Electromagnetic radiation (EMR), including visible light, travels at the speed of light in a vacuum, which is approximately 299,792,458 meters per second (or about 186,282 miles per second). This speed is commonly denoted by the symbol 'c'.
If an electromagnetic wave is to catch up with light from a star, it would need to travel at the same speed as light, which is the maximum attainable speed in the universe. Therefore, for the wave to catch up with light from a star, it must also travel at the speed of light, which is approximately 299,792,458 meters per second.
It's important to note that the speed of light is constant and does not depend on the frequency or wavelength of the light. All forms of electromagnetic radiation, regardless of their frequency or energy, travel at this same speed in a vacuum.