If the sun were replaced by Sirius, what would happen to the earth?

If Sirius becomes our star instead of the sun, and assuming that the earth is still in its original orbit, then the revolution speed of the earth will be faster. This is because Sirius has a higher mass, about twice that of the sun, so it has a stronger gravitational effect on the earth, which leads to the need for the earth to move at a faster speed to avoid being attracted by Sirius. According to the calculation, the linear speed of the earth's revolution will increase from 3 km/s to 42 km/s, and the time of the earth's rotation around Sirius will be shortened from 365 days to 256 days.

Because Sirius is much hotter than the sun, this will lead to a great migration of the livable zone. Because Sirius's radiation power is 25 times that of the sun, the area about 5 astronomical units away from Sirius is the livable zone. According to the simulation results of the software, after replacing the sun with Sirius, the temperature of the earth's surface will be heated to more than 1 degrees Celsius in less than two weeks, which means that a lot of water on the earth will evaporate. In just one month, all the oceans on the earth will be dried, and life can't survive on this earth.

in the Sirius system, the livable zone will move to Jupiter's orbit. Although Jupiter is a gas giant planet, its moons are all rocky planets, which means that they will probably become suitable for breeding life.

Although Sirius was only formed 24 million years ago, its life span is much shorter than that of the sun because of its large mass. Sirius can only continue to burn for another 1 billion years (the life span of the sun can reach 1 billion years, and the remaining 5 billion years), so the time left for life evolution is not long. You know, in the billions of years after the birth of life on the earth, life on the earth has always been very primitive, and it was not until hundreds of millions of years ago that advanced creatures gradually appeared. Considering that the temperature of Sirius will get higher and higher, the livable zone will move further outward as long as it takes another 2 million years.

In addition, Sirius is actually a binary star system. Sirius A is visible to the naked eye, and Sirius B, a companion star, is a white dwarf with a mass similar to that of the sun, but invisible to the naked eye. The closest distance between Sirius B and Sirius A is only 8 astronomical units, and the existence of companion stars will probably affect the evolution of life in the livable zone.