Are there violet stars

Answer 1

No. A stars color is determined by the heat it produces. Like a peice of metal when heating up will got from red to yellow to white (red being cooler the white) a star color is determined by its color. to get a better example of this see this chart which shows star temperature in Kelven.

Stars can be classified by their surface temperatures as determined from Wien's Displacement Law, but this poses practical difficulties for distant stars. Spectral characteristics offer a way to classify stars which gives information about temperature in a different way - particular absorption lines can be observed only for a certain range of temperatures because only in that range are the involved atomic energy levels populated. The standard classes are:

Temperature

O 30,000 - 60,000 K Blue stars

B 10,000 - 30,000 K Blue-white stars

A 7,500 - 10,000 K White stars

F 6,000 - 7,500 K Yellow-white stars

G 5,000 - 6,000 K Yellow stars (like the Sun)

K 3,500 - 5,000K Yellow-orange stars

M < 3,500 K Red stars

The fact is that starts just don't get that hot. Btw indigo would be before violet in the color spectram and I don't believe any stars of that color exist either.