The minimum temperature of protoplanetary disks around stars located in massive dense star clusters can exceed the temperature necessary for water ice to condense (~ 150 to 170 degrees Kelvin). Massive dense star clusters tend to form in single bursts of intense star formation where temperatures can remain too hot for water ice to condense on a timescale that is comparable to the planet formation timescale. This can inhibit the formation of gas giant planets as they only form in environments where the temperature is cool enough for water ice to condense. Irradiation experienced by a protoplanetary disk in a dense cluster environment is made up of flux from the stars in the cluster and flux from the central star. The minimum temperature of the protoplanetary disk is determined by the total flux it receives from stars in the cluster and if this component of flux is strong enough, it will result in a protoplanetary disk that is too hot for water ice to condense.
A protoplanetary core with about 10 Earth-mass is required for the formation of a gas giant planet. This is because only an object that massive is able to initiate the runaway accretion of hydrogen and helium from the protoplanetary disk to form a gas giant planet. In a typical protoplanetary disk where the temperature is cool enough for water ice to condense, the mass of all condensables is a factor of a few times higher than the mass of all rocky material. If the temperature is too high for water ice to condense, the protoplanetary disk will lack the surface mass density required for sufficient material to accrete and form a 10 Earth-mass protoplanetary core. Since the presence of a large amount of condensables is an essential requirement for gas giant planets to form, protoplanetary disks that are too hot for water to condense are expected to form only rocky terrestrial planets where they too are likely to be devoid of water. As a result, stars that form in massive dense star clusters may be devoid of gas giant planets and habitable planets.
There are a number of places which can have cluster environments that are massive and dense enough to keep temperatures above the water ice condensation temperature. Examples of such places include nuclear star clusters and the cores of globular clusters. The formation of stars in such environments is an exception rather than the norm. Searches for planets around stars in these places should turn up a paucity of gas giant planets if temperatures during their formative periods were high enough to prevent the condensation of water ice in protoplanetary disks around the clusters' stars. In fact, searches for gas giant planets around stars in the dense core of a globular cluster named 47 Tucanae turned up zero planets even though 10 to 15 of them were expected based on the known abundance of gas giant planets discovered around stars nearer the Sun. Lastly, in the cores of galaxies, accretion of material by supermassive black holes can put out enormous amounts of energy which can inhibit the formation of gas giant planets in protoplanetary disks around stars located up to great distances away.