编辑“︁TOI-178”︁

{{Starbox begin
| name = TOI-178
}}
<!-- {{Starbox image
| image = 
| caption = ADD APPROPRIATE IMAGE
| credit =
}} -->
{{Starbox observe
| epoch = J2000
| constell = [[玉夫座]]
| ra = {{RA|00|29|12.30}}<ref name=":1" />
| dec = {{DEC|−30|27|13.46}}<ref name=":1" />
| appmag_v = 11.95<ref name=":1" />
}}
{{Starbox character
| type = [[主序星]]
| class = [[K-型主序星|K]]<ref name=":1"/>
| variable =
}}
{{Starbox astrometry
| radial_v = {{val|57.4|0.5}}<ref name=":1" />
| prop_mo_ra = {{val|149.95|0.07}}<ref name=":1" />
| prop_mo_dec = {{val|-87.25|0.04}}<ref name=":1" />
| parallax = 15.92
| p_error = 0.05
| parallax_footnote =<ref name=":1" />
| absmag_v = 
}}
{{Starbox detail
| mass                   =   {{val|0.650|0.027|0.029}}<ref name=":1" />
| radius                 =   {{val|0.651|0.011}}<ref name=":1" />
| luminosity_bolometric  =   {{val|0.132|0.010}}<ref name=":1" />
| gravity                =   {{val|4.45|0.15}}<ref name=":1" />
| temperature            =   {{val|4316|70}}<ref name=":1" />
| metal_fe               =   {{val|-0.23|0.05}}<ref name=":1" />
| rotational_velocity    =   {{val|1.5|0.3}}<ref name=":1" />
}}
{{Starbox catalog
| names = [[2微米全天巡天|2MASS]] J00291228-3027133、Gaia DR2 2318295979126499200、TIC 251848941、TYC 6991-00475-1
}}
{{Starbox reference
| Simbad = TOI-178
}}
{{Starbox end}}

'''TOI-178'''是在[[玉夫座]]這個星座中的一個[[行星系]]<ref name="Roman1987">{{Cite journal|last=Roman|first=Nancy G.|year=1987|title=Identification of a Constellation From a Position|url=http://vizier.u-strasbg.fr/vizier/VizieR/constellations.htx|journal=Publications of the Astronomical Society of the Pacific|volume=99|issue=617|page=695–699|bibcode=1987PASP...99..695R|doi=10.1086/132034|access-date=2021-03-06|archive-date=2019-07-17|archive-url=https://web.archive.org/web/20190717180728/http://vizier.u-strasbg.fr/vizier/VizieR/constellations.htx}}. [http://vizier.cfa.harvard.edu/viz-bin/VizieR-5?-ref=VIZ5e1c7bb21397f&-out.add=.&-source=VI/42/out&-c=005.7476%20-31.1454,eq=B1875,rs=2 Requête spécifique à TOI-178] sur [[VizieR]].</ref>，在一系列[[軌道共振|拉普拉斯共振]]中至少有五顆行星，而且還可能有第六顆。這是在行星系統中發現最長的共振鏈之一。這個系統的行星，在密度上也有不尋常的變化<ref name=":0">{{Cite web|last=Plait|first=Phil|date=2021-01-25|title=A six-planet system dances in time to the tune of gravity|url=https://www.syfy.com/syfywire/a-six-planet-system-dances-in-time-to-the-tune-of-gravity|access-date=2021-01-27|website=SYFY WIRE|language=en|archive-date=2021-05-31|archive-url=https://web.archive.org/web/20210531124748/https://www.syfy.com/syfywire/a-six-planet-system-dances-in-time-to-the-tune-of-gravity}}</ref><ref name=":2">{{Cite web|title=Nearby Orange Dwarf Hosts Unique System of Six Planets {{!}} Astronomy {{!}} Sci-News.com|url=http://www.sci-news.com/astronomy/orange-dwarf-toi-178-system-six-planets-09284.html|access-date=2021-01-27|website=Breaking Science News {{!}} Sci-News.com|language=en-US|archive-date=2021-02-05|archive-url=https://web.archive.org/web/20210205011348/http://www.sci-news.com/astronomy/orange-dwarf-toi-178-system-six-planets-09284.html}}</ref><ref name=":1">{{Cite journal| last=Leleu | first=A. | last2=Alibert | first2=Y. | last3=Hara | first3=N. 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M. | last141=Ségransan | first141=D. | last142=Thomas | first142=N. | last143=Thompson | first143=S. | last144=Tilbrook | first144=R. H. | last145=Triaud | first145=A. | last146=Turner | first146=O. | last147=Udry | first147=S. | last148=Grootel | first148=Van | last149=Venus | first149=H. | last150=Verrecchia | first150=F. | last151=Vines | first151=J. I. | last152=Walton | first152=N. A. | last153=West | first153=R. G. | last154=Wheatley | first154=P. J. | last155=Wolter | first155=D. | last156=Osorio | first156=Zapatero | last157=R. | first157=M. | display-authors=20 |date=2021-01-20|title=Six transiting planets and a chain of Laplace resonances in TOI-178|journal=Astronomy & Astrophysics|language=en|arxiv=2101.09260|doi=10.1051/0004-6361/202039767|issn=0004-6361|s2cid=231693292 }}</ref>。

