|This infobox, "Template:Starbox begin", is from Wikipedia. The list of its authors can be seen in its edit history page. The data in this infobox may not agree or state what Wikipedia states.|
Epoch J2000 Equinox J2000
|Right ascension||20h 41m 25.9s|
|Declination||+45° 16′ 49″|
|Apparent magnitude (V)||1.25 (1.21 - 1.29)|
|Spectral type||A2 Ia|
|U−B color index||−0.23|
|B−V color index||+0.09|
|Variable type||Alpha Cyg|
|Radial velocity (Rv)||−4.5 km/s|
|Proper motion (μ)|| RA: 1.99 mas/yr |
Dec.: 1.95 mas/yr
|Parallax (π)||2.29 ± 0.32 mas|
|Distance||802 ± 66 pc|
|Absolute magnitude (MV)||−8.38|
|Mass||19 ± 4 M☉|
|Radius||203 ± 17 R☉|
|Diameter||203 ± 17 D☉|
|Luminosity||196,000 ± 32,000 L☉|
|Surface gravity (log g)||1.10 ± 0.05 cgs|
|Temperature||8,525 ± 75 K|
|Metallicity [Fe/H]||-0.25 dex|
|Rotational velocity (v sin i)||20 ± 2 km/s|
Deneb, also designated α Cygni (Latinised as alpha Cygni, abbreviated Alpha Cyg, α Cyg and Arided), is the brightest star in the Cygnus constellation. It is the 19th brightest star with an apparent magnitude of 1.25. A blue-white supergiant, Deneb is also one of the luminous stars, but its exact distance and luminosity have both been difficult to calculate. Deneb is estimated to be somewhere between 55,000 and 196,000 times as luminous as the Sun, rivalling the similar star Rigel as the most inherently luminous star of first magnitude. Deneb is only visible in the Northern hemisphere - it is not visible anywhere in Antarctica and is expected to become the Pole star in around 9800 AD.
Distance and properties
Deneb's exact distance from the Earth is still uncertain. The currently accepted distance of around 2,600 light-years is derived by a variety of methods, including spectral luminosity classes, atmospheric modelling, stellar evolution models, assumed membership of the Cygnus OB7 association, and direct measurements of angular diameter. Deneb's absolute magnitude is currently estimated to be −8.4, placing it among the most luminous stars known, with an estimated luminosity nearly 200,000 times that of the Sun. This is towards the upper end of various published values over the last few decades.
Deneb is the most luminous of the stars with apparent magnitude of < 1.5, and the most distant, by a factor of < 2 of the 30 brightest stars. Based on its temperature and luminosity, and also on direct measurements of its tiny angular diameter which is a mere 0.002 arcseconds, Deneb appears to have a diameter of about over 200 times that of the Sun; if placed at the center of the Solar System, Deneb would extend out to the orbit of the Earth. It is one of the largest known white stars. Deneb is a blue star of spectral type A2Ia, with a surface temperature of around 8,500 degrees Kelvin. Since 1943, its spectrum has served as one of the stable reference stars by which other stars are classified.
- Merriam-Webster's Collegiate Dictionary, Tenth Edition (1999)
- Cite error: Invalid
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