| Discovery [1] | |
|---|---|
| Discovered by | E. F. Helin |
| Discovery site | Palomar Obs. |
| Discovery date | 27 October 1989 |
| Designations | |
| (5477) Holmes | |
Named after | Robert Holmes [1] (American astronomer) |
| 1989 UH2 | |
| main-belt · (inner) [2] Hungaria [1][3][4] | |
| Orbital characteristics [2] | |
| Epoch 23 March 2018 (JD 2458200.5) | |
| Uncertainty parameter 0 | |
| Observation arc | 27.60yr (10,082 d) |
| Aphelion | 2.0613AU |
| Perihelion | 1.7732 AU |
| 1.9172 AU | |
| Eccentricity | 0.0751 |
| 2.65 yr (970 d) | |
| 295.23° | |
| 0° 22m 16.68s / day | |
| Inclination | 22.552° |
| 49.112° | |
| 290.30° | |
| Knownsatellites | 1(D:1.09 kmP:24.4 h)[3][5][6] |
| Physical characteristics | |
| 2.95±0.13 km(derived)[5] 3.147±0.137 km[7][8] 3.21 km(taken)[3] 3.215 km[9] | |
| 2.9932±0.0002 h[10][a] 2.9940±0.0002 h[11] 2.99401±0.00007 h[12] 2.99408±0.00007 h[13] 2.9943±0.0002 h[6] | |
| 0.2849[9] 0.310±0.038[7][8] | |
| E(assumed)[3] | |
| 13.99±0.03(R)[12] 14.0[2] 14.26±0.54[14] 14.4[8][13] 14.445[3][9] | |
5477 Holmes, provisional designation1989 UH2, is aHungaria asteroid andbinary system from the innermost regions of theasteroid belt, approximately 3 kilometers (2 miles) in diameter. It was discovered on 27 October 1989, by American astronomerEleanor Helin at thePalomar Observatory in California.[1] The presumedE-type asteroid is likely spherical in shape and has a shortrotation period of 2.99 hours.[3] It was named for American amateur astronomerRobert Holmes.[1] The discovery of its 1-kilometer-sizedminor-planet moon was announced in November 2005.[5][6]
Holmes is a core member of theHungaria family (003),[4] a largefamily of bright asteroids that forms the innermost dense concentration of asteroids in theSolar System, as theMars-crosser andnear-Earth populations are much more sparse. The family is part of the larger dynamical group with the same name.[1][3] It orbits the Sun in theinnermost asteroid belt at a distance of 1.8–2.1 AU once every 2 years and 8 months (970 days;semi-major axis of 1.92 AU). Its orbit has aneccentricity of 0.08 and aninclination of 23° with respect to theecliptic.[2] The body'sobservation arc begins with its official discovery observation at Palomar in October 1989.[1]
Holmes is an assumedE-type asteroid,[3] which agrees with the overallspectral type for members of the Hungaria family.[15]: 23
Since 2005, several rotationallightcurves ofHolmes have been obtained fromphotometric observations byBrian Warner andPetr Pravec in collaboration with other astronomers.[6][10][11][12][13][a] Analysis of the best-rated lightcurve gave a well-definedrotation period of 2.9940 hours with a consolidated brightness amplitude between 0.10 and 0.12magnitude, which indicates that the body has a nearly spherical shape (U=3).[3][11] The asteroid's short period is near that of afast rotator.
According to the survey carried out by theNEOWISE mission of NASA'sWide-field Infrared Survey Explorer (WISE),Holmes measures 3.147 kilometers in diameter and its surface has analbedo of 0.31,[7][8] while theCollaborative Asteroid Lightcurve Link adoptsPetr Pravec's revised WISE-data, that is, an albedo of 0.2849 and a diameter of 3.21 kilometers based on anabsolute magnitude of 14.445.[3][9] Johnston's Archive derives a diameter of 2.95 and 3.15 kilometers for the primary only and for the combined system, respectively.[5]
The photometric observations obtained by Brian Warner and collaborators during 2–12 November 2005,[13] revealed thatHolmes is a synchronousbinary asteroid with aminor-planet moon orbiting it every 24.4 hours at an estimated average distance of6.7 km. The discovery was announced immediately on 15 November 2005.[6] The mutualoccultation events indicated the presence of a satellite 37% the size of its primary, which translates into an estimated diameter of1.09–1.19 kilometers depending on the underlying size estimate of the primary.[3][5]
Thisminor planet was named after American amateur astronomerRobert E. Holmes Jr (born 1956), who directs the Astronomical Research Observatory (H21) in Westfield, Illinois.[1] The official naming citation was suggested bySergio Foglia and published by theMinor Planet Center on 18 February 2011 (M.P.C. 73983).[16]
