33 Polyhymnia

33 Polyhymnia
Orbit of 33 Polyhymnia (1 Jan 2009)
Discovery[1]
Discovered byJ. Chacornac
Discovery date28 October 1854
Designations
(33) Polyhymnia
Pronunciation/pɒliˈhɪmniə/[2]
Named after
Polyhymnia
A887 HA; 1938 FE;
1953 AK; 1957 YL;
1963 DG; 1976 YT7
Main belt
Orbital characteristics[3]
Epoch 21 November 2025 (JD 2461000.5)
Aphelion3.832 AU
Perihelion1.916 AU
2.874 AU
Eccentricity0.333
4.873 yr (1779.77 d)
107.070°
Inclination1.852°
8.212°
338.828°
Jupiter MOID1.589 AU
TJupiter3.211
Physical characteristics
Dimensions54.39±11.84 km (infrared)[4]
53.98±0.91 km[5]
64±6 km (occultation)[6]
18.60888±0.00029 h[7]
S[3] or Sq[8]
8.55[3]

33 Polyhymnia is a main belt asteroid that was discovered by French astronomer Jean Chacornac on 28 October 1854[1] and named after Polyhymnia, the Greek Muse of sacred hymns.

Rotation

Photometric observations of this asteroid at the Organ Mesa Observatory in Las Cruces, New Mexico during 2008 gave a light curve with a period of 18.609 ± 0.002 hours and a brightness variation of 0.15 ± 0.02 in magnitude. This result is in good agreement with a previous study performed during 1980.[9] These results were re-examined with additional observations in 2011, yielding a refined estimate of 18.608 ± 0.001 hours and a brightness variation of 0.18 ± 0.02 magnitude.[10] In 2020, an analysis of photometric data of Polyhymnia from 2008 to 2019 determined a more precise rotation period of 18.60888±0.00029 h. Two possible north pole orientations of Polyhymnia were also determined, with both solutions indicating an axial tilt of 151–155° (ecliptic latitudes –61° to –65°) with respect to the ecliptic.[7]

Orbit

On its highly eccentric (0.338) orbit around the Sun, Polyhymnia appears brightest (apparent magnitude 10) at its minimum distance from Earth of 0.91 AU.[11] Its orbit puts it in a 22:9 mean-motion resonance with the planet Jupiter. The computed Lyapunov time for this asteroid is 10,000 years, indicating that it occupies a chaotic orbit that will change randomly over time because of gravitational perturbations of the planets.[12] Measurements of the position for this asteroid from 1854 to 1969 were used to determine the gravitational influence of Jupiter upon Polyhymnia. This yields an inverse mass ratio of 1047.341±0.011 for Jupiter relative to the Sun.[13]

Mass and density

In 2012, a study by Benoît Carry gave a meta-estimate of a mass of (6.20±0.74)×1018 kg for Polyhymnia, based on a single study of its gravitational influence on other Solar System bodies.[5] However, given Polyhymnia's diameter of 54 km (34 mi), this mass implies an extremely high density of 75.28±9.71 g/cm3. Such a high density is unrealistic, so this mass and density estimate of Polyhymnia was considered unreliable by Carry.[5] Several other asteroids with diameters similar to Polyhymnia were also measured to have extremely high densities in Carry's study, and were rejected for being unrealistic.[5] Because of Polyhymnia's small size, its gravitational influence on other bodies is extremely difficult to detect and may lead to highly inaccurate mass and density estimates.[5] For example, the 68 km (42 mi)-diameter asteroid 675 Ludmilla was originally measured to have a density of 73.99±15.05 g/cm3 in Carry's study,[5] but improved orbit calculations in 2019 showed that it had a much lower density of 3.99±1.94 g/cm3.[14]

No other peer-reviewed study has attempted to determine a mass and density for Polyhymnia since Carry's study,[15] though in 2023, researcher Fan Li performed a preliminary analysis of Polyhymnia's close approaches with other asteroids and determined a lower mass of (1.03±0.40)×1018 kg.[16] Depending on the diameter used for Polyhymnia, this mass estimate suggests a density of 7.5±3.6 g/cm3 or 12.4 g/cm3, for an occultation-derived diameter of 64 ± 6 km (39.8 ± 3.7 mi) and infrared-derived diameter of 54 km (34 mi), respectively.[16][17]

Composition

Visible light spectroscopy of Polyhymnia from 1995 and 2002 show that it is an S-type asteroid, meaning it is mainly composed of rocky silicates.[3] In particular, Polyhymnia's spectrum exhibits an absorption band at 0.67 μm wavelengths, which indicates olivine and pyroxene on its surface, similar to Q-type asteroids.[8]: 155, 164–165  Since Polyhymnia shares both characteristics of S- and Q-type asteroids, it is further classified as an Sq-type asteroid according to the SMASS classification.[8]: 155, 164–165  Radio telescopes have studied Polyhymnia by radar in 1985.[18][19]

In 2023, researchers Evan LaForge, Will Price, and Johann Rafelski speculated the possibility that Polyhymnia could be composed of high-density superheavy elements near atomic number 164, if Polyhymnia's extremely high density were correct and superheavy elements could be sufficiently stable.[20] However, as noted above, Polyhymnia very likely does not have such a high density.[16][17]

