Gliese 581: Difference between revisions

Gliese 581
	; Size of the Sun (left) and Gliese 581 (right).
Observation data; Epoch J2000.0 Equinox J2000.0 (ICRS)
Constellation	Libra
Right ascension	15h 19m 26.8250s
Declination	−07° 43′ 20.209″
Apparent magnitude (V)	10.56 to 10.58
Characteristics
Spectral type	M3V
B−V color index	1.61
Variable type	BY Dra
Astrometry
Radial velocity (Rv)	−9.5 ± 0.5 km/s
Proper motion (μ)	RA: −1233.51 mas/yr ; Dec.: −94.52 mas/yr
Parallax (π)	160.12 ± 1.33 mas
Distance	20.4 ± 0.2 ly ly ; (6.25 ± 0.05 pc pc)
Absolute magnitude (MV)	11.6
Details
Mass	0.31 M☉
Radius	0.29 R☉
Luminosity (bolometric)	0.013 L☉
Luminosity (visual, LV)	0.002 L☉
Surface gravity (log g)	4.92±0.10 cgs
Temperature	3,480 ± 48 K
Metallicity [Fe/H]	−0.33 ± 0.12 dex
Rotation	132.5±6.3 d
Age	7 to 11 Gyr
Other designations
	HO Librae, HO Lib, BD−07°4003, GJ 581, HIP 74995, LFT 1195, LHS 394, LPM 564, LTT 6112, NLTT 39886, TYC 5594-1093-1, Wolf 562.
Database references
SIMBAD	The star
	e
	b
	c
	d
	f (artifact)
	g

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Gliese 581 (/ˈɡliːzə/) is a star of spectral type M3V (a red dwarf) at the center of the Gliese 581 planetary system, about 20 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 89th closest known star to the Sun.

History of observations

Gliese 581 is known at least from 1886, when it was included in Eduard Schönfeld's Southern Durchmusterung (SD)—the fourth part of the Bonner Durchmusterung. The corresponding designation is BD -7 4003.^[18]

Characteristics

The name Gliese 581 refers to the catalog number from the 1957 survey Gliese Catalogue of Nearby Stars of 965 stars located within 20 parsecs of the Earth. Other names of this star include BD-07° 4003 (BD catalogue, first known publication) and HO Librae (variable star designation). It does not have an individual name such as Sirius or Procyon.^[2]^[17] The star is a red dwarf with spectral type M3V, located 20.4 light-years away from Earth. It is located about two degrees north of Beta Librae, the brightest star in the Libra constellation. Its mass is estimated to be approximately a third that of the Sun, and it is the 89th closest known star system to the Sun.^[19]

An M-class dwarf star such as Gliese 581 has a much lower mass than the Sun, causing the core region of the star to fuse hydrogen at a significantly lower rate. From the apparent magnitude and distance, astronomers have estimated an effective temperature of 3200 K and a visual luminosity of 0.2 percent of that of the Sun.^[20] However, a red dwarf such as Gliese 581 radiates primarily in the near infrared, with peak emission at a wavelength of roughly 830 nm (estimated using Wien's displacement law, which assumes the star radiates as a black body), so such an estimate will underestimate the star's total luminosity.^[5] (For comparison, the peak emission of the Sun is roughly 530 nm, in the middle of the visible part of the spectrum). When radiation over the entire spectrum is taken into account (not just the part that humans are able to see), something known as the bolometric correction, this star has a bolometric luminosity 1.3% of the Sun's total luminosity.^[5]^[20] A planet would need to be situated much closer to this star in order to receive a comparable amount of energy as the Earth. The region of space around a star where a planet would receive roughly the same energy as the Earth is sometimes termed the "Goldilocks Zone", or, more prosaically, the habitable zone. The extent of such a zone is not fixed and is highly specific for each planetary system.^[21]

Gliese 581 is classified as a variable star of the BY Draconis type, and has been given the variable star designation HO Librae. This is a star that exhibits variability because of the presence of star spots combined with the rotation of the star. However, the measured variability is close to the margin of error, and, if real, is most likely a long term variability.^[5] Its brightness is stable to 1%.^[22] Gliese 581 emits X-rays.^[23]

