{{Short description|Triple-star system in the constellation Scorpius}} {{Starbox begin | name=Gliese 667 A/B/C }} {{Starbox image | image= {{Location mark |image=Scorpius constellation map.svg|alt=|float=center|width=280 |label=|position=right |mark=Red circle.svg|mark_width=10|mark_link=Gliese 667 |x=322|y=644 }} |caption=Location of Gliese 667 (circled in red) }} {{Starbox observe 2s | epoch=J2000 | constell=Scorpius<ref name=xhip/> | component1=AB | ra1={{RA|17|18|57.16483}}<ref name="van Leeuwen 2007"/> | dec1={{DEC|−34|59|23.1416}}<ref name="van Leeuwen 2007"/> | appmag_v1=5.91/7.20<ref name=CADARS/> | component2=C | ra2={{RA|17|18|58.82730}}<ref name="GaiaDR3"/> | dec2={{DEC|−34|59|48.6127}}<ref name="GaiaDR3"/> | appmag_v2=10.20<ref name=CADARS/> }} {{Starbox character | component1=AB | class={{nowrap|K3V + K5V}}<ref name=CADARS/><!-- | b-v=1.03/???/1.57 | u-b=0.83/???/1.17 | variable=A: suspected<br/>B: unknown<br/>C: flare star{{citation needed|reason=SIMBAD does not list Gliese 667 C as a flare star, there is no variable star or NSV designation, and a query of the GCVS at the coordinates only returns the NSV designation of the AB pair. No reference to Gliese 667 C being a flare star is made in the text.|date=September 2014}}--> | component2 = C | type2=main sequence<ref name=Pineda2021/> | class2=M1.5V<ref name=geballe2002/> }} {{Starbox astrometry | component1 = GJ 667 AB | parallax=138.2 | p_error=0.7 | parallax_footnote=<ref name=Staffan1999/> | absmag_v=6.75<ref name=xhip/> | component2 = GJ 667 C | radial_v2=+6.4<ref name="GaiaDR3"/> | prop_mo_ra2=1131.517 | prop_mo_dec2=−215.569 | pm_footnote2=<ref name="GaiaDR3"/> | parallax2=138.0663 | p_error2=0.0283 | parallax_footnote2=<ref name="GaiaDR3"/> }} {{Starbox visbin | reference=<ref name=Mason2023/> | primary=Gliese 667 A | name=Gliese 667 B | period={{val|42.152|0.039}} | axis={{val|1.8260|0.0017}} | eccentricity={{val|0.57374|0.00029}} | inclination={{val|127.662|0.034}} | node={{val|133.574|0.063}} | periarg={{val|68.451|0.056}} | periastron={{val|1933.752|0.079|fmt=commas}} }} {{Starbox detail | component1=Gliese 667 A | mass={{val|0.65|0.12}}<ref name=Mason2023/> | radius=0.76<ref name=Johnson1983/> | luminosity= | temperature=4,270<ref name=Johnson1983/> | metal_fe=–0.59<ref name=Cayrel2001/> | rotation= | age= | component2 = Gliese 667 B | mass2 = {{val|0.448|0.085}}<ref name=Mason2023/> | radius2 = 0.70<ref name=Johnson1983/> | temperature2 = 3,998<ref name=Johnson1983/> | metal2_fe=–0.59<ref name=Cayrel2001/> }} {{Starbox detail|no_heading=y | component1=Gliese 667 C | mass={{val|0.327|0.008}}<ref name="Pineda2021"/> | radius={{val|0.337|0.014}}<ref name="Pineda2021"/> | luminosity=0.01439{{±|0.00035}}<ref name="Pineda2021"/> | temperature={{val|3443|75|71|fmt=commas}}<ref name="Pineda2021"/> | metal_fe={{nowrap|–0.59 ± 0.10}}<ref name="Anglada-Escudé-2012"/> | rotation={{val|103.9|0.7}}<ref name=SuarezMascareno2015/> days | age_gyr={{val|6.10|2.2}}<ref name=Sloane2023/> }} {{Starbox catalog | names={{odlist| G=142 G. Scorpii |CD=−34°11626 |GJ=667 |HD=156384 |HR=6426 |WDS=J17190-3459 }} | component2 = AB | names2={{odlist |HIP=84709 |LHS=442 |SAO=208670 |2MASS= J17185698-3459236 }} | component3 = C | names3={{odlist |LHS=443 |2MASS=J17185868-3459483 }} }} {{Starbox reference |Simbad=GJ+667|sn=AB |Simbad2=GJ+667+A|sn2=A |Simbad3=GJ+667+B|sn3=B |Simbad4=GJ+667+C|sn4=C |Simbad5=GJ+667+Cb|sn5=Cb |Simbad6=GJ+667+Cc|sn6=Cc |Simbad7=GJ+667+Ce|sn7=Ce |Simbad8=GJ+667+Cf|sn8=Cf |Simbad9=GJ+667+Cg|sn9=Cg | NSTED = GJ-667 | ARICNS =01387 |an=A | ARICNS2 =01388 |an2=B | ARICNS3 =01389 |an3=C }} {{starbox end}}
'''Gliese 667''' (142 G. Scorpii) is a triple-star system in the constellation Scorpius lying at a distance of about {{convert|7.2|pc|lk=on|abbr=off}} from Earth. All three of the stars have masses smaller than the Sun. To the naked eye, the system appears to be a single faint star of magnitude 5.89. The system has a relatively high proper motion, exceeding 1 second of arc per year.
