“5 Astraea”的意思、由来-开放百科全书

Astraea was the fifth asteroid discovered, on 8 December 1845, by Karl Ludwig Hencke and named for Astræa, a goddess of justice named after the stars. It was his first of two asteroid discoveries. The second was 6 Hebe. A German amateur astronomer and post office headmaster, Hencke was looking for 4 Vesta when he stumbled on Astraea. The King of Prussia awarded him an annual pension of 1,200 marks for the discovery.^[8]

Photometry indicates prograde rotation, that the north pole points in the direction of right ascension 9 h 52 min, declination 73° with a 5° uncertainty.^[2] This gives an axial tilt of about 33°.

Astraea is physically unremarkable but notable mainly because for 38 years (after the discovery of Vesta in 1807) it had been thought that there were only four asteroids.^[9] With an apparent magnitude of 8.7 (on a favorable opposition on 15 February 2016), it is indeed only the seventeenth-brightest main-belt asteroid, and fainter than, for example, 192 Nausikaa or even 324 Bamberga (at rare near-perihelion oppositions).

After the discovery of Astraea, thousands of other asteroids would follow. Indeed, the discovery of Astraea proved to be the starting point for the eventual demotion of the four original asteroids (which were regarded as planets at the time)^[9] to their current status, as it became apparent that these four were only the largest of a whole new type of celestial body.

An occultation on 6 June 2008 produced an effective diameter (silhouette) of {{nowrap|115 ± 6 km}}.^[10]

Astraea has been studied by radar.^[11] Arecibo observed Astraea in March 2012.^[12]^[13]

See also

References

1. ^{{cite web|title=AstDyS-2 Astraea Synthetic Proper Orbital Elements|publisher=Department of Mathematics, University of Pisa, Italy|url=http://hamilton.dm.unipi.it/astdys/index.php?pc=1.1.6&n=5|accessdate=2011-10-01}}
2. ^¹²³M. J. López-Gonzáles & E. Rodríguez Lightcurves and poles of seven asteroids, Planetary and Space Science, Vol. 53, p. 1147 (2005).
3. ^¹²Calculated based on the known parameters
4. ^{{Cite journal|last=Michalak|first=G.|title=Determination of asteroid masses|journal=Astronomy & Astrophysics|volume=374|pages=703–711|date=2001|doi=10.1051/0004-6361:20010731|url=https://www.aanda.org/articles/aa/full/2001/29/aa10228/aa10228.html|accessdate=2008-11-10|bibcode=2001A&A...374..703M|issue=2}}
5. ^(Mass estimate of Astra 0.015 / Mass of Ceres 4.75) * Mass of Ceres 9.43E+20 = 2.977E+18
6. ^Michalak2001 (Table 6) assumed masses of perturbing asteroids used in calculations of perturbations of the test asteroids.
