View source for HD 21447

{{Short description|Probable binary star in the constellation Camelopardalis}}
{{Starbox begin
| name = HD 21447
}}
{{Starbox observe
| epoch = J2000
| constell = [[Camelopardalis (constellation)|Camelopardalis]]
| ra = {{RA|03|30|00.18302}}<ref name=vanLeeuwen2007/>
| dec = {{DEC|+55|27|06.5158}}<ref name=vanLeeuwen2007/>
| appmag_v = 5.09<ref name=Anderson2012/>
}}
{{Starbox character
| type =
| class = A1&nbsp;Va<ref name=Gray1987/>
| b-v = {{Val|0.022|0.015}}<ref name=Anderson2012/>
| variable =
}}
{{Starbox astrometry
| radial_v = {{Val|−1.9|0.9}}<ref name=deBruijne2012/>
| prop_mo_ra = −46.08<ref name=vanLeeuwen2007/>
| prop_mo_dec = −11.07<ref name=vanLeeuwen2007/>
| parallax = 16.42
| p_error = 0.29
| parallax_footnote = <ref name=vanLeeuwen2007/>
| absmag_v = 1.17<ref name=Anderson2012/>
}}
{{Starbox detail
| source =
| mass = 2.32<ref name=DeRosa2014/>
| radius = 1.9<ref name=PasinettiFracassini2001/>
| luminosity = 32.16<ref name=Anderson2012/>
| gravity = 4.06<ref name=David2015/>
| temperature = {{Val|10049|342|fmt=commas}}<ref name=David2015/>
| metal_fe =
| rotational_velocity = 182<ref name=David2015/>
| age_myr = 146<ref name=David2015/>
}}
{{Starbox catalog
| names = {{odlist | BD=+54°684 | HD=21447 | HIP=16292 | HR=1046 | SAO=24064 | WDS=J03300+5527A | NSV=1159 }}<ref name=SIMBAD/>
}}
{{Starbox reference
| Simbad = HD+21447
}}
{{Starbox end}}
'''HD 21447''' is a probable [[binary star]]<ref name=Eggleton2008/> system located in the constellation [[Camelopardalis]]. The star is also known as '''HR 1046'''. It can be viewed with the naked eye, having an [[apparent visual magnitude]] of 5.09.<ref name=Anderson2012/> Based upon an annual [[stellar parallax|parallax shift]] of {{Val|16.42|0.29|ul=mas}},<ref name=vanLeeuwen2007/> it is located some 199&nbsp;[[light year]]s from the Sun. It is a candidate for membership in the [[Ursa Major Moving Group]].<ref name=king2003/>
The primary component is [[A-type main-sequence star]] with a [[stellar classification]] of A1&nbsp;Va.<ref name=Gray1987/> It is around 146<ref name=David2015/>&nbsp;million years old and is spinning with a [[projected rotational velocity]] of 182&nbsp;km/s.<ref name=David2015/> The star has an estimated 2.32<ref name=DeRosa2014/> times the [[mass of the Sun]] and about 1.9<ref name=PasinettiFracassini2001/> times the [[Sun's radius]]. It is radiating around 32<ref name=Anderson2012/> times the [[Sun's luminosity]] from its [[photosphere]] at an [[effective temperature]] of 10,049&nbsp;K.<ref name=David2015/> The companion is visual magnitude 9.4 star at an [[angular separation]] of {{Val|14.8|ul=arcsec}}.<ref name=Eggleton2008/>
==References==
{{reflist|refs=
<ref name=SIMBAD>{{cite simbad | title=HD 21447 | access-date=2018-05-16 }}</ref>
<ref name=vanLeeuwen2007>{{citation
| title=Validation of the new Hipparcos reduction
| last1=van Leeuwen | first1=F. | postscript=.
| journal=Astronomy and Astrophysics
| volume=474 | issue=2 | pages=653–664 | year=2007
| arxiv=0708.1752 | bibcode=2007A&A...474..653V
| doi=10.1051/0004-6361:20078357 | s2cid=18759600 }}</ref>
<ref name=Anderson2012>{{citation
| title=XHIP: An extended hipparcos compilation
| last1=Anderson | first1=E. | last2=Francis | first2=Ch.
| journal=Astronomy Letters
| volume=38 | issue=5 | pages=331 | year=2012
| bibcode=2012AstL...38..331A | doi=10.1134/S1063773712050015
| arxiv=1108.4971 | s2cid=119257644 | postscript=. }}</ref>
<ref name=PasinettiFracassini2001>{{citation | display-authors=1
| last1=Pasinetti Fracassini | first1=L. E. | last2=Pastori | first2=L.
| last3=Covino | first3=S. | last4=Pozzi | first4=A.
