{{short description|Star in the constellation Draco}} {{Starbox begin | name = Iota Draconis / Edasich }} {{Starbox image | image= {{Location mark | image=Draco constellation map.svg | float=center | width=250 | position=right | mark=Red circle.svg | mark_width=8 | mark_link=ι Draconis | x%=68.4 | y%=73.8 }} | caption=Location of ι Draconis (circled) }} {{Starbox observe | epoch = J2000 | ra = {{RA|15|24|55.77463}}<ref name=aaa474_2_653/> | dec = {{DEC|+58|57|57.8344}}<ref name=aaa474_2_653/> | appmag_v = 3.290<ref name=mnras172_667/> | constell = [[Draco (constellation)|Draco]] }} {{Starbox character | type = [[Red giant branch]]<ref name=campante2023/> | class = K2III<ref name=araa11_29/> | b-v = +1.160<ref name=mnras172_667/> | u-b = +1.230<ref name=mnras172_667/> | variable = Suspected<ref name=apj720_2_1644/> }} {{Starbox astrometry | radial_v = −10.71<ref name=aaa430_165/> | prop_mo_ra = −8.36<ref name=aaa474_2_653/> | prop_mo_dec = +17.08<ref name=aaa474_2_653/> | parallax = 32.23 | p_error = 0.10 | parallax_footnote = <ref name=aaa474_2_653/> | absmag_v = {{Val|0.99|0.007}}<ref name=park2013/> }} {{Starbox detail | mass = {{val|1.56|0.08}}<ref name=campante2023/> | radius = {{val|11.99|0.06}}<ref name=campante2023/> | luminosity = {{val|52.8|2.1}}<ref name=campante2023/> | gravity = 2.52{{±|0.007|0.07}}<ref name=campante2023/> | temperature = {{val|fmt=commas|4,504|62}}<ref name=apj743_2_120/> | metal_fe = {{val|+0.03|0.08}}<ref name=campante2023/> | rotational_velocity = 1.5<ref name=apj720_2_1644/> | rotation = 434 days<ref name=apj720_2_1644/> | age_gyr = 2.49{{±|0.64|0.62}}<ref name=campante2023/> }} {{Starbox catalog | names = {{odlist |name=Edasich |F=12 Draconis |BD=+59 1654 |FK5=571 |HD=137759 |HIP=75458 |HR=5744 |SAO=29520 |2MASS=J15245578+5857577 }}<ref name=SIMBAD/> }} {{Starbox reference | Simbad = iot+Dra | NSTED = iot Dra }} {{Starbox end}}
'''Iota Draconis''' ('''ι Draconis''', abbreviated '''Iota Dra''', '''ι Dra'''), also named '''Edasich''' {{IPAc-en|'|E|d|@|s|I|k}},<ref name=Kunitzsch/><ref name=IAU-CSN/> is a [[star]] in the northern [[circumpolar constellation]] of [[Draco (constellation)|Draco]]. A visually unremarkable star of [[apparent magnitude]] 3.3,<ref name=mnras172_667/> in 2002 it was discovered to have a planet orbiting it<ref name="Frink2002"/> (designated [[Iota Draconis b]], later named Hypatia). From [[parallax]] measurements, this star is located at a distance of about {{Convert|101.2|ly|pc|abbr=off|lk=on}} from the [[Sun]].<ref name=aaa474_2_653/>
==Nomenclature==
''ι Draconis'' ([[Latinisation of names|Latinised]] to ''Iota Draconis'') is the star's [[Bayer designation]]. On discovery the planet was designated Iota Draconis b (or Edasich b).
It bore the traditional name ''Edasich'', derived from the [[Arabic]] {{Transliteration|ar|Al Ḍhiba}}' of [[Ulugh Beg]] and the Dresden Globe, or {{Transliteration|ar|Al dhīlī}} 'Male hyena' by Kazwini, with ''Eldsich'' being recorded in the ''Century Cyclopedia''.<ref name=allen/> In 2016, the [[International Astronomical Union]] organized a [[IAU Working Group on Star Names|Working Group on Star Names]] (WGSN)<ref name=WGSN/> to catalog and standardize proper names for stars. The WGSN's first bulletin of July 2016<ref name=WGSN1/> included a table of the first two batches of names approved by the WGSN; which included ''Edasich'' for this star.