這個系統距離地球約205[[光年]]，距離如此接近，意味著這一類的行星系統可能較為常見<ref name=":2" /><ref name=":0" />。這顆名為TOI-178a的恆星亮度有助於後續的觀測，這使它成為一個理想的系統。在這個系統中，我們可以擴展對行星形成和演化的理解<ref name=":1" />。

五個不同的行星搜索專案提供的數據證實了這個行星系統。在[[凌日系外行星巡天衛星]](TESS，Transiting Exoplanet Survey Satellite)提供了令人感興趣，具有共振鏈系統的初步線索之後，[[系外行星特性探測衛星]](CHEOPS)、{{link-en| ESPRESSO | ESPRESSO }}、[[次世代凌星巡天]]( NGTS，Next-Generation Transit Survey)、和{{link-en| SPECULOOS| SPECULOOS}}都提供了確認發現和改進量測的額外觀測。在未來幾年中，對各種行星凌日過程中[[凌日時間變分法|凌日時間變化]]的觀測，預計在數分鐘至數十分鐘之間，將有助於卻行星質量，並揭示各種軌道的扁率<ref name=":1" />。

== 軌道的共振 ==
根據IAU的{{link-en|系外行星命名慣例|Eexoplanet naming convention}}，這六顆行星命名為TOI-178b到TOI-178g，其外面的五顆行星被鎖定在[[軌道共振|拉普拉斯共振]]的鏈條中。它們繞行母恆星的軌道週期(以天為單位)是b=1.91、c=3.24、d=6.56、e=9.96、f=15.23、和g=20.71。這雖然不是一個完美的整數比，但存在一個參考系，它每天大約旋轉1.37°，行星連續的合形成了一個重複的模式<ref name=":1" />。對於在這個參考系內的觀測者而言，行星c到g形成了一個共振鏈，可以用週期比表示為 2:4:6:9:12，或是用軌道比表示為18:9:6:4:3。這意味著行星c每轉18圈，行星d就完成9圈、行星e轉6圈，行星f轉4圈，行星g轉3圈。

除此之外，行星b的軌道也很接近它共振鏈的一部分。在一個週期約比1.95天稍長的軌道上，它將與行星c形成一個3:5的共振；與其他五顆行星同一個共轉參考系中。有可能整個系統最初形成於一條長長的共振鏈中，但後來最裡面的行星可能被潮汐相互作用從中拉出<ref name=":1" />

{{clear}}

{{Orbitbox planet begin
| name = TOI-178
| table_ref =<ref name=":1" />
}}
{{OrbitboxPlanet
| exoplanet    = b
| mass_earth   = {{val|1.50|0.39|0.44}}
| period       = {{val|1.914558|0.000018}}
| semimajor    = {{val|0.02607|0.00078}}
| eccentricity = 
| inclination  = {{val|88.8|0.8|1.3}}
| radius_earth = {{val|1.152|0.073|0.070}}
}}
{{OrbitboxPlanet
| exoplanet    = c
| mass_earth   = {{val|4.77|0.55|0.68}}
| period       = {{val|3.238450|0.000020|0.000019}}
| semimajor    = {{val|0.0370|0.0011}}
| eccentricity = 
| inclination  = {{val|88.4|1.1|1.6}}
| radius_earth = {{val|1.669|0.114|0.099}}
}}
{{OrbitboxPlanet
| exoplanet    = d
| mass_earth   = {{val|3.01|0.80|1.03}}
| period       = {{val|6.557700|0.000016}}
| semimajor    = {{val|0.0592|0.0018}}
| eccentricity = 
| inclination  = {{val|88.58|0.20|0.18}}
| radius_earth = {{val|2.572|0.075|0.078}}
}}
{{OrbitboxPlanet
| exoplanet    = e
| mass_earth   = {{val|3.86|1.25|0.94}}
| period       = {{val|9.961881|0.000042}}
| semimajor    = {{val|0.0783|0.0023|0.0024}}
| eccentricity = 
| inclination  = {{val|88.71|0.16|0.13}}
| radius_earth = {{val|2.207|0.088|0.090}}
}}
{{OrbitboxPlanet
| exoplanet    = f
| mass_earth   = {{val|7.72|1.67|1.52}}
| period       = {{val|15.231915|0.000115|0.000095}}
| semimajor    = {{val|0.1039|0.0031}}
| eccentricity = 
| inclination  = {{val|88.723|0.071|0.069}}
| radius_earth = {{val|2.287|0.108|0.110}}
}}
{{OrbitboxPlanet
| exoplanet    = g
| mass_earth   = {{val|3.94|1.31|1.62}}
| period       = {{val|20.70950|0.00014|0.00011}}
| semimajor    = {{val|0.1275|0.0038|0.0039}}
| eccentricity = 
| inclination  = {{val|88.823|0.045|0.047}}
| radius_earth = {{val|2.87|0.14|0.13}}
}}
{{Orbitbox end}}

== 相關條目 ==

*[[克卜勒80]]：另一個有5顆行星在共振軌道上的[[行星系]]。

== 參考資料 ==
{{reflist}}

{{2021年太空活動}}
{{系外行星}}
{{Stars of Sculptor|state=collapsed}}
{{Sky|00|29|12.30|-|30|27|13.46|204}}

<!--- Categories --->
[[Category:玉夫座]]
[[Category:K型主序星]]
[[Category:TESS Objects of Interest|178, TOI]]
[[Category:2MASS天體|J00291228-3027133]]
[[Category:Planetary systems with six confirmed planets]]
[[Category:行星凌變星]]