| title=Catalogue of Apparent Diameters and Absolute Radii of Stars (CADARS)
| edition=Third | journal=Astronomy and Astrophysics
| volume=367 | pages=521–524 | date=February 2001
| doi=10.1051/0004-6361:20000451 | bibcode=2001A&A...367..521P
| arxiv=astro-ph/0012289 | s2cid=425754 | postscript=. }}</ref>
<ref name=king2003>{{citation
| title=Stellar Kinematic Groups. II. A Reexamination of the Membership, Activity, and Age of the Ursa Major Group
| journal=The Astronomical Journal | postscript=.
| display-authors=1 | last1=King | first1=Jeremy R.
| last2=Villarreal | first2=Adam R. | last3=Soderblom | first3=David R.
| last4=Gulliver | first4=Austin F. | last5=Adelman | first5=Saul J.
| volume=125 | issue=4 | pages=1980 | year=2003
| bibcode=2003AJ....125.1980K | doi=10.1086/368241 | url=https://tigerprints.clemson.edu/cgi/viewcontent.cgi?article=1248&context=physastro_pubs | doi-access=free }}</ref>
<ref name=Eggleton2008>{{citation
| last1=Eggleton | first1=P. P. | last2=Tokovinin | first2=A. A.
| title=A catalogue of multiplicity among bright stellar systems
| journal=Monthly Notices of the Royal Astronomical Society
| volume=389 | issue=2 | pages=869–879 | date=September 2008
| doi=10.1111/j.1365-2966.2008.13596.x | doi-access=free | bibcode=2008MNRAS.389..869E
| postscript=. | arxiv=0806.2878 | s2cid=14878976 }}</ref>
<ref name=deBruijne2012>{{citation
| last1=de Bruijne | first1=J. H. J. | last2=Eilers | first2=A.-C.
| title=Radial velocities for the HIPPARCOS-Gaia Hundred-Thousand-Proper-Motion project
| journal=Astronomy & Astrophysics
| volume=546 | id=A61 | pages=14 | date=October 2012
| doi=10.1051/0004-6361/201219219 | bibcode=2012A&A...546A..61D
| arxiv=1208.3048 | s2cid=59451347 | postscript=. }}</ref>
<ref name=DeRosa2014>{{citation
| display-authors=1
| last1=De Rosa | first1=R. J. | last2=Patience | first2=J.
| last3=Wilson | first3=P. A. | last4=Schneider | first4=A.
| last5=Wiktorowicz | first5=S. J. | last6=Vigan | first6=A.
| last7=Marois | first7=C. | last8=Song | first8=I.
| last9=Macintosh | first9=B. | last10=Graham | first10=J. R.
| last11=Doyon | first11=R. | last12=Bessell | first12=M. S.
| last13=Thomas | first13=S. | last14=Lai | first14=O.
| title=The VAST Survey - III. The multiplicity of A-type stars within 75 pc
| journal=Monthly Notices of the Royal Astronomical Society
| volume=437 | issue=2 | pages=1216–1240 | date=January 2014
| doi=10.1093/mnras/stt1932 | doi-access=free | bibcode=2014MNRAS.437.1216D
| arxiv=1311.7141 | s2cid=88503488 | postscript=. }}</ref>
<ref name=Gray1987>{{citation | postscript=.
| title=The Early A-Type Stars: Refined MK Classification, Confrontation with Stroemgren Photometry, and the Effects of Rotation
| last1=Gray | first1=R. O. | last2=Garrison | first2=R. F.
| journal=Astrophysical Journal Supplement
| volume=65 | page=581 | date=December 1987
| doi=10.1086/191237 | bibcode=1987ApJS...65..581G | doi-access=free }}</ref>
<ref name=David2015>{{citation
| title=The Ages of Early-Type Stars: Strömgren Photometric Methods Calibrated, Validated, Tested, and Applied to Hosts and Prospective Hosts of Directly Imaged Exoplanets
| journal=The Astrophysical Journal
| volume=804 | issue=2 | pages=146 | year=2015
| last1=David | first1=Trevor J. | last2=Hillenbrand | first2=Lynne A.
| bibcode=2015ApJ...804..146D | doi=10.1088/0004-637X/804/2/146
| arxiv=1501.03154 | s2cid=33401607
| postscript=. }}</ref>
}}
== External links ==
*http://www.alcyone.de/cgi-bin/search.pl?object=HR1046 {{Webarchive|url=https://web.archive.org/web/20111117064231/http://www.alcyone.de/cgi-bin/search.pl?object=HR1046 |date=2011-11-17 }}
*http://server3.wikisky.org/starview?object_type=1&object_id=1996
{{Stars of Camelopardalis}}
{{DEFAULTSORT:HD 21447}}
[[Category:A-type main-sequence stars]]
[[Category:Camelopardalis]]
[[Category:Durchmusterung objects]]
[[Category:Henry Draper Catalogue objects|021447]]
[[Category:Hipparcos objects|016292]]
[[Category:Bright Star Catalogue objects|1046]]