{{Short description|Star in the constellation Centaurus}} {{Starbox begin|name=HD 131399}} {{Starbox image |image=[[File:SPHERE observations of the planet HD 131399Ab.tif|250px]] |credit=ESO/K. Wagner et al. |caption=SPHERE image of HD 131399 A (top left), B and C (bottom right), and the background object (center) }} {{Starbox observe |epoch=[[J2000]] |constell=[[Centaurus]]<ref>{{cite constellation|HD 131399}}</ref> |ra={{RA|14|54|25.30919}}<ref name=HIP>{{cite journal|title=Validation of the new Hipparcos reduction|author=van Leeuwen, F.|display-authors=etal|journal=Astronomy and Astrophysics|volume=474|issue=2|pages=653–664|date=2007|arxiv=0708.1752|bibcode=2007A&A...474..653V|doi=10.1051/0004-6361:20078357|s2cid = 18759600}}</ref> |dec={{DEC|-34|08|34.0412}}<ref name=HIP/> |appmag_v=7.07<ref name=TYC2>{{cite journal|title=The Tycho-2 catalogue of the 2.5 million brightest stars|author=Høg, E.|display-authors=etal|date=2000|journal=Astronomy and Astrophysics|volume=355|pages=L27–L30|bibcode=2000A&A...355L..27H}}</ref> }} {{Starbox character |class=A1V + G + K<ref name=Wagner/> }} {{Starbox astrometry |radial_v={{val|0.30|1.3}}<ref name=Kharchenko>{{cite journal|title=Astrophysical supplements to the ASCC-2.5: Ia. Radial velocities of ~55000 stars and mean radial velocities of 516 Galactic open clusters and associations|author=Kharchenko, N. V.|display-authors=etal|journal=Astronomische Nachrichten|volume=328|issue=9|page=889|date=2007|bibcode=2007AN....328..889K|doi=10.1002/asna.200710776|arxiv=0705.0878|s2cid=119323941}}</ref> |dist_pc={{val|107.9|+4.5|-3.7}}<ref name=Nielsen>{{Cite journal|title=Evidence that the Directly-Imaged Planet HD 131399 Ab is a Background Star|journal=The Astronomical Journal|volume=154|issue=6|pages=218|author1=Nielsen, Eric L.|display-authors=etal|date=2017|arxiv=1705.06851|doi=10.3847/1538-3881/aa8a69|bibcode=2017AJ....154..218N|s2cid=55138870 |doi-access=free }}</ref> |dist_ly={{val|351|+15|-12}} }} {{Starbox astrometry|no_heading=y |component1 = A |prop_mo_ra = −30.702<ref name=dr3a/> |prop_mo_dec = −30.774<ref name=dr3a/> |parallax = 9.7480 |p_error = 0.0357 |parallax_footnote = <ref name=dr3a>{{cite Gaia DR3|6204835284262018688}}</ref> |absmag_v=1.89<ref name=przbylla2017/> |component2 = BC |prop_mo_ra2 = −31.523<ref name=dr3b/> |prop_mo_dec2 = −31.047<ref name=dr3b/> |parallax2 = 9.3021 |p_error2 = 0.0633 |parallax_footnote2 = <ref name=dr3b>{{cite Gaia DR3|6204835284262018176}}</ref> }} {{Starbox orbit |primary=A |name=BC |reference=<ref name=Wagner>{{cite journal|bibcode=2016Sci...353..673W|doi=10.1126/science.aaf9671|pmid=27386921|arxiv=1607.02525|title=Direct imaging discovery of a Jovian exoplanet within a triple-star system|journal=Science|volume=353|issue=6300|pages=673–8|year=2016|last1=Wagner|first1=K.|last2=Apai|first2=D.|last3=Kasper|first3=M.|last4=Kratter|first4=K.|author4-link=Kaitlin Kratter|last5=McClure|first5=M.|last6=Robberto|first6=M.|last7=Beuzit|first7=J.-L.|s2cid=206650422}}{{Retracted|doi=10.1126/science.abq1709|pmid=35420970|https://retractionwatch.com/2022/04/14/triple-sunrise-triple-sunset-science-paper-retracted-when-it-turns-out-a-planet-is-a-star/ ''Retraction Watch''|intentional=yes}}</ref> |period={{val|fmt=commas|3556|36}} |axis={{val|3.56|0.03}} |axis_unitless={{val|349|28|ul=au}} |inclination=45 to 65 |node={{val|265|20}}<ref group=note>There are two solutions; the other one is {{val|75|10|u=°}}.