|Official title (IAU-approved)||Altair|
|Different Designations||HIP 97649, Alpha Aquilae, HR 7557|
|Distance from Earth||16.7 light-years|
|Kind||Most important sequence? A7IV-V|
|Proper Ascension||19h 50m 47s|
|Declination||+08° 52′ 06”|
|A number of system?||No|
|Exoplanets standing||None recognized|
|Possible destiny||Planetary nebula/white dwarf|
Altair is the twelfth-brightest star within the evening sky and one of many closest stars to Earth, at a distance of solely 16.7 light-years. Altair seems to be on the primary sequence, the place stars nonetheless burn hydrogen of their cores, however it’s virtually twice the Solar’s measurement and mass. It’s doable that Altair has begun to make the most of helium within the core, and subsequently could possibly be on the way in which in the direction of turning into a subgiant star.
Often we discover stars (Regulus and Vega are two examples) which might be rotating so quickly, their form begins to stretch because of this. Altair falls into this class. Finishing a full rotation each 10 hours, Altair’s equator is transferring at roughly 290 kilometers a second — that’s equal to about 650,000 miles per hour. To place this quantity into perspective, think about Jupiter. The enormous planet additionally rotates each 10 hours however with solely 10% of the Solar’s girth, its equator travels solely about 13 kilometers per second (30,000 mph).
Stars usually seem as featureless factors of sunshine it doesn’t matter what telescope is used or how a lot magnification is utilized, however as a consequence of Altair’s measurement and proximity, we will see the precise floor of this star. Astronomers on the Heart for Excessive Angular Decision Astronomy (CHARA) have immediately imaged Altair, utilizing CHARA’s Mid-Infrared Combiner to seize its oblate form. The photographs additionally reveal common floor particulars, reminiscent of the truth that Altair’s equator is darker — and subsequently cooler — than its polar areas. Like its form, Altair’s darkish equator is because of its fast spin. The impact, generally known as gravity darkening, was first predicted in 1924.
Origin / Mythology
The star’s Arabic title is Al Nasr Al-Tair, which means “The Flying Eagle,” an apt title for the brightest star in a constellation that’s introduced as an eagle throughout a number of cultures. Historic Greeks, Babylonians, Egyptians, Sumerians, Aboriginal Australians — all of them shared the idea of Aquila as an eagle or predatory hen.
Nevertheless, in a single charming Chinese language delusion, Altair has nothing to do with an eagle, however as an alternative represents a humble cowherder. He’s in love with the Sky Emperor’s daughter, a weaver represented by the star Vega. The 2 had been banished on reverse sides of a river, symbolized by the Milky Method, that they can not cross. Fortunately, every year, a flock of magpies construct a bridge throughout the Milky Method in order that the cowherd and the weaver would possibly briefly reunite. Comparable tales of star-crossed lovers represented by these two stars exist in Japan and Korea.
Tips on how to See Altair
For those who’ve by no means seen Altair (or at the least have by no means recognized it), you’ll discover the star satisfying and enjoyable to find, primarily due to its brightness but additionally due to its location.
Altair is one in all three stars that make up the Summer season Triangle, the opposite two being Deneb and Vega. Whereas the Triangle could be seen throughout seasons aside from summer time, it’s enjoyable to go in search of it in July or August as a result of it is vitally excessive up within the sky, near the zenith. When in search of Altair, remember the fact that Summer season Triangle isn’t equilateral; it’s nearer in form to a proper triangle. This reality particularly helps with figuring out Altair, as Altair is the one star of the triangle that’s farther away from the opposite two. Be careful for Rasalhauge — it’s one other vivid star close by however isn’t a part of the triangle. Altair itself has two dimmer, line-of-sight companions on both facet of it, Alshain and Tarazed.
And say, whilst you’re in Aquila, take a fast leap right down to Lambda Aquilae — the Eagle’s “tail.” Someplace within the clean space between Lambda Aquilae and Scutum (the Defend) is the 1973 Pioneer 11 spacecraft, dashing on towards the house between stars.
It doesn’t take eagle eyes to see the Eye of the Eagle . . . have enjoyable viewing Altair.