Gliese 667

Last updated
Gliese 667 A/B/C
Scorpius constellation map.svg
Red circle.svg
Location of Gliese 667 (circled)
Observation data
Epoch J2000       Equinox J2000
Constellation Scorpius
Right ascension 17h 18m 57.16483s [1]
Declination −34° 59′ 23.1416″ [1]
Apparent magnitude  (V)5.91/7.20/10.20 [2]
Characteristics
Spectral type K3V + K5V + M1.5V [2] [3]
U−B color index 0.83/???/1.17
B−V color index 1.03/???/1.57
Variable type A: suspected
B: unknown
C: flare star [ citation needed ]
Astrometry
Radial velocity (Rv)6.13±0.30 [4]  km/s
Proper motion (μ)RA: 1131.517  mas/yr [4]
Dec.: −215.569  mas/yr [4]
Parallax (π)138.0663 ± 0.0283  mas [4]
Distance 23.623 ± 0.005  ly
(7.243 ± 0.001  pc)
Absolute magnitude  (MV)7.07/8.02/11.03
Details
GJ 667 AB
Mass 0.73 / 0.69 [5]   M☉
Radius 0.76 / 0.70 [2]   R☉
Metallicity [Fe/H]–0.59 [6]   dex
GJ 667 C
Mass 0.327±0.008 [7]   M☉
Radius 0.337±0.014 [7]   R☉
Luminosity0.01439±0.00035 [7]   L☉
Temperature 3,443+75
−71 [7]   K
Metallicity [Fe/H]–0.59 ± 0.10 [8]   dex
Rotation 105 days [8]
Age 2–10 [8]   Gyr
Orbit [9]
CompanionGliese 667 B
Period (P)42.15 yr
Semi-major axis (a)1.81″
Eccentricity (e)0.58
Inclination (i)128°
Longitude of the node (Ω)313°
Periastron epoch (T)1975.9
Argument of periastron (ω)
(secondary)		247°
Other designations
142 G. Scorpii, CD −34°11626, GJ 667, HD 156384, HIP  84709, HR 6426, LHS 442/442/443, SAO 208670, 2MASS J17185698-3459236
Database references
AB
A
B
C
Cb
Cc
Ce
Cf
Exoplanet Archive Gliese 667 C
ARICNS Gliese 667 A
B
C

Gliese 667 (142 G. Scorpii) is a triple-star system in the constellation Scorpius lying at a distance of about 7.2 parsecs (23 light-years ) from Earth. All three of the stars have masses smaller than the Sun. There is a 12th-magnitude star close to the other three, but it is not gravitationally bound to the system. To the naked eye, the system appears to be a single faint star of magnitude 5.89.

Contents

The system has a relatively high proper motion, exceeding 1 second of arc per year.

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. [note 1] [10] 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. [8] [11] 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. [12]

Gliese 667 AB

The largest star in the system, Gliese 667 A (GJ 667 A), is a K-type main-sequence star of stellar classification K3V. [2] It has about 73% [5] of the mass of the Sun and 76% [2] of the Sun's radius, but is radiating only around 12-13% of the luminosity of the Sun. [13] 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. [6] 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).

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 69% [5] of the Sun, or 95% 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% [7] of the mass of the Sun and 34% [7] of the Sun's radius, orbiting approximately 230 AU from the Gliese 667 AB pair. [14] 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. [7] This temperature is what gives it the red-hued glow that is a characteristic of M-type stars. [15] 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 [16] but this is likely to be in error due to failure to account for correlated noise in the radial velocity data. [17] [18] The red dwarf status of the star would allow planet Cc, which is in the habitable zone, to receive minimal amounts of ultraviolet radiation. [14]

Planetary system

Artist's impression of Gliese 667 Cb with the Gliese 667 A/B binary in the background Gliese 667.jpg
Artist's impression of Gliese 667 Cb with the Gliese 667 A/B binary in the background
An artist's impression of GJ 667 Cc, a potentially habitable planet orbiting a red dwarf constituent in a trinary star system Gliese 667 Cc sunset.jpg
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. [17] [18] There were also thought to be up to five other potential additional planets; [8] [16] however, it was later shown that they are likely to be artifacts resulting from correlated noise. [17] [18]

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. [19] Announcement of a refereed journal report came on 2 February 2012 by researchers at the University of Göttingen/Carnegie Institution for Science. [8] [20] 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. [21] A detailed orbital analysis and refined orbital parameters for Gliese 667 Cc were presented. [8] Based on GJ 667 C's bolometric luminosity, GJ 667 Cc would receive 90% of the light Earth does; [13] 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 [note 2] 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. [16] 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, [17] other studies found that that specific signal very likely originates from the stellar rotation. [18] [22] Thus, despite its inclusion in a list of planet candidates in a 2019 preprint, [23] it is unlikely that Gliese 667 Cd exists.

