{{short description|Star in the constellation Carina}} {{For|i Carinae|HD 79447}} {{Starbox begin | name = ι Carinae }} {{Starbox image | image = {{Location mark |image=Carina constellation map.svg|alt=|float=center|width=280 |label=|position=right |mark=Red circle.svg|mark_width=10|mark_link=ι Car |x=366|y=298 }} | caption = Location of ι Carinae (circled in red) }} {{Starbox observe | epoch = J2000 | ra = {{RA|09|17|05.40686}}<ref name=aaa474_2_653/> | dec = {{DEC|-59|16|30.8353}}<ref name=aaa474_2_653/> | appmag_v = 2.21<ref name=scfs/> | constell = Carina }} {{Starbox character | type = Supergiant | class = A7 Ib<ref name=mk/> | b-v = +0.18<ref name=clpl4/> | u-b = +0.16<ref name=clpl4/> | variable = Suspected<ref name=al32_9_604/> }} {{Starbox astrometry | radial_v = 13.3<ref name=scfs/> | prop_mo_ra = −19.03 | prop_mo_dec = +13.11 | pm_footnote = <ref name=aaa474_2_653/> | parallax = 4.26 | p_error = 0.1 | parallax_footnote = <ref name=aaa474_2_653/> | absmag_v = −5.1<ref name=uves/> }} {{Starbox detail | mass = 6.9<ref name=Neiner2017/> | radius = 46.4–50.1<ref name=Neiner2017/> | luminosity = 4,900<ref name=aaa449_2_655/> | temperature = 7,500<ref name=Neiner2017/>–7,700<ref name="ayres2018" /> | metal_fe = −0.14<ref name=aaa449_2_655/> | rotation = | rotational_velocity = 10.0<ref name=aaa449_2_655/> | gravity = {{val|1.85|0.1}}<ref name=Neiner2017/> | age_myr = 56<ref name=Neiner2017/> }} {{Starbox catalog | names = {{odlist | name=Aspidiske | B=iota Car | HR=3699 | HD=80404 | SAO=236808 | FK5=351 | CD=−58°2529 | CPD=−58°1465 | NSV=04444 | HIP=45556 }}<ref name=SIMBAD/> }} {{Starbox reference |Simbad=iota+Car }} {{Starbox end}}
'''Iota Carinae''' is a star in the southern constellation of Carina. It has the official name '''Aspidiske''', pronounced {{IPAc-en|,|æ|s|p|ɪ|'|d|I|s|k|iː}};<ref name="IAU-CSN"/> ''Iota Carinae'' is its Bayer designation, which is Latinized from '''ι Carinae''' and abbreviated '''Iota Car''' or '''ι Car'''. With an apparent visual magnitude of 2.2,<ref name=scfs/> it is one of the brighter stars in the night sky.
The star appears 46.0' (0.7668°) WSW of V357 Carinae, a mid-third-magnitude star, also forming part of the asterism and leading to its long, narrow projection which culminates in Canopus.<ref>[http://in-the-sky.org/skymap2.php?year=2019&month=1&day=1&town=3369157 In the Sky Map], Dominic Ford, 2011–2019.</ref>
The star and rest of southern Carina never sets on places from about 34° S southwards including Cape Town; its northernmost viewpoints are unobstructed southern horizons near to the 30th parallel north, once a day.<ref name=allen1899/>
==Location and Nomenclature== ''ι Carinae'' (Latinised to ''Iota Carinae'') is the star's Bayer designation.
The star is part of an asterism, the False Cross, from Iota Carinae, Delta Velorum, Kappa Velorum and Epsilon Carinae. The quartet is so called because they are sometimes mistaken for the Southern Cross, causing errors in astronavigation.<ref name=Moore_2010/>
It has the traditional cognate names ''Aspidiske'' (not be confused with ''Asmidiske'', the proper name of Xi Puppis), ''Scutulum'' and ''Turais'' (or ''Tureis'', a name shared with Rho Puppis). Turais is the Arabic ''تُرَيْس'' ''turais'' "small shield" (diminutive), while ''Aspidiske'' and ''Scutulum'' are Greek and Latin translations from ''ασπίδα'' and ''scūtum''.<ref name=allen1899/> In 2016, the International Astronomical Union formed its 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 it approved which included ''Aspidiske'' for this star.
