2241 Alcathous

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2241 Alcathous
Discovery [1]
Discovered by C. Kowal
Discovery site Palomar Obs.
Discovery date 22 November 1979
Designations
MPC designation (2241) Alcathous
Pronunciation /ælˈkæθəs/
al-KATH-oh-əs
Named after
Alcathous[2]
(Greek mythology)
1979 WM · 1950 NC
1968 WF
Jupiter trojan[1][3][4]
Trojan[5][6] · background[6]
Orbital characteristics[3]
Epoch 23 March 2018 (JD 2458200.5)
Uncertainty parameter 0
Observation arc 67.93 yr (24,811 d)
Aphelion 5.5311 AU
Perihelion 4.8328 AU
5.1820 AU
Eccentricity 0.0674
11.80 yr (4,309 d)
313.95°
0° 5m 0.96s / day
Inclination 16.627°
267.99°
291.80°
Jupiter MOID 0.1444 AU
TJupiter 2.9120
Physical characteristics
Mean diameter
113.68±1.72 km[7]
114.63±5.8 km[8]
118.87±2.27 km[9]
7.687±0.005 h[10]
7.689±0.001 h[11][a]
7.690±0.001 h[12]
7.691±0.001 h[13][a]
7.695±0.002 h[14][a]
7.698±0.002 h[15][a]
9.41 h (poor)[16]
0.044±0.002[9]
0.0471±0.005[8]
0.048±0.012[7]
D (Tholen)[3][4]
D0 (Barucci)[17]
D (Tedesco)[17]
U–B = 0.226[3]
B–V = 0.660±0.050[18]
V–R = 0.490±0.050[18]
V–I = 0.940±0.024[4]
8.61±0.25[19]
8.64[1][3][4][7][8][9]

2241 Alcathous, provisional designation 1979 WM, is a large Jupiter trojan from the Trojan camp, approximately 115 kilometers (71 miles) in diameter. It was discovered on 22 November 1979, by American astronomer Charles Kowal at the Palomar Observatory in southern California, United States.[1] The dark D-type asteroid belongs to the 20 largest Jupiter trojans and has a rotation period of 7.7 hours.[4] It was named after Alcathous from Greek mythology.[2]

Orbit and classification[edit]

Alcathous is a dark Jovian asteroid orbiting in the trailering Trojan camp at Jupiter's L5 Lagrangian point, 60° behind on the Gas Giant's orbit in a 1:1 resonance (see Trojans in astronomy). It is also a non-family asteroid of the Jovian background population.[6][17]

It orbits the Sun at a distance of 4.8–5.5 AU once every 11 years and 10 months (4,309 days; semi-major axis of 5.18 AU). Its orbit has an eccentricity of 0.07 and an inclination of 17° with respect to the ecliptic.[3] The body's observation arc begins with a precovery taken at Palomar in June 1950, more than 29 years prior to its official discovery observation.[1]

Physical characteristics[edit]

In the Tholen, Barucci and Tedesco taxonomy, Alcathous is classified as a dark D-type asteroid.[17] It is the 8th largest of all 46 D-type asteroids in the Tholen classification.[20]

Rotation period[edit]

A large number rotational lightcurves have been obtained since December 1991,[4] when Alcathous was first observed by Stefano Mottola with the Loiano 1.52-meter telescope at Bologna Observatory, Italy.[10] In 1994, the asteroid's rotation period was also measured by Giovanni de Sanctis and collaborators (U=2/1).[16]

Several photometric observations between 2010 and 2017, by Daniel Coley and Robert Stephens at the Center for Solar System Studies and at GMARS (G79), also include the so-far best-rated period of 7.689 hours with a brightness amplitude of 0.22 magnitude (U=2+/3-/3/3/3-).[11][12][13][14][15][a]

Diameter and albedo[edit]

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, Alcathous measures between 113.68 and 118.87 kilometers in diameter and its surface has an albedo between 0.044 and 0.048.[7][8][9] The Collaborative Asteroid Lightcurve Link adopts the results obtained by IRAS, that is, an albedo of 0.0471 and a diameter of 114.63 kilometers based on an absolute magnitude of 8.64.[4]

