Giant planets can influence potentially habitable worlds in various ways. For example they can facilitate the formation of planetary cores or modify the influx of asteroids and comets towards Earth-analogs later on.
Additionally, the sheer presence of a giant planet in an exoplanetary system alters the orbit of a potentially habitable world over time.
The variations in some of the orbital elements or the obliquity of the planet may result in the planetary atmopsphere to react strongly to changes in the incoming starlight
and hence affecting its capability of mainting liquid water near its surface.
In this work, we assess the level at which planetary systems can sustain
liquid water on the surface of Earth-like planets. Calculating the actual insolation received by a potentially habitable world,
we are able to determine more realistic habitable zone limits that has ever been done in the past.
Investigating 147 well characterized exoplanetary systems known to date that host a main sequence star and a giant
planet we show that the presence of ’giant neighbors’ can reduce a terrestrial planet’s chances to remain
habitable, even when both planets have stable orbits. In a small fraction of systems, however, giant
planets slightly increase the extent of habitable zones provided the terrestrial world has
a high climate inertia. In providing constraints on where giant planets cease to affect the habitable
zone size in a detrimental fashion, we identify prime targets in the search for habitable worlds.

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