7. ^{{Cite web |url=http://sbn.psi.edu/pds/asteroid/IRAS_A_FPA_3_RDR_IMPS_V6_0/data/diamalb.tab |title=Supplemental IRAS Minor Planet Survey |access-date=12 July 2016 |archive-url=https://web.archive.org/web/20160603231123/http://sbn.psi.edu/pds/asteroid/IRAS_A_FPA_3_RDR_IMPS_V6_0/data/diamalb.tab |archive-date=3 June 2016 |dead-url=yes |df=dmy-all }}
8. ^{{Cite web | title = Dawn Community | publisher = NASA | url = http://dawn.jpl.nasa.gov/DawnCommunity/flashbacks/fb_09.asp | accessdate = 2009-04-17 | archiveurl = https://web.archive.org/web/20090521235728/http://dawn.jpl.nasa.gov/DawnCommunity/flashbacks/fb_09.asp | archivedate = 21 May 2009 | deadurl = yes | df = }}
9. ^¹{{Cite web|title=The Planet Hygea|date=1849|work=spaceweather.com|url=http://spaceweather.com/swpod2006/13sep06/Pollock1.jpg|accessdate=2008-04-18| archiveurl= https://web.archive.org/web/20080409071528/http://spaceweather.com/swpod2006/13sep06/Pollock1.jpg| archivedate= 9 April 2008 | deadurl= no}}
10. ^{{cite journal |display-authors=6 |last=Ďurech |first=Josef |author2=Kaasalainen, Mikko |author3=Herald, David |author4=Dunham, David |author5=Timerson, Brad |author6=Hanuš, Josef |author7=Frappa, Eric |author8=Talbot, John |author9=Hayamizu, Tsutomu |author10=Warner, Brian D. |author11=Pilcher, Frederick |author12=Galád, Adrián |title=Combining asteroid models derived by lightcurve inversion with asteroidal occultation silhouettes |journal=Icarus |volume=214 |issue=2 |pages=652–670 |date=2011 |url=http://astro.troja.mff.cuni.cz/projects/asteroids3D/download/durech_et_al_2011_occ_paper.pdf |doi=10.1016/j.icarus.2011.03.016 |arxiv=1104.4227 |bibcode=2011Icar..214..652D}}
11. ^{{cite web |title=Radar-Detected Asteroids and Comets |publisher=NASA/JPL Asteroid Radar Research |url=http://echo.jpl.nasa.gov/asteroids/ |accessdate=2012-01-23}}
12. ^{{cite web |date=2012-01-18 |title=Scheduled Arecibo Radar Asteroid Observations |publisher=Planetary Radar at Arecibo Observatory |author=Mike Nolan |url=http://www.naic.edu/~pradar/sched.shtml |accessdate=2012-01-23}}
13. ^{{Cite web | url=http://www.naic.edu/~pradar/ | title=Planetary Radar Science Group}}
14. ^¹{{cite book |title = Dictionary of Minor Planet Names – (5) Astraea |last = Schmadel | first = Lutz D. |publisher = Springer Berlin Heidelberg |page = 15 |date = 2007 |isbn = 978-3-540-00238-3 |doi = 10.1007/978-3-540-29925-7_6 |chapter = (5) Astraea }}
15. ^¹²{{cite web |title = 5 Astraea |work = Minor Planet Center |url = https://www.minorplanetcenter.net/db_search/show_object?object_id=5 |accessdate = 1 June 2018}}
16. ^¹{{cite web |title = Asteroid (5) Astraea – Proper Elements |publisher = AstDyS-2, Asteroids – Dynamic Site |url = http://hamilton.dm.unipi.it/astdys/index.php?n=5&pc=1.1.6 |accessdate = 25 May 2018}}