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Largest Jupiter Trojans by survey(A)
(mean-diameter in kilometers; YoD: Year of Discovery)
Designation H WISE IRAS Akari Ln RP V–I YoD Ref
624 Hektor 7.2 225 233 230.99 L4 6.92 0.930 1907 list
617 Patroclus 8.19 140.362 140.92 140.85 L5 102.80 0.830 1906 list
911 Agamemnon 7.89 131.038 166.66 185.30 L4 6.59 0.980 1919 list
588 Achilles 8.67 130.099 135.47 133.22 L4 7.31 0.940 1906 list
3451 Mentor 8.4 126.288 116.30 117.91 L5 7.70 0.770 1984 list
3317 Paris 8.3 118.790 116.26 120.45 L5 7.09 0.950 1984 list
1867 Deiphobus 8.3 118.220 122.67 131.31 L5 58.66 0.930 1971 list
1172 Äneas 8.33 118.020 142.82 148.66 L5 8.71 0.950 1930 list
1437 Diomedes 8.3 117.786 164.31 172.60 L4 24.49 0.810 1937 list
1143 Odysseus 7.93 114.624 125.64 130.81 L4 10.11 0.860 1930 list
2241 Alcathous 8.64 113.682 114.63 118.87 L5 7.69 0.940 1979 list
659 Nestor 8.99 112.320 108.87 107.06 L4 15.98 0.790 1908 list
3793 Leonteus 8.7 112.046 86.26 87.58 L4 5.62 0.780 1985 list
3063 Makhaon 8.4 111.655 116.14 114.34 L4 8.64 0.830 1983 list
1583 Antilochus 8.6 108.842 101.62 111.69 L4 31.54 0.950 1950 list
884 Priamus 8.81 101.093 96.29 119.99 L5 6.86 0.900 1917 list
1208 Troilus 8.99 100.477 103.34 111.36 L5 56.17 0.740 1931 list
1173 Anchises 8.89 99.549 126.27 120.49 L5 11.60 0.780 1930 list
2207 Antenor 8.89 97.658 85.11 91.32 L5 7.97 0.950 1977 list
2363 Cebriones 9.11 95.976 81.84 84.61 L5 20.05 0.910 1977 list
4063 Euforbo 8.7 95.619 102.46 106.38 L4 8.85 0.950 1989 list
2357 Phereclos 8.94 94.625 94.90 98.45 L5 14.39 0.960 1981 list
4709 Ennomos 8.5 91.433 80.85 80.03 L5 12.28 0.690 1988 list
2797 Teucer 8.7 89.430 111.14 113.99 L4 10.15 0.920 1981 list
2920 Automedon 8.8 88.574 111.01 113.11 L4 10.21 0.950 1981 list
(15436) 1998 VU30 9.1 87.646 85.71 78.63 L4 8.97 0.870 1998 list
3596 Meriones 9.2 87.380 75.09 73.28 L4 12.96 0.830 1985 list
2893 Peiroos 9.23 86.884 87.46 86.76 L5 8.96 0.950 1975 list
4086 Podalirius 9.1 85.495 86.89 85.98 L4 10.43 0.870 1985 list
4060 Deipylos 9.3 84.043 79.21 86.79 L4 9.30 0.760 1987 list
1404 Ajax 9.3 83.990 81.69 96.34 L4 29.38 0.960 1936 list
4348 Poulydamas 9.5 82.032 70.08 87.51 L5 9.91 0.840 1988 list
5144 Achates 9.0 80.958 91.91 89.85 L5 5.96 0.920 1991 list
4833 Meges 8.9 80.165 87.33 89.39 L4 14.25 0.940 1989 list
2223 Sarpedon 9.41 77.480 94.63 108.21 L5 22.74 0.880 1977 list
(4489) 1988 AK 9.0 76.595 92.93 95.02 L4 12.58 0.950 1988 list
2260 Neoptolemus 9.31 76.435 71.65 81.28 L4 8.18 0.950 1975 list
5254 Ulysses 9.2 76.147 78.34 80.00 L4 28.72 0.970 1986 list
(3708) 1974 FV1 9.3 75.661 79.59 76.75 L5 6.55 0.980 1974 list
