(5587) 1990 SB
Near-Earth asteroid
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(5587) 1990 SB is an unnamed near-Earth asteroid (NEA) orbiting in the inner Solar System. It was discovered on 16 September 1990 by astronomers Henry E. Holt and J. A. Brown. An Amor asteroid, it is 3.57 kilometres (2.22 mi) in size and has a highly elongated shape. It has a rotation period of 5.05 hours, spinning in a retrograde direction.
| Discovery[1] | |
|---|---|
| Discovered by | H. E. Holt and J. A. Brown |
| Discovery site | Palomar Observatory (675) |
| Discovery date | 16 September 1990 |
| Designations | |
| (5587) 1990 SB | |
| 1990 UV12 | |
| NEO · Amor | |
| Orbital characteristics[2] | |
| Epoch 21 November 2025 (JD 2461000.5) | |
| Uncertainty parameter 0 | |
| Aphelion | 3.70727 AU |
| Perihelion | 1.09391 AU |
| 2.40059 AU | |
| Eccentricity | 0.544317 |
| 3.71951 y (1358.55 d) | |
| 209.583° | |
| 0.264987° / d | |
| Inclination | 18.0410° |
| 189.278° | |
| 87.6129° | |
| Earth MOID | 0.31005 AU |
| TJupiter | 3.251 |
| Physical characteristics | |
| 3.57 km[3]:â125â | |
| 5.05219 h[4]:â187â | |
Pole ecliptic longitude | 253°[4]:â187â |
Pole ecliptic latitude | â60°[4]:â187â |
| 0.32[3]:â125â | |
| Sq-type[2] Color indices:[5]:â368â BâV = 0.831±0.004 VâR = 0.471±0.002 VâI = 0.795±0.004 VâZ = 0.772±0.007 | |
| 13.89[2] | |
History
1990 SB was discovered on 16 September 1990 by astronomers Henry E. Holt and J. A. Brown, who noted its fast motion at that time. It was observed using the 48-in Schmidt telescope at Palomar Observatory. It was given the provisional designation 1990 SB, and its discovery was announced in an International Astronomical Union Circular on 22 September.[6] The asteroid was observed by the Crimean Astrophysical Observatory on 23 October, but it was reported as a new asteroid and given the provisional designation 1990 UV12.[7]:â44â The 23 October observation was later linked to 1990 SB by the Minor Planet Center on 4 June 1993, and the asteroid received the number (5587) that same day.[8]:â123â As of 2025[update], it remains unnamed.[2]
Orbit
1990 SB is classified as a near-Earth object (NEO) of the Amor class.[2] The Amor asteroids are a group of NEOs that have semi-major axes greater than one astronomical unit (AU) and do not cross Earth's orbit.[9] 1990 SB has a semi-major axis of 2.40 AU, taking 3.72 years to complete one orbit around the Sun. Along its orbit, its distance from the Sun varies from 1.09 AU at perihelion to 3.71 AU at aphelion, due to its orbital eccentricity of 0.54. Its orbit is inclined by 18° with respect to the ecliptic plane.[2]
Physical characteristics
1990 SB is about 3.57 kilometres (2.22 mi) in size, based on thermal models using thermal-infrared observations from the Keck telescope.[3]:â125â Photometric observations suggest that its shape is quite elongated, with axes ratios of a/b = 2.0 and b/c = 1.2. Its shape is also regular and symmetrical. Any concavities are not very deep; if it is a contact binary object, it is not very strongly bifurcated.[4]:â192â193â The asteroid is classified as a stony Sq-type asteroid under the Bus classification scheme.[2][10]:â117â It was previously suggested to be intermediate between the Q- and R-type asteroids after it was spectroscopically observed in 2001.[5]:â365â366â
Observations of 1990 SB's lightcurve, or variations in its observed brightness, indicate that it has a rotation period of 5.05 hours.[4]:â187â Its spin pole points toward the ecliptic south, meaning that the asteroid rotates in a retrograde direction.[4]:â187â
