Iota Draconis
{{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
| dec = {{DEC|+58|57|57.8344}}
| constell = Draco
}}
{{Starbox character
| type = Red giant branch
}}
{{Starbox astrometry
| parallax = 32.23
| p_error = 0.10
| absmag_v = {{Val|0.99|0.007}}
}}
{{Starbox detail
| luminosity = {{val|52.8|2.1}}
| gravity = 2.52{{±|0.007|0.07}}
| temperature = {{val|fmt=commas|4,504|62}}
| metal_fe = {{val|+0.03|0.08}}
| age_gyr = 2.49{{±|0.64|0.62}}
}}
{{Starbox catalog
| names = Edasich, Eldsich, 12 Draconis, BD+59 1654, FK5 425, FK5 571, HD 137759, HIP 75458, HR 5744, SAO 29520, 2MASS J15245578+5857577
}}
{{Starbox reference
| Simbad = iot+Dra
}}
{{Starbox end}}
Iota Draconis (ι Draconis, abbreviated Iota Dra, ι Dra), also named Edasich {{IPAc-en|'|E|d|@|s|I|k}}, is a star in the northern circumpolar constellation of Draco. A visually unremarkable star of apparent magnitude 3.3, in 2002 it was discovered to have a planet orbiting it (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.
Nomenclature
ι Draconis (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. In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN) to catalog and standardize proper names for stars. The WGSN's first bulletin of July 2016 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.[http://www.iau.org/news/pressreleases/detail/iau1404/ NameExoWorlds: An IAU Worldwide Contest to Name Exoplanets and their Host Stars]. IAU.org. 9 July 2014 The process involved public nomination and voting for the new names. In December 2015, the IAU announced the winning name was Hypatia for this planet.[http://www.iau.org/news/pressreleases/detail/iau1514/ Final Results of NameExoWorlds Public Vote Released], International Astronomical Union, 15 December 2015. The winning name was submitted by Hypatia, a student society of the Physics Faculty of the Universidad Complutense de Madrid, Spain. Hypatia was a famous Greek astronomer, mathematician, and philosopher.
In Chinese, {{lang|zh|紫微左垣}} ({{lang|zh-Latn|Zǐ Wēi Zuǒ Yuán}}), meaning Left Wall of Purple Forbidden Enclosure, refers to an asterism consisting of Iota Draconis, Theta Draconis, Eta Draconis, Zeta Draconis, Upsilon Draconis, 73 Draconis, Gamma Draconis and 23 Cassiopeiae.{{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}}. Consequently, the 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}}),{{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. representing {{lang|zh|左樞}} ({{lang|zh-Latn|Zuǒshū}}), meaning Left Pivot.{{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. 左樞 (Zuǒshū) is westernized into Tsao Choo by R.H. Allen with the same meaning [https://penelope.uchicago.edu/Thayer/E/Gazetteer/Topics/astronomy/_Texts/secondary/ALLSTA/Draco*.html Star Name - R.H. Allen p. 210]
Properties
Iota Draconis is larger and more massive than the Sun, with 1.6 times the mass and nearly 12 times the radius. The spectrum matches a stellar classification of K2 III, indicating this is an 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. This temperature gives it an orange hue that is a characteristic of K-type stars. It is rotating at a leisurely rate, with a period of around 434 days. It is about 2.5 billion years old.
In the past Iota Draconis has been suspected of 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. An excess emission of infrared radiation at a wavelength of 70μm suggests the presence of a circumstellar disk of dust; what astronomers term a debris disk.
Edasich is the faintest star of which a color has been reported in pre-telescopic times. It was classified as an orange-red star.{{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 }}
Planetary system
{{OrbitboxPlanet begin
}}
{{OrbitboxPlanet
| exoplanet = b (Hypatia)
| mass = 11.67{{±|0.45|0.46}}
| period = 510.855{{±|0.014}}
| semimajor = 1.448{{±|0.028|0.029}}
| eccentricity = 0.7008{{±|0.0018}}
|inclination=46{{±|27|19}}
}}
{{OrbitboxPlanet
| exoplanet = c
| mass = 17.0{{±|13|5.4}}
| period = 68{{±|60|36}} years
| semimajor = 19.4{{±|10|7.7}}
| eccentricity = 0.455{{±|0.12|0.084}}
|inclination=86{{±|19|19}}
}}
{{OrbitboxPlanet disk
| disk = Dust disk
| periapsis =?
| apoapsis =
| inclination =
}}
{{Orbitbox end}}
The planetary companion discovered in 2002 was the first planet known to orbit a giant star. The habitable zone for this star lies in the range of 6.8–13.5 Astronomical Units, placing this planet well inside. The alignment of this planet's orbit may make it directly detectable via the transit method. Another long-period planet or brown dwarf was discovered in 2021, and the true masses of both planets were measured via astrometry.
References
{{Reflist|colwidth=30em|refs=
{{citation | display-authors=1
| last1=Park | first1=Sunkyung | last2=Kang | first2=Wonseok
| last3=Lee | first3=Jeong-Eun | last4=Lee | first4=Sang-Gak
| title=Wilson-Bappu Effect: Extended to Surface Gravity
| journal=The Astronomical Journal
| volume=146 | issue=4 | pages=73 | year=2013
| doi=10.1088/0004-6256/146/4/73 | bibcode=2013AJ....146...73P
| arxiv=1307.0592 | s2cid=119187733 }}
{{citation | last1=Jennens | first1=P. A. | last2=Helfer | first2=H. L. | title=A new photometric metal abundance and luminosity calibration for field G and K giants | journal=Monthly Notices of the Royal Astronomical Society | volume=172 | issue=3 | pages=667–679 |date=September 1975 | bibcode=1975MNRAS.172..667J | doi=10.1093/mnras/172.3.667| doi-access=free }}
|last1=Kunitzsch |first1=Paul
|last2=Smart |first2=Tim
|date = 2006 |edition = 2nd rev.
|title = A Dictionary of Modern star Names: A Short Guide to 254 Star Names and Their Derivations
|publisher = Sky Pub |location = Cambridge, Massachusetts
|isbn = 978-1-931559-44-7
}}
}}
External links
- [https://web.archive.org/web/20071106060307/http://exoplanet.eu/star.php?st=HIP+75458 Extrasolar Planets Encyclopaedia: Notes for star HIP 75458]
- [http://www.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}}
{{DEFAULTSORT:Iota Draconis}}
Category:Draco (constellation)