The Gliese 667 C planetary system [18]
Companion
(in order from star)		 Mass Semimajor axis
(AU)		 Orbital period
(days)		 Eccentricity Inclination Radius
b ≥5.6±0.3  M🜨 0.050431±0.0000047.1999±0.00090.15±0.05——
c ≥4.1±0.6  M🜨 0.12501±0.0000928.10±0.030.27±0.1——

Related Research Articles

<span class="mw-page-title-main">Gliese 876</span> Star in the constellation Aquarius

Gliese 876 is a red dwarf star 15.2 light-years away from Earth in the constellation of Aquarius. It is one of the closest known stars to the Sun confirmed to possess a planetary system with more than two planets, after GJ 1061, YZ Ceti, Tau Ceti, and Wolf 1061; as of 2018, four extrasolar planets have been found to orbit the star. The planetary system is also notable for the orbital properties of its planets. It is the only known system of orbital companions to exhibit a near-triple conjunction in the rare phenomenon of Laplace resonance. It is also the first extrasolar system around a normal star with measured coplanarity. While planets b and c are located in the system's habitable zone, they are giant planets believed to be analogous to Jupiter.

<span class="mw-page-title-main">Gliese 436</span> Star in the constellation Leo

Gliese 436 is a red dwarf located 31.9 light-years away in the zodiac constellation of Leo. It has an apparent visual magnitude of 10.67, which is much too faint to be seen with the naked eye. However, it can be viewed with even a modest telescope of 2.4 in (6 cm) aperture. In 2004, the existence of an extrasolar planet, Gliese 436 b, was verified as orbiting the star. This planet was later discovered to transit its host star.

<span class="mw-page-title-main">Gliese 229</span> Star in the constellation Lepus

Gliese 229 is a binary system composed of a red dwarf and the first brown dwarf seen by astronomers, 18.8 light years away in the constellation Lepus. The primary component has 58% of the mass of the Sun, 69% of the Sun's radius, and a very low projected rotation velocity of 1 km/s at the stellar equator.

Gliese 674(GJ 674) is a small red dwarf star with an exoplanetary companion in the southern constellation of Ara. It is too faint to be visible to the naked eye, having an apparent visual magnitude of 9.38 and an absolute magnitude of 11.09. The system is located at a distance of 14.8 light-years from the Sun based on parallax measurements, but is drifting closer with a radial velocity of −2.9 km/s. It is a candidate member of the 200 million year old Castor stream of co-moving stars.

Gliese 581 is a red dwarf star of spectral type M3V at the center of the Gliese 581 planetary system, about 20.5 light years away from Earth in the Libra constellation. Its estimated mass is about a third of that of the Sun, and it is the 101st closest known star system to the Sun. Gliese 581 is one of the oldest, least active M dwarfs known. Its low stellar activity improves the likelihood of its planets retaining significant atmospheres, and lessens the sterilizing impact of stellar flares.

Gliese 849, or GJ 849, is a small, solitary star in the equatorial constellation of Aquarius. It has a reddish hue and is invisible to the naked eye with an apparent visual magnitude of 10.41. The distance to this star is 28.8 light-years based on parallax, but it is drifting closer to the Sun with a radial velocity of −15.3 km/s. It has a pair of confirmed gas giant companions.

Gliese 832 is a red dwarf of spectral type M2V in the southern constellation Grus. The apparent visual magnitude of 8.66 means that it is too faint to be seen with the naked eye. It is located relatively close to the Sun, at a distance of 16.2 light years and has a high proper motion of 818.16 milliarcseconds per year. Gliese 832 has just under half the mass and radius of the Sun. Its estimated rotation period is a relatively leisurely 46 days. The star is roughly 6 billion years old.

Gliese 832 b is a gas giant exoplanet about 80% the mass of Jupiter, located 16.2 light-years from the Sun in the constellation of Grus, orbiting the red dwarf star Gliese 832.

<span class="mw-page-title-main">Gliese 752</span> Binary star system in the constellation Aquila

Gliese 752 is a binary star system in the Aquila constellation. This system is relatively nearby, at a distance of 19.3 light-years.