There is a 12th-magnitude star visually close to the other three, but it is a distant background star not gravitationally bound to the system.<ref>{{cite simbad |title=UCAC3 111-246272 |access-date=24 February 2025}}</ref>
The two brightest stars in this system, GJ 667 A and GJ 667 B, are orbiting each other at an average angular separation of 1.81 arcseconds with a high eccentricity of 0.58. At the estimated distance of this system, this is equivalent to a physical separation of about 12.6 AU, or nearly 13 times the separation of the Earth from the Sun. Their eccentric orbit brings the pair as close as about 5 AU to each other, or as distant as 20 AU, corresponding to an eccentricity of 0.6.<ref group="note">Based on a calculated eccentricity value of <math>e={{r_a-r_p}\over{r_a+r_p}}</math>.</ref><ref name="bowman"/> This orbit takes approximately 42.15 years to complete and the orbital plane is inclined at an angle of 128° to the line of sight from the Earth. The third star, GJ 667 C, orbits the GJ 667 AB pair at an angular separation of about 30", which equates to a minimum separation of 230 AU.<ref name="Anglada-Escudé-2012"/><ref name=Gregory/> GJ 667 C also has a system of two confirmed super-Earths and a number of additional doubtful candidates, though the innermost, GJ 667 Cb, may be a gas dwarf; GJ 667 Cc, and the controversial Cf and Ce, are in the circumstellar habitable zone.<ref>{{Cite web|url=https://www.drewexmachina.com/2014/09/07/habitable-planet-reality-check-gj-667c/|title=Habitable Planet Reality Check: GJ 667C|date=September 7, 2014|website=Drew Ex Machina|access-date=July 18, 2019|archive-date=May 21, 2020|archive-url=https://web.archive.org/web/20200521080501/http://www.drewexmachina.com/2014/09/07/habitable-planet-reality-check-gj-667c/|url-status=live}}</ref>
== Gliese 667 A == The largest star in the system, Gliese 667 A (GJ 667 A), is a K-type main-sequence star of stellar classification K3V.<ref name=CADARS/> It has about 65%<ref name=Mason2023/> of the mass of the Sun and 76%<ref name=CADARS/> of the Sun's radius, but is radiating only around 12-13% of the luminosity of the Sun.<ref name=news/> The concentration of elements other than hydrogen and helium, what astronomers term the star's metallicity, is much lower than in the Sun with a relative abundance of around 26% solar.<ref name=Cayrel2001/> The apparent visual magnitude of this star is 6.29, which, at the star's estimated distance, gives an absolute magnitude of around 7.07 (assuming negligible extinction from interstellar matter).
== Gliese 667 B == Like the primary, the secondary star Gliese 667 B (GJ 667 B) is a K-type main-sequence star, although it has a slightly later stellar classification of K5V. This star has a mass of about 45%<ref name=Mason2023/> of the Sun, or 69% of the primary's mass, and it is radiating about 5% of the Sun's visual luminosity. The secondary's apparent magnitude is 7.24, giving it an absolute magnitude of around 8.02.