A three-dimensional model of 33 Polyhymnia based on its light curve

References

  1. ^ a b "Numbered Minor Planets 1–5000", Discovery Circumstances, IAU Minor Planet center, retrieved 7 April 2013.
  2. ^ Noah Webster (1884) A Practical Dictionary of the English Language
  3. ^ a b c d Yeomans, Donald K. "33 Polyhymnia". JPL Small-Body Database Browser. NASA Jet Propulsion Laboratory. Retrieved 22 January 2025.
  4. ^ Nugent, C. R.; Mainzer, A.; Bauer, J.; Cutri, R. M.; Kramer, E. A.; Grav, T.; et al. (September 2016). "NEOWISE Reactivation Mission Year Two: Asteroid Diameters and Albedos". The Astronomical Journal. 152 (3): 12. arXiv:1606.08923. Bibcode:2016AJ....152...63N. doi:10.3847/0004-6256/152/3/63. S2CID 119289027. 63.
  5. ^ a b c d e f Carry, B. (December 2012), "Density of asteroids", Planetary and Space Science, vol. 73, pp. 98–118, arXiv:1203.4336, Bibcode:2012P&SS...73...98C, doi:10.1016/j.pss.2012.03.009. See Table 1.
  6. ^ Broughton, John (30 April 2018). "Asteroid Dimensions from Occultations". asteroidoccultation.com. International Occultation Timing Association. Retrieved 24 October 2023.
  7. ^ a b Franco, Lorenzo; Pilcher, Frederick; Ferrero, Andrea; Maurice, Audejean (April 2020). "Spin-Shape Model for 33 Polyhymnia". The Minor Planet Bulletin. 47 (2): 120–2122. Bibcode:2020MPBu...47..120F.
  8. ^ a b c Bus, Schelte J.; Binzel, Richard P. (July 2002). "Phase II of the Small Main-Belt Asteroid Spectroscopic Survey. A Feature-Based Taxonomy". Icarus. 158 (1): 146–177. Bibcode:2002Icar..158..146B. doi:10.1006/icar.2002.6856.
  9. ^ Pilcher, Frederick (January 2009), "Period Determinations for 33 Polyhymnia, 38 Leda, 50 Virginia, 189 Phthia, and 290 Bruna", The Minor Planet Bulletin, vol. 36, no. 1, pp. 25–27, Bibcode:2009MPBu...36...25P.
  10. ^ Pilcher, Frederick (July 2011), "A Critical Re-Examination of the Rotation Period of 33 Polyhymnia", The Minor Planet Bulletin, vol. 38, no. 3, pp. 130–131, Bibcode:2011MPBu...38..130P.
  11. ^ "AstDyS (33) Polyhymnia Ephemerides for 8 Sept 2014". AstDyS-2 (Asteroids - Dynamic Site). Retrieved 23 January 2012.
  12. ^ Šidlichovský, M. (1999), Svoren, J.; Pittich, E. M.; Rickman, H. (eds.), "Resonances and chaos in the asteroid belt", Evolution and source regions of asteroids and comets : proceedings of the 173rd colloquium of the International Astronomical Union, held in Tatranska Lomnica, Slovak Republic, August 24–28, 1998, pp. 297–308, Bibcode:1999esra.conf..297S.
  13. ^ Janiczek, P. M. (1970), "Jupiter's mass from its action on Polyhymnia", Bulletin of the Astronomical Society, vol. 2, p. 247, Bibcode:1970BAAS....2S.247J.
  14. ^ Kretlow, Mike. "Size, Mass and Density of Asteroids (SiMDA) – Summary for: (675) Ludmilla". Size, Mass and Density of Asteroids (SiMDA). Retrieved 24 October 2023.
  15. ^ Kretlow, Mike. "Size, Mass and Density of Asteroids (SiMDA) – Summary for: (33) Polyhymnia". Size, Mass and Density of Asteroids (SiMDA). Retrieved 12 October 2023.
  16. ^ a b c Li, Fan (19 October 2023). "Re: (33) Polyhymnia". Minor Planets Mailing List. Groups.io. Retrieved 24 October 2023.
  17. ^ a b Li, Fan (19 October 2023). "Re: (33) Polyhymnia". Minor Planets Mailing List. Groups.io. Retrieved 24 October 2023.
  18. ^ "Radar-Detected Asteroids and Comets". NASA/JPL Asteroid Radar Research. Retrieved 30 October 2011.
  19. ^ Magri, C.; et al. (December 1998), "Mainbelt Asteroids: Results of Arecibo and Goldstone Radar Observations of 37 Objects During 1980-1995" (PDF), Bulletin of the American Astronomical Society, 30: 1450, Bibcode:1998DPS....30.5516M, archived from the original (PDF) on 15 April 2012, retrieved 26 July 2011
  20. ^ LaForge, Evan; Price, Will; Rafelski, Johann (15 September 2023). "Superheavy elements and ultradense matter". The European Physical Journal Plus. 138 (9): 812. arXiv:2306.11989. Bibcode:2023EPJP..138..812L. doi:10.1140/epjp/s13360-023-04454-8.
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