Gliese 433 is a dim red dwarf star with multiple exoplanetary companions, located in the equatorial constellation of Hydra. The system is located at a distance of 29.6 light-years from the Sun based on parallax measurements, and it is receding with a radial velocity of +18 km/s. Based on its motion through space, this is an old disk star. It is too faint to be viewed with the naked eye, having an apparent visual magnitude of 9.81 and an absolute magnitude of 10.07.

<span class="mw-page-title-main">Gliese 667 Cc</span> Goldilocks super-Earth orbiting Gliese 667 C

Gliese 667 Cc is an exoplanet orbiting within the habitable zone of the red dwarf star Gliese 667 C, which is a member of the Gliese 667 triple star system, approximately 23.62 light-years away in the constellation of Scorpius. The exoplanet was found by using the radial velocity method, from radial-velocity measurements via observation of Doppler shifts in the spectrum of the planet's parent star.

Gliese 163 is a faint red dwarf star with multiple exoplanetary companions in the southern constellation of Dorado. Other stellar catalog names for it include HIP 19394 and LHS 188. It is too faint to be visible to the naked eye, having an apparent visual magnitude of 11.79 and an absolute magnitude of 10.91. This system is located at a distance of 49.4 light-years from the Sun based on parallax measurements. Judging by its space velocity components, it is most likely a thick disk star.

Gliese 221, also known as BD-06 1339, is a star with an exoplanetary companion in the equatorial constellation of Orion. It is too faint to be visible to the naked eye, having an apparent visual magnitude of 9.70 and an absolute magnitude of 8.15. Using parallax measurements, the distance to this system can be estimated as 66.2 light-years. It is receding from the Sun with a radial velocity of +23 km/s. This is a high proper motion star, traversing the celestial sphere at an angular rate of 0.333″·yr−1.

Gliese 754 is a dim star in the southern constellation of Telescopium. It has an apparent visual magnitude of 12.25, which requires a telescope to view. The star is located at a distance of 19.3 light-years from the Sun based on parallax, and it is drifting further away with a radial velocity of +7 km/s. It is one of the hundred closest stars to the Solar System. Calculations of its orbit around the Milky Way showed that it is eccentric, and indicate that it might be a thick disk object.

<span class="mw-page-title-main">Gliese 180</span> Star in the constellation Eridanus

Gliese 180, is a small red dwarf star in the equatorial constellation of Eridanus. It is invisible to the naked eye with an apparent visual magnitude of 10.9. The star is located at a distance of 39 light years from the Sun based on parallax, and is drifting closer with a radial velocity of −14.6 km/s. It has a high proper motion, traversing the sky at the rate of 0.765 arcseconds per year.

GJ 3323 is a nearby single star located in the equatorial constellation Eridanus, about 0.4° to the northwest of the naked eye star Psi Eridani. It is invisible to the naked eye with an apparent visual magnitude 12.20. Parallax measurements give a distance estimate of 17.5 light-years from the Sun. It is drifting further away with a radial velocity of +42.3 km/s. Roughly 104,000 years ago, the star is believed to have come to within 7.34 ± 0.16 light-years of the Solar System.

Luyten b is a confirmed exoplanet, likely rocky, orbiting within the habitable zone of the nearby red dwarf Luyten's Star. It is the fourth-closest potentially habitable exoplanet known, at a distance of 12 light-years. Only Proxima Centauri b, Ross 128 b, and GJ 1061 d are closer. Discovered alongside Gliese 273c in June 2017, Luyten b is a super-Earth of around 2.89 times the mass of Earth and receives only 6% more starlight than Earth, making it one of the best candidates for habitability.

Gliese 49 is a star in the northern constellation of Cassiopeia. Visually, it is located 106 arcminutes north of the bright star γ Cassiopeiae. With an apparent visual magnitude of 9.56, it is not observable with the naked eye. It is located, based on the reduction of parallax data of Gaia, 32.1 light-years away from the Solar System. The star is drifting closer to the Sun with a radial velocity of −6 km/s.

<span class="mw-page-title-main">GJ 1002</span> Red dwarf star in the constellation Cetus

GJ 1002 is a nearby red dwarf star, located 15.8 light-years away from the Solar System in the constellation of Cetus. The star has 12% the mass and 14% the radius of the Sun, and a temperature of 3,024 K. It hosts a system of two known exoplanets.

