  Astronomers have always wanted to know whether there are other planets around
other stars that support life like our Earth. The search for life elsewhere has
led us to new findings of extreme planetary conditions that humans were unaware
of. Here we present the habitability index values of three earlier discovered
exoplanets: Kepler-504 b (of the star Kepler-504), Kepler-315 b and Kepler-315
c (of the Kepler-315 stellar system). We wanted to know what are the ideal
factors that decide the chances of habitability, e.g., the orbital distance
from the star, the type of star, or a combination of multiple properties. We
hypothesized that there should exist a combination of these properties that
will increase the chances that the exoplanet would be similar to Earth. We have
adopted the Earth Similarity Index (ESI) for calculating the physical
similarity of exoplanets to Earth, and hence the probability of them being
habitable. Using available telescope data, we found that Kepler-504 b, with a
host M-type star (small red dwarf), and Kepler-315 c, with a host G-type star,
had ESI values of 71.23% and 69.44%, respectively, thereby showing high
similarity to Earth. Kepler-315 b, with a host G-type star, on the other hand,
had an ESI value of only 35.68%, showing poor similarity to Earth. We have also
listed previously calculated ESI values of additional exoplanets from the
Planet Habitability Laboratory catalog, which supports our hypothesis. Thus, it
suggests that a combination of star-type and orbital radius seems to make
conditions favorable. Future work can study more exoplanets with such
combinations to further validate these findings.