Planets

The Gliese 581 planetary system^[24]
Companion (in order from star)	Mass	Semimajor axis (AU)	Orbital period (days)	Eccentricity	Inclination	Radius
e	≥1.7 ± 0.2 $M$ _🜨	0.02815 ± 0.00006	3.1490 ± 0.0002	0.00-0.06	—	—
b	≥15.8 ± 0.3 $M$ _🜨	0.04061 ± 0.00003	5.3686 ± 0.0001	0.00-0.03	—	—
c	≥5.5 ± 0.3 $M$ _🜨	0.0721 ± 0.0003	12.914 ± 0.002	0.00-0.06	—	—
g (unconfirmed)	≥2.2 M_🜨	0.13	32	0.00	—	—
d^[25] (unconfirmed)	6.98 ± 0.3 M_🜨	0.21847 ± 0.00028	66.87 ± 0.13	0.00-0.25	—	—
Debris disk^[26]	25 ± 12 AU–>60 AU				30° – 70°	—

Notes

^ Gliese 581 is classified as a BY Draconis variable in the General Catalogue of Variable Stars.^[3] This catalog gives a maximum magnitude of 10.56 and minimum of magnitude 10.58 for a relatively low 20 mmag (0.020 magnitudes) variability.^[4] For full data see data description and "The combined table of GCVS Vols I-III and NL 67-78 with improved coordinates, General Catalogue of Variable Stars". Sternberg Astronomical Institute. Retrieved 27 April 2009.
^ In 1994 Edward Weis concluded that Gliese 581, like half the 43 dwarf M stars he studied over a multi-year period, showed long term variability (and page 1137, Fig 1 shows Gliese 581 had magnitude 10.58 in 1982 and between 10.57 and 10.56 from 1985 to 1990).^[7] Bonfils noted in 2005 that Gliese 581 "has been classified as a variable star (HO Lib), but its variability (Weis 1994) is only marginally significant. If real it would be on a time scale of several years, with short term variability being at most ∼0.006 mag."^[8] Measurements by MOST showed short term variability of about 5 mmag (half a percent) over a period of a few weeks.^[9]
^ Taking the absolute magnitude of Gliese 581, ${\begin{smallmatrix}M_{V_{\ast }}=11.59\end{smallmatrix}}$ , with the absolute magnitude of the Sun, ${\begin{smallmatrix}M_{V_{\odot }}=4.83\end{smallmatrix}}$ , the visual luminosity can be calculated from, ${\begin{smallmatrix}{\frac {L_{V_{\ast }}}{L_{V_{\odot }}}}=10^{0.4\left(M_{V_{\odot }}-M_{V_{\ast }}\right)}\end{smallmatrix}}$ .