</ref> |periastron=[[Besselian year|B]] {{val|502|33}} |eccentricity={{val|0.13|0.05}} |periarg={{val|145.3|15}}<ref group=note>There are two solutions; the other one is {{val|310|10|u=°}}.</ref> }} {{Starbox detail |source= |age_myr={{val|21.9|+4.1|-3.8}}<ref name=Nielsen/> |component2=HD 131399 A |mass2={{val|1.95|0.08|0.06}}<ref name=przbylla2017/> |luminosity2={{val|14.8|2.6|2.2}}<ref name=przbylla2017/> |temperature2={{val|9200|100|fmt=commas}}<ref name=przbylla2017/> |radius2={{val|1.51|0.13|0.10}}<ref name=przbylla2017/> |gravity2={{val|4.37|0.10}}<ref name=przbylla2017/> |rotational_velocity2={{val|26|2}}<ref name=przbylla2017/> }} {{Starbox detail|no_heading=y |component1=HD 131399 B |mass={{val|0.95|0.04}}<ref name=Nielsen/> |temperature={{val|4890|190|170|fmt=commas}}<ref name=Nielsen/> |gravity={{val|4.40|0.03}}<ref name=Nielsen/> |component2=HD 131399 C |mass2={{val|0.35|0.04}}<ref name=Nielsen/> |temperature2={{val|3460|60|fmt=commas}}<ref name=Nielsen/> |gravity2={{val|4.45|0.05}}<ref name=Nielsen/> }} {{Starbox catalog |names={{odlist|CD=-33°10153|HIP=72940|SAO=206071}} }} {{Starbox reference |Simbad=HD+131399 }} {{Starbox end}} '''HD 131399''' is a [[star system]] in the [[constellation]] of [[Centaurus]]. Based on the system's electromagnetic spectrum, it is located around 350 light-years (107.9 parsecs) away.<ref name=Nielsen/> The total [[apparent magnitude]] is 7.07,<ref name=Nielsen/> but because of [[interstellar dust]] between it and the Earth, it appears {{val|0.22|0.09}} magnitudes [[Interstellar extinction|dimmer]] than it should.<ref name=Nielsen/>
The brightest star, is a young [[A-type main-sequence star]], and further out are three lower-mass stars.<ref name=Wagner/> A [[Jupiter]]-mass planet or a low-mass [[brown dwarf]] was once thought to be orbiting the central star, but this has been ruled out.<ref name=Nielsen/><ref name=Wagner_retraction>{{Cite journal |last1=Wagner |first1=Kevin |last2=Apai |first2=Dániel |last3=Kasper |first3=Markus |last4=Kratter |first4=Kaitlin|author4-link=Kaitlin Kratter |last5=McClure |first5=Melissa |last6=Robberto |first6=Massimo |last7=Beuzit |first7=Jean-Luc |date=2022-04-15 |title=Retraction |journal=Science |language=en |volume=376 |issue=6590 |pages=255 |doi=10.1126/science.abq1709|pmid=35420970 |bibcode=2022Sci...376..255W |s2cid=248180563 |issn=0036-8075|url=https://www.science.org/doi/10.1126/science.abq1709 |url-access=subscription }}</ref>
==Stellar system== The brightest star in the HD 131399 system is designated HD 131399 A. Its spectral type is A1V,<ref name=Wagner/> and it is 2.08 times as massive as the Sun.<ref name=Nielsen/> The two lower-mass stars are designated HD 131399 B and C, respectively. B is a [[G-type main-sequence star]], while HD 131399 C is a [[K-type main-sequence star]].<ref name=Wagner/> Both stars are less massive than the Sun.<ref name=Nielsen/> A lower-mass companion to HD 131399 A was announced in 2017, at a separation of 0.12 [[astronomical unit]]s (au).<ref>{{Cite journal |last1=Lagrange |first1=A.-M. |last2=Keppler |first2=M. |last3=Beust |first3=H. |last4=Rodet |first4=L. |last5=Meunier |first5=N. |last6=Lillo-Box |first6=J. |last7=Bonnefoy |first7=M. |last8=Galland |first8=F. |date=December 2017 |title=Discovery of a stellar companion to HD 131399A |journal=Astronomy & Astrophysics |volume=608 |pages=L9 |doi=10.1051/0004-6361/201730978 |bibcode=2017A&A...608L...9L |issn=0004-6361}}</ref>
