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New Kepler Potential Planet Transit Signals

posted Nov 4, 2013, 8:00 AM by Abel Mendez   [ updated Nov 4, 2013, 8:03 AM ]
The NASA Kepler team released a revised global list of 16,285 potential planet transit signals (formally known as Threshold-Crossing Events or TCE) from quarters one to sixteen, the four years of operation of Kepler (Table 1). This list already includes most of the 3,602 Kepler Objects of interest (KOI) with 170 Kepler Confirmed Planets.

Additional analysis is necessary to confirm the planetary nature of the over 12,000 remaining TCE objects. Many of these transits signals are expected to be false alarms, specially for long periods objects such as those orbiting within the habitable zone (HZ).

Nearly 1,500 TCE objects match our standard criteria for potentially habitable planets (planet size 0.4 — 2.6 Earth radii orbiting within the empirical HZ), but only about 20% of them might turn out to be real planets, still a large number. Nevertheless, this analysis provides some upper limits to interesting objects in the Kepler TCE sample (Table 2).

Table 1. Summary statistics of some planetary and stellar characteristics of the new 16,285 TCE list.
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                      Property         MIN         AVG         MAX    Count
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           Planet Radius (EU):        0.00       15.53     5312.00    16285
         Planet Period (days):        0.50      197.33      707.28    16285
  Planet Semi-Major Axis (AU):      0.0101      0.5349      2.3200    16285
        Planet Temperature(K):       63.10      875.85    14200.00    16285

               Star Mass (SU):        0.09        1.06        3.71    16285
             Star Radius (SU):        0.12        4.18      219.50    16285
         Star Temperature (K):     2661.00     5715.10    15896.00    16285
         Star Luminosity (SU):      0.0006     48.2446  14036.8495    16285
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EU = earth units, SU = solar units

Table 2. Basic analysis of the TCE objects. 
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Habitable Exoplanets Catalog (HEC) Statistics
  Data Source: NASA Kepler Threshold Crossing Events (TCE)
  [Nov  4, 2013] Planetary Habitability Laboratory (phl.upr.edu) 
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                         Stellar Systems  9743
                              Exoplanets 16285
              Exoplanets in the Hot Zone 10982 (67.4%)
 Exoplanets in the Warm 'Habitable' Zone  3646 (22.4%)
             Exoplanets in the Cold Zone  1657 (10.2%)
                            Unclassified     0 ( 0.0%)
          Potential Habitable Exoplanets  1486 ( 9.1%)
   Expected Potential Habitable Exomoons   185 ( 1.1%)
                               Eta Earth  15.3 %
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Number of Multiple Systems
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     1      2      3      4      5      6     7      8      9     10
  6520   1832    537    292    228    204    93     30      3      4
  66.9   18.8    5.5    3.0    2.3    2.1   1.0    0.3    <0.1  <0.1
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Planetary Class
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Mercurian    Subterran     Terran    Superterran    Neptunian    Jovian
42           327           1382      5766           5063         3355
0.3          2.0           8.5       35.4           31.1         20.6
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Hot Zone
            Category     Count   Percent
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          Mercurians        19       0.1
          Subterrans       274       1.7
             Terrans      1123       6.9
        Superterrans      3664      22.5
          Neptunians      2695      16.5
             Jovians      2858      17.5
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Warm 'Habitable' Zone
            Category     Count   Percent
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          Mercurians         3       0.0
          Subterrans        29       0.2
             Terrans       117       0.7
        Superterrans      1340       8.2
          Neptunians      1760      10.8
             Jovians       396       2.4
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Cold Zone
            Category     Count   Percent
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          Mercurians        20       0.1
          Subterrans        24       0.1
             Terrans       142       0.9
        Superterrans       762       4.7
          Neptunians       608       3.7
             Jovians       101       0.6
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