In July 2014 the [[International Astronomical Union]] launched [[NameExoWorlds]], a process for giving proper names to certain exoplanets and their host stars.<ref>[http://www.iau.org/news/pressreleases/detail/iau1404/ NameExoWorlds: An IAU Worldwide Contest to Name Exoplanets and their Host Stars] {{Webarchive|url=https://web.archive.org/web/20170904221813/https://www.iau.org/news/pressreleases/detail/iau1404/ |date=2017-09-04 }}. IAU.org. 9 July 2014</ref> The process involved public nomination and voting for the new names.<ref name=nameexoworlds/> In December 2015, the IAU announced the winning name was Hypatia for this planet.<ref>[http://www.iau.org/news/pressreleases/detail/iau1514/ Final Results of NameExoWorlds Public Vote Released] {{Webarchive|url=https://web.archive.org/web/20171202072549/http://www.iau.org/news/pressreleases/detail/iau1514/ |date=2017-12-02 }}, International Astronomical Union, 15 December 2015.</ref> The winning name was submitted by Hypatia, a student society of the Physics Faculty of the [[Complutense University of Madrid|Universidad Complutense de Madrid]], [[Spain]]. [[Hypatia]] was a famous Greek astronomer, mathematician, and philosopher.<ref name=nameexoworldsnames/>
In [[Chinese astronomy|Chinese]], {{lang|zh|紫微左垣}} ({{lang|zh-Latn|Zǐ Wēi Zuǒ Yuán}}), meaning ''[[Purple Forbidden enclosure|Left Wall of Purple Forbidden Enclosure]]'', refers to an [[Asterism (astronomy)|asterism]] consisting of Iota Draconis, [[Theta Draconis]], [[Eta Draconis]], [[Zeta Draconis]], [[Upsilon Draconis]], [[73 Draconis]], [[Gamma Draconis]] and [[23 Cassiopeiae]].<ref>{{in lang|zh}} ''中國星座神話'', written by 陳久金. Published by 台灣書房出版有限公司, 2005, {{ISBN|978-986-7332-25-7}}.</ref> Consequently, the [[Chinese star names|Chinese name]] for Iota Draconis itself is {{lang|zh|紫微左垣一}} ({{lang|zh-Latn|Zǐ Wēi Zuǒ Yuán yī}}, {{langx|en|the First Star of Left Wall of Purple Forbidden Enclosure}}),<ref>{{in lang|zh}} [http://www.lcsd.gov.hk/CE/Museum/Space/Research/StarName/c_research_chinengstars_e_g.htm 香港太空館 - 研究資源 - 亮星中英對照表] {{webarchive|url=https://web.archive.org/web/20110130063007/http://www.lcsd.gov.hk/CE/Museum/Space/Research/StarName/c_research_chinengstars_e_g.htm |date=2011-01-30 }}, Hong Kong Space Museum. Accessed on line November 23, 2010.</ref> representing {{lang|zh|左樞}} ({{lang|zh-Latn|Zuǒshū}}), meaning ''Left Pivot''.<ref>{{in lang|zh}} [http://www.lcsd.gov.hk/CE/Museum/Space/Research/StarName/e_research_chinengstarzone_b.htm#PrupleForbiddenEnclosure English-Chinese Glossary of Chinese Star Regions, Asterisms and Star Name] {{webarchive|url=https://web.archive.org/web/20080924022136/http://www.lcsd.gov.hk/CE/Museum/Space/Research/StarName/e_research_chinengstarzone_b.htm |date=2008-09-24 }}, Hong Kong Space Museum. Accessed on line November 23, 2010.</ref> 左樞 (Zuǒshū) is westernized into ''Tsao Choo'' by R.H. Allen with the same meaning <ref>[https://penelope.uchicago.edu/Thayer/E/Gazetteer/Topics/astronomy/_Texts/secondary/ALLSTA/Draco*.html Star Name - R.H. Allen p. 210]</ref>
==Properties== Iota Draconis is larger and more massive than the Sun, with 1.6 times the mass and nearly 12 times the radius.<ref name=campante2023/> The [[stellar spectrum|spectrum]] matches a [[stellar classification]] of K2 III,<ref name=araa11_29/> indicating this is an [[stellar evolution|evolved]] star that has exhausted the supply of hydrogen at its core and left the [[main sequence]]. It is currently on the [[red giant branch]], fusing hydrogen in a shell around its helium core. With an expanded outer envelope, it is radiating over 50 times the luminosity of the Sun at an [[effective temperature]] of 4,504 K.<ref name=apj743_2_120/> This temperature gives it an orange hue that is a characteristic of K-type stars.<ref name=csiro/> It is rotating at a leisurely rate, with a period of around 434 days.<ref name=apj720_2_1644/> It is about 2.5 billion years old.<ref name=campante2023/>
