View source for TIC 168789840

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[[File:Transiting Exoplanet Survey Satellite artist concept (transparent background).png | left | thumb | Astronomers used the orbiting TESS telescope to determine TIC 168789840 was lined up so all six star's eclipses could be observed.]]
'''TIC 168789840''' is a stellar system with six stars.<ref name=nytimes2021-01-23/><ref name=arxiv2101-03433/>  Three pairs of binary stars circle a common [[barycenter]]. ''[[The New York Times]]'' noted that, while other systems with six pairs of stars had been discovered, this was the first system where the stars can be observed eclipsing one another, as their plane of rotation pointed towards the earth.

Orbital telescope [[Transiting Exoplanet Survey Satellite]] identified that the star system consisted of six eclipsing stars.<ref name=Wion2021-01-28/>  The discovery was announced in January 2021.  It is approximately 1900 lightyears from Earth, in the constellation [[Eridanus]].

Two of the pairs of binaries were close binaries, while the orbit of the third pair of binary stars took 2,000 years to orbit the barycenter.<ref name=nytimes2021-01-23/><ref name=SciNews2021-01-25/><ref name=Forbes2021-01-28/>

According to [[Jeanette Kazmierczak]] of [[NASA]]'s [[Goddard Space Flight Center]]<ref name=Nasa2021-01-27/>:
{| class="wikitable"
|
: ''The stars in the A and C systems orbit each other roughly every day and a half, and the two binaries orbit each other about every four years. The B binary’s members circle each other about every eight days, but the pair is much farther away, orbiting around the inner systems roughly every 2,000 years.<ref name=Nasa2021-01-27/>
|}
All primary stars of all three binaries are slightly brighter than [[Sol]], Earth's sun, while the secondary stars are all about one third dimmer.<ref name=Wion2021-01-28/>  Because the two closely bound pairs are so close only the third, more distant pair could have planets.<ref name=nytimes2021-01-23/>

==References==
{{Reflist|refs= 
<ref name=arxiv2101-03433>
{{cite news     
| url         = https://arxiv.org/abs/2101.03433
| title       = TIC 168789840: A Sextuply-Eclipsing Sextuple Star System
| work        = [[AAS Journals]]
| author      = 
| date        = 2021-01-09
| page        = 
| location    = 
| isbn        = 
| language    = 
| trans-title = 
| archiveurl  = https://web.archive.org/web/20210128161105/https://arxiv.org/abs/2101.03433
| archivedate = 2021-01-28
| accessdate  = 2021-01-29
| url-status  = live
| quote       = 
}}
</ref>

<ref name=Nasa2021-01-27>
{{cite news     
| url         = https://exoplanets.nasa.gov/news/1672/discovery-alert-first-six-star-system-where-all-six-stars-undergo-eclipses/
| title       = Discovery Alert: First Six-star System Where All Six Stars Undergo Eclipses
| work        = [[NASA]]'s [[Goddard Space Flight Center]]
| author      = Jeanette Kazmierczak
| date        = 2021-01-27
| location    = [[Greenbelt, Maryland]]
| archiveurl  = https://web.archive.org/web/20210127224045/https://exoplanets.nasa.gov/news/1672/discovery-alert-first-six-star-system-where-all-six-stars-undergo-eclipses/
| archivedate = 2021-01-27
| accessdate  = 2021-01-29
| url-status  = live
| quote       = The system, also called TIC 168789840, is the first known sextuple composed of three sets of eclipsing binaries, stellar pairs whose orbits tip into our line of sight so we observe the stars alternatively passing in front of each other.
}}
</ref>

<ref name=SciNews2021-01-25>
{{cite news     
| url         = http://www.sci-news.com/astronomy/tess-sextuply-eclipsing-six-star-system-09282.html
| title       = TESS Discovers Sextuply-Eclipsing Six-Star System
| work        = [[Sci-News]]
| author      = Natali Anderson
| date        = 2021-01-25
| archiveurl  = https://web.archive.org/web/20210126210223/http://www.sci-news.com/astronomy/tess-sextuply-eclipsing-six-star-system-09282.html
| archivedate = 2021-01-26
| accessdate  = 2021-01-29
| url-status  = live
| quote       = {{'}}Prior to the discovery of TIC 168789840, there were 17 known sextuple star systems according to the June 2020 update of the Multiple Star Catalog,{{'}} lead author Dr. Brian Powell of NASA’s Goddard Space Flight Center and colleagues wrote in their paper.
}}
</ref>

<ref name=Forbes2021-01-28>
{{cite news     
| url         = https://www.forbes.com/sites/jamiecartereurope/2021/01/28/you-should-know-about-the-weird-sextuple-star-system-just-found-by-nasa-where-six-suns-eclipse-each-other/?sh=60bfadcc7698
| title       = A Weird ‘Sextuple’ Star System Has Been Found By NASA Where Six Suns Eclipse Each Other
| work        = [[Forbes magazine]]
| author      = Jamie Carter
| date        = 2021-01-28
| page        = 
| location    = 
| isbn        = 
| language    = 
| trans-title = 
| archiveurl  = https://web.archive.org/web/20210129101812/https://www.forbes.com/sites/jamiecartereurope/2021/01/28/you-should-know-about-the-weird-sextuple-star-system-just-found-by-nasa-where-six-suns-eclipse-each-other/?sh=60bfadcc7698
| archivedate = 2021-01-29
| accessdate  = 2021-01-29
| url-status  = live      
| quote       = 
}}
</ref>

<ref name=Wion2021-01-28>
{{cite news     
| url         = https://www.wionews.com/science/astronomers-find-a-system-of-six-stars-made-of-three-eclipsing-binaries-359797
| title       = Astronomers find a system of six stars made of three eclipsing binaries
| work        = [[WION]]
| date        = 2021-01-28
| location    = [[Washington, DC]]
| archiveurl  = https://web.archive.org/web/20210128050008/https://www.wionews.com/science/astronomers-find-a-system-of-six-stars-made-of-three-eclipsing-binaries-359797
| archivedate = 2021-01-28
| accessdate  = 2021-01-29
| url-status  = live
| quote       = The primary stars in all three binaries are all slightly bigger and more massive than the Sun and about as hot. The system, also called TIC 168789840, is located about 1,900 light-years away in the constellation Eridanus.
}}
</ref>

<ref name=nytimes2021-01-23>
{{cite news     
| url         = https://www.nytimes.com/2021/01/23/science/six-stars-eclipses.html
| title       = Six Stars, Six Eclipses: ‘The Fact That It Exists Blows My Mind’
| work        = [[The New York Times]]
| author      = Robin George Andrews
| date        = 2021-01-23
| archiveurl  = https://web.archive.org/web/20210128114723/https://www.nytimes.com/2021/01/23/science/six-stars-eclipses.html
| archivedate = 2021-01-28
| accessdate  = 2021-01-29
| url-status  = live
| quote       = But only one of the pairs could have any planets. Two of the system’s binaries orbit extremely close to one another, forming their own quadruple subsystem. Any planets there would likely be ejected or engulfed by one of the four stars. The third binary is farther out, orbiting the other two once every 2,000 years or so, making it a possible exoplanetary haven.
}}
</ref>
}}

[[Category:Multiple star systems|6]]