== Gliese 667 C == Gliese 667 C is the smallest star in the system, with only around 33%<ref name="Pineda2021"/> of the mass of the Sun and 34%<ref name="Pineda2021"/> of the Sun's radius, orbiting approximately 230 AU from the Gliese 667 AB pair.<ref name="Anglada-Escudé-2013">{{cite journal |title=A dynamically-packed planetary system around GJ 667C with three super-Earths in its habitable zone |first1=Guillem |last1=Anglada-Escudé |first2=Mikko |last2=Tuomi |first3=Enrico |last3=Gerlach |first4=Rory |last4=Barnes |first5=René |last5=Heller |first6=James S. |last6=Jenkins |first7=Sebastian |last7=Wende |first8=Steven S. |last8=Vogt |first9=R. Paul |last9=Butler |last10= Reiners |first10=Ansgar |last11= Jones |first11=Hugh R. A. |journal=Astronomy & Astrophysics |date=2013 |doi=10.1051/0004-6361/201321331 |arxiv = 1306.6074 |bibcode = 2013A&A...556A.126A |volume=556 |pages=A126|s2cid=14559800 }}</ref> It is a red dwarf with a stellar classification of M1.5. This star is radiating only 1.4% of the Sun's luminosity from its outer atmosphere at a relatively cool effective temperature of 3,440 K.<ref name="Pineda2021"/> This temperature is what gives it the red-hued glow that is a characteristic of M-type stars.<ref name=csiro/> The apparent magnitude of the star is 10.25, giving it an absolute magnitude of about 11.03. It is known to have a system of two planets; claims have been made for up to five additional planets<ref name="Anglada-Escudé"/> but this is likely to be in error due to failure to account for correlated noise in the radial velocity data.<ref name="ferozhobson2014"/><ref name="RobertsonMahadevan2014"/> The red dwarf status of the star would allow planet Cc, which is in the habitable zone, to receive minimal amounts of ultraviolet radiation.<ref name="Anglada-Escudé-2013"/>
=== Planetary system === thumb|left|Artist's impression of Gliese 667 Cb with the Gliese 667 A/B binary in the background [[File:Gliese 667 Cc sunset.jpg|thumb|left|An artist's impression of GJ 667 Cc, a potentially habitable planet orbiting a red dwarf constituent in a trinary star system]]
Two extrasolar planets, Gliese 667 Cb (GJ 667 Cb) and Cc, have been confirmed orbiting Gliese 667 C by radial velocity measurements of GJ 667.<ref name="ferozhobson2014"/><ref name="RobertsonMahadevan2014"/> There were also thought to be up to five other potential additional planets;<ref name="Anglada-Escudé-2012"/><ref name="Anglada-Escudé"/> however, it was later shown that they are likely to be artifacts resulting from correlated noise.<ref name="ferozhobson2014"/><ref name="RobertsonMahadevan2014"/>
Planet Cb was first announced by the European Southern Observatory's HARPS group on 19 October 2009. The announcement was made together with 29 other planets, while Cc was first mentioned by the same group in a pre-print made public on 21 November 2011.<ref name=Bonfils2013/> Announcement of a refereed journal report came on 2 February 2012 by researchers at the University of Göttingen/Carnegie Institution for Science.<ref name="Anglada-Escudé-2012"/><ref name="Göttingen"/> In this announcement, GJ 667 Cc was described as one of the best candidates yet found to harbor liquid water, and thus, potentially, support life on its surface.<ref name="Space-20120202"/> A detailed orbital analysis and refined orbital parameters for Gliese 667 Cc were presented.<ref name="Anglada-Escudé-2012"/> Based on GJ 667 C's bolometric luminosity, GJ 667 Cc would receive 90% of the light Earth does;<ref name=news/> however, much of that electromagnetic radiation would be in the invisible infrared light part of the spectrum.
