Altair (Alpha Aquilae) - Wide Field (Harold Freckhaus)

Altair (Alpha Aquilae) - Wide Field

Altaïr (α Aquilae / α Aql) est l'étoile la plus brillante de la constellation de l'Aigle. De magnitude apparente 0,762, elle est la douzième étoile la plus brillante de la voûte céleste. Située à environ 17 années-lumière de la Terre1, elle est aussi l'une des étoiles les plus proches visibles à l'œil nu.

Altaïr est une étoile blanche de type spectral A7Vn3, avec une classe de luminosité cinq, qui indique qu'il s'agit d'une étoile de la séquence principale. Elle est environ deux fois plus grande que le Soleil et 1,8 fois plus massive que lui, et elle est près de onze fois plus lumineuse que lui. Ce qui la caractérise est sa rotation extrêmement rapide : il lui faut 8,9 heures pour effectuer une rotation, là où le Soleil met un peu plus de 25 jours. Altaïr tourne donc à son équateur à une vitesse de 240 km/s. En conséquence, Altaïr est oblongue, aplatie aux pôles et renflée à l'équateur : son diamètre équatorial est au moins 14 % plus grand que son diamètre polaire. Le suffixe « n » derrière sa classe de luminosité indique que son spectre présente des raies « nébuleuses » en raison de sa rotation rapide.

[i]Source: Wikipedia.fr[/i]

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Altair, designation α Aquilae (Latinised to Alpha Aquilae, abbreviated Alpha Aql, α Aql), is the brightest star in the constellation of Aquila and the twelfth brightest star in the night sky. It is currently in the G-cloud—a nearby interstellar cloud, an accumulation of gas and dust. Altair is an A-type main sequence star with an apparent visual magnitude of 0.77 and is one of the vertices of the Summer Triangle asterism (the other two vertices are marked by Deneb and Vega). It is 16.7 light-years (5.13 parsecs) from the Sun and is one of the closest stars visible to the naked eye.

Altair rotates rapidly, with a velocity at the equator of approximately 286 km/s. This is a significant fraction of the star's estimated breakup speed of 400 km/s. A study with the Palomar Testbed Interferometer revealed that Altair is not spherical, but is flattened at the poles due to its high rate of rotation. Other interferometric studies with multiple telescopes, operating in the infrared, have imaged and confirmed this phenomenon.

Source: Wikipedia.en

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Status	Advanced success
Started	...
Astrometry.net job	3635043
PixInsight job	M27N7T29YBBZ6H1WRA15DUKBJD4RLBYF
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RA (center)	19h50m48s.15
RA (top/left)	19h49m51s.55
RA (top/right)	19h48m43s.49
RA (bottom/right)	19h51m44s.56
RA (bottom/left)	19h52m53s.79

Dec (center)	+08°51′31″.9
Dec (top/left)	+09°47′36″.8
Dec (top/right)	+08°02′46″.4
Dec (bottom/right)	+07°55′27″.2
Dec (bottom/left)	+09°40′17″.7

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