词条	5 Astraea
释义	See also References External links {{about\|the asteroid\|\|Astraea (disambiguation)}}{{Infobox planet \| minorplanet = yes \| name = 5 Astraea \| symbol = \| background = #D6D6D6 \| image = 5Astraea (Lightcurve Inversion).png \| image_size = 265 \| caption = Lightcurve-based 3D-model of Astraea \| discovery_ref = ^[1] \| discoverer = K. L. Hencke \| discovery_site = Driesen Obs. \| discovered = 8 December 1845 \| mpc_name = (5) Astraea \| alt_names = 1969 SE \| pronounced = {{IPAc-en\|ae\|ˈ\|s\|t\|r\|iː\|ə}} {{respell\|a\|STREE\|ə}} \| adjectives = Astraean \| named_after = Astraea {{small\|(Greek goddess)}}^[2] \| mp_category = main-belt ^[1]{{·}}{{small\|(middle)}} Astraea ^[5] \| orbit_ref = \| epoch = 23 March 2018 (JD 2458200.5) \| uncertainty = 0 \| observation_arc = 171.93 yr (62,799 d) \| aphelion = 3.0659 AU \| perihelion = 2.0810 AU \| semimajor = 2.5735 AU \| eccentricity = 0.1914 \| period = 4.13 yr (1,508 d) \| mean_anomaly = 186.83° \| mean_motion = {{Deg2DMS\|0.2387\|sup=ms}} / day \| inclination = 5.3677° \| asc_node = 141.58° \| arg_peri = 358.75° \| p_orbit_ref = ^[1] \| p_semimajor = 2.5761849 \| p_eccentricity = 0.1980486 \| p_inclination = 4.5118628° \| p_mean_motion = 87.046396 \| perihelion_rate = 52.210903 \| node_rate = −57.357951 \| dimensions={{val\|167\|×\|123\|×\|82\|ul=km}}^[2] \| mean_diameter= 119 km^[2] \| surface_area=48 300 km²^[3] \| volume=882 000 km³^[3] \| mass=2.9{{e\|18}} kg^[4]^[5] (assumed)^[6] \| density=~3.3 g/cm³ \| rotation=0.700 03 d (16.801 h)^[2] \| rot_velocity=6.44 m/s^[3] \| spectral_type=S \| magnitude = 8.74 to 12.89 \| abs_magnitude=6.85 \| albedo=0.227^[7] \| angular_size = 0.15" to 0.041" }}Astraea (minor planet designation: 5 Astraea) is a large asteroid from the asteroid belt. Its surface is highly reflective (bright) and its composition is probably a mixture of nickel–iron with silicates of magnesium and iron. It is a S-type object in the Tholen classification system. Astraea was the fifth asteroid discovered, on 8 December 1845, by Karl Ludwig Hencke and named for Astræa, a goddess of justice named after the stars. It was his first of two asteroid discoveries. The second was 6 Hebe. A German amateur astronomer and post office headmaster, Hencke was looking for 4 Vesta when he stumbled on Astraea. The King of Prussia awarded him an annual pension of 1,200 marks for the discovery.^[8] Photometry indicates prograde rotation, that the north pole points in the direction of right ascension 9 h 52 min, declination 73° with a 5° uncertainty.^[2] This gives an axial tilt of about 33°. Astraea is physically unremarkable but notable mainly because for 38 years (after the discovery of Vesta in 1807) it had been thought that there were only four asteroids.^[9] With an apparent magnitude of 8.7 (on a favorable opposition on 15 February 2016), it is indeed only the seventeenth-brightest main-belt asteroid, and fainter than, for example, 192 Nausikaa or even 324 Bamberga (at rare near-perihelion oppositions). After the discovery of Astraea, thousands of other asteroids would follow. Indeed, the discovery of Astraea proved to be the starting point for the eventual demotion of the four original asteroids (which were regarded as planets at the time)^[9] to their current status, as it became apparent that these four were only the largest of a whole new type of celestial body. An occultation on 6 June 2008 produced an effective diameter (silhouette) of {{nowrap\|115 ± 6 km}}.^[10] Astraea has been studied by radar.^[11] Arecibo observed Astraea in March 2012.^[12]^[13] {{multiple image \|direction = horizontal \|align= left \|width1= 320 \|width2= 180 \|image1=Moon and Asteroids 1 to 10.svg \|image2=AstraeaOrbit.png \|footer= Left: A size comparison of the first 10 numbered asteroids profiled against Earth's Moon. Right: The orbit of 5 Astraea in white compared with those of Earth, Mars and Jupiter. }}{{clear\|left}} See also Former classification of planets References 1. ^{{cite web\|title=AstDyS-2 Astraea Synthetic Proper Orbital Elements\|publisher=Department of Mathematics, University of Pisa, Italy\|url=http://hamilton.dm.unipi.it/astdys/index.php?pc=1.1.6&n=5\|accessdate=2011-10-01}} 2. ^¹²³M. J. López-Gonzáles & E. Rodríguez Lightcurves and poles of seven asteroids, Planetary and Space Science, Vol. 53, p. 1147 (2005). 