References

  1. 1 2 van Leeuwen, F. (November 2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics, 474 (2): 653–664, arXiv: 0708.1752 , Bibcode:2007A&A...474..653V, doi:10.1051/0004-6361:20078357, S2CID   18759600
  2. 1 2 3 4 5 Pasinetti Fracassini, L. E.; et al. (February 2001), "Catalogue of Apparent Diameters and Absolute Radii of Stars (CADARS) - Third edition - Comments and statistics", Astronomy and Astrophysics, 367 (2): 521–524, arXiv: astro-ph/0012289 , Bibcode:2001A&A...367..521P, doi:10.1051/0004-6361:20000451, S2CID   425754 Note: see VizieR catalogue J/A+A/367/521.
  3. ↑ Suárez Mascareño, A.; et al. (September 2015), "Rotation periods of late-type dwarf stars from time series high-resolution spectroscopy of chromospheric indicators", Monthly Notices of the Royal Astronomical Society, 452 (3): 2745–2756, arXiv: 1506.08039 , Bibcode:2015MNRAS.452.2745S, doi:10.1093/mnras/stv1441, S2CID   119181646.
  4. 1 2 3 4 Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv: 2208.00211 . Bibcode:2023A&A...674A...1G. doi: 10.1051/0004-6361/202243940 . S2CID   244398875. Gaia DR3 record for this source at VizieR.
  5. 1 2 3 Tokovinin, A. (September 2008), "Comparative statistics and origin of triple and quadruple stars", Monthly Notices of the Royal Astronomical Society , 389 (2): 925–938, arXiv: 0806.3263 , Bibcode:2008MNRAS.389..925T, doi:10.1111/j.1365-2966.2008.13613.x, S2CID   16452670
  6. 1 2 Cayrel de Strobel, G.; Soubiran, C.; Ralite, N. (July 2001), "Catalogue of [Fe/H] determinations for FGK stars: 2001 edition", Astronomy and Astrophysics, 373: 159–163, arXiv: astro-ph/0106438 , Bibcode:2001A&A...373..159C, doi:10.1051/0004-6361:20010525, S2CID   17519049
  7. 1 2 3 4 5 6 7 Pineda, J. Sebastian; Youngblood, Allison; France, Kevin (September 2021). "The M-dwarf Ultraviolet Spectroscopic Sample. I. Determining Stellar Parameters for Field Stars". The Astrophysical Journal. 918 (1): 23. arXiv: 2106.07656 . Bibcode:2021ApJ...918...40P. doi: 10.3847/1538-4357/ac0aea . S2CID   235435757. 40.
  8. 1 2 3 4 5 6 7 Anglada-Escudé, Guillem; Arriagada, Pamela; Vogt, Steven S.; Rivera, Eugenio J.; Butler, R. Paul; Crane, Jeffrey D.; Shectman, Stephen A.; Thompson, Ian B.; Minniti, Dante; Haghighipour, Nader; Carter, Brad D.; Tinney, C. G.; Wittenmyer, Robert A.; Bailey, Jeremy A.; O'Toole, Simon J.; Jones, Hugh R. A.; Jenkins, James S. (2012). "A Planetary System around the nearby M Dwarf GJ 667C with At Least One Super-Earth in Its Habitable Zone". The Astrophysical Journal Letters. 751 (1). L16. arXiv: 1202.0446 . Bibcode:2012ApJ...751L..16A. doi:10.1088/2041-8205/751/1/L16. S2CID   16531923.
  9. ↑ Söderhjelm, Staffan (January 1999), "Visual binary orbits and masses POST HIPPARCOS", Astronomy and Astrophysics, 341: 121–140, Bibcode:1999A&A...341..121S
  10. ↑ Bowman, Richard L. "Interactive Planetary Orbits - Kepler's Laws Calculations". Archived from the original on 12 December 2012. Retrieved 23 February 2012.
  11. ↑ Philip C. Gregory (2012). "Additional Keplerian Signals in the HARPS data for Gliese 667C from a Bayesian Re-analysis". arXiv: 1212.4058 [astro-ph.EP].
  12. ↑ "Habitable Planet Reality Check: GJ 667C". Drew Ex Machina. September 7, 2014.
  13. 1 2 Sven Wedemeyer. "Life on Gliese 667Cc?". Institute of Theoretical Astrophysics. Archived from the original on 2013-07-03. Retrieved 2012-12-28.
  14. 1 2 Anglada-Escudé, Guillem; Tuomi, Mikko; Gerlach, Enrico; Barnes, Rory; Heller, René; Jenkins, James S.; Wende, Sebastian; Vogt, Steven S.; Butler, R. Paul; Reiners, Ansgar; Jones, Hugh R. A. (2013-06-07). "A dynamically-packed planetary system around GJ 667C with three super-Earths in its habitable zone" (PDF). Astronomy & Astrophysics . 556: A126. arXiv: 1306.6074 . Bibcode:2013A&A...556A.126A. doi:10.1051/0004-6361/201321331. S2CID   14559800. Archived from the original (PDF) on 2013-06-30. Retrieved 2013-06-25.
