Introduction to angular momentum

2013-10-28T18:15:39Z

134.139.29.189:

{{Starbox begin
| name=Beta Pyxidis
}}
{{Starbox image
| image =
<div style="position: relative">[[File:Pyxis IAU.svg|250px|alt=Diagram showing star positions and boundaries of the Pyxis constellation and its surroundings]]
<div style="position: absolute; left: 137px; top: 145px">[[File:Cercle rouge 100%.svg|12px]]</div>
</div>
| caption=Location of β Pyxidis (circled)
}}
{{Starbox observe
| epoch = J2000
| ra = {{RA|08|40|06.14363}}<ref name=aaa474_2_653/>
| dec = {{DEC|–35|18|30.0}}<ref name=aaa474_2_653/>
| appmag_v = 3.954<ref name="gutierrez"/>
| constell = [[Pyxis]]
}}
{{Starbox character
| class = G7Ib-II<ref name="SIMBAD"/>
| b-v = +0.935<ref name="gutierrez"/>
| u-b = +0.646<ref name="gutierrez"/>
| variable =
}}
{{Starbox astrometry
| radial_v = –13.4<ref name=rgcrv/>
| prop_mo_ra = +9.84<ref name=aaa474_2_653/>
| prop_mo_dec = –20.80<ref name=aaa474_2_653/>
| parallax = 7.84
| p_error = 0.19
| parallax_footnote = <ref name=aaa474_2_653/>
| absmag_v = –0.78<ref name="apj107"/>
}}
{{Starbox detail
| age =
| metal_fe =
| mass =
| radius = 28<ref name=lang2006/>
| rotational_velocity =
| luminosity =
| temperature = 5,400<ref name=apj507_2_919/>
| gravity =
}}
{{Starbox catalog
| names=β Pyxidis, β Pyx, Beta Pyx, [[Durchmusterung|CPD]]−34  2846, [[Fifth Fundamental Catalogue|FK5]] 2681, [[Henry Draper catalogue|HD]] 74006, [[Hipparcos catalogue|HIP]] 42515, [[Bright Star Catalogue|HR]] 3438, [[Smithsonian Astrophysical Observatory|SAO]] 199490, [[Washington Double Star Catalog|WDS]] J08401-3518A<ref name="SIMBAD"/>
}}
{{Starbox end}}

'''Beta Pyxidis''' ('''Beta Pyx''', '''β Pyxidis''', '''β Pyx''') is a [[double star]]<ref name="SIMBAD"/> located in the southern [[constellation]] [[Pyxis]]. It has an [[apparent visual magnitude]] of 3.954, making it the [[List of stars in Pyxis|second brightest star]] in this faint constellation.

Based upon [[parallax]] measurements, this star is an estimated 420 [[light-year]]s (128 [[parsec]]s) from the [[Earth]].<ref name=aaa474_2_653/> The [[spectrum]] matches a [[bright giant]] or [[supergiant]] star of [[stellar classification]] G7Ib-II. The [[interferometer]]-measured [[angular diameter]] of this star is {{nowrap|2.05 ± 0.14 [[milliarcsecond|mas]]}}.<ref name=aaa431_773/> At its estimated distance, this yields a physical size of about 28 times the [[Solar radius|radius of the Sun]].<ref name=lang2006/> The [[effective temperature]] of the star's outer envelope is about 5,400 K, giving it the characteristic yellow hue of a [[G-type star]].<ref name=apj507_2_919/><ref name=csiro/>

In 2010, this star was among a survey of massive, lower [[effective temperature]] supergiants in an attempt to detect a magnetic field. This star may have a longitudinal [[stellar magnetic field|magnetic field]] with a strength of less than a [[Gauss (unit)|Gauss]].<ref name=mnras408_4_2290/> It is a [[Metallicity|young disk star]] system with [[Space velocity (astronomy)|space velocity]] components, {{nowrap|[U, V, W]}} = {{nowrap|[–11.0, +11.8, –2.2] km/s}}.<ref name="apj107"/> There is a magnitude 12.5 optical companion, located at an angular separation of 12.7 [[arcsecond]]s and a [[position angle]] of 118° as of the year 1943.<ref name=wdsc84/>

==Naming==
In [[Chinese language|Chinese]], {{lang|zh|天狗}} ({{lang|zh-Latn|Tiān Gǒu}}), meaning ''[[Ghost (Chinese constellation)|Celestial Dog]]'', refers to an asterism consisting of β Pyxidis, [[e Velorum]], [[f Velorum]], [[Alpha Pyxidis|α Pyxidis]], [[Gamma Pyxidis|γ Pyxidis]] and [[Delta Pyxidis|δ Pyxidis]]. Consequently, β Pyxidis itself is known as {{lang|zh|天狗四}} ({{lang|zh-Latn|Tiān Gǒu sì}}, {{lang-en|the Fourth Star of Celestial Dog}}.)<ref>{{zh icon}} [http://aeea.nmns.edu.tw/2006/0607/ap060717.html AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 7 月 17 日]</ref>