2674 Pandarus 9.1 74.267 98.10 101.72 L5 8.48 1.000 1982 list
3564 Talthybius 9.4 73.730 68.92 74.11 L4 40.59 0.900 1985 list
4834 Thoas 9.1 72.331 86.82 96.21 L4 18.19 0.950 1989 list
(7641) 1986 TT6 9.4 71.839 68.97 75.28 L4 27.77 0.980 1986 list
3540 Protesilaos 9.3 70.225 76.84 87.66 L4 8.95 0.940 1973 list
(11395) 1998 XN77 9.8 68.977 64.71 67.78 L4 17.38 1998 list
(4035) 1986 WD 9.6 68.733 68.23 66.99 L4 13.47 0.970 1986 list
5264 Telephus 9.4 68.472 73.26 81.38 L4 9.53 0.970 1991 list
1868 Thersites 9.5 68.163 70.08 78.89 L4 10.48 0.960 1960 list
(9799) 1996 RJ 9.6 68.033 64.87 72.42 L4 21.52 0.910 1996 list
4068 Menestheus 9.5 67.625 62.37 68.46 L4 14.40 0.950 1973 list
(23135) 2000 AN146 9.9 66.230 58.29 68.50 L4 8.69 0.860 2000 list
2456 Palamedes 9.3 65.916 91.66 99.60 L4 7.24 0.920 1966 list
3709 Polypoites 9.1 65.297 99.09 85.23 L4 10.04 1.000 1985 list
1749 Telamon 9.5 64.898 81.06 69.14 L4 16.98 0.970 1949 list
3548 Eurybates 9.6 63.885 72.14 68.40 L4 8.71 0.730 1973 list
4543 Phoinix 9.7 63.836 62.79 69.54 L4 38.87 1.200 1989 list
12444 Prothoon 9.8 63.835 64.31 62.41 L5 15.82 1996 list
4836 Medon 9.5 63.277 67.73 78.70 L4 9.82 0.920 1989 list
(16070) 1999 RB101 9.7 63.191 64.13 68.98 L5 20.24 0.960 1999 list
(15440) 1998 WX4 9.6 62.519 66.48 71.88 L4 21.43 0.970 1998 list
(4715) 1989 TS1 9.7 62.097 63.91 65.93 L5 8.81 0.850 1989 list
(34746) 2001 QE91 9.8 61.684 60.51 63.63 L5 19.63 0.950 2001 list
(38050) 1998 VR38 9.8 61.603 61.04 50.44 L4 18.85 0.990 1998 list
5130 Ilioneus 9.7 60.711 59.40 52.49 L5 14.77 0.960 1989 list
5027 Androgeos 9.6 59.786 57.86 n.a. L4 11.38 0.910 1988 list
(6090) 1989 DJ 9.4 59.568 74.53 81.92 L4 18.48 0.980 1989 list
(5648) 1990 VU1 9.7 59.295 63.91 n.a. L5 37.56 0.900 1990 list
7119 Hiera 9.7 59.150 76.40 77.29 L4 400 0.950 1989 list
4805 Asteropaios 10.0 57.647 53.16 43.44 L5 12.37 1990 list
16974 Iphthime 9.8 57.341 55.43 57.15 L4 78.9 0.960 1998 list
4867 Polites 9.8 57.251 58.29 64.29 L5 11.24 1.010 1989 list
2895 Memnon 10.0 56.706 55.67 n.a. L5 7.50 0.710 1981 list
4708 Polydoros 9.9 54.964 55.67 n.a. L5 7.52 0.960 1988 list
(21601) 1998 XO89 10.0 54.909 55.67 56.08 L4 12.65 0.970 1998 list
(12929) 1999 TZ1 9.9 54.077 61.04 55.34 L5 9.27 0.880 1999 list
17492 Hippasos 10.0 53.975 55.67 n.a. L5 17.75 1991 list
5652 Amphimachus 10.1 53.921 53.16 52.48 L4 8.37 1.050 1992 list
2759 Idomeneus 9.9 53.676 61.01 52.55 L4 32.38 0.910 1980 list
(5258) 1989 AU1 10.2 53.275 50.77 n.a. L4 19.85 1.010 1989 list
(12126) 1999 RM11 10.1 53.202 n.a. n.a. L5 n.a. ? 1999 list
(15502) 1999 NV27 10.0 53.100 55.67 50.86 L5 15.13 0.875 1999 list
