Deneb is the brightest star in the constellation Cygnus and one of the vertices of the Summer Triangle. The 19th brightest star in the night sky, with an apparent magnitude of 1.25, Deneb is also one of the most luminous stars known...
Deneb's exact distance from the Earth is uncertain. The
most likely distance is 3,200 light years, but the parallax
uncertainties do not rule out a distance as close as 2,100
light years or as far as 7,400 light years. This distance
uncertainty makes determining many of Deneb's other
properties similarly imprecise.Deneb is the farthest first-magnitude star from Earth.
Estimates for Deneb's luminosity range from about 60,000
times the brightness of our Sun (if Deneb is 1600 light
years away) to 250,000 times the Sun's brightness (if
3,200 light years away).
Estimates for Deneb's radius range from 200 to 300 times
that of the Sun. This is the approximate size of the Sun
(right) relative to Deneb.
Estimates for Deneb's radius range from 200 to 300 times
that of the Sun. This is the approximate size of the Sun
(right) relative to Deneb.
Based on its temperature and luminosity and also on
direct measurements of its tiny angular diameter (a mere
0.002 second of arc), Deneb appears to have a diameter
about 200 to 300 times that of the Sun; if placed at the
center of our Solar System, Deneb would extend to the
orbit of the Earth. It is one of the largest stars known
and the most powerful class A star identified.A star of spectral type A2Ia, Deneb has a surface
temperature of 8,400 kelvins. Deneb is the prototype of a
class of variable stars known as Alpha Cygni variables. Its
surface undergoes non-radial fluctuations, which cause its
brightness and spectral type to change slightly.
Deneb's mass is estimated at 20 to 25 solar masses.
As a white supergiant, its high mass and temperature
mean that the star will have a short lifespan and will
probably become a supernova within a few million years.
It has already stopped fusing hydrogen in its core.
Deneb's solar wind causes it to lose mass at a rate of 0.8
millionth of a solar mass per year, a hundred thousand
times the flow rate from the Sun ....DENEB (Alpha Cygni). One of the truly great stars of our Galaxy, Deneb serves a three-fold role among the constellations. Its very name tells the first. "Deneb" is from an Arabic word meaning "tail" .... it represents the tail of Cygnus the Swan, a classical figure seen flying perpetually to the south along the route of the Milky Way.First magnitude Deneb (Alpha Cygni) shines at far right, while fourth magnitude Xi Cygni lies at the far left edge just below center. The color contrast is obvious, Deneb a white class A supergiant, Xi Cyg a much cooler mid-class K orange supergiant. In between (and closer to Xi) is the faint reddish glow of the North America Nebula, NGC 7000; the fainter Pelican Nebula is down and to the right.