In Chinese, {{lang|zh|海石}} ({{lang|zh-Latn|Hǎi Shí}}), meaning ''Sea Rock'', refers to an asterism consisting of Iota Carinae, Epsilon Carinae, HD 83183, HD 84810 and Upsilon Carinae.<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, Iota Carinae itself is known as {{lang|zh|海石二}} ({{lang|zh-Latn|Hǎi Shí èr}}, {{langx|en|the Second Star of Sea Rock}}).<ref>{{in lang|zh}} [http://www.lcsd.gov.hk/CE/Museum/Space/Research/StarName/c_research_chinengstars_ama_b.htm 香港太空館 – 研究資源 – 亮星中英對照表] {{webarchive|url=https://web.archive.org/web/20100811014924/http://www.lcsd.gov.hk/CE/Museum/Space/Research/StarName/c_research_chinengstars_ama_b.htm |date=2010-08-11 }}, Hong Kong Space Museum. Accessed on line November 23, 2010.</ref>
==Properties== Based on parallax measurements this star is about {{Convert|770|ly|pc|abbr=off|lk=on}} from the Earth. It has a stellar classification of A7 Ib,<ref name=mk/> with the luminosity class of 'Ib' indicating it has reached the stage of its evolution where it has expanded to become a lower-luminosity supergiant. It is just entering the Hertzsprung gap of the Hertzsprung–Russell diagram, and is evolving towards a red supergiant phase.<ref name=Neuhäuser_et_al_2022/>
Iota Carinae has around seven times the Sun's mass and has expanded to roughly 50 times the Sun's radius.<ref name=Neiner2017/> It is radiating about 4,900 times the luminosity of the Sun.<ref name=aaa449_2_655/> However, this luminosity appears to vary, causing the star's apparent magnitude to range between 2.23 and 2.28.<ref name=al32_9_604/> This energy is being radiated into space from the star's outer envelope at an effective temperature of 7,500 K,<ref name=Neiner2017/> giving Iota Carinae the white hue typical of an A-type star.<ref name=csiro/> Being short of the rough initial mass limit above which stars collapse and explode as supernovae, Iota Carinae will likely end its life as a white dwarf with roughly the current mass of the Sun, similar to Sirius B today<ref name="kaler" /> (which was also estimated to have an initial mass of up to 7 solar masses).<ref name=Whittet_1999/>
Due to precession of the Earth's axis of rotation, in the next 7,500 years the south celestial pole will pass close to this star and Upsilon Carinae and it will become the South Star around 8100 CE.<ref name=Precession/> {{clear|right}} == References == {{Reflist|refs=
<ref name=aaa474_2_653>{{cite journal | first=F. | last=van Leeuwen |date=November 2007 | title=Validation of the new Hipparcos reduction | journal=Astronomy and Astrophysics | volume=474 | issue=2 | pages=653–664 | bibcode=2007A&A...474..653V | doi=10.1051/0004-6361:20078357 |arxiv = 0708.1752 | s2cid=18759600 }}</ref>
<ref name=mk>{{Cite journal |last1=Gray |first1=R. O. |last2=Garrison |first2=R. F. |date=1989-07-01 |title=The Late A-Type Stars: Refined MK Classification, Confrontation with Stroemgren Photometry, and the Effects of Rotation |bibcode=1989ApJS...70..623G |journal=The Astrophysical Journal Supplement Series |volume=70 |pages=623 |doi=10.1086/191349 |issn=0067-0049}}</ref>