  15. ↑ "The Colour of Stars", Australia Telescope, Outreach and Education, Commonwealth Scientific and Industrial Research Organisation, December 21, 2004, archived from the original on 2012-03-18, retrieved 2012-01-16
  16. 1 2 3 Anglada-Escudé, Guillem; Tuomi, Mikko; Gerlach, Enrico; Barnes, Rory; Heller, René; Jenkins, James S.; Wende, Sebastian; Vogt, Steven S.; Butler, R. Paul; Reiners, Ansgar; Jones, Hugh R. A. (2013-06-07). "A dynamically-packed planetary system around GJ 667C with three super-Earths in its habitable zone" (PDF). Astronomy & Astrophysics . 556: A126. arXiv: 1306.6074 . Bibcode:2013A&A...556A.126A. doi:10.1051/0004-6361/201321331. S2CID   14559800 . Retrieved 2013-06-25.
  17. 1 2 3 4 Feroz, F.; Hobson, M. P. (2014). "Bayesian analysis of radial velocity data of GJ667C with correlated noise: evidence for only two planets". Monthly Notices of the Royal Astronomical Society . 437 (4): 3540–3549. arXiv: 1307.6984 . Bibcode:2014MNRAS.437.3540F. doi:10.1093/mnras/stt2148. S2CID   119287992.
  18. 1 2 3 4 5 Robertson, Paul; Mahadevan, Suvrath (October 2014). "Disentangling Planets and Stellar Activity for Gliese 667C". The Astrophysical Journal . 793 (2): L24. arXiv: 1409.0021 . Bibcode:2014ApJ...793L..24R. doi:10.1088/2041-8205/793/2/L24. S2CID   118404871.
  19. ↑ Bonfils, Xavier; Delfosse, Xavier; Udry, Stéphane; Forveille, Thierry; Mayor, Michel; Perrier, Christian; Bouchy, François; Gillon, Michaël; Lovis, Christophe; Pepe, Francesco; Queloz, Didier; Santos, Nuno C.; Ségransan, Damien; Bertaux, Jean-Loup (2011). "The HARPS search for southern extra-solar planets XXXI. The M-dwarf sample". Astronomy and Astrophysics. 549: A109. arXiv: 1111.5019 . Bibcode:2013A&A...549A.109B. doi:10.1051/0004-6361/201014704. S2CID   119288366.
  20. ↑ University of Göttingen. Presseinformation: Wissenschaftler entdecken möglicherweise bewohnbare Super-Erde - Göttinger Astrophysiker untersucht Planeten in 22 Lichtjahren Entfernung. Nr. 17/2012 - 02.02.2012. Announcement on university homepage, retrieved 2012-02-02
  21. ↑ Chow, Denise (February 2, 2012). "Newfound Alien Planet is Best Candidate Yet to Support Life, Scientists Say". Space.com . Retrieved February 3, 2012.
  22. ↑ Suárez Mascareño, A.; et al. (September 2015), "Rotation periods of late-type dwarf stars from time series high-resolution spectroscopy of chromospheric indicators", Monthly Notices of the Royal Astronomical Society, 452 (3): 2745–2756, arXiv: 1506.08039 , Bibcode:2015MNRAS.452.2745S, doi:10.1093/mnras/stv1441, S2CID   119181646.
  23. ↑ Tuomi, M.; et al. (11 June 2019). "Frequency of planets orbiting M dwarfs in the Solar neighbourhood". arXiv: 1906.04644 [astro-ph.EP].

Notes

  1. ↑ Based on a calculated eccentricity value of .
  2. ↑ .[ citation needed ] where is the angular diameter of the star from the surface of the planet in orbit (GJ667Cc in this case), is the angular diameter of the Sun (sol) from the surface of Earth, is the effective temperature of the Sun (sol), the effective temperature of the star, is the luminosity of the star as a fraction of the Sun's luminosity and 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 radius=sqrt(luminosity)/temp^2 (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 (atan(distance/radius)*2), 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.

Commons-logo.svg Media related to Gliese 667 at Wikimedia Commons

This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.