_imaging_of_Asteroid_118401_(geminiann06008a).jpg) | |
| Discovery | |
|---|---|
| Discovered by | LINEAR |
| Discovery date | 7 September 1999 |
| Designations | |
| (118401) LINEAR | |
Named after | LINEAR |
| 176P/LINEAR · 1999 RE70 | |
| main-belt[1] · Themis MBC[2][3] | |
| Orbital characteristics[1] | |
| Epoch 13 January 2016 (JD 2457400.5) T_jup = 3.166 | |
| Uncertainty parameter 0 | |
| Observation arc | 5808 days (15.90 yr) |
| Aphelion | 3.8110 AU (570.12 Gm) |
| Perihelion | 2.5793 AU (385.86 Gm) |
| 3.1951 AU (477.98 Gm) | |
| Eccentricity | 0.19276 |
| 5.71yr (2086.1d) | |
Averageorbital speed | 16.51 km/s |
| 286.74° | |
| 0.17257°/day | |
| Inclination | 0.23477° |
| 345.96° | |
| 35.460° | |
| Earth MOID | 1.58057 AU (236.450 Gm) |
| Jupiter MOID | 1.6475 AU (246.46 Gm) |
| Physical characteristics | |
| Dimensions | 4.0±0.4 km (Spitzer)[4] |
| Mass | 4.3×1013? kg[5] |
Meandensity | 1.3? g/cm3 (assumed) |
Equatorialsurface gravity | <0.0017 m/s2 |
Equatorialescape velocity | <0.0032 km/s |
| ? d | |
| 0.06±0.02R[4] | |
| Temperature | ~156K |
| ? | |
| 18.19 to 21.91 | |
| 15.1[1] | |
| Discovery | |
|---|---|
| Discovered by | LINEAR |
| Discovery date | October 18, 2005 |
| Designations | |
| P/1999 RE70 | |
| Orbital characteristics | |
| Epoch | November 6, 2005 (JD 2453680.5) |
| Aphelion | 3.811678 AU |
| Perihelion | 2.5811186 AU |
| Semi-major axis | 3.19640AU |
| Eccentricity | 0.1924908 |
| Orbital period | 5.714a |
| Inclination | 0.23795° |
| Last perihelion | November 21, 2022[6] 2017 March 12[6] June 30, 2011[7] October 18, 2005 |
| Next perihelion | 2028-Aug-05[8] |
118401 LINEAR (provisional designation1999 RE70, comet designation176P/LINEAR) is anactive asteroid andmain-belt comet[2][3] that was discovered by theLincoln Near-Earth Asteroid Research (LINEAR) 1-metre telescopes inSocorro, New Mexico on September 7, 1999. (118401) LINEAR was discovered to becometary on November 26, 2005, byHenry H. Hsieh andDavid C. Jewitt as part of theHawaii Trails project using theGemini North 8-m telescope onMauna Kea and was confirmed by theUniversity of Hawaii's 2.2-m (88-in) telescope on December 24–27, 2005, and Gemini on December 29, 2005. Observations using theSpitzer Space Telescope have resulted in an estimate of 4.0±0.4 km for the diameter of (118401) LINEAR.[4]
The main-belt comets are unique in that they have flat (within the plane of the planets' orbits), approximately circular (smalleccentricity),asteroid-likeorbits, and not the elongated, often tilted orbits characteristic of all other comets. Because (118401) LINEAR can generate acoma (produced by vapour boiled off the comet), it must be an icy asteroid. When a typical comet approaches theSun, itsice heats up andsublimates (changes directly from ice togas), venting gas anddust intospace, creating a tail and giving the object a fuzzy appearance. Far from the Sun, sublimation stops, and the remaining ice stays frozen until the comet's next pass close to the Sun. In contrast, objects in the asteroid belt have essentially circular orbits and are expected to be mostly baked dry of ice by their confinement to the inner Solar System (seeextinct comet).
It is suggested that these main-belt asteroid-comets are evidence of a recent impact exposing an icy interior to solar radiation.[2] It is estimated short-period comets remain active for about 10,000 years before having most of their ice sublimated away and going dormant.
Eight other objects are classified as both periodic comets and numbered asteroids:2060 Chiron (95P/Chiron),4015 Wilson–Harrington (107P/Wilson–Harrington),7968 Elst–Pizarro (133P/Elst–Pizarro),60558 Echeclus (174P/Echeclus),(323137) 2003 BM80 (282P/2003 BM80),(300163) 2006 VW139 (288P/2006 VW139),(457175) 2008 GO98 (362P/2008 GO98),[9] and(248370) 2005 QN173 (433P/2005 QN173).[10] As a dual-status object,astrometric observations of 118401 LINEAR should be reported under theminor planet designation.[9]
118401 LINEAR last came toperihelion on 2017 March 12.[6]
| Numbered comets | ||
|---|---|---|
| Previous 175P/Hergenrother | 176P/LINEAR | Next 177P/Barnard |
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