References

^ Smith, Yvette. "NASA and NSF-Funded Research Finds First Potentially Habitable Exoplanet". nasa.gov. NASA. Retrieved 9 June 2016.
^ ^a ^b ^c ^d ^e ^f GJ 581 , SIMBAD. Retrieved 2008-08-21.
^ Lopez-Morales, M.; et al. (2006). "Limits to Transits of the Neptune-mass planet orbiting Gl 581". Publications of the Astronomical Society of the Pacific. 118 (849): 1506–1509. arXiv:astro-ph/0609255. Bibcode:2006PASP..118.1506L. doi:10.1086/508904. V* HO Lib … BY Draconis (page 2 of pre-print submitted 9 September 2006)
^ "General Catalogue of Variable Stars Query results". Sternberg Astronomical Institute. Retrieved 27 April 2009.
^ ^a ^b ^c ^d ^e ^f Bonfils, X.; et al. (2005). "The HARPS search for southern extra-solar planets VI: A Neptune-mass planet around the nearby M dwarf Gl 581". Astronomy and Astrophysics Letters. 443 (3): L15–L18. arXiv:astro-ph/0509211. Bibcode:2005A&A...443L..15B. doi:10.1051/0004-6361:200500193.
^ Samus, N. N.; Durlevich, O. V.; et al. (2009). "VizieR Online Data Catalog: General Catalogue of Variable Stars (Samus+ 2007–2013)". VizieR On-line Data Catalog: B/gcvs. Originally published in: 2009yCat....102025S. 1. Bibcode:2009yCat....102025S.
^ Weis, E. W. (1994). "Long term variability in dwarf M stars". The Astronomical Journal. 107 (3): 1138. Bibcode:1994AJ....107.1135W. doi:10.1086/116925.
^ Bonfils page L15
^ Matthews, J. M.; et al. (2007). "MOST Exoplanet System Photometry" (PDF). p. 80. Retrieved 27 April 2009.
^ ^a ^b van Leeuwen, F. (2007). "HIP 74995". Hipparcos, the New Reduction. Centre de données astronomiques de Strasbourg. Retrieved 16 August 2008.
^ ^a ^b ^c von Braun, Kaspar; Boyajian, Tabetha S.; Kane, Stephen R.; van Belle, Gerard T.; Ciardi, David R.; López-Morales, Mercedes; McAlister, Harold A.; Henry, Todd J.; Jao, Wei-Chun; Riedel, Adric R.; Subasavage, John P.; Schaefer, Gail; ten Brummelaar, Theo A.; Ridgway, Stephen; Sturmann, Laszlo; Sturmann, Judit; Mazingue, Jude; Turner, Nils H.; Farrington, Chris; Goldfinger, P. J.; Boden, Andrew F. (2011). "Astrophysical Parameters and Habitable Zone of the Exoplanet Hosting Star GJ 581". The Astrophysical Journal Letters. 729 (2): L26. arXiv:1102.0237. Bibcode:2011ApJ...729L..26V. doi:10.1088/2041-8205/729/2/L26.
^ From apparent magnitude and parallax.
^ ^a ^b "Star: Gliese 581". Extrasolar Planets Encyclopaedia. Archived from the original on 4 July 2012. Mass 0.31 M_Sun, Age 8+3
−1 Gyr {{cite web}}: Unknown parameter |deadurl= ignored (|url-status= suggested) (help)
^ ^a ^b ^c Bean, J. L; Benedict, G. F.; Endl, M. (2006). "Metallicities of M Dwarf Planet Hosts from Spectral Synthesis". Astrophysical Journal Letters. 653 (1): L65–L68. arXiv:astro-ph/0611060. Bibcode:2006ApJ...653L..65B. doi:10.1086/510527.
^ 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.{{citation}}: CS1 maint: unflagged free DOI (link)
^ Selsis 3.4-page 1382 "lower limit of the age that, considering the associated uncertainties, could be around 7 Gyr", "preliminary estimate", "should not be above 10–11 Gyr"
^ ^a ^b "Entry 5594-1093-1". The Hipparcos and Tycho Catalogues. Centre de données astronomiques de Strasbourg. ID I/239.
^ Schönfeld, Eduard; et al. (1886). "BD -7 4003". Southern Durchmusterung.
^ "The One Hundred Nearest Star Systems". Research Consortium On Nearby Stars, Georgia State University. 1 January 2009. Retrieved 4 June 2010.
^ ^a ^b Udry, S; et al. (2007). "The HARPS search for southern extra-solar planets XI: Super-Earths (5 and 8 M_⊕) in a 3-planet system" (PDF). Astronomy and Astrophysics Letters. 469 (3): L43–L47. arXiv:0704.3841. Bibcode:2007A&A...469L..43U. doi:10.1051/0004-6361:20077612.
^ Selsis, F.; et al. (2007). "Habitable planets around the star Gl 581?". Astronomy and Astrophysics. 476 (3): 1373–1387. arXiv:0710.5294. Bibcode:2007A&A...476.1373S. doi:10.1051/0004-6361:20078091.
^ Dragomir, D.; et al. (2012). "A Search for Transits of GJ 581e and Characterization of the Host Star Variability Using MOST Space Telescope Photometry". The Astrophysical Journal. 759 (1): 2f. arXiv:1211.0577. Bibcode:2012ApJ...759....2D. doi:10.1088/0004-637X/759/1/2.
^ Schmitt, J. H. M. M; Fleming, T. A; Giampapa, M. S. (1995). "The X-Ray View of the Low-Mass Stars in the Solar Neighborhood". Astrophysical Journal. 450 (9): 392–400. Bibcode:1995ApJ...450..392S. doi:10.1086/176149.
^ Robertson, Paul; Mahadevan, Suvrath; Endl, Michael; Roy, Arpita (3 July 2014). "Stellar activity masquerading as planets in the habitable zone of the M dwarf Gliese 581". Science. 345: 440–444. arXiv:1407.1049. Bibcode:2014Sci...345..440R. doi:10.1126/science.1253253. Retrieved 8 July 2014.
^ "Reanalysis of data suggests 'habitable' planet GJ 581d really could exist". Astronomy Now. 9 March 2015. Retrieved 27 May 2015.
^ J.-F. Lestrade; et al. (2012). "A DEBRIS Disk Around The Planet Hosting M-star GJ581 Spatially Resolved with Herschel". Astronomy and Astrophysics. 548: A86. arXiv:1211.4898. Bibcode:2012A&A...548A..86L. doi:10.1051/0004-6361/201220325.

