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Three Hot Subterran Exoplanets around KOI-961

posted Jan 11, 2012, 6:05 PM by Abel Mendez   [ updated Jun 30, 2012, 11:10 AM ]

Here are some quick stellar and planetary properties (Tables 1 and 2) for the three exoplanets system KOI-961 plus the basic habitability assessment with the Habitable Zone Distance (HZD) and Earth Similarity Index (ESI). This is the smallest system of exoplanets so far and the first three confirmed hot subterrans, between Mars and Earth size (this image will be updated soon). The exoplanets of KOI-691 are too close to their star for liquid water (HZD < -1) and not potentially habitable (ESI < 0.7). Check the HEC Top 10 for a list of other small exoplanets.

Table 1: Stellar properties of KOI-961, a red dwarf star (M4) 126 light years away.
 
Radius (SU) Mass (SU) Eff. Temperature (K) Luminosity (SU) Habitable Zone (AU)
0.17 0.13 3068 0.00240 0.036 - 0.098
SU = solar units.

Table 2: Planetary properties of the three exoplanets around KOI-961. All are probably subterrans (mass between 0.1 to 0.5 Earth masses) orbiting in the hot zone of their parent star (the inner region outside the habitable zone).

Planet pClass Radius
(EU)
Mass*
(EU)
Eq. Temperature
(K)
Period
(days)
 Distance
(AU)
HZD  ESI
KOI 961.01 Hot Subterran 0.78 0.44 520 1.21 0.0116 -1.64 0.56
KOI 961.02 Hot Subterran 0.73 0.36 724 0.45 0.0060 -1.79 0.41
KOI 961.03 Hot Subterran 0.57 0.16 452 1.87 0.0154 -1.54 0.59
* mass was estimated assuming an Earth-like rocky planet composition. EU = Earth Units.

References

  • Muirhead, P. S. et al. (2012) Characterizing The Cool KOIs III. KOI-961: A Small Star With Large Proper Motion And Three Small Planets. ArXiv:1201.2189v1.