2009 SE

2009 SE is a small asteroid and Mars trojan orbiting near the L₅ point of Mars (60 degrees behind Mars on its orbit).^[2]

2009 SE

Discovery
Discovered by	Catalina Sky Survey
Discovery date	16 September 2009
Designations
MPC designation	2009 SE
Minor planet category	Martian L5
Orbital characteristics[1]
Epoch 31 May 2020 (JD 2459000.5)
Uncertainty parameter 0
Observation arc	3133 days (8.58 yr)
Aphelion	1.623684 AU (242.8997 Gm)
Perihelion	1.425261 AU (213.2160 Gm)
Semi-major axis	1.524472 AU (228.0578 Gm)
Eccentricity	0.0650794
Orbital period (sidereal)	1.88 yr (687.508 d)
Mean anomaly	240.916°
Mean motion	0° 31m 25.069s /day
Inclination	20.6248°
Longitude of ascending node	6.82030°
Argument of perihelion	354.156°
Earth MOID	0.42422 AU (63.462 Gm)
Jupiter MOID	3.5304 AU (528.14 Gm)
Physical characteristics
Mean diameter	400 m
Geometric albedo	0.5–0.05 (assumed)
Absolute magnitude (H)	19.9

Discovery, orbit and physical properties

2009 SE was first observed on 16 September 2009 by the Catalina Sky Survey (CSS).^[3] Its orbit is characterized by low eccentricity (0.065), moderate inclination (20.6°) and a semi-major axis of 1.52 AU.^[3] Upon discovery, it was classified as Mars-crosser by the Minor Planet Center. Its orbit is well determined as it is currently (January 2021) based on 56 observations with a data-arc span of 3,133 days.^[1] 2009 SE has an absolute magnitude of 19.9 which gives a characteristic diameter of 400 m.^[1]

Mars trojan and orbital evolution

Recent calculations indicate that it is a stable L₅ Mars trojan with a libration period of 1430 yr and an amplitude of 70°.^[2] The libration amplitude is not similar to that of 5261 Eureka and related objects.^{[citation needed]}

Mars trojan

L₄ (leading):

• (121514) 1999 UJ7 †

L₅ (trailing):

• 5261 Eureka (1990 MB) †
• (101429) 1998 VF31 †
• (311999) 2007 NS2 †
• (385250) 2001 DH47
• 2009 SE
• 2011 SC191
• 2011 SL25
• 2011 SP189
• 2011 UB256
• 2011 UN63
• 2016 CP31
• 2018 EC4
• 2018 FC4

See also

• 2020 VT1