Iota Arietis
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Iota Arietis, Latinized from ι Arietis, is the Bayer designation for a binary star system in the northern constellation of Aries. It has 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 5.117; bright enough to be dimly seen with the naked eye. Parallax measurements made during the Hipparcos mission yield an estimated distance of from Earth. The variable radial velocity of this system was announced by W. W. Campbell in 1922. K. C. Gordon published
orbital element Orbital elements are the parameters required to uniquely identify a specific orbit. In celestial mechanics these elements are considered in two-body systems using a Kepler orbit. There are many different ways to mathematically describe the same ...
s for this single-lined spectroscopic binary system in 1946, giving 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 and 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 ...
(ovalness) of 0.36. For the visible component, in 1952 N. G. Roman found a stellar classification of K1p, where the 'p' indicates some type of peculiarity with the
spectrum A spectrum (plural ''spectra'' or ''spectrums'') is a condition that is not limited to a specific set of values but can vary, without gaps, across a continuum. The word was first used scientifically in optics to describe the rainbow of colors ...
. Her comments indicated that the "Hydrogen lines and λ 4290 are strong enough to indicate a class II star, but the CN is barely strong enough for class III, and the Sr II is not much stronger than this would require.". E. A. Harlan published a class of K peculiar in 1969, commenting, "Hδ strong, Fe I λ4045 is weak for type". In 1990, K. Sato and S. Kuji gave a class of G8III, suggesting this is an aging G-type
giant star A giant star is a star with substantially larger radius and luminosity than a main-sequence (or ''dwarf'') star of the same surface temperature.Giant star, entry in ''Astronomy Encyclopedia'', ed. Patrick Moore, New York: Oxford University Press ...
and questioning its peculiar status. Bayesian inference of the stellar properties indicates this star is on the horizontal branch. The companion is a suspected
white dwarf A white dwarf is a stellar core remnant composed mostly of electron-degenerate matter. A white dwarf is very dense: its mass is comparable to the Sun's, while its volume is comparable to the Earth's. A white dwarf's faint luminosity comes ...
.


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External links


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HR 563
{{DEFAULTSORT:Iota Arietis G-type giants Horizontal-branch stars Spectroscopic binaries Aries (constellation) Arietis, Iota Durchmusterung objects Arietis, 08 011909 009110 0563