After watching Amy's Choice which is an episode of Doctor Who from May 2010 again, it got me wondering. What is the coldest star out there? Not all stars are the same temperature, blue stars are the hottest that can reach in excess of 30,000k such as Naos in the constellation of Puppis.
At the other end of the temperature spectrum to Naos are red, brown and white dwarf stars. Red dwarf stars can go down to about 3,850K (Georgia State University) . They are both still hot, iron boils at 1811K (Patent Invent) . However as I researched further I found that there are stars out there can be touched by the human because they're so cool. Not advisable because they're still radioactive.
According to research, one of the coldest stars out there is a neighbour, in fact, it is the seventh closest star to our Solar System. If you count the three stars that make up the Alpha Centauri multi-star system including Proxima Centauri as one then it becomes the fourth nearest.
The coldest nearest star is Wise 0855-0714 and its to be found in the constellation of Hydra. It is a Y2 class dwarf star, it may not be the coldest ever star but for this article, it is the coldest we'll be talking about. The star is a mere 7.27 Light Years from the Earth. Its temperature has been estimated at being about 225 -260k, which equates to about -48c to -13c (-55f to 8f). To put this in context, the mean coastal temperature of Antartica is about -12c going all the way down to -60c in areas about 4000 meters high. Ref: Antartica
Although the star won't burn you, it will certain not be a wise move as you'll get frostbite if you touch it and die. In addition to frostbite, there's a whole lot of other issues that you could also get through touching it. It may even be a failed star, one that didn't have sufficient mass to start nuclear fusion. It is speculated that these brown dwarfs aren't stars but are rogue planets. There is a scientific paper on another brown dwarf star WISE 1828+2650 that discusses that star as to whether should be classed as a brown dwarf or a planet.
But what has it to do with Amy Choice? In the episode, the TARDIS is moving towards a Coldstar and the temperature in the TARDIS is freezing. Watching that prompted me to look into the coldest stars. As for whether the coldstar could have such an effect on a spaceship is unlikely in my view.