391 Ingeborg
Mars-crossing asteroid
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391 Ingeborg (prov. designation: A894 VB or 1894 BE) is an asteroid and second-largest Mars-crosser on an eccentric orbit from the asteroid belt. It was discovered by German astronomer Max Wolf on 1 November 1894, at the Heidelberg Observatory in southwest Germany. When discovered, it was observed for a couple of weeks, and follow-up observations were made in 1901 and 1904.[3][4]
_Ingeborg.png)
Modelled shape of Ingeborg from its lightcurve | |
| Discovery[1] | |
|---|---|
| Discovered by | M. F. Wolf |
| Discovery site | Heidelberg Obs. |
| Discovery date | 1 November 1894 |
| Designations | |
| (391) Ingeborg | |
| Pronunciation | German: [ˈɪŋəbɔʁk] ⓘ[2] |
Named after | unknown (Ingeborg)[3] |
| 1894 BE · 1934 AJ A894 VB | |
| Mars-crosser[1][4][5] | |
| Orbital characteristics[1] | |
| Epoch 4 September 2017 (JD 2458000.5) | |
| Uncertainty parameter 0 | |
| Observation arc | 122.86 yr (44,875 days) |
| Aphelion | 3.0285 AU |
| Perihelion | 1.6120 AU |
| 2.3203 AU | |
| Eccentricity | 0.3052 |
| 3.53 yr (1,291 days) | |
| 292.16° | |
| 0° 16m 44.04s / day | |
| Inclination | 23.202° |
| 212.88° | |
| 147.06° | |
| Mars MOID | 0.2350 AU |
| Physical characteristics | |
| Dimensions | 15.75±3.05 km[6] 17.33±1.73 km[7] 18.15±0.19 km[8] 19.63 km (calculated)[5] |
| 16 h[9] 26.39±0.02 h[10] 26.391±0.006 h[11] 26.4145±0.0005 h[12] 26.4146±0.0005 h[13] 26.4149±0.0001 h[14] | |
| 0.20 (assumed)[5] 0.282±0.056[7] 0.290±0.110[6] 0.34±0.16[6] 0.495±0.013[8] | |
| Tholen = S[1] SMASS = S[1][5] | |
| 10.10[8] · 10.21±0.81[15] · 10.80[1][6][7] · 10.9[5] · 10.9±0.2[16][9] | |
Among the many thousands of named minor planets, Ingeborg is one of 120 asteroids, for which no official naming citation has been published. All of these low-numbered asteroids have numbers between 164 Eva and 1514 Ricouxa and were discovered between 1876 and the 1930s, predominantly by astronomers Auguste Charlois, Johann Palisa, Max Wolf and Karl Reinmuth.[17]
Ingeborg orbits the Sun in the inner main-belt at a distance of 1.6–3.0 AU once every 3 years and 6 months (1,291 days). Its orbit has an eccentricity of 0.31 and an inclination of 23° with respect to the ecliptic.[1] The stony S-type asteroid has a rotation period of 26.4 hours[3]
According to the surveys carried out by the Japanese Akari satellite and the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer, Ingeborg measures between 15.75 and 18.15 kilometers in diameter and its surface has an albedo between 0.282 and 0.495.[6][7][8] The Collaborative Asteroid Lightcurve Link assumes an albedo of 0.20 and calculates a diameter of 19.63 kilometers based on an absolute magnitude of 10.9.[5] Other large Mars crossing minor planets include 132 Aethra (43 km), 323 Brucia (36 km), and 2204 Lyyli (25 km).
