| Discovery[1] | |
|---|---|
| Discovered by | E. F. Helin |
| Discovery site | Palomar Obs. |
| Discovery date | 30 January 1992 |
| Designations | |
| (7187) Isobe | |
Named after | Syuzo Isobe (Japanese astronomer)[2] |
| 1992 BW · 1985 QC3 | |
| main-belt · (inner)[1] Hungaria[3][4] | |
| Orbital characteristics[1] | |
| Epoch 4 September 2017 (JD 2458000.5) | |
| Uncertainty parameter 0 | |
| Observation arc | 30.61 yr (11,182 days) |
| Aphelion | 2.1048AU |
| Perihelion | 1.7700 AU |
| 1.9374 AU | |
| Eccentricity | 0.0864 |
| 2.70yr (985 days) | |
| 251.94° | |
| 0° 21m 55.8s / day | |
| Inclination | 21.784° |
| 315.32° | |
| 86.408° | |
| Knownsatellites | 1(likely)[4][5] |
| Physical characteristics | |
| Dimensions | 3.85 km(calculated)[4] 4.85±1.43 km[6] 5.421±1.086 km[7] 6.05±1.46 km[8] |
| 2.440±0.002h[9] 2.58±0.01 h[10] 4.241±0.006 h[11] 4.2427±0.002 h[5] 4.2432±0.0005 h[12] | |
| 0.093±0.027[13] 0.12±0.09[6] 0.134±0.104[8] 0.167±0.094[7] 0.3(assumed)[4] | |
| E[4] | |
| 13.89[8] · 13.90[7] · 14.0[1][4] · 14.50[6] | |
7187 Isobe, provisional designation1992 BW, is a likelybinary Hungariaasteroid from the inner regions of theasteroid belt, approximately 5 kilometers in diameter. It was discovered on 30 January 1992, by American astronomerEleanor Helin atPalomar Observatory in California, United States.[3] It is named after Japanese astronomer Syuzo Isobe.[2]
The presumedE-type asteroid is a member of theHungaria family, which form the innermost dense concentration of asteroids in theSolar System.[3][4]Isobe orbits the Sun in theinner main-belt at a distance of 1.8–2.1 AU once every 2 years and 8 months (985 days). Its orbit has aneccentricity of 0.09 and aninclination of 22° with respect to theecliptic.[1] It was first identified as1985 QC3 at the discovery observatory in 1985, extending the body'sobservation arc by 7 years prior to its official discovery observation.[3]
According to the survey carried out by NASA'sWide-field Infrared Survey Explorer with its subsequentNEOWISE mission,Isobe measures between 4.85 and 6.05 kilometers in diameter, and its surface has analbedo between 0.12 and 0.167.[6][7][8] The Collaborative Asteroid Lightcurve Link assumes an albedo of 0.30 – a compromise value between 0.4 and 0.2, corresponding to the Hungaria asteroids both as family and orbital group – and calculates a diameter of 3.85 kilometers with anabsolute magnitude of 14.0.[4]
Since August 2004, American astronomerBrian Warner obtained several rotationallightcurves ofIsobe at his Palmer Divide Observatory in Colorado. Light curve and follow-up analysis gave a well-definedrotation period of 4.2432 hours with a brightness amplitude of 0.22magnitude (U=3), after initial photometric observations indicated a shorter period solution of 2.4 hours.[5]
In 2012, observations by Brian Warner also indicated thatIsobe is very likely a synchronousbinary asteroid, orbited by aminor-planet moon every 33 hours. The size of this satellite remains unknown and no secondary-to-primary diameter ratio has been published.Isobe's binary nature still needs further observations.
Isobe was also observed by American astronomerRobert Stephens at the Center for Solar System Studies in September 2015, giving a period of 4.241 hours with an amplitude of 0.22 magnitude. However, no mutualoccultation events have been found during the two-night long observation period (U=3-).[11]
The asteroid has been named afterSyuzo Isobe (born 1942), a Japanese scientist atNAOJ, individual member of theIAU, and president of theJapan Spaceguard Association. He significantly contributed in establishing theBisei Spaceguard Center, an observatory designed for the observation ofNEOs and earth-orbiting space debris.[2][14] The approved naming citation was published by theMinor Planet Center on 1 November 2001 (M.P.C. 43762).[15]
