| p:abstract
| - Zeta Aquarii (ζ Aqr / ζ Aquarii) is a binary star,the central star in the “water jar” asterism in the constellation Aquarius. It is approximately 103 light years from Earth. The brighter component, ζ² Aquarii, is a yellow-white F-type main sequence dwarf with an apparent magnitude of +4.42. Its companion, ζ¹ Aquarii, is a yellow-white F-type subgiant with an apparent magnitude of +4.59. The fact that their brightness is so close makes the pair easy to measure and resolve. The binary system has a combined brightness of +3.65 magnitudes. The two stars are 1.67 arcseconds apart and have an orbital period of 760 years. Christian Mayer, director of the Mannheim Observatory, is considered the first to have observed Zeta Aquarii to be double. He did so in 1777. A couple of years later, William Herschel also discovered this duality. Zeta Aquarii has only been observed through half its orbit; hence, the size and shape of the orbit, and therefore, the orbital period, are undetermined. According to Martin Gaskell, the latest orbital calculation was made in 1968, and gave a period of 856 years. (This information was catalogued in Norton’s, 2000.) The greatest distance in the elliptical orbit of the two components, which appears to be a clockwise movement, is approximately four times greater than their closest distance, which is about the distance of our Sun and Pluto. The stars currently have an ephemeris of about 2.5". It is projected that at the end of the twenty-third century, the stars should be about 6.4" apart. The change per year a very slight, however. The two components, simply labeled star A and star B, each have a mass of 1.1 solar masses and 0.9 solar masses, respectively. Despite this similitude in mass, they are about seven times more luminous than our sun, which means they are more evolved. The spectroscopic interpretation of both stars classifies them as subgiants. This supports the prediction that the hydrogen in their cores is exhausted and that they are becoming red giants. There have been claims that there is a third component orbiting star B with a period of 25.5 years. But, it is possible that this is simply an over-interpretation of residuals, as has been the case with other perceived third components of binary systems. Such tertiaries have a luminosity too low to be seen directly. The speculated tertiary in the Zeta Aquarii system allegedly has a mass of 0.28 solar masses and is likely a red or white dwarf. It is located at 9 astronomical units from star B, the same distance as Saturn from our Sun. Zeta Aquarii is currently a northern hemisphere object. In 2004 it was directly above the celestial equator, and before that it was located south of it. (en)
- Zeta Aquarii (ζ Aqr) es una estrella binaria en la constelación de Acuario que se encuentra a unos 103 años luz de la Tierra. Se considera que Christian Mayer, director del Observatorio de Mannheim, fue el primero en observar su duplicidad en 1777. Las dos estrellas del sistema son blanco-amarillas, de tipo espectral F. La estrella más brillante, Zeta Aquarii A, tiene magnitud aparente +4,36 y es una subgigante de tipo F2 IV, 15 veces más luminosa que el Sol. Zeta Aquarii B es una estrella de la secuencia principal con una luminosidad de 12 soles y tipo espectral F3 V. Las masas de ambas estrellas son 1,1 y 0,9 masas solares respectivamente. La mayor luminosidad de ambas en relación al Sol se debe a que están más evolucionadas que éste.El sistema Zeta Aquarii sólo ha sido observado durante la mitad de su órbita. Por ello, el tamaño y la forma de la órbita están indeterminadas. Su período orbital puede ser en torno a 760 años y parece ser claramente excéntrica, con la distancia en el apoastro unas cuatro veces mayor que en el periastro, en donde la distancia es aproximadamente la del Sol a Plutón. Zeta Aquarii se encuentra prácticamente en el ecuador celeste. De hecho, antes de finales de 2003 estaba en el hemisferio sur, momento en que cruzó al hemisferio norte. (es)
- Zeta Aquarii é uma estrela binária localizada na constelação de Aquarius. (pt)
|
![[RDF Data]](http://dbpedia.org/statics/sw-cube.png)
