4709 Ennomos
Discovery [1] | |
---|---|
Discovered by | C. Shoemaker |
Discovery site | Palomar Obs. |
Discovery date | 12 October 1988 |
Designations | |
MPC designation | (4709) Ennomos |
Pronunciation | /ˈɛnəməs/ EN-ə-məs |
Named after |
Ennomus [1] (or Ennomos) (Greek mythology) |
1988 TU2 · 1954 UM1 1977 UT2 | |
Jupiter trojan [1][2][3] · Trojan [4][5] Ennomos [6] · background [5] | |
Orbital characteristics [2] | |
Epoch 23 March 2018 (JD 2458200.5) | |
Uncertainty parameter 0 | |
Observation arc | 66.80 yr (24,398 d) |
Aphelion | 5.3542 AU |
Perihelion | 5.1345 AU |
5.2443 AU | |
Eccentricity | 0.0209 |
12.01 yr (4,387 d) | |
204.60° | |
0° 4m 55.56s / day | |
Inclination | 25.452° |
253.12° | |
86.215° | |
Jupiter MOID | 0.0877 AU |
TJupiter | 2.8050 |
Physical characteristics | |
Mean diameter |
±2.17 km 80.03[7] ±4.3 km 80.85[8] 81.23 km (derived)[3] ±0.78 km 91.43[9] |
±0.01 h 11.12[10] ±0.002 h 12.267[11][lower-alpha 1] ±0.001 h 12.269[12][lower-alpha 1] h 12.2696[3] ±0.001 h 12.271[13][lower-alpha 1] ±0.008 h 12.275[14] | |
±0.009 0.0744[8] ±0.009 0.077[9] ±0.005 0.078[7] 0.0972(derived)[3] | |
C (assumed)[3] B–V = ±0.060 0.670[15] V–R = ±0.040 0.350[15] V–I = ±0.017 0.690[3] | |
8.5[1][2] 8.6[3][9] ±0.57 8.62[16] 8.90[7][8] | |
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4709 Ennomos, provisional designation 1988 TU2, is a large Jupiter trojan from the Trojan camp and the namesake of the small Ennomos family, approximately 81 kilometers (50 miles) in diameter. It was discovered on 12 October 1988, by American astronomer Carolyn Shoemaker at the Palomar Observatory in California.[1] The relatively bright and possibly elongated Jovian asteroid belongs to the 40 largest Jupiter trojans and has a rotation period of 12.3 hours.[3] It was named after Ennomus (Ennomos), a Trojan warrior killed by Achilles.[1]
Orbit and classification
Ennomos is a Jovian asteroid orbiting in the trailering Trojan camp at Jupiter's L5 Lagrangian point, 60° behind the Gas Giant's orbit in a 1:1 resonance (see Trojans in astronomy).[4]
It orbits the Sun at a distance of 5.1–5.4 AU once every 12 years (4,387 days; semi-major axis of 5.24 AU). Its orbit has an eccentricity of 0.02 and an inclination of 25° with respect to the ecliptic.[2] The body's observation arc begins with a precovery taken at Palomar in August 1951, more than 37 years prior to its official discovery observation.[1]
Small Ennomos family
This Jupiter trojan is also the namesake of the Ennomos family (009),[6] a small Jovian asteroid family with 30 known members.[17] The family was first identified by Jakub Rozehnal and Miroslav Brož in 2011.[18] It also includes 1867 Deiphobus, one of the largest Jovian trojans.[17]
As the existence of this family is not well established, Ennomos is still considered part of the Jovian background population by another HCM-analysis (Knezevic and Milan).[5] It is speculated that Ennomos might be an unrelated interloper in its own family rather than its parent body.[18] As of 2018, only a few families have been identified among the Jovian asteroids. These are the Hektor family, the Eurybates family, and the Arkesilaos family as well as two unnamed families, 006 and 010).[17]
Naming
This minor planet was named by the discoverer from Greek mythology after the Trojan warrior Ennomus (Ennomos), who was one of many Trojans killed by Achilles in the waters of the River Skamander.[1] The official naming citation was published by the Minor Planet Center on 28 April 1991 (M.P.C. 18144).[19]
Physical characteristics
Ennomos is an assumed C-type asteroid. Its V–I color index of 0.69 is untypically low compared to most other large Jupiter trojans.[3]
Rotation period
In December 1990, a rotational lightcurve of Ennomos was obtained by Italian astronomers Stefano Mottola and Mario Di Martino using the 1.52-meter Loiano Telescope at the Observatory of Bologna in Italy. Lightcurve analysis gave a well-defined rotation period of 12.275 hours with a relatively high brightness amplitude of 0.47 magnitude (U=3), indicative of a non-spherical, elongated shape.[3][14]
Between 2015 and 2017, photometric observations by Daniel Coley and Robert Stephens at the Center for Solar System Studies, California, gave several concurring periods of 12.267, 12.269 and 12.271 with an amplitude between 0.43 and 0.46 magnitude (U=3/3/3).[11][12][13] This also supersedes a period form Stephens taken at the GMARS Observatory (G79) in September 2011.[10]
Diameter and albedo
According to the 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, Ennomos measures between 80.03 and 91.43 kilometers in diameter and its surface has an albedo between 0.077 and 0.078.[7][8][9] The Collaborative Asteroid Lightcurve Link derives an albedo of 0.0972 and a diameter of 81.23 kilometers based on an absolute magnitude of 8.6.[3] Also, Rozehnal and Brož cite a high visual albedo of approximately 0.15 in their publication.[18]
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Notes
- 1 2 3 Lightcurve plots of (4709) Ennomos from Feb 2015, Dec 2015/Jan 2016 and Feb 2017 by Daniel Coley and Robert Stephens at the Center for Solar System Studies (U81). Quality code is 3/3-/2 (lightcurve rating at CS3). Summary figures at the LCDB and CS3.
