Probabilities in the Galaxy
A Distribution Model for habitable Planets
Copyright © Klaus Piontzik Claude Bärtels

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2 – Evaluation of Catalogue Data

2.1 - Newer Catalog Data for Exoplanets

In September 2015, a total of 1,952 exoplanets were known. According to the "Habitable Exoplanets Catalog" [1] there are 31 star systems with planets in habitable zones. 21 were superearth and only 10 were classified as approximatly earth-great. Only in 4 systems could you classify planets as approximatly earth-like. [2]
If 31 systems of 1,952 systems have habitable planets, this corresponds to a share of 1.588 %, so: F
h2 = 0.015,88 = 31: 1,952.

NASA released on 9 May 2016, the latest data on the Kepler telescope. [3] [4] In the meantime, 1,284 new exoplanets have been discovered.Thus, a total of 2,325 exoplanets are now known. There are probably rocky planets in 550 systems, like Earth. 9 planets are in a habitable zone.
Thus, the probability is F
h3 = 0.016,36 = 9:550 for habitable planets.

According to Wikipedia, as of October 1, 2017, a total of 3,671 exoplanets in 2,751 systems are known, including 616 systems with two to seven planets. [5]

According to the "Habitable Exoplanets Catalog" [1] of December 2017, 53 star systems with planets exist in habitable zones. 30 are super-earths, 22 are classified as approximately earth-great and a planet of the class subearth, thus planets which are smaller than the earth. Only in 5 of 13 selected systems, planets could be classified as approximately earth-like.
If of 2,751 known star systems with planets, 53 systems with habitable planets exist, then the probability is F
h4 = 0.019,265 = 53:2.751for habitable planets.

The data from 2015 to 2017 show the minimum and maximum probability of a planet in the habitable zone:

2.1.1 Equation 0.015,88 ≤ Fh ≤ 0.019,265


The reason for the differences is that we are dealing with a much smaller data population than in the Petigura investigation and the time intervals of the information are not constant, as well as the individual information sources are not synchronized. Small fluctuations are therefore unavoidable.

It should be noted once again that the exact position of a habitable zone in a solar system depends on the star type, i.e. on the radiation and the temperature of the star. The catalogue data for exoplanets did not always show the type of stars.

To make matters worse, the data material viewed here is not homogeneous in its statements. Some data are therefore difficult to compare, so a certain filtering had to be carried out.

A proven method is first of all to determine the limits, i.e. the maximum deviations, which is implemented with equation 2.1.1. The next step is to calculate the mean value from the three observation data and thus obtain:

  Fhm = 0.017,572 ± 0.001,693
F
hm = 1:57

which corresponds quite well with the value Fh1 = 0.016,588 = 10:603 from the Petigura investigation. The error is 4 percent.

If you round the Petigura value a little from 10:603 to 10:600, you get 1:60, which comes quite close to the mean value of 1:57 from the observation data. To simplify all further calculations, the rounded value from the Patigura analysis can be used, i.e.:

  Fh0 = 0.016,66... = 1:60

Overall, this results in a good agreement between the Petigura data and the observations made in the meantime and the resulting catalogue data.

The consistency of the data, as well as further information from the catalogue data can be used to derive further probabilities for subsets of habitable planets. These are the subearths, the superearths, approximatly earth-great planets and approximatly earth-like planets, which will be treated in the next sections.

 

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