_Marlu.png) Modelled shape ofMarlu from itslightcurve | |
| Discovery[1] | |
|---|---|
| Discovered by | F. Kaiser |
| Discovery site | Heidelberg Obs. |
| Discovery date | 1 March 1913 |
| Designations | |
| (746) Marlu | |
Named after | Marie-Louise Kaiser (Discoverer's daughter)[2] |
| A913 EJ · 1926 WA 1975 XN · 1913 QY | |
| Orbital characteristics[3] | |
| Epoch 31 May 2020 (JD 2459000.5) | |
| Uncertainty parameter 0 | |
| Observation arc | 104.37yr (38,122 d) |
| Aphelion | 3.8461AU |
| Perihelion | 2.3728 AU |
| 3.1094 AU | |
| Eccentricity | 0.2369 |
| 5.48 yr (2,003 d) | |
| 60.352° | |
| 0° 10m 47.28s / day | |
| Inclination | 17.480° |
| 1.9385° | |
| 306.79° | |
| Physical characteristics | |
| Dimensions | 72.0 km × 65.0 km[5] |
| 7.787 h[9][10] | |
746 Marlu (prov. designation:A913 EJor1913 QY) is a dark and largebackground asteroid from the outer regions of theasteroid belt, approximately 72 kilometers (45 miles) in diameter. It was discovered on 1 March 1913, by German astronomerFranz Kaiser at theHeidelberg Observatory in southwest Germany.[1] The primitiveP-type asteroid has arotation period of 7.8 hours. It was named after the discoverer's daughter, Marie-Louise Kaiser.[2]
Marlu is a non-family asteroid of the main belt'sbackground population when applying thehierarchical clustering method to itsproper orbital elements.[4][5] It orbits the Sun in theouter asteroid belt at a distance of 2.4–3.8 AU once every 5 years and 6 months (2,003 days;semi-major axis of 3.11 AU). Its orbit has aneccentricity of 0.24 and aninclination of 17° with respect to theecliptic.[3] The body'sobservation arc begins at Heidelberg on 12 September 1915, more than two years after its official discovery observation.[1]
Franz Kaiser named thisminor planet after his daughter, the physician Marie-Louise Kaiser. The discoverer also named another asteroid,743 Eugenisis, in honor of his daughter. Thenaming was mentioned inThe Names of the Minor Planets byPaul Herget in 1955 (H 75).[2]
In theTholen classification,Marlu is a dark and primitiveP-type asteroid,[3] while it is anX-type and P-type asteroid, in the Tholen- and SMASS-like taxonomic variant of theSmall Solar System Objects Spectroscopic Survey (S3OS2), respectively.[5][11] P-type asteroids are common in the outer asteroid belt and among theJupiter trojan population. In the Moving Object Catalog (MOC) of theSloan Digital Sky Survey, however,Marlu is a common carbonaceousC-type asteroid.[12]
In September 1981, a rotationallightcurve ofMarlu was obtained fromphotometric observations by American astronomerAlan W. Harris. Lightcurve analysis gave arotation period of7.787 hours with a brightness variation of0.23magnitude (U=2).[9] In October 2014,Daniel A. Klinglesmith confirmed the exact same period of (7.787±0.001 h) hours with an amplitude of (0.22±0.01) magnitude (U=3).[10]
In 2016, a modeled lightcurve gave a concurring sidereal period of7.78887±0.00005 hours using data from a large collaboration of individual observers. The study also determined twospin axes of (202.0°, −66.0°) and (64.0°, −27.0°) inecliptic coordinates (λ, β).[5][13][14]
According to the surveys carried out by the Infrared Astronomical SatelliteIRAS, the JapaneseAkari satellite, and theNEOWISE mission of NASA'sWide-field Infrared Survey Explorer (WISE),Marlu measures (69.75±4.0), (71.55±1.41) and (74.274±1.122) kilometers in diameter and its surface has a lowalbedo of0.0363±0.005), (0.036±0.002) and (0.032±0.007), respectively.[6][7][8]
TheCollaborative Asteroid Lightcurve Link adopts an albedo of 0.0431 and derives a diameter of 69.87 kilometers based on anabsolute magnitude of 9.81.[13] The WISE-team also published two alternative mean-diameters of (70.00±19.03 km) and (78.34±21.54 km) with a corresponding albedo of (0.04±0.01) and (0.04±0.05).[5][13] Anasteroid occultation on 1 May 1985, gave a best-fit ellipse dimension of (72.0 km × 65.0 km) with an intermediate quality rating of 2.[5] These timed observations are taken when the asteroid passes in front of a distant star.[5]
