1437_Diomedes

1437 Diomedes

1437 Diomedes

Trojan asteroid

1437 Diomedes /ˌdaɪəˈmiːdiːz/ is a large Jupiter trojan from the Greek camp, approximately 150 kilometers (90 miles) in diameter. It was discovered on 3 August 1937, by astronomer Karl Reinmuth at the Heidelberg-Königstuhl State Observatory in southwest Germany.[1] The dark D/P-type asteroid belongs to the largest Jupiter trojans and has a notably elongated shape and a longer than average rotation period of 24.49 hours.[5] Diomedes was the first Jupiter trojan successfully observed during an occultation event of star.[9] It was named after the hero Diomedes from Greek mythology.[3]

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Orbit and classification

Diomedes is a dark Jovian asteroid orbiting in the leading Greek camp at Jupiter's L4 Lagrangian point, 60° ahead of the Gas Giant's orbit in a 1:1 resonance (see Trojans in astronomy). It is also a non-family asteroid in the Jovian background population.[7] Jupiter trojans are thought to have been captured into their orbits during or shortly after the early stages of the formation of the Solar System. More than 4,500 Jupiter trojans in the Greek camp have already been discovered.[6]

It orbits the Sun at a distance of 5.0–5.4 AU once every 11 years and 10 months (4,329 days; semi-major axis of 5.2 AU). Its orbit has an eccentricity of 0.04 and an inclination of 20° with respect to the ecliptic.[4] The asteroid was first observed as 1931 DN at Lowell Observatory in February 1931. The body's observation arc begins at Heidelberg with its official discovery observation in August 1937.[1]

Physical characteristics

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In the Tholen classification, Diomedes has an ambiguous spectral type, closest to the dark D-type asteroids and somewhat similar to the primitive P-type asteroids.[4] Its V–I color index of 0.810 is also lower than that measured for most D-type Jupiter trojans (0.95).[5]

Rotation period

Several rotational lightcurves of Diomedes have been obtained from photometric observations since the 1960s.[9][13][14][15][16] The so-far best-rated photometric observations by Robert Stephens at the Goat Mountain Astronomical Research Station (G79) and Santana Observatory (646) in November 2008, gave a longer-than average rotation period of 24.49±0.01 hours with a brightness variation of 0.34 magnitude (U=3-).[17]

Diameter and albedo

In the 1970s, radiometric observations were published in the Tucson Revised Index of Asteroid Data (TRIAD) compilation gave a diameter of 173.0 kilometers with a radiometric albedo 0.021.[8]

According to the space-based surveys carried out by the Infrared Astronomical Satellite IRAS, the Japanese Akari satellite and the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer, Diomedes measures between 117.786 and 172.60 kilometers in diameter and its surface has an albedo between 0.028 and 0.061.[10][11][12] The Collaborative Asteroid Lightcurve Link adopts the results obtained by IRAS, that is, an albedo of 0.0313 and a diameter of 164.31 kilometers based on an absolute magnitude of 8.30.[5] The Collaborative Asteroid Lightcurve Link adopts the results obtained by IRAS, that is, an albedo of 0.0313 and a diameter of 164.31 kilometers based on an absolute magnitude of 8.30.[5]

Diomedes is the third largest Jupiter trojan according to IRAS and Akari, and the 9th largest based on NEOWISE data:

More information Largest Jupiter Trojans by survey(A) (mean-diameter in kilometers; YoD: Year of Discovery), Designation ...
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Occultation and shape

Diomedes was the first Jupiter trojan that was successfully observed during an asteroid occultation, when it occulted the star HIP 014402A over Japan on 7 November 1997. The silhouette was elongated with a major and minor occultation axis of 284 × 126 kilometers (poor fit).[8][9] The ellipsoid dimensions of 284 × 126 × 65 kilometers – corresponding to a mean-diameter of 132.5 kilometers, equivalent to the volume of a sphere – were estimated using follow-up photometry at Ondřejov Observatory and Mitaka Observatory (388) that determined the body's rotational phase at the exact time of the occultation event.[9]

Naming

This minor planet was named from Greek mythology after the hero Diomedes, King of Argos and known for his participation in the Trojan War, regarded as the best warriors of the Achaeans, just behind Achilles and alongside Ajax. The official naming citation was mentioned in The Names of the Minor Planets by Paul Herget in 1955 (H 129).[3]

