BD -12°2449

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BD -12°2449
The planetary system around BD -12°2449 (image courtesy ESO)
Stellar characteristics
Right ascension (Epoch J2000)08h 18m 23.90s
Declination (Epoch J2000)-12° 37' 55.80"
Spectral typeG7.5-K0 V
Distance from Sol40.1 ly
Other designationsHR 3259, Gl 302, Hip 40693, HD 69830, BD-12 2449, SAO 154093, LHS 245.
PlanetsBD -12°2449 b,<br\>BD -12°2449 c,<br\>BD -12°2449 d
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BD -12°2449 is located about 41.0 light-years from Sol. This southern star lies in the northeastern part of the constellation Puppis, the Stern. Some astronomers prefer to refer to this star as HD 69830, as it is listed in the Henry Draper (1837-82) Catalogue.

BD -12°2449 is a yellow-orange to orange-red, main sequence dwarf star of spectral and luminosity type G7.5-K0 V. The star has a mass of 86 +/- 3 percent of Sol's[1], 87 to 89 percent of its diameter[2][3][4], and 45 percent of its bolometric ("total") luminosity[5][6]. It appears to be slightly less abundant 89 to 93 percent in iron than Sol[1][7]. The star is around 87 to 93 percent as enriched as Sol in elements heavier than hydrogen[8][9].

While a recent age estimate indicates 7 +/- 3 billion years[1], a prior estimate indicated only around half of Sol's 4.6 billion years.

For an Earth-type planet around BD -12°2449 to have liquid water at its surface, it would need a stable orbit centered around 0.75 AU -- between the orbital distances of Venus and Earth in the Solar System, with an orbital period around 259 days. However, the presence of planet "d" would probably perturb the orbit of such a hypothetical Earth-mass planet. Life on such a planet would also be under a relatively higher frequency of asteroid impacts, than is Earth at present.

Known Places Around BD -12°2449

In April 2005, a team of astronomers announced the discovery of an asteroid belt around this star with some 25 times the mass of The Main Belt in the Solar System[10]. By July 2006, the team had confirmed that the debris was indeed derived from the break up of a P or D-type, outer Main-Belt asteroid lacking in carbonaceous or iron-rich materials with a diameter of around some 30 kilometers (19 miles), that is located around one AU from the star[11].

On May 17, 2006, astronomers using the HARPS spectrograph on the European Southern Observatory's 3.6-meter telescope at La Silla, Chile, announced the discovery of three planets (ranging around Uranus or Neptune in mass) around this Sol-type star[12].

  • BD -12°2449 b masses 10.5 Earths and orbits its primary at 0.0785 AUs with a period of 8.67 days.
  • BD -12°2449 c masses 12.1 Earths and orbits its primary at 0.186 AUs with a period of 31.6 days.
  • BD -12°2449's Asteroid Belt lies between planets c and d.
  • BD -12°2449 d masses 18.4 Earths and orbits its primary at 0.63 AUs with a period of 197 days.
The night sky from Eayn, a moon of BD -12°2449 d. The bright band is light reflected from the system's asteroid belt.
Theoretical simulations indicate that innermost planet is rocky and very hot, that the middle one is rocky with gas, and that outermost planet is likely to have a rocky core that may be surrounded by a highly pressurized water layer as well as a massive outer gas envelope. The outermost planet appears to be located near the inner edge of the habitable zone, where surface liquid water may exist. Although this planet does not appear Earth-like due to its Neptune-like mass, some astronomers speculate that it may have moons suitable for Earth-type life.

(Data from


  1. 1.0 1.1 1.2 (Lovis et al, 2006)
  2. (Pasinetti-Fracassini et al, 2001)
  3. (Johnson and Wright, 1983, page 663)
  4. (NASA Star and Exoplanet Database, derived from Kenneth R. Lang, 1980)
  5. (Beichman et al, 2005)
  6. (Arthur N. Cox, 2000)
  7. (Cayrel de Strobel et al, 2001)
  8. (Valenti and Fischer, 2005)
  9. (Santos et al, 2004)
  10. (press release from the Spitzer Space Telescope)
  11. (Lisse el al, 2007)
  12. (ESO press release and Nature abstract)