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The Stein 2051 System

  • K. Aa. Strand (a1)

Abstract

An investigation is currently being made of the parallax, proper motion, orbital motion, and mass ratio of the nearby binary star Stein 2051 [04h 11 m .4, + 58°49’; (1900); mv = 11.08 and 12.44] based upon photographs taken with the Sproul Observatory 61-cm refractor, the 155-cm astrometric reflector of the U.S. Naval Observatory, and the 33-cm Vatican Carte du Ciel astrograph.

A parallax of 0”185 reduced to absolute has been obtained from the material of the Sproul and Naval Observatories which covers the period 1965 to 1975.

Since an arc of only 64° in the orbital motion of the visible components has been described from the 1908 epoch of the earliest Vatican plate, and since the separation has increased from 6.” 3 at that time to 7.“ 3 at present and still on the increase, the period of the orbit can only be roughly estimated to be in excess of 300 years.

With all plates measured in the same reference frame it has been possible to determine the individual motions of the two components and the mass ratio between them. Preliminary results indicate a perturbation in the orbital motion of the red component with a period of 20 years and a semi-major axis of 0’.’065. The mass ratio between the red dwarf system and the white dwarf is 0.5.

A mass of 0.22 M of the red component has been determined based upon comparison of its luminosity (Mv = 12.42) with the red dwarfs Krüger 60 A (Mv = 11.82), o2 Eri C (Mv = 12.73) and Krüger 60 B (Mv = 13.48) which have the same spectral type (M4) and known masses of 0.26, 0.19, and 0.16 respectively in units of solar masses. Its dark compainion has a mass of 0.02 M The white dwarf of spectral type DC and Mv = 13.78 has a mass of 0.48 M as determined from the mass ratio of 0.5 mentioned above.

Resumen

Se está haciendo una investigación sobre la paralaje, movimiento propio, movimiento orbital y la relación de masas de la binaria cercana Stein 2051 [04h 11m.4, + 58°49’ (1900); mv = 11.08 y 12.44] basada en fotografías tomadas con el refractor de 61-cm del Observatorio Sproul, el reflector astrométrico de 155-cm del Observatorio Naval de los EUA y el astrógrafo Carta del Cielo, de 33-cm del Vaticano.

Se ha obtenido una paralaje absoluta de 0.”185 con material de los observatorios Sproul y Naval, que cubre el período de 1965 a 1975.

Dado que solamente se ha descrito un arco de 64° del movimiento orbital de las componentes visibles desde la época de 1908 de la placa más antigua del Vaticano y dado que la separación ha aumentado de 6.“3 en ese tiempo a 7.“3 en la actualidad y que aún sigue en aumento, sólo se puede decir aproximadamente que el período es mayor de 300 años.

La medición de todas las placas en el mismo sistema de referencia ha permitido determinar los movimientos individuales de las dos componentes y su relación de masa. Resultados preliminares muestran una perturbación en el movimiento orbital de la componente roja con un período de 20 años y un semieje mayor de 0”065. La relación de masa entre el sistema con la enana roja y la enana blanca es 0.5.

Una masa de 0.22 M de la componente roja, se ha determinado basada en la comparación de su luminosidad (Mv = 12.42) con la de las enanas rojas Krüger 60 A (Mv = 11.82), o2 Eri C (Mv = 12.73) y Krüger 60 B (Mv = 13.48 las cuales tienen el mismo tipo espectral (M4) y masas conocidas de 0.26, 0.19 y 0.16 M respectivamente. Su compañera invisible tiene una masa de 0.02 M La enana blanca de tipo espectral DC y Mv = 13.78 tiene una masa de 0.48 M determinada a partir de la relación de masa de 0.5 mencionada anteriormente.

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The Stein 2051 System

  • K. Aa. Strand (a1)

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