(155140) 2005 UD

(155140) 2005 UD (provisional designation 2005 UD) is an asteroid on an eccentric orbit, classified as a near-Earth object of the Apollo group. It was discovered on 22 October 2005, by the Catalina Sky Survey at the Catalina Station in Arizona, United States. 2005 UD is thought to be a possible fragment of 3200 Phaethon due to its similar orbit,^[8][9] although it is not dynamically associated with the Geminid meteor stream produced by Phaethon.^[10][11]

(155140) 2005 UD

Discovery[1][2]
Discovered by	Catalina Sky Srvy.
Discovery site	Catalina Stn.
Discovery date	22 October 2005
Designations
MPC designation	2005 UD
Minor planet category	NEO · Apollo[3]
Orbital characteristics[3]
Epoch 1 July 2020 (JD 2459396.5)
Uncertainty parameter 0
Observation arc	38.76 yr (14,157 days)
Earliest precovery date	11 November 1982[4]
Aphelion	2.387 AU
Perihelion	0.1629 AU
Semi-major axis	1.275 AU
Eccentricity	0.8722
Orbital period (sidereal)	1.44 yr (525.8 days)
Mean anomaly	1.976°
Mean motion	0° 41m 5.026s / day
Inclination	28.660°
Longitude of ascending node	19.714°
Argument of perihelion	207.603°
Earth MOID	0.07759 AU (11,607,000 km)
Mercury MOID	0.09496 AU (14,206,000 km)
Venus MOID	0.07997 AU (11,963,000 km)
Mars MOID	0.04058 AU (6,071,000 km)[1]
Physical characteristics
Mean diameter	1.28±0.02 km[5]
Synodic rotation period	5.23400+0.00004 −0.00001 h[5]
Pole ecliptic longitude	285.8°+1.1° −5.3°[5]
Pole ecliptic latitude	−25.8°+5.3° −12.5°[5]
Geometric albedo	0.14±0.02[5]
Spectral type	C[6]
Apparent magnitude	17.0 (discovery)[2]
Absolute magnitude (H)	17.22±0.03[5] 17.51±0.02[7] 17.42[3][1]

Due to 2005 UD's highly eccentric orbit, it experiences extreme temperature variations up to 975 K (702 °C; 1,295 °F) at perihelion, leading to thermal fracturing of its surface regolith and ejection of dust particles.^[12] However, no activity from 2005 UD has been observed as of yet, though it has been suspected that it could be the inactive parent body of the Daytime Sextantids meteor shower.^[7][13] 2005 UD and Phaethon share a bluish surface color at visible wavelengths, but differ at near-infrared wavelengths where 2005 UD appears redder than Phaethon.^[13]

2005 UD will pass 0.0558 AU (8.35 million km) from Mars on 20 July 2024.^[3]

Potential Family Members^[14]

Object	Size	Earth MOID (AU)	Perihelion (AU)	Mars MOID (AU)
3200 Phaethon	6 km	0.02 AU (3.0 million km)	0.14 AU (21 million km)	0.14 AU (21 million km)
(155140) 2005 UD[3]	1.3 km	0.08 AU (12 million km)	0.16 AU (24 million km)	0.04 AU (6.0 million km)[1]
(225416) 1999 YC[15]	1.7 km	0.25 AU (37 million km)	0.24 AU (36 million km)	0.10 AU (15 million km)

See also

• Active asteroid
• (196256) 2003 EH1, a suspected extinct comet and proposed parent body of the Quadrantids meteor shower^[13]