Often for molecules to form in interstellar space, dust is used as a catalyst. The reason is that in typical interstellar environments, densities are so immensely low that even for just two atoms to meet, the probability is so small that formation time scales are very long. For 3+ atoms, the chance decreases rapidly. The temperature in the heliosphere is about one million Kelvin, lower (but still very hot) in the outer regions of the heliosphere, higher close to the sun. But the density of the plasma is very low, so you wouldn't feel the heat (except close to the sun). Within Earth's exosphere, reaching up to 10,000 km, the temperature is lower, roughly 1,000 to 1,500 C. In interstellar space there exist. The interstellar medium (ISM) is primarily atomic hydrogen, and has an average density of 1 proton per cubic centimetre, although it can vary widely in different parts of the galaxy. Thus although the material injected back into the interstellar medium is enriched with heavier elements, there is still plenty of hydrogen to start a new generation of stars. One type is diffuse nebulae, which are clouds of gas and dust in interstellar space, often many light years across. They include emission nebulae which are heated by stars and so emit light, reflection nebulae which reflect light from stars, and dark nebulae which block light from stars and nebulae beyond them. A similar phrase, gentle singularity, is used in the movie Interstellar. There has been some discussion about that, in which the consensus seems to be that the size of a supermassive black hole reduces the tidal forces at the event horizon, such that a falling entity would not be spaghettified. The heliopause is the far boundary of the heliosphere, beyond which the interstellar medium takes control. Inside layers are bounded by the termination shock and the heliosheath. In summary, while the Solar System is made of many regions, the heliopause is considered to be its outer boundary. The number of interstellar vagabond planets has been estimated to be as many as the number of stars. And simulations show that if the Solar System started out with an extra gas giant next to Jupiter which was ejected, then one can end up with a very good fit with today's Solar System. In the movie Interstellar, astronauts orbit a supermassive black hole. When they visit a planet in the vicinity of the black hole, though they think they only have stayed there for a few hours, over 20 years have passed. This mechanism will be an important contributor to the carbon, nitrogen and oxygen abundances in the interstellar medium. The winds may also be enhanced in much heavier elements (even heavier than iron, such as Barium and Strontium) that have been produced via the s-process, where pre-existing iron-peak nuclei in the nuclear burning regions are.