Transcript Altair - Documents

Altair
By: Nora Lynn Puryear
History and Facts
• “The name Altair is derived from the Arabic
for “’The Flying Eagle’”.
• The star is located about 16.7 light years
away from our sun.
• It is the 12th brightest star visible from Earth.
• Altair is best seen in the summer and autumn
skies.
• Altair is the brightest star in Aquila.
Constellations
• Altair is located in the constellation ‘Aquila’ or
‘the Eagle’.
• This constellation lies in the equatorial region.
• “It is one of the 48 constellations documented
by Greek astronomer Ptolemy in the 2nd
century”.
• It has a star on each side of it which names
are Tarazed and Alshain.
Interesting Facts
• Altair is the southern apex of the Summer Triangle.
• It rotates at the fast speed of more than 200 km (120
miles) per second.
• “Altair is famous for its extremely rapid rotation,
which makes its equator perform a complete rotation
in about 6 hours, when our Sun requires just over 25
days for a complete rotation.
• Pictures taken of its surface show that the fast
rotation also causes the equator to be darker, which
means the star is cooler there than at the poles.
Magnitude, Color, and Size
• Although Altair appears to be blue in many of its
pictures, it is a white sub giant which means it’s very
hot.
• Its apparent magnitude is 0.76 and its absolute is 2.20
which makes this star pretty bright.
• “Because of its fast rotation, it has a flattened shape,
with its equatorial diameter about 20 percent larger
than its polar diameter”.
• Higher temperature usually reveals greater mass, at
least for Main Sequence stars, and Altair is thought to
be in excess of 1.7 times the mass of our sun.
Interesting Facts (Continued)
• An eagle is the symbol of the constellation Altair is
located in (Aquila).
• “On the first of June, Altair rises about 90 minutes
after the sunset, as viewed from mid-north
latitude.”
• “By the end of September it approaches the
meridian as night falls.”
• “By the end of the year, late-night observers will
miss it altogether as it sets less than three hours
after the sun.
More Stuff to Know! 
• “In mythology, Aquila was owned by the
Roman god Jupiter and performed many
tasks for him.”
• “In classical mythology Aquila, and by
extension Altair as well, was an eagle favored
by Zeus.”
• “In another myth Aquila is the eagle that
torments Prometheus, and is shot with a
poisoned arrow by Hercules.”
Facts, Facts, and More Facts!
• “In India, Altair with its two flanking stars,
(Tarazed and Alshain), are sometimes thought
to be the celestial footprints of the god
Vishnu.”
• Once visualized, Aquila the Eagle can be seen
flying eastward through the Milky Way.
• “Altair is separated from the similar-looking
(but brighter) star Vega in the constellation
Lyra by the great starlit band of the Milky
Way.”
Altair
• Another fact that makes Altair stand out is that
it is a weak and unusual variable star with as
many as 9 different rates of brightness waxings
and wanings.
• “Along with Beta Aquilae and Gamma Aquilae, it
forms the well known line of stars sometimes
referred to as the Family of Aquila or Shaft of
Aquila.”
• Also one of the most visible stars to the naked
eye.
Star Stuff
• “If Altair was substituted for our sun, at the
distance the sun is now, life on Earth would
be doomed, as Altair shines with 11 times the
sun’s visible light.”
• Altair has a surface temperature of about
7550 K degrees, which isn’t much hotter than
the sun.
• Altair is thought to be in excess of 1.7 times
the mass of our sun because of its greater
mass.
Citations
• http://solstation.com/stars/altair.htm
• http:/earthsky.org/brightest-stars/altair-the-bluishjewel-of-the-eagle/
• http://www.topastronomer.com/StarCharts/Constell
ations/Aquila.php
• http://www.britannica.com/EBchecked/topic/17491/
Altair
• http://www.brighthub.com/science/space/articles/2
6544.aspx
• http://www.freebase.com/view/en/altair