In this deep image of Cygnus,
Deneb -- its brightest star -- lies
toward upper left, while Albireo,
at the head of the Swan, is at the lower
right corner. The Milky Way runs down the middle. Reddish interstellar gas
one of which is called IC 1318) surrounds Sadr,
the star at center, while the North America Nebula
lies to the left of Deneb.
P Cygni is a massive, erupting, "luminous
blue variable," 61 Cygni is the first star whose distance was
measured, the Cygnus Loop (part of which is
only barely visible) is the remnant of an ancient exploded star,
and Cyg X-1 is a blue supergiant that has a black hole companion,
the pair radiating powerful X-rays as a result of mass transfer
from the supergiant to the black hole.