 Ursula imaged atamag 11.4 near the star TYC 581-36-1 (magnitude 11.9). The two galaxies are about magnitude 15. | |
| Discovery[1] | |
|---|---|
| Discovered by | A. Charlois |
| Discovery site | Nice Obs. |
| Discovery date | 18 September 1893 |
| Designations | |
| (375) Ursula | |
| Pronunciation | /ˈɜːrsjuːlə/ |
Named after | unknown[2] |
| 1893 AL | |
| main-belt · (outer)[3] Ursula[4] | |
| Adjectives | Ursulian/ɜːrˈsjuːliən/ |
| Orbital characteristics[1] | |
| Epoch 4 September 2017 (JD 2458000.5) | |
| Uncertainty parameter 0 | |
| Observation arc | 124.06 yr (45,314 days) |
| Aphelion | 3.4544AU |
| Perihelion | 2.7928 AU |
| 3.1236 AU | |
| Eccentricity | 0.1059 |
| 5.52yr (2,016 days) | |
| 189.03° | |
| 0° 10m 42.6s / day | |
| Inclination | 15.943° |
| 336.57° | |
| 342.15° | |
| Physical characteristics | |
| Dimensions | 189.45±54.76 km[5] 191.65±4.01 km[6] 193.63±2.52 km[7] 215.67±54.80 km[8] 216±10 km[9] 216.10 km(taken)[3] |
| Mass | (8.45±5.26)×1018 kg[6] |
Meandensity | 2.29±1.43 g/cm3[6] |
| 16.78±0.01h[3] 16.83 h[10][11] 16.899±0.001 h[12] 16.900±0.003 h[13] | |
| 0.04±0.03[8] 0.042±0.027[5] 0.049±0.001[7] 0.0494(derived)[3] | |
| Tholen =C[1] SMASS = Xc[1] B–V = 0.683[1] U–B = 0.341[1] | |
| 7.21[3] · 7.21±0.02[13][14] · 7.45[8] · 7.47[1][5][7] · 7.58±0.31[15] | |
375 Ursula, provisional designation1893 AL, is a darkasteroid and parent body of theUrsula family from the outer regions of theasteroid belt. It is one of thelargest asteroids with a diameter of approximately 200 kilometers. It was discovered on 18 September 1893, by French astronomerAuguste Charlois atNice Observatory in France.[16] Thereferent of the asteroids's name is unknown.[2]
Ursula is theparent body of theUrsula family (631),[4] a largefamily ofC- andX-type asteroids.[17]: 23 It orbits the Sun in theouter asteroid belt at a distance of 2.8–3.5 AU once every 5 years and 6 months (2,016 days;semi-major axis of 3.12 AU). Its orbit has aneccentricity of 0.11 and aninclination of 16° with respect to theecliptic.[1] The body'sobservation arc begins atVienna Observatory in October 1893, three weeks after its official discovery observation at Nice.[16]
In theTholen classification,Ursula is a carbonaceousC-type asteroid, while in theSMASS taxonomy, it is a Xc-subtype that transitions to theX-type asteroids.[1]
In January 2017, the so-far best-rated rotationallightcurve ofUrsula was obtained from photometric observations by American astronomerFrederick Pilcher at the Organ Mesa Observatory (G50), New Mexico. Lightcurve analysis gave arotation period of 16.899 hours with a brightness amplitude of 0.11magnitude (U=3).[12]
According to the surveys carried out by the JapaneseAkari satellite and theNEOWISE mission of NASA'sWide-field Infrared Survey Explorer,Ursula measures between 189.45 and 215.67 kilometers in diameter and its surface has analbedo between 0.04 and 0.049.[5][7][8]
Observations of anoccultation on 15 November 1984, produced sixchords indicating an estimated diameter of 216±10 km.[9] TheCollaborative Asteroid Lightcurve Link derives an albedo of 0.0494 and adopts a diameter of 216.1 kilometers based on anabsolute magnitude of 7.21.[3]
Any reference of thisminor planet's name to a person or occurrence is unknown.[2]
Among the many thousands ofnamed minor planets,Ursula is one of only 120 for which no official naming citation has been published. All of these asteroids have low numbers between164 Eva and1514 Ricouxa and were discovered between 1876 and the 1930s, predominantly by astronomersAuguste Charlois,Johann Palisa,Max Wolf andKarl Reinmuth.[18]
