{{Short description|Star in the constellation Draco}} {{DISPLAYTITLE:Psi<sup>2</sup> Draconis}} {{other stars by Bayer designation|Psi Draconis{{!}}ψ Draconis}} {{Starbox begin | name = ψ<sup>2</sup> Draconis }} {{Starbox image | image = {{Location mark |image=Draco constellation map.svg|alt=|float=center|width=280 |label=|position=right |mark=Red circle.svg|mark_width=10|mark_link=Psi2 Draconis |x=355|y=532 }} | caption = Location of ψ<sup>2</sup> Draconis (circled in red) }} {{Starbox observe | epoch = [[J2000.0]] | equinox = [[J2000.0]] ([[International Celestial Reference System|ICRS]]) | constell = [[Draco (constellation)|Draco]] | ra = {{RA|17|55|11.15296}}<ref name=dr2/> | dec = {{DEC|+72|00|18.4470}}<ref name=dr2/> | appmag_v = 5.45<ref name=Oja1983/> }} {{Starbox character | type = | class = F2 III+<ref name=Gray2001/> or F3 II-III<ref name=Cowley_Bidelman_1979/> | b-v = +0.30<ref name=Oja1983/> | u-b = +0.15<ref name=Oja1983/> | r-i = | variable = }} {{Starbox astrometry | radial_v = −2.0<ref name=Casagrande2011/> | prop_mo_ra = +8.545<ref name=dr2/> | prop_mo_dec = −2.133<ref name=dr2/> | parallax = 3.4888 | p_error = 0.0832 | parallax_footnote = <ref name=dr2/> | absmag_v = {{Val|−2.12|0.14}}<ref name=Holmberg2009/> }} {{Starbox detail | source = <ref name=Casagrande2011/> | mass = 2.02 | radius = {{val|14.70|0.64|0.34}}<ref name=dr2/> | luminosity = {{val|448|13}}<ref name=dr2/> | temperature = {{Val|6925|83|152}}<ref name=dr2/> | gravity = 2.32 | metal_fe = −1.29 | age_myr = 800 | rotational_velocity = 50<ref name=Danziger_Faber_1972/> }} {{Starbox catalog | names = {{odlist | B=ψ<sup>2</sup> Dra | F=34 Dra | BD=+72°818 | FK5=3429 | HD=164613 | HIP=87728 | HR=6725 | SAO=8961 }}<ref name=SIMBAD/> }} {{Starbox reference | Simbad = psi02+Dra }} {{Starbox end}}
'''Psi<sup>2</sup> Draconis''' is a solitary<ref name=Eggleton2008/> [[giant star]] in the northern [[circumpolar constellation]] of [[Draco (constellation)|Draco]], also designated '''34 Draconis'''. It lies just over a degree east of the brighter [[Psi1 Draconis|Psi<sup>1</sup> Draconis]].<ref name=Sinnott_Perryman_1997/> Psi<sup>2</sup> Draconis has a yellow-white hue and is dimly visible to the naked eye with an [[apparent visual magnitude]] of 5.45.<ref name=Oja1983/> It is located at a distance of {{convert|287|pc|ly|order=flip|abbr=off}} from the [[Sun]] based on [[stellar parallax|parallax]], but is drifting closer with a [[radial velocity]] of −2 km/s.<ref name=Casagrande2011/>
According to R. O. Gray and associates (2001), the [[stellar classification]] of Psi<sup>2</sup> Draconis is F2III+;<ref name=Gray2001/> a star that has used up its core [[hydrogen]], cooled, and expanded away from the [[main sequence]]. [[Anne Cowley|A. P. Cowley]] and [[William P. Bidelman|W. P. Bidelman]] (1979) found a similar class of F3 II-III, with the comment that the [[stellar spectrum|spectrum]] showed "many weak [[absorption line|lines]]".<ref name=Cowley_Bidelman_1979/> Based on the abundance of iron, the [[metallicity]] of this star is much lower than in the Sun. It is about 800<ref name=Casagrande2011/> million years old and is spinning with a [[projected rotational velocity]] of 50 km/s.<ref name=Danziger_Faber_1972/> The star has double<ref name=Casagrande2011/> the [[mass of the Sun]] but has expanded to 15<ref name=dr2/> times the [[Sun's radius]]. It is radiating 448<ref name=dr2/> times the [[luminosity of the Sun]] from its enlarged [[photosphere]] at an [[effective temperature]] of 6,925 K.<ref name=dr2/>
==References== <references> <ref name=dr2>{{cite DR2|1639295390892588288}}</ref>