In the past Iota Draconis has been suspected of [[variable star|variability]]. However, the star has been found to have a constant luminosity to within about 0.004 magnitudes. Hence, as of 2010, the variability remains unconfirmed.<ref name=apj720_2_1644/> An [[infrared excess|excess emission of infrared radiation]] at a [[wavelength]] of 70[[Micrometre|μm]] suggests the presence of a circumstellar disk of dust; what astronomers term a [[debris disk]].<ref name=apjl700_2_L73/>
Edasich is the faintest star of which a color has been reported in pre-telescopic times. It was classified as an orange-red star.<ref name="Neuhäuser_et_al_2022">{{cite journal | title=Colour evolution of Betelgeuse and Antares over two millennia, derived from historical records, as a new constraint on mass and age | display-authors=1 | last1=Neuhäuser | first1=R. | last2=Torres | first2=G. | last3=Mugrauer | first3=M. | last4=Neuhäuser | first4=D. L. | last5=Chapman | first5=J. | last6=Luge | first6=D. | last7=Cosci | first7=M. | journal=Monthly Notices of the Royal Astronomical Society | date=July 2022 | volume=516 | issue=1 | pages=693–719 | doi=10.1093/mnras/stac1969 | doi-access=free | arxiv=2207.04702 | bibcode=2022MNRAS.516..693N }}</ref>
==Planetary system== {{OrbitboxPlanet begin | table_ref = <ref name=Hill2021/> | period_unit = year }} {{OrbitboxPlanet | exoplanet = [[Iota Draconis b|b (Hypatia)]] | mass = 16.4{{±|9.3|4.0}} | period = 1.39864{{±|0.00004}} | semimajor = 1.453{{±|0.026}} | eccentricity = 0.7010{{±|0.0016|0.0017}} | inclination= 46{{±|27|19}} }} {{OrbitboxPlanet | exoplanet = c | mass = 17.0{{±|13|5.4}} | period = 68{{±|60|36}} | semimajor = 19.4{{±|10|7.7}} | eccentricity = 0.455{{±|0.12|0.084}} |inclination=86{{±|19}} }} {{OrbitboxPlanet disk | disk = Dust disk | periapsis =? | apoapsis = | inclination = <!--Inclination from the plane of the sky, in degrees--> }} {{Orbitbox end}}
The planetary companion discovered in 2002 was the first planet known to orbit a giant star.<ref name="Frink2002"/> It was noted that the alignment of this planet's eccentric orbit means it has about 11% probability of [[transit method|transiting]] its star.<ref name=apj720_2_1644/><ref name="2019PASP..131c4401D"/> Another long-period planet or brown dwarf was discovered in 2021, and the true masses of both planets were measured via [[astrometry]].<ref name=Hill2021/>
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}}
==External links== *[https://web.archive.org/web/20071106060307/http://exoplanet.eu/star.php?st=HIP+75458 ''Extrasolar Planets Encyclopaedia'': Notes for star HIP 75458] *[https://web.archive.org/web/20020420065521/http://solstation.com/stars2/edasich.htm ''SolStation'': Edasich/Iota Draconis] {{Sky|15|24|55.7747|+|58|57|57.836|102.7}}{{Stars of Draco}} {{Authority control}}
[[Category:K-type giants]] [[Category:Draco (constellation)]] [[Category:Bayer objects|Draconis, Iota]] [[Category:Flamsteed objects|Draconis, 12]] [[Category:Henry Draper Catalogue objects|137759]] [[Category:Hipparcos objects|075458]] [[Category:Bright Star Catalogue objects|5744]] [[Category:Durchmusterung objects|BD+59 1654]] [[Category:Stars with proper names|Edasich]] [[Category:Planetary systems with two confirmed planets]] [[Category:Circumstellar disks]] [[Category:Suspected variables]]