Part of a series I'm starting since the recent What could make a star green? did quite well and others could use the information here in their worlds.
There aren't any "violet" stars.
When a star emits a significant amount of violet light, it also emits blue light, which humans are better at detecting. If any stars out there are actually violet, we see them as dark blue.
How can such a star come about if they do not exist that way in nature (as far as we know) that appears violet to the unaided human eye? What natural circumstances would change the appearance or composition of a star in this way (so that it emits violet light)?
The criteria for this are the same as they were with the previous question:
- Have elements or molecules outside the star (exotic if you wish) as long as they are stable wherever you put them and can as long as they can form naturally in real life.
- Change the composition of the star itself with (exotic if you wish) matter as long as it is stable and produces the desired effects
- Provide a solution that will eventually change color when the star expands
- Provide a somewhat speculative explanation but it should be based in real science
- Have the star "capture" whatever makes it violet after formation or have it form with this quality in the first place
- Simply change the atmosphere of a nearby planet so it looks violet; it should appear violet(ish) from space
- Change the eyes of creatures viewing it; assume human eyes
- Have intelligent intervention; all circumstances should be possible in nature (rare is fine)
- Change the laws of physics or the characteristics of light
- Create the illusion of violet color from either an actual binary or an optical binary; this star should be standalone
While the ideas provided in the answers here may overlap those in the sister question to some degree, there are significant differences: the likes of oxygen and chlorophyl, for example, will not produce violet.