HD 131399 B and C are located very close to each other, and the two orbit each other at about 10 AU.<ref name="SciNews"/> In turn, the B-C pair orbits the central star A at a distance of 349 AU. This orbit takes about 3,600 years to complete, and it has an eccentricity of about 0.13<ref name=Wagner/> The entire system is about 21.9 million years old.<ref name=Nielsen/>
One paper has reported that HD 131399 A has a companion in an inclined 10-day orbit with a [[semi-major axis]] of {{val|0.1|ul=AU}}.<ref name=lagrange2017>{{cite journal |doi=10.1051/0004-6361/201730978 |title=Discovery of a stellar companion to HD 131399A |year=2017 |last1=Lagrange |first1=A.-M. |last2=Keppler |first2=M. |last3=Beust |first3=H. |last4=Rodet |first4=L. |last5=Meunier |first5=N. |last6=Lillo-Box |first6=J. |last7=Bonnefoy |first7=M. |last8=Galland |first8=F. |journal=Astronomy & Astrophysics |volume=608 |pages=L9 |bibcode=2017A&A...608L...9L |doi-access=free }}</ref> HD 131399 A has been described as a "nascent [[Am star]]"; although it has a very slow projected rotation rate and would be expected to show [[chemically peculiar star|chemical peculiarities]], its [[stellar spectrum|spectrum]] is relatively normal, possibly due to its young age.<ref name=przbylla2017>{{cite journal |doi=10.1051/0004-6361/201731384 |title=Candidate exoplanet host HD 131399A: A nascent Am star |year=2017 |last1=Przybilla |first1=N. |last2=Aschenbrenner |first2=P. |last3=Buder |first3=S. |journal=Astronomy & Astrophysics |volume=604 |pages=L9 |arxiv=1707.07920 |bibcode=2017A&A...604L...9P |s2cid=119230582 }}</ref>
==Claims of a planetary system== {{Main|HD 131399 Ab}} [[File:An artist’s impression of planet in the HD 131399 system.tif|thumb|Artist's impression of HD 131399 Ab, before it was found to be a background star.]] The claimed discovery of a massive planet, named HD 131399 Ab, was announced in a paper published in the journal ''[[Science (journal)|Science]]''.<ref name=Wagner/> The object was imaged using the [[Spectro-Polarimetric High-Contrast Exoplanet Research|SPHERE]] imager of the [[Very Large Telescope]] at the [[European Southern Observatory]], located in the [[Atacama Desert]] of [[Chile]], and announced in a July 2016 paper in the journal ''[[Science (journal)|Science]]''.<ref name="Wagner"/><ref name="cbsnews"/> It was thought to be a [[T-type star|T-type]] object with a mass of {{val|4|1|ul=Jupiter mass}},<ref name=Wagner/> but its orbit would have been unstable, causing it to be ejected between the primary's [[red giant branch|red giant phase]] and [[white dwarf]] phase.<ref>{{cite journal|bibcode=2017MNRAS.465.1499V|doi=10.1093/mnras/stw2821|arxiv=1611.00007|title=The unstable fate of the planet orbiting the a star in the HD 131399 triple stellar system|journal=Monthly Notices of the Royal Astronomical Society|volume=465|issue=2|pages=1499|year=2017|last1=Veras|first1=Dimitri|last2=Mustill|first2=Alexander J.|last3=Gänsicke|first3=Boris T.