| 词条 | 121 Hermione |
| 释义 |
| minorplanet = yes | name = 121 Hermione | background = #D6D6D6 | image = 121Hermione (Lightcurve Inversion).png | image_size = 265 | caption = Lightcurve-based 3D-model of Hermione | discovery_ref = [1] | discoverer=James Craig Watson | discovered=12 May 1872 | mpc_name = (121) Hermione | alt_names = {{mp|1970 VE}} | pronounced = {{IPAc-en|h|ɜːr|ˈ|m|aɪ|.|ə|n|i}} {{Respell|hur|MY|ə-nee}} | named_after = Hermione [2] {{small|(Greek mythology)}} | mp_category=main-belt{{·}}Cybele | orbit_ref = | epoch = 23 March 2018 (JD 2458200.5) | uncertainty = 0 | observation_arc = 145.96 yr (53,312 d) | aphelion = 3.9067 AU | perihelion = 2.9889 AU | semimajor = 3.4478 AU | eccentricity = 0.1331 | period = 6.40 yr (2,338 d) | mean_anomaly = 157.08° | mean_motion = {{Deg2DMS|0.1540|sup=ms}} / day | inclination = 7.5975° | asc_node = 73.127° | arg_peri = 298.18° | satellites = S/2002 (121) 1 | dimensions=268×186×183 km[1] 254±4 × 125±9 km[2] | mean_radius = 95 km[2] | mass=5.38 ± 0.3 {{e|18}} kg[1] 5.4 ± 0.3{{e|18}} kg[3] | density=1.13 ± 0.3 g/cm³[1] 1.8 ± 0.2 g/cm³[3][4] | surface_grav=0.022 m/s²[5] | escape_velocity=0.075 km/s[5] | sidereal_day =0.2313 d (5.551 h)[6] | axial_tilt = 73° | pole_ecliptic_lat = +10 ± 2°[3] | pole_ecliptic_lon = 1.5 ± 2° | albedo = 0.0482 ± 0.002[7] | spectral_type = C [8] | abs_magnitude = 7.31[7] }}Hermione (minor planet designation: 121 Hermione) is a very large binary asteroid discovered in 1872. It orbits in the Cybele group in the far outer asteroid belt.[19] As an asteroid of the dark C spectral type, it is probably composed of carbonaceous materials. In 2002, a small moon was found to be orbiting Hermione.[9] DiscoveryHermione was discovered by J. C. Watson on 12 May 1872 from Ann Arbor, Michigan, in the United States,[9] and named after Hermione, daughter of Menelaus and Helen in Greek mythology.[2] Physical propertiesThe asteroid has a bi-lobed shape, as evidenced by adaptive optics images, the first of which were taken in December 2003 with the Keck telescope.[2] Of several proposed shape models that agreed with the images, a "snowman"-like shape was found to best fit the observed precession rate of Hermione's satellite.[3] In this "snowman" model, the asteroid's shape can be approximated by two partially overlapping spheres of radii 80 and 60 km, whose centers are separated by a distance of 115 km. A simple ellipsoid shape was ruled out. Observation of the satellite's orbit has made possible an accurate determination of Hermione's mass.[3] For the best-fit "snowman" model, the density is found to be 1.8 ± 0.2 g/cm³, giving a porosity on the order of 20%, and possibly indicating that the main components are fractured solid bodies, rather than the asteroid being a rubble pile. Occultations by Hermione have been successfully observed three times so far, the last time in February 2004. {{Infobox planet| name=S/2002 (121) 1 | bgcolour=#A0FFA0 | minorplanet=yes | discovery_ref = [10] | discoverer=W. J. Merline, P. M. Tamblyn, C. Dumas, L. M. Close, C. R. Chapman, F. Menard, W. M. Owen, and D. C. Slater | discovered=2002-09-28 | alt_names =LaFayette | mp_category=main-belt{{·}}Cybele | orbit_ref=[11] | semimajor= 768 ± 11 km | eccentricity= 0.001 ± 0.001 | period=2.582 ± 0.002 d | satellite_of = 121 Hermione | inclination = 3 ± 2° {{small|(with respect to Hermione pole)}} | dimensions= 12 ± 4 km[2] | mass = ~1.6{{e|15}} kg[12] | abs_magnitude=13.0[2] }} MoonA satellite of Hermione was discovered in 2002 with the Keck II telescope.