Astronomy:33 Polyhymnia

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Short description: Main-belt asteroid
33 Polyhymnia
33 Polyhymnia orbit on 01 Jan 2009.png
Orbit of 33 Polyhymnia (1 Jan 2009)
Discovery[1]
Discovered byJ. Chacornac
Discovery dateOctober 28, 1854
Designations
(33) Polyhymnia
Pronunciation/pɒliˈhɪmniə/[2]
Named afterPolyhymnia
A887 HA; 1938 FE;
1953 AK; 1957 YL;
1963 DG; 1976 YT7
Minor planet categoryMain belt
Orbital characteristics[3]
Epoch April 18, 2013 (JD 2456400.5)
|{{{apsis}}}|helion}}573.518 Gm (3.83373 AU)
|{{{apsis}}}|helion}}284.409 Gm (1.90116 AU)
428.964 Gm (2.86745 AU)
Eccentricity0.33698
Orbital period1,773.541 d (4.86 a)
Mean anomaly256.476°
Inclination1.869°
Longitude of ascending node8.595°
338.123°
Physical characteristics
Dimensions54.39±11.84 km (infrared)[4]
53.98±0.91 km[5]
64±6 km (occultation)[6]
Rotation period18.60888±0.00029 h[7]
S[3] or Sq[8]
Absolute magnitude (H)8.55[3]


Polyhymnia (minor planet designation: 33 Polyhymnia) is a main belt asteroid that was discovered by French astronomer Jean Chacornac on October 28, 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 2008-2019 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

Due to its high eccentricity (0.338), it can approach close enough to Earth (minimum orbit intersection distance 0.91 AU) that it can reach up to apparent magnitude 10 in the sky.[11] The orbit of Polyhymnia 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 33 Polyhymnia. This yields an inverse mass ratio of 1,047.341 ± 0.011 for Jupiter relative to the Sun.[13]

Mass and density

In 2012, a study by Benoît Carry estimated a mass of (6.20±0.74)×1018 kg for Polyhymnia based on 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](pp155, 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](pp155, 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]

References

  1. ↑ 1.0 1.1 "Numbered Minor Planets 1–5000", Discovery Circumstances (IAU Minor Planet center), https://www.minorplanetcenter.net/iau/lists/NumberedMPs000001.html, retrieved 2013-04-07. 
  2. ↑ Noah Webster (1884) A Practical Dictionary of the English Language
  3. ↑ 3.0 3.1 3.2 3.3 Yeomans, Donald K.. "33 Polyhymnia". JPL Small-Body Database Browser. NASA Jet Propulsion Laboratory. https://ssd.jpl.nasa.gov/sbdb.cgi?sstr=33. 
  4. ↑ Nugent, C. R.Expression error: Unrecognized word "etal". (September 2016). "NEOWISE Reactivation Mission Year Two: Asteroid Diameters and Albedos". The Astronomical Journal 152 (3): 12. doi:10.3847/0004-6256/152/3/63. 63. Bibcode: 2016AJ....152...63N. 
  5. ↑ 5.0 5.1 5.2 5.3 5.4 5.5 Carry, B. (December 2012), "Density of asteroids", Planetary and Space Science 73: pp. 98–118, doi:10.1016/j.pss.2012.03.009, Bibcode: 2012P&SS...73...98C.  See Table 1.
  6. ↑ Broughton, John (30 April 2018). "Asteroid Dimensions from Occultations". International Occultation Timing Association. https://www.asteroidoccultation.com/observations/Asteroid_Dimensions_from_Occultations.html. Retrieved 24 October 2023. 
  7. ↑ 7.0 7.1 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. ↑ 8.0 8.1 8.2 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. doi:10.1006/icar.2002.6856. Bibcode: 2002Icar..158..146B. 
  9. ↑ Pilcher, Frederick (January 2009), "Period Determinations for 33 Polyhymnia, 38 Leda, 50 Virginia, 189 Phthia, and 290 Bruna", The Minor Planet Bulletin 36 (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 38 (3): pp. 130–131, Bibcode: 2011MPBu...38..130P. 
  11. ↑ "AstDyS (33) Polyhymnia Ephemerides for 8 Sept 2014". AstDyS-2 (Asteroids - Dynamic Site). https://newton.spacedys.com/astdys/index.php?pc=1.1.3.1&n=33&oc=500&y0=2014&m0=09&d0=01&h0=0&mi0=0&y1=2014&m1=09&d1=20&h1=0&mi1=0&ti=1&tiu=days. 
  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 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). https://astro.kretlow.de/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). https://astro.kretlow.de/simda/. Retrieved 12 October 2023. 
  16. ↑ 16.0 16.1 16.2 Li, Fan (19 October 2023). "Re: (33) Polyhymnia". Minor Planets Mailing List. Groups.io. https://groups.io/g/mpml/message/39045. Retrieved 24 October 2023. 
  17. ↑ 17.0 17.1 Li, Fan (19 October 2023). "Re: (33) Polyhymnia". Minor Planets Mailing List. Groups.io. https://groups.io/g/mpml/message/39046. Retrieved 24 October 2023. 
  18. ↑ "Radar-Detected Asteroids and Comets". NASA/JPL Asteroid Radar Research. http://echo.jpl.nasa.gov/asteroids/. 
  19. ↑ Magri, C. et al. (December 1998), "Mainbelt Asteroids: Results of Arecibo and Goldstone Radar Observations of 37 Objects During 1980-1995", Bulletin of the American Astronomical Society 30: 1450, Bibcode: 1998DPS....30.5516M, http://trs-new.jpl.nasa.gov/dspace/bitstream/2014/20186/1/98-1067.pdf, retrieved 2011-07-26 
  20. ↑ LaForge, Evan; Price, Will; Rafelski, Johann (September 2023). "Superheavy elements and ultradense matter". The European Physical Journal Plus 138 (9): 120–2122. doi:10.1140/epjp/s13360-023-04454-8. 812. Bibcode: 2023EPJP..138..812L. 

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