|doi-access=free |s2cid=73723946}}</ref> This was the first exoplanet candidate to be discovered by SPHERE. The image was created from two separate SPHERE observations: one to image the three stars and one to detect the faint planet.<ref name=ESO>{{cite web|url=https://www.eso.org/public/news/eso1624/|title=A Surprising Planet with Three Suns|last=|work=[[ESO]]|access-date=7 July 2016}}</ref> After its discovery, the team unofficially named the system "Scorpion-1" and the planet "Scorpion-1b", after the survey that prompted its discovery, the Scorpion Planet Survey (principal investigator: [[Daniel Apai]]).<ref name="Scorpion-1b">{{cite web|last1=Miller|first1=Michael|title=UC mountaineer, galactic explorer|url=http://magazine.uc.edu/editors_picks/recent_features/scorpion.html|website=UC Magazine|publisher=[[University of Cincinnati]]|date=12 April 2017|access-date=3 May 2017}}</ref>
In May 2017, observations made by the [[Gemini Planet Imager]] and including a reanalysis of the SPHERE data suggest that this target is, in fact, a [[Fixed stars|background star]]. This object's [[spectrum]] seems to be like that of a [[K-type main-sequence star|K-type]] or [[red dwarf|M-type dwarf]], not a T-type object as first thought. It also initially appeared to be associated with HD 131399, but this was because of its unusually high [[proper motion]] (in the top 4% fastest-moving stars).<ref name=Nielsen/> After subsequent data published in 2022 confirmed that the object is a background star,<ref>{{Cite journal |last1=Wagner |first1=Kevin |last2=Apai |first2=Dániel |last3=Kasper |first3=Markus |last4=McClure |first4=Melissa |last5=Robberto |first5=Massimo |date=2022-02-01 |title=The Scorpion Planet Survey: Wide-orbit Giant Planets Around Young A-type Stars |journal=The Astronomical Journal |volume=163 |issue=2 |pages=80 |doi=10.3847/1538-3881/ac409d |doi-access=free |issn=0004-6256|arxiv=2112.02168 }}</ref> the paper announcing the putative discovery was [[Retractions in academic publishing|retracted]].<ref name=Wagner_retraction/><ref>{{cite web |last1=Oransky |first1=Ivan |title=Triple sunrise, triple sunset: Science paper retracted when it turns out a planet is a star |url=https://retractionwatch.com/2022/04/14/triple-sunrise-triple-sunset-science-paper-retracted-when-it-turns-out-a-planet-is-a-star/#more-124683 |website=Retraction Watch |access-date=25 April 2022 |date=14 April 2022}}</ref>
==References== <references> <ref name="SciNews">{{Cite web|url=http://www.sci-news.com/astronomy/hd-131399ab-super-jupiter-triple-star-system-04008.html|title=HD 131399Ab: Astronomers Find Super-Jupiter in Triple-Star System {{!}} Astronomy {{!}} Sci-News.com|language=en-US|access-date=8 July 2016}}</ref>
<ref name="cbsnews">{{cite web |title=This strange new planet has three suns |url=https://www.cbsnews.com/news/planet-with-three-suns-triple-sunrises-sunsets/ |work=[[CBS News]] |date=7 July 2016 |access-date=7 July 2016}}</ref> </references>
==Notes== {{reflist|group=note}}
{{Stars of Centaurus}}
[[Category:Centaurus]] [[Category:Hypothetical planetary systems]] [[Category:A-type main-sequence stars]] [[Category:G-type main-sequence stars]] [[Category:K-type main-sequence stars]] [[Category:Durchmusterung objects]] [[Category:Henry Draper Catalogue objects|131399]] [[Category:Hipparcos objects|072940]] [[Category:Triple star systems]]