[9] It is about 8 miles (13 km) in diameter.[9] The satellite is provisionally designated S/2002 (121) 1. It has not yet been officially named, but "LaFayette" has been proposed by a group of astronomers in reference to the frigate used in secret by the Marquis de Lafayette to reach America to help the insurgents.{{Citation needed|date=January 2012}} References1. ^1 2 {{cite web |date=2008 |title=Recent Asteroid Mass Determinations |publisher=Personal Website |author=Jim Baer |url=http://home.earthlink.net/~jimbaer1/astmass.txt |accessdate=2008-12-07}} [13][14]2. ^1 2 3 4 {{cite journal|author=F. Marchis|title=Shape, size and multiplicity of main-belt asteroids I. Keck Adaptive Optics survey|journal=Icarus|volume=185|pages=39–63|date=2006|doi=10.1016/j.icarus.2006.06.001|pmid=19081813|issue=1|pmc=2600456|bibcode=2006Icar..185...39M|display-authors=etal}} 3. ^1 2 3 4 {{cite journal|author=F. Marchis|title=Mass and density of Asteroid 121 Hermione from an analysis of its companion orbit|journal=Icarus|volume=178|pages=450–464|date=2005|doi=10.1016/j.icarus.2005.05.003|bibcode=2005Icar..178..450M|issue=2|display-authors=etal}} 4. ^Using the "snowman" shape model, which best matches the value of J2 implied from precession. 5. ^1 On the extremities of the long axis. 6. ^IAUC 8264 {{Webarchive|url=https://web.archive.org/web/20080709060512/http://cfa-www.harvard.edu/iauc/08200/08264.html#Item1#Item1 |date=9 July 2008 }} 7. ^1 Supplemental IRAS minor planet survey {{webarchive |url=https://www.webcitation.org/5mqp8r4gD?url=http://www.psi.edu/pds/resource/imps.html |date=2010-01-17 }} 8. ^PDS node taxonomy database {{webarchive |url=https://www.webcitation.org/5mpuUMP1Q?url=http://www.psi.edu/pds/resource/taxonomy.html |date=2010-01-17 }} 9. ^1 2 3 4 {{cite book|author=Linda T. Elkins-Tanton|title=Asteroids, Meteorites, and Comets|url=https://books.google.com/books?id=K-0xBsMsursC&pg=PA96|year=2010|publisher=Infobase Publishing|isbn=978-1-4381-3186-3|page=96}} 10. ^IAUC 7980 {{webarchive|url=https://web.archive.org/web/20060501175811/http://cfa-www.harvard.edu/iauc/07900/07980.html |date=2006-05-01 }} 11. ^121 Hermione and S/2002 (121) 1, orbit data website maintained by F. Marchis. 12. ^Assuming a similar density to the primary. 13. ^1 2 {{cite book |title = Dictionary of Minor Planet Names – (121) Hermione |last = Schmadel | first = Lutz D. |publisher = Springer Berlin Heidelberg |page = 26 |date = 2007 |isbn = 978-3-540-00238-3 |doi = 10.1007/978-3-540-29925-7_122 |chapter = (121) Hermione }} 14. ^1 {{cite web |title = 121 Hermione |work = Minor Planet Center |url = https://www.minorplanetcenter.net/db_search/show_object?object_id=121 |accessdate = 14 September 2018}} }} External links
9 : Cybele asteroids|Discoveries by James Watson|Minor planets named from Greek mythology|Named minor planets|Binary asteroids|Objects observed by stellar occultation|C-type asteroids (Tholen)|Ch-type asteroids (SMASS)|Astronomical objects discovered in 1872 |
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