External links

Template:Wikinews2

Major Discovery: New Planet Could Harbor Water and Life Space.com
Gliese 581 / HO Librae Solstation.com
Extrasolar Planets Encyclopaedia: Gl 581
AstronomyCast: Gliese 581
SETI Range Calculator
All Wet? Astronomers Claim Discovery of Earth-like Planet, Scientific American
Position of Gliese 581 marked on local space (Top right corner)
Photo of Constellation Libra with Gliese 581
Artist conceptions of planets of Gliese 581
Speculation about geology/geochemistry of Gliese 581c The Geochemical Society
Computer models suggest planetary and extrasolar planet atmospheres – A gas, gas, gas Washington University in St. Louis
Extrasolar Planet Interactions by Rory Barnes & Richard Greenberg, Lunar and Planetary Lab, University of Arizona
Earth-like planet found that may support life Ctv.ca
Gliese 581 – The "Red Dwarf" and implications for its "earthlike" planet Gliese 581c
Earth's Twin Discovered?

[5] Gliese 581 is classified as a BY Draconis variable in the General Catalogue of Variable Stars.^[3] This catalog gives a maximum magnitude of 10.56 and minimum of magnitude 10.58 for a relatively low 20 mmag (0.020 magnitudes) variability.^[4] For full data see data description and "The combined table of GCVS Vols I-III and NL 67-78 with improved coordinates, General Catalogue of Variable Stars". Sternberg Astronomical Institute. Retrieved 27 April 2009.

[11] In 1994 Edward Weis concluded that Gliese 581, like half the 43 dwarf M stars he studied over a multi-year period, showed long term variability (and page 1137, Fig 1 shows Gliese 581 had magnitude 10.58 in 1982 and between 10.57 and 10.56 from 1985 to 1990).^[7] Bonfils noted in 2005 that Gliese 581 "has been classified as a variable star (HO Lib), but its variability (Weis 1994) is only marginally significant. If real it would be on a time scale of several years, with short term variability being at most ∼0.006 mag."^[8] Measurements by MOST showed short term variability of about 5 mmag (half a percent) over a period of a few weeks.^[9]

[luminosity_visual-16] Taking the absolute magnitude of Gliese 581, ${\begin{smallmatrix}M_{V_{\ast }}=11.59\end{smallmatrix}}$ , with the absolute magnitude of the Sun, ${\begin{smallmatrix}M_{V_{\odot }}=4.83\end{smallmatrix}}$ , the visual luminosity can be calculated from, ${\begin{smallmatrix}{\frac {L_{V_{\ast }}}{L_{V_{\odot }}}}=10^{0.4\left(M_{V_{\odot }}-M_{V_{\ast }}\right)}\end{smallmatrix}}$ .

