Editing 308 Polyxo

{{Short description|Main-belt asteroid}}
{{Use dmy dates|date=October 2024}}
{{Infobox planet
 | minorplanet     = yes
 | background      = #D6D6D6
 | name            = 308 Polyxo
 | discoverer      = [[Alphonse Borrelly]]
 | discovered      = 31 March 1891
 | mpc_name        = (308) Polyxo
   |image= 308 Polyxo Orbit Diagram.png
|caption=Orbital diagram
| pronounced      = {{IPAc-en|p|ə|'|l|ɪ|k|s|oʊ}}<ref name=Webster1884/>
 | alt_names       = 
 | named_after     = [[Polyxo|Πολυξώ]] ''Polyxō''
 | adjective       = Polyxoian {{IPAc-en|p|ɒ|l|ᵻ|k|'|s|oʊ|i|ə|n}}
 | mp_category     = [[Asteroid belt|Main belt]]
 | epoch           = 31 July 2016 ([[Julian day|JD]] 2457600.5)
 | semimajor       = {{cvt|2.74975|AU|Gm|1|adj=ri3}}
 | perihelion      = {{cvt|2.63975|AU|Gm|1|adj=ri3}}
 | aphelion        = {{cvt|2.85974|AU|Gm|1|adj=ri3|lk=on}}
 | eccentricity    = 0.040003
 | period          = {{cvt|1665.5|days|years|2|order=flip}}
 | inclination     = 4.36141°
 | asc_node        = 181.727°
 | arg_peri        = 115.501°
 | mean_anomaly    = 70.4189°
 | dimensions      = {{val|140.69|3.8|ul=km}}<ref name="jpldata"/><br />{{val|130|u=km}}<ref name="Marchis2006"/>
 | mass            = 
 | density         = 
 | rotation        = {{Convert|12.031|±|0.009|h|d|abbr=on|lk=on}}<ref name=Dotto_et_al_2004/>
 | spectral_type   = [[T-type asteroid|T]]<ref name=Dotto_et_al_2004/> (Tholen)
 | abs_magnitude   = 8.17
 | albedo          = {{val|0.043|0.002}}<ref name=Dotto_et_al_2002/>
 | mean_motion     = {{Deg2DMS|0.216155|sup=ms}} / day
 | orbit_ref       = <ref name="jpldata"/>
 | observation_arc = {{cvt|45521|days|years|order=flip}}
 | uncertainty     = 0
}}

'''308 Polyxo''' is a [[Asteroid belt|main-belt]] [[asteroid]] that was discovered by [[Alphonse Borrelly]] on 31 March 1891, in [[Marseille]]. It is orbiting the [[Sun]] at a distance of {{val|2.75|ul=AU}} with a low [[orbital eccentricity]] (ovalness) of 0.04 and a [[orbital period|period]] of {{cvt|1665.5|days|years|2|disp=out}}. The [[orbital plane]] is tilted at an angle of 4.36° to the [[plane of the ecliptic]].<ref name="jpldata"/>

308 Polyxo is classified as a rare [[T-type asteroid]], with a spectrum that bears some similarity to the [[Tagish Lake (meteorite)|Tagish Lake meteorite]].<ref name=Hiroi_Hasegawa_2003/> A spectral feature at a wavelength of {{val|3.0|u=micrometre}} suggests aqueous alteration of some surface materials.<ref name=Dotto_et_al_2004/> [[Photometry (astronomy)|Photometric]] measurements reported in 1983 give a [[rotation period]] of 12.03 hours and a brightness variation of 0.20 in [[Magnitude (astronomy)|magnitude]]. The [[adaptive optics]] instrument at the [[W. M. Keck Observatory]] shows an oblate object with a diameter of 130&nbsp;km. The size ratio between the major and minor axes is 1.26 ± 0.11.<ref name="Marchis2006"/> [[Light curve]]s for this object suggests it has a very irregular shape.<ref name=Dotto_et_al_2004/>

[[Stellar occultation]] events were observed for this asteroid during 2000 and 2004. The resulting [[Chord (astronomy)|chords]] provided cross-section diameter estimates of 144.4 and 117.1&nbsp;km, respectively.<ref name=Shevchenko_Tedesco_2006/>

