Deneb

Deneb is the brightest star ( α Cygni ) in the constellation Cygnus. He, together with Vega and Altair, the Summer Triangle. With an apparent magnitude of 1.2 like the Alpha Cygni star prototype light is Strong Blue variables. Deneb is the 19th - brightest star in the night sky, along with Eta Carinae ( also LBV star) known so far the brightest star of the galaxy in visible light. He is also the farthest star first size class. If Deneb the same distance from Earth as Vega (25 light years), it would be nearly as bright as the moon shine in sickle shape.

Word Clearing

The name Deneb means " tail" and is a shortening of the Arabic name ذنب الدجاجة ḏanab al - daǧāǧa, tail of the hen '. Other names of α Cygni: Arided, Aridif, Arrioph, Deneb el Adige, Gallina.

Distance

Denebs removal can only be within a wide range specify, since as far distant stars, the measurement error have great impact on the result. In the previously most accurate parallax by the satellite Hipparcos parallax of 1.0 milliarcseconds was determined, which corresponds to a distance of about 3200 light years. Due to the high uncertainty of the distance of Deneb could but 1600-7400 are light years ( the information in the information box based on the Hipparcos parallax). Recent analysis (second Hipparcos reduction 2007) give values ​​of about 1400 light years; According to a study from 2008 is the most likely distance 1550 light years with an uncertainty of less than 20%. Therefore, the other properties of Deneb are subject to large uncertainties.

Physical Properties

Deneb is a hot supergiant, he is currently in the transition phase from the Blue Giant to red supergiant. With an absolute magnitude of -8.5 like he is one of the brightest stars known. The radiation output is approximately 1.2 × 1032 W and is thus approximately 300,000 times greater than that of the sun. Since the distance could not be determined accurately vary the values ​​of the brightness between 60,000 and 250.000facher sun brightness. The star produced in a minute more light than the sun in a month.

Based on its temperature and luminosity and the tiny apparent diameter of just 0.002 seconds of arc, the diameter of the 200 - to 300 times the sun will set. Would Deneb in the center of the solar system would reach its edges up to half of the Earth's orbit. It is therefore also one of the largest known star and the most powerful A- Star, which can be observed with the naked eye.

As A2iA - star Deneb has a surface temperature of 8400 Kelvin. He is the prototype of a series of variable stars, which are known as Alpha Cygni variables. Its surface vibrates slightly, which results in small variations in brightness and change of spectral type. Its mass is on the 20 - to 25 -fold the estimated mass of the Sun.

Because of its large mass and high temperature, there will be Deneb in this state for long. As a star of about 20 solar masses Deneb finished his dwarf stage ( the stage of hydrogen burning ) around 40,000 years ago as a hot B star.

In a few million years, he could develop into a supernova. Denebs stellar winds cause a material loss of 0.8 millionths of a solar mass per year. This is 100,000 times more than the loss of mass of the sun.

The main star is possibly surrounded by a faint companion is known about the still little. With an apparent magnitude of 11.7 like it is visible only with the aid of telescopes.

Mythology

In Chinese love story of Kwee Deneb means a formed by a magpie bridge across the Milky Way, which allows the separated lovers Niu Lang ( Altair ) and Zhi ( Wega ) on a particular night in late summer to reunite. In Japanese culture there is a arisen from this story Festival ( Tanabata ). In other versions of this story Deneb is a fairy that serves as a chaperone when the lovers meet on this bridge.

Notes and References

• Swan ( constellation )
• Binary star
• Individual star of first magnitude and brighter
• Variable star