ذنب الدجاجة

Deneb's absolute magnitude of −6.93 makes it one of the most intrinsically luminous stars catalogued, a distant giant whose light crosses roughly 1,412 light-years to reach Earth. That it still appears at apparent magnitude 1.25 across such a distance testifies to an output tens of thousands of times the Sun's. It is Alpha Cygni, the tail of the constellation Cygnus, a white A-type star with a B–V index of 0.092. A northern declination of +45° makes Deneb circumpolar from much of the northern hemisphere, and it completes the Summer Triangle with Vega and Altair — the most remote of the three by a vast margin.