6 Draconis

{{Short description|Binary star system in the constellation Draco}}

{{Starbox begin

| name = 6 Draconis

}}

{{Starbox image

| image = 300px

| caption = 6 Draconis(center) and κ Draconis (below)

}}

{{Starbox observe

| epoch = J2000

| constell = Draco

| ra = {{RA|12|34|44.00337}}

| dec = {{DEC|+70|01|18.4185}}

| appmag_v = 4.95

}}

{{Starbox character

| type =

| class = {{nowrap|K2.5 III Fe-2}} + A8–9 V

| b-v = {{Val|1.312|0.003}}

| u-b =

| variable =

}}

{{Starbox astrometry

| radial_v = {{Val|3.38|0.30}}

| prop_mo_ra = −27.213

| prop_mo_dec = −5.329

| parallax = 7.5358

| p_error = 0.2774

| parallax_footnote =

| absmag_v = −1.35

}}

{{Starbox orbit

| reference =

| primary =

| name =

| period =

| period_unitless = {{Val|561.7|0.3|u=days}}

| axis =

| axis_unitless =

| eccentricity = {{Val|0.262|0.017}}

| inclination =

| node =

| periastron = {{Val|45525|5|u=MJD}}

| periarg = {{Val|9|4}}

| periarg_primary =

| k1 = {{Val|6.90|0.12}}

| k2 =

}}

{{Starbox detail

| source =

| mass =

| radius = 36

| luminosity = 602.72

| temperature = 4,210

| gravity = 2.20

| metal_fe = −0.21

| rotational_velocity = 1.7

| age_myr =

}}

{{Starbox catalog

| names = {{odlist | F=6 Dra | BD=+70°705 | HD=109551 | HIP=61384 | HR=4795 | SAO=7600 }}

}}

{{Starbox reference

| Simbad=6+Dra

}}

6 Draconis is a single-lined spectroscopic binary star system in the northern constellation of Draco, located about 430 light years away from the Sun. It is visible to the naked eye as an orange-hued star with an apparent visual magnitude of 4.95. The system is moving further from the Earth with a heliocentric radial velocity of 3 km/s.

The variable radial velocity of this star system was announced by W. W. Campbell in 1922. Griffin et al. (1990) found an orbital period of {{Convert|561.7|days|years|sigfig=2|disp=out}} and an eccentricity of 0.26. The primary has an "a sin i" value of {{Convert|51.4|Gm|AU|lk=on|abbr=on|sigfig=2}}, where a is the semimajor axis and i is the (unknown) orbital inclination. This value provides a lower bound on the actual semimajor axis, which is one half of the longest dimension of their elliptical orbit.

The visible component is an evolved giant star with a stellar classification of {{nowrap|K2.5 III Fe-2}}, where the suffix notation indicates a pronounced underabundance of iron in the spectrum. The measured angular diameter of this star, after correction for limb darkening, is {{val|2.54|0.04|ul=mas}}. At its estimated distance, this yields a physical size of about 36 times the radius of the Sun. It is radiating 603 times the Sun's luminosity from its enlarged photosphere at an effective temperature of 4,210 K. The companion is most likely an A-type main-sequence star with a class of A8–9 V.

References

{{reflist|refs=

{{citation

| title=The Rotation of Binary Systems with Evolved Components

| display-authors=1 | last1=De Medeiros | first1=J. R.

| last2=Da Silva | first2=J. R. P. | last3=Maia | first3=M. R. G.

| journal=The Astrophysical Journal | postscript=.

| volume=578 | issue=2 | pages=943–950 | date=October 2002

| doi=10.1086/342613 | bibcode=2002ApJ...578..943D | arxiv=astro-ph/0207288| s2cid=16196039 }}

{{citation

| title=The Perkins catalog of revised MK types for the cooler stars

| last1=Keenan | first1=Philip C. | last2=McNeil | first2=Raymond C.

| journal=Astrophysical Journal Supplement Series

| volume=71 | pages=245 | year=1989 | postscript=.

| bibcode=1989ApJS...71..245K | doi=10.1086/191373 }}

{{citation

| display-authors=1 | last1=Griffin | first1=R. F.

| last2=Eitter | first2=J. J. | last3=Reimers | first3=D.

| title= The spectroscopic orbit of 6 Draconis

| journal=Journal of Astrophysics and Astronomy

| volume=11 | page=255 | date=June 1990

| issue=2 | doi=10.1007/BF02715020 | bibcode=1990JApA...11..255G | s2cid=120297735 }}

{{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=. }}

{{citation

| last=McWilliam | first=Andrew | postscript=.

| title=High-resolution spectroscopic survey of 671 GK giants. I - Stellar atmosphere parameters and abundances

| journal=Astrophysical Journal Supplement Series

| volume=74 | pages=1075–1128 | date=December 1990

| doi=10.1086/191527 | bibcode=1990ApJS...74.1075M | doi-access=free }}

{{citation

| last1=Richichi | first1=A. | last2=Percheron | first2=I.

| last3=Khristoforova | first3=M.

| title=CHARM2: An updated Catalog of High Angular Resolution Measurements

| journal=Astronomy and Astrophysics | postscript=.

| volume=431 | issue=2 | pages=773–777 | date=February 2005

| doi=10.1051/0004-6361:20042039 | bibcode=2005A&A...431..773R | doi-access=free }}

{{citation

| first1=Kenneth R. | last1=Lang

| title=Astrophysical formulae | volume=1 | series=Astronomy and astrophysics library

| edition=3rd | publisher=Birkhäuser

| date=2006 | isbn=3-540-29692-1 | postscript=.

| url=https://books.google.com/books?id=OvTjLcQ4MCQC&pg=PA41 }} The radius (R_*) is given by:

: $\begin{align} 2\cdot R_*
& = \frac{(132.7\cdot 2.54\cdot 10^{-3})\ \text{AU}}{0.0046491\ \text{AU}/R_{\bigodot}} \\
& \approx 72.5\cdot R_{\bigodot}
\end{align}$

}}

Category:K-type giants

Category:A-type main-sequence stars

Category:Spectroscopic binaries

Category:Draco (constellation)

Category:Durchmusterung objects