<ref name=Danziger_Faber_1972>{{citation | title=Rotation of evolving A and F stars | last1=Danziger | first1=I. J. | last2=Faber | first2=S. M. | journal=Astronomy and Astrophysics | volume=18 | page=428 | date=May 1972 | bibcode=1972A&A....18..428D | postscript=. }}</ref>
<ref name=Sinnott_Perryman_1997>{{citation | postscript=. | first1=Roger W. | last1=Sinnott | first2=Michael A. C. | last2=Perryman | title=Millennium Star Atlas | page=1054 | volume=3 | year=1997 | isbn=0-933346-84-0 | publisher=Sky Publishing Corporation and the European Space Agency }}</ref>
<ref name=Cowley_Bidelman_1979>{{citation | title=MK spectral types for some F and G stars | last1=Cowley | first1=A. P. | author1-link=Anne Cowley | last2=Bidelman | first2=W. P. | journal=Publications of the Astronomical Society of the Pacific | volume=91 | pages=83–86 | date=February 1979 | postscript=. | doi=10.1086/130446 | bibcode=1979PASP...91...83C | doi-access=free }}</ref>
<ref name=Holmberg2009>{{citation | display-authors=1 | last1=Holmberg | first1=J. | last2=Nordström | first2=B. | last3=Andersen | first3=J. | title=The Geneva-Copenhagen survey of the solar neighbourhood. III. Improved distances, ages, and kinematics | volume=501 | issue=3 |date=July 2009 | pages=941–947 | journal=Astronomy and Astrophysics | doi=10.1051/0004-6361/200811191 | bibcode=2009A&A...501..941H | arxiv=0811.3982 | s2cid=118577511 | postscript=. }}</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 | arxiv=0806.2878 | s2cid=14878976 | postscript=. }}</ref>
<ref name=Casagrande2011>{{citation | last1=Casagrande | first1=L. | last2=Schönrich | first2=R. | last3=Asplund | first3=M. | last4=Cassisi | first4=S. | last5=Ramírez | first5=I. | last6=Meléndez | first6=J. | last7=Bensby | first7=T. | last8=Feltzing | first8=S. | title=New constraints on the chemical evolution of the solar neighbourhood and Galactic disc(s). Improved astrophysical parameters for the Geneva-Copenhagen Survey | journal=Astronomy & Astrophysics | display-authors=1 | volume=530 | issue=A138 | pages=21 | date=2011 | doi=10.1051/0004-6361/201016276 | bibcode=2011A&A...530A.138C | arxiv=1103.4651 | s2cid=56118016 | postscript=. }}</ref>
<ref name=Gray2001>{{citation | display-authors=1 | last1=Gray | first1=R. O. | last2=Napier | first2=M. G. | last3=Winkler | first3=L. I. | title=The Physical Basis of Luminosity Classification in the Late A-, F-, and Early G-Type Stars. I. Precise Spectral Types for 372 Stars | journal=The Astronomical Journal | postscript=. | volume=121 | issue=4 | pages=2148–2158 | date=April 2001 | doi=10.1086/319956 | bibcode=2001AJ....121.2148G | doi-access=free }}</ref>
<ref name=Oja1983>{{citation | title=UBV photometry of FK4 and FK4 supplement stars | last1=Oja | first1=T. | journal=Astronomy and Astrophysics Supplement Series | volume=52 | pages=1311–34 | date=April 1983 | bibcode=1983A&AS...52..131O | postscript=. }}</ref>
<ref name=SIMBAD>{{citation | title=psi02 Dra -- Star | work=SIMBAD Astronomical Database | publisher=Centre de Données astronomiques de Strasbourg | url=http://simbad.u-strasbg.fr/simbad/sim-id?Ident=psi02+Dra | access-date=2017-05-29 | postscript=. }}</ref> </references>
{{Stars of Draco|state=collapsed}}
[[Category:F-type giants]] [[Category:Draco (constellation)]] [[Category:Bayer objects|Draconis, Psi2]] [[Category:Durchmusterung objects|BD+72 0818]] [[Category:Flamsteed objects|Draconis, 34]] [[Category:Henry Draper Catalogue objects|164613]] [[Category:Hipparcos objects|087728]] [[Category:Bright Star Catalogue objects|6725]]