3. ^¹²Calculated based on the known parameters 4. ^{{Cite journal\|last=Michalak\|first=G.\|title=Determination of asteroid masses\|journal=Astronomy & Astrophysics\|volume=374\|pages=703–711\|date=2001\|doi=10.1051/0004-6361:20010731\|url=https://www.aanda.org/articles/aa/full/2001/29/aa10228/aa10228.html\|accessdate=2008-11-10\|bibcode=2001A&A...374..703M\|issue=2}} 5. ^(Mass estimate of Astra 0.015 / Mass of Ceres 4.75) * Mass of Ceres 9.43E+20 = 2.977E+18 6. ^Michalak2001 (Table 6) assumed masses of perturbing asteroids used in calculations of perturbations of the test asteroids. 7. ^{{Cite web \|url=http://sbn.psi.edu/pds/asteroid/IRAS_A_FPA_3_RDR_IMPS_V6_0/data/diamalb.tab \|title=Supplemental IRAS Minor Planet Survey \|access-date=12 July 2016 \|archive-url=https://web.archive.org/web/20160603231123/http://sbn.psi.edu/pds/asteroid/IRAS_A_FPA_3_RDR_IMPS_V6_0/data/diamalb.tab \|archive-date=3 June 2016 \|dead-url=yes \|df=dmy-all }} 8. ^{{Cite web \| title = Dawn Community \| publisher = NASA \| url = http://dawn.jpl.nasa.gov/DawnCommunity/flashbacks/fb_09.asp \| accessdate = 2009-04-17 \| archiveurl = https://web.archive.org/web/20090521235728/http://dawn.jpl.nasa.gov/DawnCommunity/flashbacks/fb_09.asp \| archivedate = 21 May 2009 \| deadurl = yes \| df = }} 9. ^¹{{Cite web\|title=The Planet Hygea\|date=1849\|work=spaceweather.com\|url=http://spaceweather.com/swpod2006/13sep06/Pollock1.jpg\|accessdate=2008-04-18\| archiveurl= https://web.archive.org/web/20080409071528/http://spaceweather.com/swpod2006/13sep06/Pollock1.jpg\| archivedate= 9 April 2008 \| deadurl= no}} 10. ^{{cite journal \|display-authors=6 \|last=Ďurech \|first=Josef \|author2=Kaasalainen, Mikko \|author3=Herald, David \|author4=Dunham, David \|author5=Timerson, Brad \|author6=Hanuš, Josef \|author7=Frappa, Eric \|author8=Talbot, John \|author9=Hayamizu, Tsutomu \|author10=Warner, Brian D. \|author11=Pilcher, Frederick \|author12=Galád, Adrián \|title=Combining asteroid models derived by lightcurve inversion with asteroidal occultation silhouettes \|journal=Icarus \|volume=214 \|issue=2 \|pages=652–670 \|date=2011 \|url=http://astro.troja.mff.cuni.cz/projects/asteroids3D/download/durech_et_al_2011_occ_paper.pdf \|doi=10.1016/j.icarus.2011.03.016 \|arxiv=1104.4227 \|bibcode=2011Icar..214..652D}} 11. ^{{cite web \|title=Radar-Detected Asteroids and Comets \|publisher=NASA/JPL Asteroid Radar Research \|url=http://echo.jpl.nasa.gov/asteroids/ \|accessdate=2012-01-23}} 12. ^{{cite web \|date=2012-01-18 \|title=Scheduled Arecibo Radar Asteroid Observations \|publisher=Planetary Radar at Arecibo Observatory \|author=Mike Nolan \|url=http://www.naic.edu/~pradar/sched.shtml \|accessdate=2012-01-23}} 13. ^{{Cite web \| url=http://www.naic.edu/~pradar/ \| title=Planetary Radar Science Group}} 14. ^¹{{cite book \|title = Dictionary of Minor Planet Names – (5) Astraea \|last = Schmadel \| first = Lutz D. \|publisher = Springer Berlin Heidelberg \|page = 15 \|date = 2007 \|isbn = 978-3-540-00238-3 \|doi = 10.1007/978-3-540-29925-7_6 \|chapter = (5) Astraea }} 15. ^¹²{{cite web \|title = 5 Astraea \|work = Minor Planet Center \|url = https://www.minorplanetcenter.net/db_search/show_object?object_id=5 \|accessdate = 1 June 2018}} 16. ^¹{{cite web \|title = Asteroid (5) Astraea – Proper Elements \|publisher = AstDyS-2, Asteroids – Dynamic Site \|url = http://hamilton.dm.unipi.it/astdys/index.php?n=5&pc=1.1.6 \|accessdate = 25 May 2018}} ^[14]^[15]^[16] }} External links 2 Telescope images of 5 Astraea MNRAS 7 (1846) 27 [https://sbntools.psi.edu/ferret/SimpleSearch/results.action?targetName=5+Astraea Physical characteristics of (5) Astraea] at the Small Bodies Data Ferret Discovery Circumstances: Numbered Minor Planets (1)-(5000) – Minor Planet Center [https://books.google.com/books?id=aeAg1X7afOoC&pg Dictionary of Minor Planet Names], Google books {{AstDys\|5}} {{JPL small body}} {{Use dmy dates\|date=June 2018}}{{Minor planets navigator \|4 Vesta \|number=5 \|6 Hebe}}{{Small Solar System bodies}}{{Authority control}}{{DEFAULTSORT:000005}} 7 : Astraea asteroids\|Discoveries by Karl Hencke\|Minor planets named from Greek mythology\|Named minor planets\|S-type asteroids (SMASS)\|S-type asteroids (Tholen)\|Astronomical objects discovered in 1845
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See also

References

External links