Zeta¹ Lyrae, Latinized from ζ¹ Lyrae, is a binary star in the northern constellation of

Lyra Lyra (; Latin for lyre, from Greek ''λύρα'') is a small constellation. It is one of the 48 listed by the 2nd century astronomer Ptolemy, and is one of the modern 88 constellations recognized by the International Astronomical Union. Lyra wa ...

. Based upon an annual parallax shift of 20.89 mas as seen from Earth, the pair are located about 156 light years from the

Sun The Sun is the star at the center of the Solar System. It is a nearly perfect ball of hot plasma, heated to incandescence by nuclear fusion reactions in its core. The Sun radiates this energy mainly as light, ultraviolet, and infrared radi ...

. It is visible to the naked eye with an

apparent visual magnitude Apparent magnitude () is a measure of the brightness of a star or other astronomical object observed from Earth. An object's apparent magnitude depends on its intrinsic luminosity, its distance from Earth, and any extinction of the object's lig ...

of 4.37.

Observational history

ζ¹ Lyrae was discovered to be a spectroscopic binary by

William Wallace Campbell William Wallace Campbell (April 11, 1862 – June 14, 1938) was an American astronomer, and director of Lick Observatory from 1901 to 1930. He specialized in spectroscopy. He was the tenth president of the University of California from 1923 to 1 ...

and

Heber Doust Curtis Heber Doust Curtis (June 27, 1872 – January 9, 1942) was an American astronomer. He participated in 11 expeditions for the study of solar eclipses, and, as an advocate and theorist that additional galaxies existed outside of the Milky Way, wa ...

in 1905 from photographic plates taken at the Lick Observatory between 1902 and 1904. The first orbit was calculated by Frank Craig Jordan of

Allegheny Observatory The Allegheny Observatory is an American astronomical research institution, a part of the Department of Physics and Astronomy at the University of Pittsburgh. The facility is listed on the National Register of Historic Places (ref. # 79002157, ad ...

in 1910 with results in good agreement with the most recent orbit. Several other faint stars within about an

arc-minute A minute of arc, arcminute (arcmin), arc minute, or minute arc, denoted by the symbol , is a unit of angular measurement equal to of one degree. Since one degree is of a turn (or complete rotation), one minute of arc is of a turn. The n ...

have been listed as companions, but none are physically associated with ζ¹ Lyrae.

Binary system

This is a single-lined spectroscopic binary system with an

orbital period The orbital period (also revolution period) is the amount of time a given astronomical object takes to complete one orbit around another object. In astronomy, it usually applies to planets or asteroids orbiting the Sun, moons orbiting planets ...

of 4.3 days and a nearly circular orbit with an

eccentricity Eccentricity or eccentric may refer to: * Eccentricity (behavior), odd behavior on the part of a person, as opposed to being "normal" Mathematics, science and technology Mathematics * Off-Centre (geometry), center, in geometry * Eccentricity (g ...

of 0.01. The primary, component A, is an

Am star An Am star or metallic-line star is a type of chemically peculiar star of spectral type A whose spectrum has strong and often variable absorption lines of metals such as zinc, strontium, zirconium, and barium, and deficiencies of others, such as ca ...

with a stellar classification of kA5hF0mF2. This complex notation indicates that the spectral type determined solely from the

calcium K line In physics and optics, the Fraunhofer lines are a set of spectral absorption lines named after the German physicist Joseph von Fraunhofer (1787–1826). The lines were originally observed as dark features (absorption lines) in the optical spectru ...

would be A5, the spectral type determined from other metallic lines would be F2, and the type determined from hydrogen lines would be F0.

Variability

ζ¹ Lyrae appears to be slightly variable, with a frequency of 0.65256 cycles per day and an amplitude of 0.0032 in magnitude. The star has an estimated 2.36 times the mass of the Sun and around 2.5 times the Sun's radius. The position of this system is associated with an X-ray source with a luminosity of .

References

{{Stars of Lyra, state=collapsed Am stars Lyra (constellation) Lyrae, Zeta1 Lyrae, 06 173648 091971 7056 Spectroscopic binaries Durchmusterung objects