References

  1. [1]
    "1437 Diomedes (1937 PB)". Minor Planet Center. Retrieved 26 October 2017.
  2. [2]
    "Diomedes". Merriam-Webster.com Dictionary.
  3. [3]
    Schmadel, Lutz D. (2007). "(1437) Diomedes". Dictionary of Minor Planet Names. Springer Berlin Heidelberg. p. 115. doi:10.1007/978-3-540-29925-7_1438. ISBN 978-3-540-00238-3.
  4. [4]
    "JPL Small-Body Database Browser: 1437 Diomedes (1937 PB)" (2017-09-27 last obs.). Jet Propulsion Laboratory. Archived from the original on 11 July 2020. Retrieved 26 October 2017.
  5. [5]
    "LCDB Data for (1437) Diomedes". Asteroid Lightcurve Database (LCDB). Retrieved 26 October 2017.
  6. [6]
    "List of Jupiter Trojans". Minor Planet Center. 7 October 2017. Retrieved 26 October 2017.
  7. [7]
    "Asteroid (1437) Diomedes – Proper elements". AstDyS-2, Asteroids – Dynamic Site. Retrieved 13 June 2018.
  8. [8]
    "Asteroid 1437 Diomedes". Small Bodies Data Ferret. Retrieved 13 June 2018.
  9. [9]
    Sato, Isao; Sarounová, Lenka; Fukushima, Hideo (May 2000). "Size and Shape of Trojan Asteroid Diomedes from Its Occultation and Photometry". Icarus. 145 (1): 25–32. Bibcode:2000Icar..145...25S. doi:10.1006/icar.1999.6316. Retrieved 26 October 2017.
  10. [10]
    Grav, T.; Mainzer, A. K.; Bauer, J. M.; Masiero, J. R.; Nugent, C. R. (November 2012). "WISE/NEOWISE Observations of the Jovian Trojan Population: Taxonomy". The Astrophysical Journal. 759 (1): 10. arXiv:1209.1549. Bibcode:2012ApJ...759...49G. doi:10.1088/0004-637X/759/1/49. S2CID 119101711. (online catalog)
  11. [11]
    Tedesco, E. F.; Noah, P. V.; Noah, M.; Price, S. D. (October 2004). "IRAS Minor Planet Survey V6.0". NASA Planetary Data System – IRAS-A-FPA-3-RDR-IMPS-V6.0: IRAS-A-FPA-3-RDR-IMPS-V6.0. Bibcode:2004PDSS...12.....T. Retrieved 15 June 2018.
  12. [12]
    Usui, Fumihiko; Kuroda, Daisuke; Müller, Thomas G.; Hasegawa, Sunao; Ishiguro, Masateru; Ootsubo, Takafumi; et al. (October 2011). "Asteroid Catalog Using Akari: AKARI/IRC Mid-Infrared Asteroid Survey". Publications of the Astronomical Society of Japan. 63 (5): 1117–1138. Bibcode:2011PASJ...63.1117U. doi:10.1093/pasj/63.5.1117. (online, AcuA catalog p. 153)
  13. [13]
    Binzel, Richard P.; Sauter, Linda M. (February 1992). "Trojan, Hilda, and Cybele asteroids – New lightcurve observations and analysis". Icarus. 95 (2): 222–238. Bibcode:1992Icar...95..222B. doi:10.1016/0019-1035(92)90039-A. ISSN 0019-1035. Retrieved 26 October 2017.
  14. [14]
    Taylor, Ronald C. (December 1970). "Photometric Observations and Reductions of Lightcurves of Asteroids". Physical Studies of Minor Planets. 267: 117–131. Bibcode:1971NASSP.267..117T. Retrieved 26 October 2017.
  15. [15]
    Dunlap, J. L.; Gehrels, T. (August 1969). "Minor Planets. III. Lightcurves of a Trojan Asteroid". Astronomical Journal. 74: 796. Bibcode:1969AJ.....74..796D. doi:10.1086/110860. Retrieved 26 October 2017.
  16. [16]
    Mottola, Stefano; Di Martino, Mario; Erikson, Anders; Gonano-Beurer, Maria; Carbognani, Albino; Carsenty, Uri; et al. (May 2011). "Rotational Properties of Jupiter Trojans. I. Light Curves of 80 Objects". The Astronomical Journal. 141 (5): 32. Bibcode:2011AJ....141..170M. doi:10.1088/0004-6256/141/5/170.
  17. [17]
    Stephens, Robert D. (April 2009). "Asteroids Observed from GMARS and Santana Observatories". The Minor Planet Bulletin. 36 (2): 59–62. Bibcode:2009MPBu...36...59S. ISSN 1052-8091. Retrieved 26 October 2017.
  18. [18]
    Veres, Peter; Jedicke, Robert; Fitzsimmons, Alan; Denneau, Larry; Granvik, Mikael; Bolin, Bryce; et al. (November 2015). "Absolute magnitudes and slope parameters for 250,000 asteroids observed by Pan-STARRS PS1 – Preliminary results". Icarus. 261: 34–47. arXiv:1506.00762. Bibcode:2015Icar..261...34V. doi:10.1016/j.icarus.2015.08.007. S2CID 53493339.
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