[NASA-1] Smith, Yvette. "NASA and NSF-Funded Research Finds First Potentially Habitable Exoplanet". nasa.gov. NASA. Retrieved 9 June 2016.

[sb0-2] ^ ^a ^b ^c ^d ^e ^f GJ 581 , SIMBAD. Retrieved 2008-08-21.

[3] Lopez-Morales, M.; et al. (2006). "Limits to Transits of the Neptune-mass planet orbiting Gl 581". Publications of the Astronomical Society of the Pacific. 118 (849): 1506–1509. arXiv:astro-ph/0609255. Bibcode:2006PASP..118.1506L. doi:10.1086/508904. V* HO Lib … BY Draconis (page 2 of pre-print submitted 9 September 2006)

[4] "General Catalogue of Variable Stars Query results". Sternberg Astronomical Institute. Retrieved 27 April 2009.

[bonfils-6] ^ ^a ^b ^c ^d ^e ^f Bonfils, X.; et al. (2005). "The HARPS search for southern extra-solar planets VI: A Neptune-mass planet around the nearby M dwarf Gl 581". Astronomy and Astrophysics Letters. 443 (3): L15–L18. arXiv:astro-ph/0509211. Bibcode:2005A&A...443L..15B. doi:10.1051/0004-6361:200500193.

[gcvs-7] Samus, N. N.; Durlevich, O. V.; et al. (2009). "VizieR Online Data Catalog: General Catalogue of Variable Stars (Samus+ 2007–2013)". VizieR On-line Data Catalog: B/gcvs. Originally published in: 2009yCat....102025S. 1. Bibcode:2009yCat....102025S.

[8] Weis, E. W. (1994). "Long term variability in dwarf M stars". The Astronomical Journal. 107 (3): 1138. Bibcode:1994AJ....107.1135W. doi:10.1086/116925.

[9] Bonfils page L15

[10] Matthews, J. M.; et al. (2007). "MOST Exoplanet System Photometry" (PDF). p. 80. Retrieved 27 April 2009.

[newred-12] van Leeuwen, F. (2007). "HIP 74995". Hipparcos, the New Reduction. Centre de données astronomiques de Strasbourg. Retrieved 16 August 2008.

[von_Braun2011-13] von Braun, Kaspar; Boyajian, Tabetha S.; Kane, Stephen R.; van Belle, Gerard T.; Ciardi, David R.; López-Morales, Mercedes; McAlister, Harold A.; Henry, Todd J.; Jao, Wei-Chun; Riedel, Adric R.; Subasavage, John P.; Schaefer, Gail; ten Brummelaar, Theo A.; Ridgway, Stephen; Sturmann, Laszlo; Sturmann, Judit; Mazingue, Jude; Turner, Nils H.; Farrington, Chris; Goldfinger, P. J.; Boden, Andrew F. (2011). "Astrophysical Parameters and Habitable Zone of the Exoplanet Hosting Star GJ 581". The Astrophysical Journal Letters. 729 (2): L26. arXiv:1102.0237. Bibcode:2011ApJ...729L..26V. doi:10.1088/2041-8205/729/2/L26.

[14] From apparent magnitude and parallax.

[epe-15] "Star: Gliese 581". Extrasolar Planets Encyclopaedia. Archived from the original on 4 July 2012. Mass 0.31 M_Sun, Age 8+3
−1 Gyr {{cite web}}: Unknown parameter |deadurl= ignored (|url-status= suggested) (help)

[apj653-17] Bean, J. L; Benedict, G. F.; Endl, M. (2006). "Metallicities of M Dwarf Planet Hosts from Spectral Synthesis". Astrophysical Journal Letters. 653 (1): L65–L68. arXiv:astro-ph/0611060. Bibcode:2006ApJ...653L..65B. doi:10.1086/510527.

