Today, I was taking some shots of night sky. For each, I had 20 sec exposure. During picture review, I found a red dot which is referred as "Hot Pixel" according to some people on the Internet. Because I found this red dot with 20 sec exposures (which I took for the first time to capture the night sky) and not with the normal shots, I thought to test if this was a result of long exposure. To test this, I took two shots with lens cap on. One was with 20 sec exposure and another one with 1 sec exposure. I found the red dot again with 20 sec exposure but none with 1 sec exposure.
Additional info: Camera : Canon 600D, ISO : 200 - 800, White Balance : Tungsten, Auto and Fluorescent.
Hot pixel with long exposure, 20 sec (crop out from the night sky shot):
My question is, does this red dot/hot pixel is a result of long exposure or something else (sensor processing etc)?
Also, how to reduce or remove this effect as it seems very annoying for the astro-photography (initially, I got confused with it as a star with red shift)?
Thanks in advance!