59 Draconis

{{short description|Star in the constellation Draco}} {{Starbox begin}} {{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=59 Draconis |x=309|y=390 }} | caption = Location of 59 Draconis (circled in red) }} {{Starbox observe | epoch = [[J2000]] | constell = [[Draco (constellation)|Draco]]<ref name=xhip/> | ra = {{RA|19|09|09.88146}}<ref name=GaiaDR3/> | dec = {{DEC|+76|33|37.8138}}<ref name=GaiaDR3/> | appmag_v = 5.11<ref name=xhip/> }} {{Starbox character | type = [[main sequence]]<ref name=GaiaDR3/> | class = A9V<ref name=Galland2006/> | b-v = 0.308<ref name=xhip/> | variable = [[Gamma Doradus variable|γ Dor]]?<ref name=Galland2006/> }} {{Starbox astrometry | radial_v = {{val|-3.77|0.50}}<ref name=GaiaDR3/> | prop_mo_ra = +52.390 | prop_mo_dec = −119.469 | pm_footnote = <ref name=GaiaDR3/> | parallax = 36.5363 | p_error = 0.1299 | parallax_footnote = <ref name=GaiaDR3/> | absmag_v = 2.93<ref name=xhip/> }} {{Starbox orbit | reference = <ref name=Galland2006/> | period_unitless = {{val|28.44|0.01|ul=d}} | axis_unitless = {{val|0.22|ul=AU}} | eccentricity = {{val|0.20|0.01}} | inclination =  | node =  | periastron = {{val|2453244.3|0.3|ul=JD}} | periarg = {{val|56|4}} | k1 = {{val|1.20|0.02}} }} {{Starbox detail | component1 = A | mass = {{val|1.447|0.014|0.015}}<ref name=Jones2015/> | radius = {{val|1.488|0.031|0.033}}<ref name=Jones2015/> | luminosity = {{val|4.861|0.285|0.290}}<ref name=Jones2015/> | gravity = {{val|4.18|0.21}}<ref name=Saffe2021/> | temperature = {{val|7053|194}}<ref name=Saffe2021/> | metal_fe = | rotation = | rotational_velocity = {{val|53.0|1.1}}<ref name=Saffe2021/> | age_myr = {{val|436|156|203}}<ref name=Jones2015/> | component2 = B | mass_mj2 = {{val|25|p=≥}}<ref name=Galland2006/> }} {{Starbox catalog | names = {{odlist | F=59 Dra | BD=+76 717 | GC=26484 | GJ=9649 | GJ2=748.1 | HD=180777 | HIP=94083 | HR=7312 | NSV=11824 | PLX=4497 | PPM=10093 | SAO=9341}}<ref name=SIMBAD/> }} {{Starbox reference | Simbad = *+59+Dra }} {{Starbox end}}

'''59 Draconis''' is a star with a likely [[brown dwarf]] companion, located {{convert|89.3|ly|pc|lk=on|abbr=off}} away in the constellation [[Draco (constellation)|Draco]]. With an [[apparent magnitude]] of 5.1, it is faintly visible to the [[naked eye]] under good viewing conditions. In [[Chinese astronomy]], this star is known as Tiānzhùsì ({{lang|zh|天柱四}}), meaning it is the fourth star of the asterism Tiānzhù ({{lang|zh|天柱}}, Celestial Pillar).{{refn|[[Stellarium (software)|Stellarium]], citing Yi Shitong, 1981<ref name=Yi1981/>}}

The [[stellar classification]] of 59 Draconis is A9V,<ref name=Galland2006/> indicating that it is an [[A-type main-sequence star]] that is generating energy through [[hydrogen fusion]] at its [[stellar core|core]]. Other sources classify it as A7V<ref name=vanBelle2009/> or F0Vs.<ref name=xhip/> It has a similar [[chemical abundance]] to the Sun.<ref name=Saffe2021/> The star is listed as a suspected [[variable star|variable]],<ref name=vsx/> with [[stellar pulsation|pulsations]] resembling those of [[Gamma Doradus star]]s.<ref name=Galland2006/> It is a candidate member of the [[Ursa Major Moving Group]] stream,<ref name=King2003/><ref name=Jones2015/> though a 2020 study listed its membership probability as only 33%.<ref name=Ujjwal2020/> It appears to be [[stellar rotation|rotating]] with an [[inclination]] of about {{val|28|u=deg}} to the [[plane of the sky]].<ref name=Jones2015/>

The detection of a companion via [[Doppler spectroscopy]] was announced in 2006.<ref name=Galland2006/> This object orbits with a [[orbital period|period]] of 28.4 days and has a [[minimum mass]] of {{Jupiter mass|25|link=y}}, in the range of [[brown dwarf]]s. Since the inclination of the orbit is unknown, the true mass cannot be determined, and it remains possible that it is a star rather than a brown dwarf.<ref name=Galland2006/> [[Hipparcos]] [[astrometry]] has set an upper limit on its mass of {{Solar mass|0.27|link=y}}.<ref name=Sahlmann2011/> If confirmed as a brown dwarf, it is within the [[brown dwarf desert]], a range of orbits where few brown dwarfs are found.<ref name=Galland2006/>

