If we were to replace our Sun-like star with a black hole with a diameter of 7310 km (which is remarkably small for a black hole) and an accretion disk temperature of 6800°C, several significant changes would occur.
Gravitational Effects: The gravitational pull near a black hole is incredibly strong due to its high mass concentrated in a small volume. Objects near the black hole would experience an intense gravitational force, leading to significant tidal forces and extreme time dilation effects.
Accretion Disk: An accretion disk is a rotating disk of gas and dust that forms around a black hole as it attracts and absorbs surrounding matter. The temperature of 6800°C you mentioned is exceptionally high for an accretion disk. Such a high temperature would result in intense radiation emission, primarily in the form of X-rays and gamma rays.
Absence of Light: Black holes have such strong gravitational pull that they can trap even light itself within a region called the event horizon. Therefore, if a black hole replaced our Sun, the intense gravitational field would prevent light from escaping, plunging the surroundings into darkness.
Disruption of Planetary Orbits: The replacement of the Sun with a black hole would significantly disrupt the stable orbits of planets in our solar system. The gravitational forces exerted by the black hole would cause drastic changes in the trajectories of planets, potentially leading to their ejection from the system or causing them to fall into the black hole.
It's worth noting that the size of the black hole you described, 7310 km in diameter, is highly unusual. Most stellar black holes are formed from the collapse of massive stars and have diameters on the order of a few kilometers. Black holes with such small sizes are not currently known to exist in nature.