<ref name=scfs>{{cite journal | display-authors=1 | title=Sixth Catalogue of Fundamental Stars (FK6). Part I. Basic fundamental stars with direct solutions | journal=Veröff. Astron. Rechen-Inst. Heidelb | volume=35 | last1=Wielen | first1=R. | last2=Schwan | first2=H. | last3=Dettbarn | first3=C. | last4=Lenhardt | first4=H. | last5=Jahreiß | first5=H. | last6=Jährling | first6=R. | publisher=Astronomisches Rechen-Institut Heidelberg | issue=35 | date=1999 | page=1 | bibcode=1999VeARI..35....1W }}</ref>
<ref name=clpl4>{{cite journal | display-authors=1 | last1=Johnson | first1=H. L. | last2=Iriarte | first2=B. | last3=Mitchell | first3=R. I. | last4=Wisniewskj | first4=W. Z. | title=UBVRIJKL photometry of the bright stars | journal=Communications of the Lunar and Planetary Laboratory | volume=4 | issue=99 | pages=99 | date=1966 | bibcode=1966CoLPL...4...99J }}</ref>
<ref name=al32_9_604>{{cite journal | display-authors=1 | last1=Ruban | first1=E. V. | last2=Alekseeva | first2=G. A. | last3=Arkharov | first3=A. A. | last4=Hagen-Thorn | first4=E. I. | last5=Galkin | first5=V. D. | last6=Nikanorova | first6=I. N. | last7=Novikov | first7=V. V. | last8=Pakhomov | first8=V. P. | last9=Puzakova | first9=T. Yu. | title=Spectrophotometric observations of variable stars | journal=Astronomy Letters | volume=32 | issue=9 | pages=604–607 |date=September 2006 | doi=10.1134/S1063773706090052 | bibcode=2006AstL...32..604R | s2cid=121747360 }}</ref>
<ref name=aaa449_2_655>{{cite journal | display-authors=1 | last1=Smiljanic | first1=R. | last2=Barbuy | first2=B. | last3=de Medeiros | first3=J. R. | last4=Maeder | first4=A. | title=CNO in evolved intermediate mass stars | journal=Astronomy and Astrophysics | volume=449 | issue=2 | pages=655–671 |date=April 2006 | doi=10.1051/0004-6361:20054377 | bibcode=2006A&A...449..655S |arxiv = astro-ph/0511329 | s2cid=3711409 }}</ref>
<ref name=SIMBAD>{{cite web | title=iot Car -- Variable Star | work=SIMBAD | publisher=Centre de Données astronomiques de Strasbourg | url=http://simbad.u-strasbg.fr/simbad/sim-id?Ident=Iota+Carinae | access-date=2012-01-14 }}</ref>
<ref name=kaler>{{cite web | first1=James B. | last1=Kaler | title=ASPIDISKE (Iota Carinae) | work=Stars | publisher=University of Illinois | url=http://stars.astro.illinois.edu/sow/aspidiske.html | access-date=2012-01-14 }}</ref>
<ref name=allen1899>{{cite journal | first1=Richard Hinckley | last1=Allen | title=Star-names and their meanings | journal=New York | publisher=G. E. Stechert | date=1899 | page=74 | url=https://books.google.com/books?id=5xQuAAAAIAAJ&pg=PA74 | bibcode=1899sntm.book.....A }}</ref>
<ref name="ayres2018">{{Cite journal |last=Ayres |first=Thomas R. |date=2018-02-20 |title=Cracking the Conundrum of F-Supergiant Coronae |journal=The Astrophysical Journal |volume=854 |issue=2 |pages=95 |arxiv=1802.02552 |bibcode=2018ApJ...854...95A |doi=10.3847/1538-4357/aaa6d7 |issn=0004-637X |doi-access=free}}</ref>
<ref name=Neiner2017>{{Cite journal | display-authors=1 |last1=Neiner |first1=Coralie |last2=Oksala |first2=Mary E. |last3=Georgy |first3=Cyril |last4=Przybilla |first4=Norbert |last5=Mathis |first5=Stéphane |last6=Wade |first6=Gregg |last7=Kondrak |first7=Matthias |last8=Fossati |first8=Luca |last9=Blazère |first9=Aurore |last10=Buysschaert |first10=Bram |last11=Grunhut |first11=Jason |date=2017-10-01 |title=Discovery of magnetic A supergiants: the descendants of magnetic main-sequence B stars |bibcode=2017MNRAS.471.1926N |arxiv=1707.00560|journal=Monthly Notices of the Royal Astronomical Society |volume=471 |issue=2 |pages=1926–1935 |doi=10.1093/mnras/stx1549 |doi-access=free |issn=0035-8711}}</ref>