References
- 1 2 3 4 5 6 7 8 "4709 Ennomos (1988 TU2)". Minor Planet Center. Retrieved 11 June 2018.
- 1 2 3 4 "JPL Small-Body Database Browser: 4709 Ennomos (1988 TU2)" (2018-05-23 last obs.). Jet Propulsion Laboratory. Retrieved 11 June 2018.
- 1 2 3 4 5 6 7 8 9 10 11 "LCDB Data for (4709) Ennomos". Asteroid Lightcurve Database (LCDB). Retrieved 11 June 2018.
- 1 2 "List of Jupiter Trojans". Minor Planet Center. 30 May 2018. Retrieved 11 June 2018.
- 1 2 3 "Asteroid (4709) Ennomos – Proper elements". AstDyS-2, Asteroids – Dynamic Site. Retrieved 6 June 2018.
- 1 2 "Asteroid 4709 Ennomos". Small Bodies Data Ferret. Retrieved 11 June 2018.
- 1 2 3 4 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. Retrieved 15 June 2018. (online, AcuA catalog p. 153)
- 1 2 3 4 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. Bibcode:2004PDSS...12.....T. Retrieved 15 June 2018.
- 1 2 3 4 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" (PDF). The Astrophysical Journal. 759 (1): 10. arXiv:1209.1549. Bibcode:2012ApJ...759...49G. doi:10.1088/0004-637X/759/1/49. Retrieved 11 June 2018. (online catalog)
- 1 2 French, Linda M.; Stephens, Robert D.; Coley, Daniel R.; Megna, Ralph; Wasserman, Lawrence H. (July 2012). "Photometry of 17 Jovian Trojan Asteroids". The Minor Planet Bulletin. 39 (3): 183–187. Bibcode:2012MPBu...39..183F. ISSN 1052-8091. Retrieved 11 June 2018.
- 1 2 Stephens, Robert D.; Coley, Daniel R.; French, Linda M. (July 2016). "A Report from the L5 Trojan Camp - Lightcurves of Jovian Trojan Asteroids from the Center for Solar System Studies". The Minor Planet Bulletin. 43 (3): 265–270. Bibcode:2016MPBu...43..265S. ISSN 1052-8091. Retrieved 11 June 2018.
- 1 2 Stephens, Robert D.; Coley, Daniel R. (July 2017). "Lightcurve Analysis of Trojan Asteroids at the Center for Solar System Studies 2017 January - March". The Minor Planet Bulletin. 44 (3): 252–257. Bibcode:2017MPBu...44..252S. ISSN 1052-8091. Retrieved 11 June 2018.
- 1 2 Stephens, Robert D.; Coley, Daniel, R.; French, Linda M. (January 2016). "Large L5 Jovian Trojan Asteroid Lightcurves from the Center for Solar System Studies". The Minor Planet Bulletin. 43 (1): 15–22. Bibcode:2016MPBu...43...15S. ISSN 1052-8091. Retrieved 11 June 2018.
- 1 2 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. Retrieved 11 June 2018.
- 1 2 Chatelain, Joseph P.; Henry, Todd J.; French, Linda M.; Winters, Jennifer G.; Trilling, David E. (June 2016). "Photometric colors of the brightest members of the Jupiter L5 Trojan cloud". Icarus. 271: 158–169. Bibcode:2016Icar..271..158C. doi:10.1016/j.icarus.2016.01.026. Retrieved 11 June 2018.
- ↑ 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" (PDF). Icarus. 261: 34–47. arXiv:1506.00762. Bibcode:2015Icar..261...34V. doi:10.1016/j.icarus.2015.08.007. Retrieved 11 June 2018.
- 1 2 3 Nesvorný, D.; Broz, M.; Carruba, V. (December 2014). "Identification and Dynamical Properties of Asteroid Families" (PDF). Asteroids IV: 297–321. arXiv:1502.01628. Bibcode:2015aste.book..297N. doi:10.2458/azu_uapress_9780816532131-ch016. Retrieved 11 June 2018.
- 1 2 3 Broz, M.; Rozehnal, J. (June 2011). "Eurybates – the only asteroid family among Trojans?" (PDF). Monthly Notices of the Royal Astronomical Society. 414 (1): 565–574. arXiv:1109.1109. Bibcode:2011MNRAS.414..565B. doi:10.1111/j.1365-2966.2011.18420.x. Retrieved 11 June 2018.
- ↑ "MPC/MPO/MPS Archive". Minor Planet Center. Retrieved 11 June 2018.
External links
- Long-term evolution of asteroid families among Jovian Trojans, Jakub Rozehnal and Miroslav Brož (2014)
- Asteroid Lightcurve Database (LCDB), query form (info)
- Dictionary of Minor Planet Names, Google books
- Discovery Circumstances: Numbered Minor Planets (1)-(5000) – Minor Planet Center
- 4709 Ennomos at AstDyS-2, Asteroids—Dynamic Site
- 4709 Ennomos at the JPL Small-Body Database