==References==
{{reflist|30em|refs=

<ref name=aaa474_2_653>{{cite journal | first=F. | last=van Leeuwen |date=November 2007 | title=Validation of the new Hipparcos reduction | journal=Astronomy and Astrophysics | volume=474 | issue=2 | pages=653–664 | bibcode=2007A&A...474..653V | doi=10.1051/0004-6361:20078357 |arxiv = 0708.1752 }}</ref>

<ref name="SIMBAD">{{cite web | title=bet Pyx -- Star in double system | work=SIMBAD | publisher=Centre de Données astronomiques de Strasbourg | url=http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=Beta+Pyx | accessdate=2009-04-15 }}</ref>

<ref name="gutierrez">{{cite journal | display-authors=1 | last1=Gutierrez-Moreno | first1=Adelina | last2=Moreno | first2=H. | last3=Stock | first3=J. | last4=Torres | first4=C. | last5=Wroblewski | first5=H. | title=A System of photometric standards | publisher=Publicaciones Universidad de Chile, Department de Astronomy | volume=1 | pages=1–17 | year=1966 | bibcode=1966PDAUC...1....1G }}</ref>

<ref name=rgcrv>{{cite conference | first=D. S. | last=Evans | title=The Revision of the General Catalogue of Radial Velocities | booktitle=Proceedings from IAU Symposium no. 30, Determination of Radial Velocities and their Applications | publisher=Dordrecht, D. Reidel Publishing Co. | date=June 20-24, 1966 | location=University of Toronto | bibcode=1967IAUS...30...57E }}</ref>

<ref name="apj107">{{cite journal | last=Eggen | first=O. J. | year=1994 | title=Photometry of F-K type bright giants and supergiants. 3: The luminosity, reddening, and heavy element abundance of GK stars | journal=The Astrophysical Journal | volume=107 | issue=6 | pages=2184–2210 | bibcode=1994AJ....107.2184E | doi = 10.1086/117030 }} – see p. 2205.</ref>

<ref name=wdsc84>{{citation | last1=Worley | first1=C. E. | last2=Douglas | first2=G. G. | title=The Washington double star catalogue (WDS, 1996.0) | journal=Astronomy & Astrophysics Supplement Series | volume=125 |date=November 1997 | page=523 |bibcode = 1997A&AS..125..523W |doi = 10.1051/aas:1997239 }}</ref>

<ref name=mnras408_4_2290>{{citation | display-authors=1 | last1=Grunhut | first1=J. H. | last2=Wade | first2=G. A. | last3=Hanes | first3=D. A. | last4=Alecian | first4=E. | title=Systematic detection of magnetic fields in massive, late-type supergiants | journal=Monthly Notices of the Royal Astronomical Society | volume=408 | issue=4 | pages=2290–2297 |date=November 2010 | doi=10.1111/j.1365-2966.2010.17275.x | bibcode=2010MNRAS.408.2290G |arxiv = 1006.5891 }}</ref>

<ref name=aaa431_773>{{citation | last1=Richichi | pages=A. | last2=Percheron | first2=I. | last3=Khristoforova | first3=M. | title=CHARM2: An updated Catalog of High Angular Resolution Measurements | journal=Astronomy and Astrophysics | volume=431 | pages=773–777 |date=February 2005 | doi=10.1051/0004-6361:20042039 | bibcode=2005A&A...431..773R }}</ref>

<ref name=lang2006>{{citation | first1=Kenneth R. | last1=Lang | title=Astrophysical formulae | volume=1 | series=Astronomy and astrophysics library | edition=3 | publisher=Birkhäuser | year=2006 | isbn=3-540-29692-1 | url=http://books.google.com/books?id=OvTjLcQ4MCQC&pg=PA41 }}. The radius (R<sub>*</sub>) is given by:
:<math>\begin{align} 2\cdot R_*
& = \frac{(10^{-3}\cdot 128\cdot 2.05)\ \text{AU}}{0.0046491\ \text{AU}/R_{\bigodot}} \\
& \approx 56\cdot R_{\bigodot}
\end{align}</math></ref>

<ref name=apj507_2_919>{{citation | last1=O'Neal | first1=Douglas | last2=Neff | first2=James E. | last3=Saar | first3=Steven H. | title=Measurements of Starspot Parameters on Active Stars using Molecular Bands in Echelle Spectra | journal=The Astrophysical Journal | volume=507 | issue=2 | pages=919–937 |date=November 1998 | doi=10.1086/306340 | bibcode=1998ApJ...507..919O }}</ref>

<ref name=csiro>{{citation | title=The Colour of Stars | date=December 21, 2004 | work=Australia Telescope, Outreach and Education | publisher=Commonwealth Scientific and Industrial Research Organisation | url=http://outreach.atnf.csiro.au/education/senior/astrophysics/photometry_colour.html | accessdate=2012-01-16 }}</ref>

}}

{{Stars of Pyxis}}
[[Category:Bayer objects|Pyxidis, Beta]]
[[Category:G-type giants]]
[[Category:Pyxis (constellation)]]

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Introduction to angular momentum