[mnras452_3_2745-18] 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.{{citation}}: CS1 maint: unflagged free DOI (link)

[19] Selsis 3.4-page 1382 "lower limit of the age that, considering the associated uncertainties, could be around 7 Gyr", "preliminary estimate", "should not be above 10–11 Gyr"

[catl-20] "Entry 5594-1093-1". The Hipparcos and Tycho Catalogues. Centre de données astronomiques de Strasbourg. ID I/239.

[21] Schönfeld, Eduard; et al. (1886). "BD -7 4003". Southern Durchmusterung.

[recons-22] "The One Hundred Nearest Star Systems". Research Consortium On Nearby Stars, Georgia State University. 1 January 2009. Retrieved 4 June 2010.

[Sel3-23] Udry, S; et al. (2007). "The HARPS search for southern extra-solar planets XI: Super-Earths (5 and 8 M_⊕) in a 3-planet system" (PDF). Astronomy and Astrophysics Letters. 469 (3): L43–L47. arXiv:0704.3841. Bibcode:2007A&A...469L..43U. doi:10.1051/0004-6361:20077612.

[24] Selsis, F.; et al. (2007). "Habitable planets around the star Gl 581?". Astronomy and Astrophysics. 476 (3): 1373–1387. arXiv:0710.5294. Bibcode:2007A&A...476.1373S. doi:10.1051/0004-6361:20078091.

[25] Dragomir, D.; et al. (2012). "A Search for Transits of GJ 581e and Characterization of the Host Star Variability Using MOST Space Telescope Photometry". The Astrophysical Journal. 759 (1): 2f. arXiv:1211.0577. Bibcode:2012ApJ...759....2D. doi:10.1088/0004-637X/759/1/2.

[26] Schmitt, J. H. M. M; Fleming, T. A; Giampapa, M. S. (1995). "The X-Ray View of the Low-Mass Stars in the Solar Neighborhood". Astrophysical Journal. 450 (9): 392–400. Bibcode:1995ApJ...450..392S. doi:10.1086/176149.

[SCI-20140703-27] Robertson, Paul; Mahadevan, Suvrath; Endl, Michael; Roy, Arpita (3 July 2014). "Stellar activity masquerading as planets in the habitable zone of the M dwarf Gliese 581". Science. 345: 440–444. arXiv:1407.1049. Bibcode:2014Sci...345..440R. doi:10.1126/science.1253253. Retrieved 8 July 2014.

[Astronomy_Now-28] "Reanalysis of data suggests 'habitable' planet GJ 581d really could exist". Astronomy Now. 9 March 2015. Retrieved 27 May 2015.

[debris-29] J.-F. Lestrade; et al. (2012). "A DEBRIS Disk Around The Planet Hosting M-star GJ581 Spatially Resolved with Herschel". Astronomy and Astrophysics. 548: A86. arXiv:1211.4898. Bibcode:2012A&A...548A..86L. doi:10.1051/0004-6361/201220325.

