Because theorbital plane lies close to the line of sight with the Earth, they form aneclipsing binary system.[5] The two components are each distorted by the gravity of the other star, and their shapes mean that the magnitude of the star system varies constantly even outside of the eclipses, an arrangement known as aBeta Lyrae variable. The brightness of the pair decreases during eacheclipse, which occurs with a frequency determined by theirorbital period of 1.95028 days. During the eclipse of the primary component the magnitude decreases by 0.20 to a net of 5.37; the eclipse of the secondary component results in a magnitude decrease of 0.10 to a net of 5.27.[14]
The primary component has 5.8 times the mass of the Sun and 3.7 times the Sun's radius.[7] It is radiating 1,862 times the luminosity of the Sun from itsphotosphere at aneffective temperature of 18,493 K.[8] The smaller secondary has 4.6 times the mass, 3.3 times the radius,[7] and 524 times the luminosity of the Sun. Itsouter atmosphere has an effective temperature of 15,848 K.[8] This star has a high rate of spin, showing aprojected rotational velocity of 120 km/s.[4]
^abcdNicolet, B. (1978), "Photoelectric photometric Catalogue of homogeneous measurements in the UBV System",Astronomy and Astrophysics Supplement Series,34:1–49,Bibcode:1978A&AS...34....1N.
^abcdLevato, H. (January 1975), "Rotational velocities and spectral types for a sample of binary systems",Astronomy and Astrophysics Supplement Series,19:91–99,Bibcode:1975A&AS...19...91L.
^abWilson, Ralph Elmer (1953), "General catalogue of stellar radial velocities",Carnegie Institute Washington D.C. Publication, Carnegie Institution of Washington,Bibcode:1953GCRV..C......0W.
^abcdefghQuadri, U.; et al. (June 2023), "Spectroscopic and Photometric Study of the Eclipsing Binary Star sigma Aquilae",The Journal of the American Association of Variable Star Observers,51 (1): 59,Bibcode:2023JAVSO..51...59Q.
^abPan, Kaike; et al. (July 1998), "Orbital circularization in detached binaries with early-type primaries",Astronomy and Astrophysics,335:179–182,Bibcode:1998A&A...335..179P.
