Pi Mensae

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Pi Mensae
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Mensa
Right ascension 05h 37m 09.89s [1]
Declination –80° 28′ 08.8″ [1]
Apparent magnitude (V) +5.65[2]
Spectral type G0 V[3]
U−B color index 0.11[2]
B−V color index 0.60[2]
V−R color index 0.31
R−I color index 0.29
Variable type none
Radial velocity (Rv) +10.9[4] km/s
Proper motion (μ) RA: 312.01±0.24[1] mas/yr
Dec.: 1,050.38±0.26[1] mas/yr
Parallax (π) 54.60 ± 0.21[1] mas
Distance 59.7 ± 0.2 ly
(18.32 ± 0.07 pc)
Absolute magnitude (MV) +4.35±0.01[5]
Mass 1.11±0.01 M
Radius 1.15±0.01 R
Luminosity 1.532±0.004 L
Surface gravity (log g) 4.35±0.01 cgs
Temperature 6,013±18 K
Metallicity [Fe/H] 0.09[7] dex
Rotational velocity (v sin i) 2.96[7] km/s
Age 3.4±0.6 Gyr
Other designations
π Men, CD−80° 195, CPD−80° 161, GJ 9189, HD 39091, HIP 26394, HR 2022, SAO 258421, LFT 429, LHS 208, LTT 2359
Database references

Pi Mensae (π Men) is a yellow dwarf star[3] in the constellation of Mensa. This star has a high proper motion. The apparent magnitude is 5.67, which can be visible to the naked eye in exceptionally dark, clear skies. It is nearly 60 ly away. The star dwarfs the Sun in terms of mass, size, luminosity, temperature, and metallicity and is about 730 million years younger. It ranks 100th on the list of top 100 target stars for the planned Terrestrial Planet Finder mission to search for Earth-like planets.

Planetary system[edit]

On October 15, 2001, an extrasolar planet was found orbiting the star.[8] It is one of the most massive planets ever discovered. It has a very eccentric orbit that takes approximately 2151 days (5.89 years). Because of its eccentricity, and being a massive superjovian that passes through the habitable zone, it would have disrupted the orbits of any Earth-like planets, and possibly thrown them into the star, or out into the interstellar medium.

The Pi Mensae planetary system[9]
(in order from star)
Mass Semimajor axis
Orbital period
Eccentricity Inclination Radius
b ≥10.27 ± 0.84 MJ 3.38 ± 0.22 2151 ± 85 0.6405 ± 0.0072

See also[edit]


  1. ^ a b c d e van Leeuwen, F. (2007). "HIP 26394". Hipparcos, the New Reduction. Retrieved 2010-02-28. 
  2. ^ a b c Johnson, H. L.; et al. (1966). "UBVRIJKL photometry of the bright stars". Communications of the Lunar and Planetary Laboratory. 4 (99). Bibcode:1966CoLPL...4...99J. 
  3. ^ a b Gray, R. O.; et al. (July 2006). "Contributions to the Nearby Stars (NStars) Project: spectroscopy of stars earlier than M0 within 40 pc-The Southern Sample". The Astronomical Journal. 132 (1): 161–170. Bibcode:2006AJ....132..161G. arXiv:astro-ph/0603770Freely accessible. doi:10.1086/504637. 
  4. ^ Valenti, Jeff A.; Fischer, Debra A. (July 2005). "Spectroscopic Properties of Cool Stars (SPOCS). I. 1040 F, G, and K Dwarfs from Keck, Lick, and AAT Planet Search Programs". The Astrophysical Journal Supplement Series. 159 (1): 141–166. Bibcode:2005ApJS..159..141V. doi:10.1086/430500. 
  5. ^ Holmberg, J.; et al. (July 2009), "The Geneva-Copenhagen survey of the solar neighbourhood. III. Improved distances, ages, and kinematics", Astronomy and Astrophysics, 501 (3): 941–947, Bibcode:2009A&A...501..941H, arXiv:0811.3982Freely accessible, doi:10.1051/0004-6361/200811191. 
  6. ^ Bonfanti, A.; et al. (2015). "Revising the ages of planet-hosting stars". Astronomy and Astrophysics. 575. A18. Bibcode:2015A&A...575A..18B. arXiv:1411.4302Freely accessible. doi:10.1051/0004-6361/201424951. 
  7. ^ a b Delgado Mena, E.; et al. (April 2015), "Li abundances in F stars: planets, rotation, and Galactic evolution", Astronomy & Astrophysics, 576: 24, Bibcode:2015A&A...576A..69D, arXiv:1412.4618Freely accessible, doi:10.1051/0004-6361/201425433, A69. 
  8. ^ Jones; et al. (2002). "A probable planetary companion to HD 39091 from Anglo-Australian Planet Search". Monthly Notices of the Royal Astronomical Society. 333 (4): 871–875. Bibcode:2002MNRAS.333..871J. arXiv:astro-ph/0112084Freely accessible. doi:10.1046/j.1365-8711.2002.05459.x.  (web Preprint)
  9. ^ Butler; et al. (2006). "Catalog of Nearby Exoplanets". The Astrophysical Journal. 646 (1): 505–522. Bibcode:2006ApJ...646..505B. arXiv:astro-ph/0607493Freely accessible. doi:10.1086/504701. 

External links[edit]

Coordinates: Sky map 05h 37m 09.89s, −80° 28′ 08.84″