==References== <references>

<ref name=SIMBAD>{{cite simbad |title=* 59 Dra |access-date=18 June 2025}}</ref>

<ref name=vsx>{{cite web |url=https://vsx.aavso.org/index.php?view=detail.top&oid=50448 |title=NSV 11824 |website=International Variable Star Index |publisher=[[AAVSO]] |access-date=29 June 2025}}</ref>

<ref name=Yi1981>{{cite book|script-title=zh:中西对照恒星图表|language=zh|trans-title=Atlas Comparing Chinese and Western Star Maps and Catalogues|last=Yi|first=Shitong|date=April 1981|publisher=科学出版社}}</ref>

<ref name=King2003>{{cite journal |last1=King |first1=Jeremy R. |last2=Villarreal |first2=Adam R. |display-authors=etal |date=April 2003 |title=Stellar Kinematic Groups. II. A Reexamination of the Membership, Activity, and Age of the Ursa Major Group |journal=[[The Astronomical Journal]] |volume=125 |issue=4 |pages=1980–2017 |doi=10.1086/368241 |doi-access=free |bibcode=2003AJ....125.1980K}}</ref>

<ref name=Galland2006>{{cite journal |last1=Galland |first1=F. |last2=Lagrange |first2=A.-M. |display-authors=etal |date=June 2006 |title=Extrasolar planets and brown dwarfs around A-F type stars. IV. A candidate brown dwarf around the A9V pulsating star HD 180777 |journal=[[Astronomy and Astrophysics]] |volume=452 |issue=2 |pages=709–714 |doi=10.1051/0004-6361:20054079 |doi-access=free |arxiv=astro-ph/0602592 |bibcode=2006A&A...452..709G}}</ref>

<ref name=vanBelle2009>{{cite journal |last1=van Belle |first1=Gerard T. |last2=von Braun |first2=Kaspar |date=April 2009 |title=Directly Determined Linear Radii and Effective Temperatures of Exoplanet Host Stars |journal=[[The Astrophysical Journal]] |volume=694 |issue=2 |pages=1085–1098 |doi=10.1088/0004-637X/694/2/1085 |doi-access=free |arxiv=0901.1206 |bibcode=2009ApJ...694.1085V}}</ref>

<ref name=Sahlmann2011>{{cite journal |last1=Sahlmann |first1=J. |last2=Ségransan |first2=D. |display-authors=etal |date=January 2011 |title=Search for brown-dwarf companions of stars |journal=[[Astronomy and Astrophysics]] |volume=525 |issue= |pages=A95 |doi=10.1051/0004-6361/201015427 |doi-access=free |arxiv=1009.5991 |bibcode=2011A&A...525A..95S}}</ref>

<ref name=Jones2015>{{cite journal |last1=Jones |first1=Jeremy |last2=White |first2=R. J. |display-authors=etal |date=November 2015 |title=The Ages of A-Stars. I. Interferometric Observations and Age Estimates for Stars in the Ursa Major Moving Group |journal=[[The Astrophysical Journal]] |volume=813 |issue=1 |pages=58 |doi=10.1088/0004-637X/813/1/58 |doi-access=free |arxiv=1508.05643 |bibcode=2015ApJ...813...58J}}</ref>

<ref name=Ujjwal2020>{{cite journal |last1=Ujjwal |first1=K. |last2=Kartha |first2=Sreeja S. |display-authors=etal |date=April 2020 |title=Analysis of Membership Probability in Nearby Young Moving Groups with Gaia DR2 |journal=[[The Astronomical Journal]] |volume=159 |issue=4 |pages=166 |doi=10.3847/1538-3881/ab76d6 |doi-access=free |arxiv=2002.04801 |bibcode=2020AJ....159..166U}}</ref>

<ref name=Saffe2021>{{cite journal |last1=Saffe |first1=C. |last2=Miquelarena |first2=P. |display-authors=etal |date=March 2021 |title=Chemical analysis of early-type stars with planets |journal=[[Astronomy & Astrophysics]] |volume=647 |issue= |pages=A49 |doi=10.1051/0004-6361/202040132 |doi-access=free |arxiv=2101.04416 |bibcode=2021A&A...647A..49S}}</ref>

</references>

[[Category:Draco (constellation)]] [[Category:A-type main-sequence stars]] [[Category:Spectroscopic binaries]] [[Category:Brown dwarfs]] [[Category:Suspected variables]] [[Category:Ursa Major moving group]] [[Category:Flamsteed objects|Draconis, 59]] [[Category:Bright Star Catalogue objects|7312]] [[Category:Durchmusterung objects|BD+76 0717]] [[Category:Gliese and GJ objects|9649]] [[Category:Henry Draper Catalogue objects|180777]] [[Category:Hipparcos objects|094083]]