| Discovery[1] | |
|---|---|
| Discovered by | F. Kaiser |
| Discovery site | Heidelberg Obs. |
| Discovery date | 22 December 1913 |
| Designations | |
| (773) Irmintraud | |
| Pronunciation | German:[ˈɪʁmɪntʁaʊt] |
Named after | Irmtraud (German given-name)[2] |
| 1913 TV · 1946 SO A910 CG | |
| main-belt · (outer)[3] | |
| Orbital characteristics[1] | |
| Epoch 31 July 2016 (JD 2457600.5) | |
| Uncertainty parameter 0 | |
| Observation arc | 102.32 yr (37372 d) |
| Aphelion | 3.0876 AU (461.90 Gm) |
| Perihelion | 2.6294 AU (393.35 Gm) |
| 2.8585 AU (427.63 Gm) | |
| Eccentricity | 0.080135 |
| 4.83yr (1765.2d) | |
| 220.21° | |
| 0° 12m 14.184s / day | |
| Inclination | 16.684° |
| 322.41° | |
| 331.91° | |
| Earth MOID | 1.62349 AU (242.871 Gm) |
| Jupiter MOID | 2.21251 AU (330.987 Gm) |
| TJupiter | 3.236 |
| Physical characteristics | |
| Dimensions | 95.88 km[4] 87.07±1.76 km[5] 91.67±0.90 km[6] |
| 47.94±0.9km | |
| 6.7514 h (0.28131 d)[1][7] 6.750±0.002 h[8] 6.75 h[9] 6.746±0.004 h[9] 6.748±0.001 h[10] | |
| 0.0440[4] 0.053±0.003[5] 0.048±0.006[6] 0.0440±0.002[1] | |
| B–V = 0.706 U–B = 0.284 D(Tholen), T(SMASS)[1] T[3] | |
| 9.10[1] | |
773 Irmintraud, provisional designation 1913 TV, is a dark and reddish, rare-typeasteroid from the outer region of theasteroid belt, about 92 kilometers in diameter. It was discovered on 22 December 1913, by German astronomerFranz Kaiser atHeidelberg Observatory in southern Germany.[11]
The asteroid is classified as aD-type andT-type body in theTholen andSMASS taxonomy, respectively. The rare spectral T-type is similar to D-types which are often found amongJupiter trojans thought to have originated from theKuiper belt. It orbits the Sun at a distance of 2.6–3.1 AU once every 4 years and 10 months (1,763 days). Its orbit istilted by 17 degrees to the plane of theecliptic and shows a loweccentricity of 0.08. According to the surveys carried out by the Infrared Astronomical Satellite,IRAS, the JapaneseAkari satellite, and theWide-field Infrared Survey Explorer with its subsequentNEOWISE mission, the minor planet's lowalbedo lies in the range of 0.04–0.05.[4][5][6] It has a well-definedrotation period of 6.75 hours, determined by several concurring observations.[7][8][9][10]
773 Irmintraud commemorates the antiquated German feminine name, Irmtraud, that appears frequently in old songs andsagas.[2] The asteroid is a likely source of theTagish Lake meteorite which landed in Canada on January 18, 2000.[12]
In 1992, Larry Lebofsky and colleagues published an article in which they noted that "unaltered asteroids are thought to represent the raw materials available for terrestrial planet formation and so are important to our understanding of the origin and evolution of the Solar System."[13] Since at least 1980, it was believed that D-type asteroids were unaltered asteroids, ultraprimitive in composition and composed largely of hydratedsilicates and organic material.[13] However, in analyzing the spectra of 773 Irmintraud for the water of hydration band (the 3-μm absorption feature of hydrated silicates), Lebofsky discovered the first D-type asteroid to show the water of hydration band on the surface of the asteroid.[13] Lebofsky concluded that 773 Irmintraud had undergone an alteration process typically seen in aC-type asteroid, making 773 Irmintraud and perhaps other D-type asteroids less likely to represent the raw materials available for terrestrial planet formation.[13] In addition, the discovery of water of hydration band on 773 Irmintraud meant that there may be major differences in mineralogy within individual type classification and astronomers must be careful in assuming that the C-, D-, and other type classification relate directly to mineralogy.[13]
In 1997,NASA added 773 Irmintraud and eventually over one million other names to a microchip placed on board theStardust spacecraft that launched February 7, 1999.[14] Placing the names onto the Stardust spacecraft was a public outreach effort.[14] In particular, this served to promote public interest, awareness and support of the space program.[14]
In September 2001, there was speculation thatTagish Lake meteorite which struck inBritish Columbia,Canada on January 18, 2000, was derived from aD-type asteroid, since the spectral shape and brightness of the meteorite was similar to D-type asteroids.[12] Of the three studied, the 0.032IRASalbedos (8) of368 Haidea and the 0.033 IRAS albedos (8) of 773 Irmintraud are both considered close to the reflectance of the Tagish Lake meteorite. Moreover, even though 368 Haidea was closestspectrally to the Tagish Lake meteorite, 773 Irmintraud was no more than 0.034 AU to a chaotic zone associated with one of theKirkwood gaps due to the mean motionresonance withJupiter. This made 773 Irmintraud the closest of the three candidates to the associated chaotic zone and thus the most likely of the three as the source of the 2000 Earth impacted meteorite.[12]
The idea that humans held a piece of the asteroid 773 Irmintraud spurred others to act. In 2002, theUniversity of Tokyo performednear-infrared photometric andspectroscopic observations of 773.[15] In addition, the University obtained an accurate lightcurve in Japan throughvisible photometry and ultimately found a gap betweenK- andL-band spectra. From this, the university concluded that results support the idea that Tagish Lake meteorite has a link with D-type asteroids.[15]
On May 22, 2007, at 06:07 UT, IrmintraudoccultedTYC 4908-00263-1, a 10.7 magnitude star in the constellationSextans, for observers along a path across New Zealand.[16]
