| Discovery[1] | |
|---|---|
| Discovered by | M. F. Wolf |
| Discovery site | Heidelberg Obs. |
| Discovery date | 12 November 1918 |
| Designations | |
| (907) Rhoda | |
| Pronunciation | /ˈroʊdə/[2] |
Named after | Rhoda Barnard (wife ofE. E. Barnard)[3] |
| A918 VA · A901 BA A913 SC · 1918 EU 1913 SC · 1901 BA | |
| main-belt[1][4] · (middle) background[5][6] | |
| Orbital characteristics[4] | |
| Epoch 31 May 2020 (JD 2459000.5) | |
| Uncertainty parameter 0 | |
| Observation arc | 118.67yr (43,343 d) |
| Aphelion | 3.2553AU |
| Perihelion | 2.3468 AU |
| 2.8010 AU | |
| Eccentricity | 0.1622 |
| 4.69 yr (1,712 d) | |
| 183.55° | |
| 0° 12m 36.72s / day | |
| Inclination | 19.525° |
| 42.980° | |
| 88.326° | |
| Physical characteristics | |
| 22.44±0.02 h[11][a] | |
| 9.7[1][4] | |
907 Rhoda is a largebackground asteroid from the central region of theasteroid belt, that measures approximately 75 kilometers (47 miles) in diameter. It was discovered on 12 November 1918, by astronomerMax Wolf at theHeidelberg Observatory in southwest Germany.[1] The darkC/X-type asteroid has a longrotation period of 22.4 hours and is likely spherical in shape. It was named after Rhoda Barnard, wife of American astronomerEdward Emerson Barnard (1857–1923).[3]
Rhoda is a non-family asteroid of the main belt'sbackground population when applying thehierarchical clustering method to itsproper orbital elements.[5][6] It orbits the Sun in thecentral asteroid belt at a distance of 2.3–3.3 AU once every 4 years and 8 months (1,712 days;semi-major axis of 2.8 AU). Its orbit has aneccentricity of 0.16 and aninclination of 20° with respect to theecliptic.[4] The body'sobservation arc begins with its first observation asA901 BA (1901 BA) at theHeidelberg-Königstuhl State Observatory on 18 January 1901, where it was officially discovered almost 18 years later on 12 November 1918.[1]
Thisminor planet was named after Rhoda Barnard (née Calvert), wife of the American astronomerEdward Emerson Barnard (1857–1923), who was himself honored with the asteroid819 Barnardiana. The official naming was published in the journalAstronomische Nachrichten in 1922 (AN 215, 471). Thenaming was also mentioned inThe Names of the Minor Planets byPaul Herget in 1955 (H 88).[3]
In theTholen classification,Rhoda is a common, carbonaceousC-type asteroid, while in the Bus–BinzelSMASS classification it is a Xk-subtype, which transitions from theX-type to the uncommonK-type asteroids.[4] In the Barucci-taxonomy, which classified a total of 438 asteroids in 1987,Rhoda is a C0-type.[6]
In April 2004, a rotationallightcurve ofRhoda was obtained fromphotometric observations byBrian Warner at thePalmer Divide Observatory (716) in Colorado. Lightcurve analysis gave arotation period of22.44±0.02 hours with a low brightness variation of0.16±0.02magnitude, indicative of a non-elongated, spherical shape (U=3−).[11][a] Other period determinations were made by Marciniak as well as by Raphaël Nicollerat andRaoul Behrend, giving a low-amplitude lightcurve with a period of22.46±0.01 and22.4±0.5 hours, respectively (U=2/1).[12][13]
According to the survey carried out by the Infrared Astronomical SatelliteIRAS, the JapaneseAkari satellite, and theNEOWISE mission of NASA'sWide-field Infrared Survey Explorer (WISE),Rhoda measures (62.73±1.7), (75.22±0.83) and (82.660±0.340) kilometers in diameter and its surface has analbedo of (0.0560±0.003), (0.040±0.001) and (0.032±0.005), respectively.[7][9][10] TheCollaborative Asteroid Lightcurve Link adopts the results obtained by IRAS, that is, an albedo of 0.0560 and calculates a diameter of 62.73 kilometers based on anabsolute magnitude of 10.74.[12] Alternative mean-diameter measurements published by the WISE team include in ascending order (67.246±26.594 km), (84.062±30.075 km), (91.045±2.093 km) and (95.22±22.26 km) and albedos of (0.0266±0.0058), (0.03±0.02), (0.031±0.015) and (0.044±0.035).[6][12] Anasteroid occultation, observed on 23 March 2009, gave a best-fit ellipse dimension of 63.0 × 63.0 kilometers.[6] These timed observations are taken when the asteroid passes in front of a distant star.[6]