<ref name=csiro>{{cite web |title=The Colour of Stars |date=December 21, 2004 |work=Australia Telescope, Outreach and Education |publisher=Commonwealth Scientific and Industrial Research Organisation |url=http://outreach.atnf.csiro.au/education/senior/astrophysics/photometry_colour.html |access-date=2012-01-16 |url-status=dead |archive-url=https://web.archive.org/web/20120318151427/http://outreach.atnf.csiro.au/education/senior/astrophysics/photometry_colour.html |archive-date=March 18, 2012 }}</ref>
<ref name=uves>{{cite journal|bibcode=2016NewA...47...46T|arxiv=1512.03762|title=Abundance analysis of the supergiant stars HD 80057 and HD 80404 based on their UVES Spectra|journal=New Astronomy|volume=47|pages=46–56|last1=Tanrıverdi|first1=T.|last2=Baştürk|first2=Ö.|year=2016|doi=10.1016/j.newast.2016.02.006|s2cid=119220398}}</ref>
<ref name="IAU-CSN">{{cite web | url=http://www.pas.rochester.edu/~emamajek/WGSN/IAU-CSN.txt | title=IAU Catalog of Star Names |access-date=28 July 2016}}</ref>
<ref name=Whittet_1999>{{Cite journal | last=Whittet | first=D. C. B. | date=December 1999 | title=A physical interpretation of the 'red Sirius' anomaly | journal=Monthly Notices of the Royal Astronomical Society | volume=310 | issue=2 | pages=355–359 | doi=10.1046/j.1365-8711.1999.02975.x | doi-access=free | bibcode=1999MNRAS.310..355W | issn=0035-8711 }}</ref>
<ref name=Neuhäuser_et_al_2022>{{Cite journal | 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. | date=July 29, 2022 | title=Colour evolution of Betelgeuse and Antares over two millennia, derived from historical records, as a new constraint on mass and age | journal=Monthly Notices of the Royal Astronomical Society | volume=516 | issue=1 | pages=693–719 | doi=10.1093/mnras/stac1969 | doi-access=free | issn=0035-8711 | arxiv=2207.04702 | bibcode=2022MNRAS.516..693N }}</ref>
<ref name="WGSN">{{cite web | url=https://www.iau.org/science/scientific_bodies/working_groups/280/ | title=IAU Working Group on Star Names (WGSN) | publisher=International Astronomical Union | access-date=22 May 2016 | archive-date=10 June 2016 | archive-url=https://web.archive.org/web/20160610172014/https://www.iau.org/science/scientific_bodies/working_groups/280/ | url-status=dead }}</ref>
<ref name="WGSN1">{{cite web | url=http://www.pas.rochester.edu/~emamajek/WGSN/WGSN_bulletin1.pdf | title=Bulletin of the IAU Working Group on Star Names, No. 1 | access-date=28 July 2016 }}</ref>
<ref name=Moore_2010>{{cite book | last=Moore | first=Patrick | title=Patrick Moore's Astronomy: Teach Yourself | publisher=Hachette | year=2010 | isbn=978-1444129779 | url=https://books.google.com/books?id=D7M0Rgc1ONAC&pg=PT127 }}</ref>
<ref name=Precession>{{Cite web | first=Kieron | last=Taylor | date=March 1, 1994 | url=http://moonkmft.co.uk/Precession.html | website=moonkmft | title=Precession | access-date=2025-09-08 }}</ref>
}}
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<!--Physical properties --> Category:A-type supergiants Category:Suspected variables <!-- Constellation/catalogues --> Category:Carina (constellation) Carinae, Iota 3699 Category:Durchmusterung objects 080404 045556 Aspidiske Category:Brightest stars