Proxima Centauri is located in the southern constellation of the sky, only 4.22 light-years from the sun, but its luminosity is very dim, and its apparent magnitude is about 11, which is impossible to see with the naked eye. This is also because Proxima Centauri is a red dwarf star with a low surface temperature of only about 3000 degrees Celsius.
Altair, belonging to the constellation Aquila, is the twelfth bright star in the sky, and it is white. It is 16.7 light-years away from the sun, its mass is 1.7 times that of the sun, its diameter is 1.8 times that of the sun, its brightness is 10.6 times that of the sun, and its surface temperature is about 7000 degrees Celsius.
There are many similarities between the star and the famous Sirius: they are both very young stars (possibly formed only hundreds of millions of years), and their cores are made of helium produced by the nuclear fusion reaction of hydrogen.
Vega, belonging to the constellation Lyra, is the fifth brightest star in the sky and is blue. Its mass is 2.1 times that of the sun, and its surface temperature is about 9,000 degrees Celsius. It is currently at the midpoint of its life. The spectrum of Vega is classified as A0V, and its temperature is a little higher than A1V of Sirius. It is still in the main sequence star stage, using the hydrogen fusion reaction in the core to generate light and heat.
Although Proxima Neighbor is closer to the earth, it has entered the later years of life, and the nuclear fusion reaction has decayed, and its light is no longer enough for people to observe with the naked eye.