From the surface of Gliese 667 Cc, the second-confirmed planet out that orbits along the middle of the habitable zone, Gliese 667 C would have an angular diameter of 1.24 degrees—2.3 times<ref name="Apparentsize" group="note"><math>\frac {h} {{h}_{\odot}}={\left( \frac{{{T}_{\odot}}_{\rm eff}} {{T}_{\rm eff}} \right)^2} *\frac{\sqrt{L}} {a}</math>.{{citation needed|date=March 2012}} where <math>{h}</math> is the angular diameter of the star from the surface of the planet in orbit (GJ667Cc in this case), <math>{{h}_{\odot}}</math> is the angular diameter of the Sun (sol) from the surface of Earth, <math>{{T}_{\odot}}_{\rm eff}</math> is the effective temperature of the Sun (sol), <math>{{T}_{\rm eff}}</math> the effective temperature of the star, <math>{L}</math> is the luminosity of the star as a fraction of the Sun's luminosity and <math>{a}</math> is the distance of the planet from the star in AU. This formula has been used as the luminosity and surface temperature published do not agree with the published radius. If you calculate the radius from the formula <math>radius=\sqrt(luminosity)/temp^2</math> (with all units given in multiples of the Sun's values), you will see that the luminosity and temperature give a radius of 0.286 times the radius of the Sun, not the same figure published in the literature. If you calculate the angular diameter in the sky using a trigonometric formula <math>atan(distance/radius)*2</math>, the angular diameter derived using this revised radius agrees with the figures given here, by the shortcut formula above, which essentially makes the same calculation.<!--used this formula rather than the simpler h=1/d*a or angular diameter = 2arcsin*(1/2dact/D) because the diameter comes from a different source paper and is not consistent with luminosity, temperature and distance figures which all come from the same paper by Anglada-Escudé, Guillem et al., 2012--> </ref> larger than the Sun appears from the surface of the Earth, covering 5.4 times more area—but would still only occupy 0.003% of Gliese 667 Cc's sky sphere or 0.006% of the visible sky when directly overhead.
At one point, up to five additional planets were thought to exist in the system, with three of them thought to be relatively certain to exist.<ref name="Anglada-Escudé"/> However, multiple subsequent studies showed that the other proposed planets in the system were likely to be artifacts of noise and stellar activity, cutting the number of confirmed planets down to two. While one analysis did find some evidence for a third planet, Gliese 667 Cd with a period of about 90 days, but was unable to confirm it,<ref name="ferozhobson2014"/> other studies found that that specific signal very likely originates from the stellar rotation.<ref name="RobertsonMahadevan2014"/><ref name=SuarezMascareno2015/> Thus, despite its inclusion in a list of planet candidates in a 2019 preprint (never accepted for publication as of 2024),<ref name="Tuomi2019"/> it is unlikely that Gliese 667 Cd exists.
{{OrbitboxPlanet begin | name = Gliese 667 C | table_ref = <ref name="RobertsonMahadevan2014"/> | period_unit = day }} {{OrbitboxPlanet | exoplanet = b | mass_earth = {{val|5.6|0.3|p=≥}} | semimajor = {{val|0.050431|0.000004|fmt=none}} | period = {{val|7.1999|0.0009|fmt=none}} | eccentricity = {{val|0.15|0.05}} }} {{OrbitboxPlanet | exoplanet = c | mass_earth = {{val|4.1|0.6|p=≥}} | semimajor = {{val|0.12501|0.00009|fmt=none}} | period = {{val|28.10|0.03}} | eccentricity = {{val|0.27|0.1}} }} {{Orbitbox end}} {{Clear}}
==See also== *41 G. Arae * List of nearest K-type stars
==Notes==
{{Reflist|group=note}}
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==External links== {{Commons category-inline}} *{{cite web | title=MLO 4 | work=SolStation | url=http://www.solstation.com/stars/mlo4abc.htm | access-date=June 29, 2013 | archive-date=April 23, 2019 | archive-url=https://web.archive.org/web/20190423075526/http://www.solstation.com/stars/mlo4abc.htm | url-status=dead }} * ''exoplanet art sites:'' :* {{cite web | title=Gliese 667 | work=Orion's Arm | url=http://www.orionsarm.com/eg-article/4fbac899f11d0 | access-date=June 29, 2013 | archive-date=January 2, 2020 | archive-url=https://web.archive.org/web/20200102134906/https://www.orionsarm.com/eg-article/4fbac899f11d0 | url-status=live }} :* {{cite web | title=Gliese 667 | work=Open Exoplanet Catalogue | url=http://www.openexoplanetcatalogue.com/system.html?id=Gliese%20667%20C%20c | access-date=June 29, 2013}}
{{Gliese 667}} {{Extraterrestrial life}} {{Stars of Scorpius}} {{Sky|17|18|57.16483|-|34|59|23.1416|22.1}}
Category:Gliese 667 Category:K-type main-sequence stars Category:M-type main-sequence stars Category:Scorpius Category:Planetary systems with two confirmed planets 156384 3 Category:Triple star systems Scorpii, 142 084709 0667