4754 Panthoos 10.0 53.025 53.15 56.96 L5 27.68 1977 list
4832 Palinurus 10.0 52.058 53.16 n.a. L5 5.32 1.000 1988 list
5126 Achaemenides 10.5 51.922 44.22 48.57 L4 53.02 1989 list
3240 Laocoon 10.2 51.695 50.77 n.a. L5 11.31 0.880 1978 list
4902 Thessandrus 9.8 51.263 61.04 71.79 L4 738 0.960 1989 list
11552 Boucolion 10.1 51.136 53.16 53.91 L5 32.44 1993 list
(20729) 1999 XS143 10.4 50.961 46.30 n.a. L4 5.72 1.000 1999 list
(6545) 1986 TR6 10.1 50.951 53.16 n.a. L4 16.26 0.910 1986 list
4792 Lykaon 10.1 50.870 53.16 n.a. L5 40.09 0.960 1988 list
21900 Orus 10.0 50.810 55.67 53.87 L4 13.45 0.950 1999 list
1873 Agenor 10.1 50.799 53.76 54.38 L5 20.60 1971 list
5028 Halaesus 10.2 50.770 50.77 n.a. L4 24.94 0.900 1988 list
2146 Stentor 9.9 50.755 58.29 n.a. L4 16.40 1976 list
4722 Agelaos 10.0 50.378 53.16 59.47 L5 18.44 0.910 1977 list
5284 Orsilocus 10.1 50.159 53.16 n.a. L4 10.31 0.970 1989 list
11509 Thersilochos 10.1 49.960 53.16 56.23 L5 17.37 1990 list
5285 Krethon 10.1 49.606 58.53 52.61 L4 12.04 1.090 1989 list
4791 Iphidamas 10.1 49.528 57.85 59.96 L5 9.70 1.030 1988 list
9023 Mnesthus 10.1 49.151 50.77 60.80 L5 30.66 1988 list
5283 Pyrrhus 9.7 48.356 64.58 69.93 L4 7.32 0.950 1989 list
4946 Askalaphus 10.2 48.209 52.71 66.10 L4 22.73 0.940 1988 list
(22149) 2000 WD49 10.2 48.190 50.77 50.37 L4 7.84 1.090 2000 list
(32496) 2000 WX182 10.2 48.017 50.77 51.63 L5 23.34 0.950 2000 list
5120 Bitias 10.2 47.987 50.77 n.a. L5 15.21 0.780 1988 list
12714 Alkimos 10.1 47.819 61.04 54.62 L4 28.48 1991 list
(7352) 1994 CO 9.9 47.731 55.67 47.07 L5 648 0.850 1994 list
1870 Glaukos 10.6 47.649 42.23 n.a. L5 5.99 1971 list
4138 Kalchas 10.1 46.462 53.16 61.04 L4 29.2 0.810 1973 list
(23958) 1998 VD30 10.2 46.001 50.77 47.91 L4 562 0.990 1998 list
4828 Misenus 10.4 45.954 46.30 43.22 L5 12.87 0.920 1988 list
4057 Demophon 10.1 45.683 53.16 n.a. L4 29.82 1.060 1985 list
4501 Eurypylos 10.4 45.524 46.30 n.a. L4 6.05 1989 list
4007 Euryalos 10.3 45.515 48.48 53.89 L4 6.39 1973 list
5259 Epeigeus 10.3 44.741 42.59 44.42 L4 18.42 1989 list
30705 Idaios 10.4 44.546 46.30 n.a. L5 15.74 1977 list
16560 Daitor 10.7 43.861 51.42 43.38 L5 1991 list
(15977) 1998 MA11 10.4 43.530 46.30 51.53 L5 250 0.906 1998 list
7543 Prylis 10.6 42.893 42.23 n.a. L4 17.80 1973 list
4827 Dares 10.5 42.770 44.22 n.a. L5 19.00 1988 list
1647 Menelaus 10.5 42.716 44.22 n.a. L4 17.74 0.866 1957 list
(A) Used sources: WISE/NEOWISE catalog (NEOWISE_DIAM_V1 PDS, Grav, 2012); IRAS data (SIMPS v.6 catalog);
and Akari catalog (Usui, 2011); RP: rotation period and V–I (color index) taken from the LCDB

