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Resonant Scattering and Recombination in CAL 87

Published online by Cambridge University Press:  22 February 2018

J. Greiner ,
A. Iyudin ,
M. Jimenez-Garate ,
V. Burwitz ,
R. Schwarz ,
R. DiStefano  and
N. Schulz
J. Greiner
Affiliation:
MPE Garching, 85741 Garching, Germany
A. Iyudin
Affiliation:
MPE Garching, 85741 Garching, Germany Moscow, Russia
M. Jimenez-Garate
Affiliation:
MIT, Cambridge, MA 02139USA
V. Burwitz
Affiliation:
MPE Garching, 85741 Garching, Germany
R. Schwarz
Affiliation:
Universität Göttingen, 37083 Germany
R. DiStefano
Affiliation:
CfA, Cambridge, MA 02138USA
N. Schulz
Affiliation:
MIT, Cambridge, MA 02139USA

Abstract

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The eclipsing supersoft X-ray binary CAL 87 has been observed with Chandra on August 13/14, 2001 for nearly 100 ksec, covering two full orbital cycles and three eclipses. The shape of the eclipse light curve derived from the zeroth-order photons indicates that the size of the X-ray emission region is about 1.5 R⊙. The ACIS/LETG spectrum is completely dominated by emission lines without any noticeable continuum. The brightest emission lines are significantly redshifted and double-peaked, suggestive of emanating in a 2000 km/s wind. We model the X-ray spectrum by a mixture of recombination and resonant scattering. This allows us to deduce the temperature and luminosity of the ionizing source to be kT ~ 50 — 100 eV and Lx ~ 5 x 1037 erg/s.

Resumen

Resumen

Se observó la binaria (eclipsante de rayos X supersuave CAL 87 con Chandra el 13/14 de agosto de 2001, durante; casi 100 ksec, completando dos ciclos orbitales totales y tres eclipses. La forma de la curva de luz del eclipse derivada de los fotones de orden cero indica que el tamano de la región de emisión de rayos X es de alrededor de 1.5 R⊙ El espectro ACIS/LETG está dominado por completo por las líneas de emisión sin ningún continuo apreciable. Las líneas de emisión más brillantes presentan un corrimiento al rojo significativo y dos picos, sugiriendo que se producen en un viento de 2000 km/s. Realizamos un modelo del espectro de rayos X mezclando la dispersión de recombinación y resonancia. Esto nos permite deducir que la temperatura y la luminosidad de la fuente ionizante son kT ~ 50 — 100 eV y Lx ~ 5 x 1037 erg/s, respectivamente

Keywords

BinariesClose — StarsIndividual (CAL 87) — X-RayStars
Type
The Contributed Papers
Information
International Astronomical Union Colloquium , Volume 194: Compact binaries in the galaxy and beyond , 2004 , pp. 18 - 20
Copyright
Copyright © Instituto de astronomia/revista mexicana de astronomίa y astrofίsica 2004

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