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Altair
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Altair
Altair in the constellation of Aquila.
Observation data
Epoch J2000.0 Equinox J2000.0 (ICRS)
Constellation
Aquila
Right ascension
19h 50m 46.99855s
Declination
+08° 52' 05.9563?
Apparent magnitude (V)
0.77
Characteristics
Spectral type
A7 V
U-B color index
+0.08
B-V color index
+0.22
V-R color index
0.0
R-I color index
+0.14
Variable type
Delta Scuti
Astrometry
Radial velocity (Rv)
-26.1 ± 0.9 km/s
Proper motion (µ)
RA: +536.23 mas/yr
Dec.: +385.29 mas/yr
Parallax (p)
194.95 ± 0.57 mas
Distance
16.73 ± 0.05 ly
(5.13 ± 0.01 pc)
Absolute magnitude (MV)
2.21
Details
Mass
1.79 M?
Radius
1.63 to 2.03 R?
Luminosity
10.6 L?
Surface gravity (log g)
4.29 cgs
Temperature
6,900 to 8,500 K
Metallicity
-0.2 dex
Rotation
8.9 hours
Rotational velocity (v sin i)
240 km/s
Age
Gyr
Other designations
Database references
SIMBAD
data
Altair (Alpha Aquilae, Alpha Aql, a Aquilae, a Aql, Atair) is the brightest star in the constellation Aquila and the twelfth brightest star in the night sky. It is currently in the G-cloud. 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 (the other two vertices are marked by Deneb and Vega).Altair rotates rapidly, with a velocity at the equator of approximately 286 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.
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^ a b c d e f g Imaging the Surface of Altair, J. Monnier et al., Science 317, #5836 (July 20, 2007), pp. 342–345, doi:10.1126/science.1143205, Bibcode: 2007Sci...317..342M, PubMed 17540860. Accessed on line November 25, 2008. See second column of Table 1 for stellar parameters.
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^ http://interstellar.jpl.nasa.gov/interstellar/probe/introduction/neighborhood.html, Our Local Galactic Neighborhood, NASA
^ http://www.centauri-dreams.org/?p=14203, Into the Interstellar Void, Centauri Dreams
^ Summer Triangle, entry, The Internet Encyclopedia of Science, David Darling. Accessed on line November 26, 2008.
^ Altair's Oblateness and Rotation Velocity from Long-Baseline Interferometry, Gerard T. van Belle, David R. Ciardi, Robert R. Thompson, Rachel L. Akeson, and Elizabeth A. Lada, Astrophysical Journal 559 (October 1, 2001), pp. 1155–1164, doi:10.1086/322340, Bibcode: 2001ApJ...559.1155V.
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