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@@ Line 31: / Line 31: @@
 }}
 {{Starbox detail
-| mass                 = 0.31<ref name="epe">{{cite web |title=Star: Gliese 581 |url=http://exoplanet.eu/star.php?st=Gl+581 |publisher=[[Extrasolar Planets Encyclopaedia]] |quote=Mass 0.31 M<sub>Sun</sub>, Age {{val|8|+3|-1}} Gyr }}</ref>
+| mass                 = 0.31<ref name="epe">{{cite web |title=Star: Gliese 581 |url=http://exoplanet.eu/star.php?st=Gl+581 |publisher=[[Extrasolar Planets Encyclopaedia]] |quote=Mass 0.31 M<sub>Sun</sub>, Age {{val|8|+3|-1}} Gyr |deadurl=yes |archiveurl=https://www.webcitation.org/68uUsn7yC?url=http://exoplanet.eu/star.php?st=Gl%20581 |archivedate=4 July 2012 |df=dmy-all }}</ref>
 | radius               = 0.29<ref name="bonfils" />
 | luminosity_bolometric= 0.013<ref name="bonfils" />
@@ Line 140: / Line 140: @@
 * [http://www.space.com/scienceastronomy/070424_hab_exoplanet.html Major Discovery: New Planet Could Harbor Water and Life] Space.com
 * [http://www.solstation.com/stars/gl581.htm Gliese 581 / HO Librae] Solstation.com
-* [http://exoplanet.eu/star.php?st=Gl+581 ''Extrasolar Planets Encyclopaedia'': Gl 581]
+* [https://www.webcitation.org/68uUsn7yC?url=http://exoplanet.eu/star.php?st=Gl%20581 ''Extrasolar Planets Encyclopaedia'': Gl 581]
 * [http://www.astronomycast.com/astronomy/planets/extrasolar-planets/ep-202-the-planets-at-gliese-581/ AstronomyCast: Gliese 581]
 * [http://www.satsig.net/seticalc.htm SETI Range Calculator]
@@ Line 150: / Line 150: @@
 * [http://news-info.wustl.edu/news/page/normal/9607.html Computer models suggest planetary and extrasolar planet atmospheres – A gas, gas, gas] [[Washington University in St. Louis]]
 * [http://www.lpl.arizona.edu/~rory/research/xsp/dynamics/ Extrasolar Planet Interactions] by Rory Barnes & Richard Greenberg, Lunar and Planetary Lab, University of Arizona
-* [http://www.ctv.ca/servlet/ArticleNews/story/CTVNews/20070424/new_planet_070424/20070424?hub=SciTech Earth-like planet found that may support life] Ctv.ca
+* [https://web.archive.org/web/20071023075235/http://www.ctv.ca/servlet/ArticleNews/story/CTVNews/20070424/new_planet_070424/20070424?hub=SciTech Earth-like planet found that may support life] Ctv.ca
 * [http://members.misty.com/don/g581.html Gliese 581 – The "Red Dwarf" and implications for its "earthlike" planet Gliese 581c]
 * [http://video.foxnews.com/v/1301110758001/earths-twin-discovered/ Earth's Twin Discovered?]

Observation data Epoch J2000.0 Equinox J2000.0 (ICRS)
Size of the Sun (left) and Gliese 581 (right).
Constellation	Libra^[1]
Right ascension	15^h 19^m 26.8250^s^[2]
Declination	−07° 43′ 20.209″^[2]
Apparent magnitude (V)	10.56 to 10.58^{[note 1]}
Characteristics
Spectral type	M3V^[5]
B−V color index	1.61^[2]
Variable type	BY Dra^[6]^{[note 2]}
Astrometry

Radial velocity (R_v)	−9.5 ± 0.5^[2] km/s
Proper motion (μ)	RA: −1233.51^[10] mas/yr Dec.: −94.52^[10] mas/yr
Parallax (π)	160.12 ± 1.33 mas^[11]
Distance	20.4 ± 0.2 ly^[11] ly (6.25 ± 0.05 pc^[11] pc)
Absolute magnitude (M_V)	11.6^[12]

Details

Mass	0.31^[13] `M`_☉
Radius	0.29^[5] `R`_☉
Luminosity (bolometric)	0.013^[5] `L`_☉
Luminosity (visual, L_V)	0.002^{[note 3]} `L`_☉
Surface gravity (log g)	4.92±0.10^[14] cgs
Temperature	3,480 ± 48^[14] K
Metallicity [Fe/H]	−0.33 ± 0.12^[14] dex
Rotation	132.5±6.3 d^[15]
Age	7 to 11^[13]^[16] Gyr

Other designations
HO Librae, HO Lib, BD−07°4003, GJ 581, HIP 74995, LFT 1195, LHS 394, LPM 564, LTT 6112, NLTT 39886, TYC 5594-1093-1, Wolf 562.^[2]^[17]
Database references
SIMBAD	The star
	e
	b
	c
	d
	f (artifact)
	g

v t e Gliese 581 system

Star	Gliese 581
Planets	Gliese 581e Gliese 581b Gliese 581c Gliese 581g^† Gliese 581d? Gliese 581f^†
Messages	A Message from Earth Hello from Earth
^† - Disproven Category:Gliese 581 Portal:Astronomy