Note: missing data was completed with figures from the JPL SBDB (query) and from the LCDB (query form) for the
WISE/NEOWISE and SIMPS catalogs, respectively. These figures are given in italics. Also, listing is incomplete above #100.

Naming[edit]

This minor planet was named after Alcathous, brave and handsome Trojan leader in Homer's Iliad. Alcathous was the husband of Hippodamia (also see 692 Hippodamia) the eldest daughter of Anchises (also see 1173 Anchises), who excelled all other girls of her age in beauty, skill and wit. Alcathous, previously uninjured in the Trojan War, was struck by Poseidon (also see 4341 Poseidon) with blindness and paralysis and was killed easily by a spear thrown by the Greek general and Cretan commander, Idomeneus (also see 2759 Idomeneus).[2] The official naming citation was published by the Minor Planet Center on 10 November 1992 (M.P.C. 21128).[21]

Notes[edit]

  1. ^ a b c d e Lightcurve plots of (2241) Alcathous from Jul 2013, Oct 2014, Sep 2015, Dec 2016 and Dec 2017 by Daniel Coley and Robert Stephens at the Center for Solar System Studies (U80) and (U81). Quality code is 2+/3/3/3/3 (lightcurve rating at CS3). Summary figures at the LCDB and CS3.

References[edit]

  1. ^ a b c d e "2241 Alcathous (1979 WM)". Minor Planet Center. Retrieved 12 June 2018. 
  2. ^ a b c Schmadel, Lutz D. (2007). Dictionary of Minor Planet Names – (2241) Alcathous. Springer Berlin Heidelberg. p. 182. ISBN 978-3-540-00238-3. Retrieved 7 December 2016. 
  3. ^ a b c d e f "JPL Small-Body Database Browser: 2241 Alcathous (1979 WM)" (2018-05-24 last obs.). Jet Propulsion Laboratory. Retrieved 12 June 2018. 
  4. ^ a b c d e f g "LCDB Data for (2241) Alcathous". Asteroid Lightcurve Database (LCDB). Retrieved 12 June 2018. 
  5. ^ "List of Jupiter Trojans". Minor Planet Center. 30 May 2018. Retrieved 12 June 2018. 
  6. ^ a b c "Asteroid (2241) Alcathous – Proper elements". AstDyS-2, Asteroids – Dynamic Site. Retrieved 5 June 2018. 
  7. ^ a b c d 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:1209.1549Freely accessible. Bibcode:2012ApJ...759...49G. doi:10.1088/0004-637X/759/1/49. Retrieved 9 June 2018.  (online catalog)
  8. ^ a b c d 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. 
  9. ^ a b c d 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)
  10. ^ a b 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 12 June 2018. 
  11. ^ a b Stephens, Robert D.; Coley, Daniel R.; French, Linda M. (July 2015). "Dispatches from the Trojan Camp - Jovian Trojan L5 Asteroids Observed from CS3: 2014 October - 2015 January". The Minor Planet Bulletin. 42 (3): 216–224. Bibcode:2015MPBu...42R.216S. ISSN 1052-8091. Retrieved 12 June 2018. 
  12. ^ a b French, Linda M.; Stephens, Robert D.; Lederer, Susan M.; Coley, Daniel R.; Rohl, Derrick A. (April 2011). "Preliminary Results from a Study of Trojan Asteroids". The Minor Planet Bulletin. 38 (2): 116–120. Bibcode:2011MPBu...38..116F. ISSN 1052-8091. Retrieved 12 June 2018. 
  13. ^ a b Stephens, Robert D.; Coley, Daniel R.; Warner, Brian D.; French, Linda, M. (October 2016). "Lightcurves of Jovian Trojan Asteroids from the Center for Solar System Studies: L4 Greek Camp and Spies". The Minor Planet Bulletin. 43 (4): 323–331. Bibcode:2016MPBu...43..323S. ISSN 1052-8091. Retrieved 12 June 2018. 
  14. ^ a b Stephens, Robert D.; French, Linda M.; Davitt, Chelsea; Coley, Daniel R. (April 2014). "At the Scaean Gates: Observations Jovian Trojan Asteroids, July- December 2013". The Minor Planet Bulletin. 41 (2): 95–100. Bibcode:2014MPBu...41...95S. ISSN 1052-8091. Retrieved 12 June 2018. 
  15. ^ a b Stephens, Robert D. (April 2017). "Lightcurve Analysis of Trojan Asteroids at the Center for Solar System Studies 2016 October - December". The Minor Planet Bulletin. 44 (2): 123–125. Bibcode:2017MPBu...44..123S. ISSN 1052-8091. Retrieved 12 June 2018. 
  16. ^ a b de Sanctis, M. C.; Barucci, M. A.; Angeli, C. A.; Fulchignoni, M.; Burchi, R.; Angelini, P. (October 1994). "Photoelectric and CCD observations of 10 asteroids". Planetary and Space Science: 859–864. Bibcode:1994P&SS...42..859D. doi:10.1016/0032-0633(94)90066-3. ISSN 0032-0633. Retrieved 12 June 2018. 
  17. ^ a b c d "Asteroid 2241 Alcathous". Small Bodies Data Ferret. Retrieved 12 June 2018. 
  18. ^ a b 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 12 June 2018. 
  19. ^ 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:1506.00762Freely accessible. Bibcode:2015Icar..261...34V. doi:10.1016/j.icarus.2015.08.007. Retrieved 12 June 2018. 
  20. ^ "JPL Small-Body Database Search list of D-type minor planets (Tholen and SMASSII)". JPL Solar System Dynamics. Retrieved 15 December 2015. 
  21. ^ "MPC/MPO/MPS Archive". Minor Planet Center. Retrieved 12 June 2018. 

External links[edit]