==References==
{{Reflist|refs=

<ref name=Webster1884>{{citation
 | first=Noah | last=Webster | date=1884
 | title=A Practical Dictionary of the English Language }}</ref>

<ref name="jpldata">{{Cite web
 | url=https://ssd.jpl.nasa.gov/sbdb.cgi?sstr=308;cad=1
 | title=308 Polyxo
 | work=[[JPL Small-Body Database]]
 | publisher=[[NASA]]/[[Jet Propulsion Laboratory]]
 | access-date=11 May 2016 }}</ref>

<ref name=Hiroi_Hasegawa_2003>{{Citation
 | title=Revisiting the search for the parent body of the Tagish Lake meteorite - Case of a T/D asteroid 308 Polyxo
 | last1=Hiroi | first1=Takahiro | last2=Hasegawa | first2=Sunao
 | journal=Antarctic Meteorite Research | postscript=.
 | volume=16 | pages=176–184 | date=March 2003
 | bibcode=2003AMR....16..176H }}</ref>

<ref name=Dotto_et_al_2004>{{Citation
 | title=308 Polyxo: ISO-SWS spectrum up to 26 micron
 | display-authors=1 | last1=Dotto | first1=E.
 | last2=Barucci | first2=M. A. | last3=Brucato | first3=J. R.
 | last4=Müller | first4=T. G. | last5=Carvano | first5=J.
 | journal=Astronomy and Astrophysics | postscript=.
 | volume=427 | pages=1081–1084 | date=December 2004
 | doi=10.1051/0004-6361:20041638 | bibcode=2004A&A...427.1081D | doi-access=free }}</ref>

<ref name=Dotto_et_al_2002>{{citation
 | title=ISO observations of low and moderate albedo asteroids. PHT-P and PHT-S results
 | display-authors=1 | last1=Dotto | first1=E.
 | last2=Barucci | first2=M. A. | last3=Müller | first3=T. G.
 | last4=Brucato | first4=J. R. | last5=Fulchignoni | first5=M.
 | last6=Mennella | first6=V. | last7=Colangeli | first7=L.
 | journal=Astronomy and Astrophysics | postscript=.
 | volume=393 | pages=1065–1072 | date=October 2002
 | doi=10.1051/0004-6361:20021190 | bibcode=2002A&A...393.1065D | doi-access=free }}</ref>

<ref name="Marchis2006">{{Citation
 | title=Shape, size and multiplicity of main-belt asteroids. I. Keck Adaptive Optics survey
 | first1=F. | last1=Marchis | first2=M. | last2=Kaasalainen
 | first3=E. F. Y. | last3=Hom | first4=J. | last4=Berthier
 | first5=J. | last5=Enriquez | first6=D. | last6=Hestroffer
 | first7=D. | last7=Le Mignant | first8=I. | last8=de Pater
 | display-authors=1 | work=Icarus
 | volume=185 | issue=1 | pages=39–63 | date=November 2006
 | bibcode=2006Icar..185...39M | pmid=19081813
 | doi=10.1016/j.icarus.2006.06.001 | pmc=2600456
 | postscript=. }}</ref>

<ref name=Shevchenko_Tedesco_2006>{{citation
 | title=Asteroid albedos deduced from stellar occultations
 | last1=Shevchenko | first1=Vasilij G. | last2=Tedesco | first2=Edward F.
 | journal=Icarus | postscript=.
 | volume=184 | issue=1 | pages=211–220 | date=September 2006
 | doi=10.1016/j.icarus.2006.04.006 | bibcode=2006Icar..184..211S }}</ref>

}} <!-- end of reflist -->

== External links ==
* {{AstDys|308}}
* {{JPL small body}}

{{Minor planets navigator |307 Nike |number=308 |309 Fraternitas}}
{{Small Solar System bodies}}
{{Authority control}}

{{DEFAULTSORT:Polyxo}}
[[Category:Background asteroids|000308]]
[[Category:Discoveries by Alphonse Borrelly]]
[[Category:Named minor planets]]
[[Category:T-type asteroids (Tholen)|000308]]
[[Category:T-type asteroids (SMASS)|000308]]
[[Category:Astronomical objects discovered in 1891|18910331]]