| Discovery [1] | |
|---|---|
| Discovered by | E. Bowell |
| Discovery site | Anderson Mesa Stn. |
| Discovery date | 15 April 1985 |
| Designations | |
| (4175) Billbaum | |
Named after | William A. Baum [1] (American astronomer) |
| 1985 GX · 1974 UE 1978 QF2 · 1978 RL4 | |
| main-belt [1][2] · (middle) background [3] · Eunomia [4] | |
| Orbital characteristics [2] | |
| Epoch 23 March 2018 (JD 2458200.5) | |
| Uncertainty parameter 0 | |
| Observation arc | 66.14yr (24,159 d) |
| Aphelion | 3.1831AU |
| Perihelion | 2.1842 AU |
| 2.6836 AU | |
| Eccentricity | 0.1861 |
| 4.40 yr (1,606 d) | |
| 239.61° | |
| 0° 13m 27.12s / day | |
| Inclination | 13.612° |
| 163.41° | |
| 316.77° | |
| Physical characteristics | |
| 8.873±0.278 km[5] 9.60 km(calculated)[4] | |
| 2.730±0.005 h[a] 2.7425±0.0009 h[6] 2.908±0.001 h[7] | |
| 0.21(assumed)[4] 0.270±0.038[5] | |
| L [8] · S(assumed)[4] | |
| 11.96±0.72[8] 12.30[5] 12.4[2][4] | |
4175 Billbaum, provisional designation1985 GX, is a backgroundasteroid from the central regions of theasteroid belt, approximately 9 kilometers (6 miles) in diameter. It was discovered on 15 April 1985, by American astronomerEdward Bowell at theAnderson Mesa Station of theLowell Observatory near Flagstaff, Arizona. The uncommonL-type asteroid has a shortrotation period of 2.73 hours and was named for American astronomerWilliam A. Baum.[1][4]
Billbaum is a non-family asteroid of the main belt'sbackground population when applying thehierarchical clustering method to itsproper orbital elements.[3] Based on osculating Keplerianorbital elements, the asteroid has also been classified as a member of theEunomia family (502), a prominentfamily of stonyS-type asteroid and the largest one in the intermediate main belt with more than 5,000 members.[4]
It orbits the Sun in thecentral main-belt at a distance of 2.2–3.2 AU once every 4 years and 5 months (1,606 days;semi-major axis of 2.68 AU). Its orbit has aneccentricity of 0.19 and aninclination of 14° with respect to theecliptic.[2] The body'sobservation arc begins with aprecovery taken atPalomar Observatory in August 1951, almost 34 years prior to its official discovery observation at Anderson Mesa.[1]
Billbaum has been characterized as an uncommonL-type asteroid byPan-STARRS survey.[8][4]
In January and February 2011, three rotationallightcurves ofBillbaum were obtained fromphotometric observations by Ralph Megna, Josep Aymami and astronomers at theOakley Southern Sky Observatory.[6][7][a] Analysis of the best-rated lightcurve gave a shortrotation period of 2.73 hours and a consolidated brightness amplitude between 0.08 and 0.15magnitude (U=3-).[4]
According to the survey carried out by theNEOWISE mission of NASA'sWide-field Infrared Survey Explorer,Billbaum measures 8.87 kilometers in diameter and its surface has analbedo of 0.27,[5] while theCollaborative Asteroid Lightcurve Link assumes a stony standard albedo of 0.21, derived from15 Eunomia, the Eunomia family's parent body – and calculates a diameter of 9.60 kilometers based on anabsolute magnitude of 12.4.[4]
Thisminor planet was named after American astronomerWilliam A. Baum (1924–2012) who was on the directorship of the Lowell Observatory's Planetary Research Center. He also worked on the Hubble Space Telescope.[1] The official naming citation was published by theMinor Planet Center on 28 April 1991 (M.P.C. 18139).[9]
