteroid, a group that combines both the Tholen B and F types. The spectrum of this object suggests the presence of magnetite (Fe3O4), which gives it the spectrally blue coloration that is a characteristic of this SMASS class.[4]

Origin of 162173 Ryugu may be either 495 Eulalia or 142 Polana[5]
   Sun ·    Earth ·    162173 Ryugu ·    142 Polana ·    495 Eulalia

Mars resonance[edit]

Polana is in a 1:2 orbital resonance with Mars, meaning that Polana orbits the Sun once for every two orbits that Mars completes. This resonance helps protect the asteroid from orbital erosion: the orbital eccentricities of the resonant asteroids are clearly greater than the non-resonant asteroids. There is a peak in the number of asteroids located at 2.419 AU from the Sun.[6] In spite of strong perturbations caused by the passing of both Jupiter and Mars, the 1:2 Mars resonance brings about stability for billions of years. There are up to 1,500 asteroids in this resonance, and the resonance between Polana and Mars will strengthen over the next million years due to Polana transitioning into a strong libration period with Mars.[7]

References[edit]

  1. ^ a b c d e f g h i j "142 Polana". JPL Small-Body Database Browser. August 14, 2007. Retrieved May 12, 2016.
  • ^ a b c Lazzarin, M.; Barbieri, C.; Barucci, M. A. (December 1995), "Visible Spectroscopy of Dark, Primitive Asteroids", Astronomical Journal, 110: 3058, Bibcode:1995AJ....110.3058L, doi:10.1086/117747
  • ^ Cellino, A.; et al. (August 2001). "The Puzzling Case of the Nysa-Polana Family". Icarus. 152 (2): 225–237. Bibcode:2001Icar..152..225C. doi:10.1006/icar.2001.6634.
  • ^ Yang, Bin; Jewitt, David (September 2010), "Identification of Magnetite in B-type Asteroids", The Astronomical Journal, 140 (3): 692–698, arXiv:1006.5110, Bibcode:2010AJ....140..692Y, doi:10.1088/0004-6256/140/3/692, S2CID 724871
  • ^ S. Sugita; et al. (March 19, 2019). "The geomorphology, color, and thermal properties of Ryugu: Implications for parent-body processes". Science. 364 (6437): eaaw0422. Bibcode:2019Sci...364..252S. doi:10.1126/science.aaw0422. hdl:1893/29363. PMC 7370239. PMID 30890587.
  • ^ Gallardo, Tabaré (2007). "A new population of asteroids: the resonants 1:2 with Mars". Montevideo, Uruguay: Institute of Physics, Faculty of Sciences. Retrieved December 17, 2009.
  • ^ Gallardo, Tabaré (2009). "A New Dynamical Population of Asteroids" (PDF). Revista Mexicana de Astronomía y Astrofísica, Serie de Conferencias. 35: 21–22. Bibcode:2009RMxAC..35...21G. Retrieved December 17, 2009.
  • External links[edit]


    Retrieved from "https://en.wikipedia.org/w/index.php?title=142_Polana&oldid=1195661895"

    Categories: 
    Minor planet object articles (numbered)
    Nysa asteroids
    Discoveries by Johann Palisa
    Named minor planets
    Mars
    F-type asteroids (Tholen)
    B-type asteroids (SMASS)
    Astronomical objects discovered in 1875
    Hidden categories: 
    Articles with short description
    Short description matches Wikidata
    Use mdy dates from February 2012
    All articles with unsourced statements
    Articles with unsourced statements from March 2020
    Articles with JPL SBDB identifiers
    Articles with MPC identifiers
     



    This page was last edited on 14 January 2024, at 20:11 (UTC).

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