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Preprint C/06

Establishing HZ43 A, Sirius B, and RX J185635-3754 as soft X-ray standards: a cross-calibration between the Chandra LETG+HRC-S, the EUVE spectrometer, and the ROSAT PSPC

K. Beuermann (1), V. Burwitz (2), T. Rauch (3)

(1) Institut für Astrophysik, Universität Göttingen, Germany
(2) Max-Planck-Institut für Extraterrestrische Physik, Germany
(3) Institut für Astronomie und Astrophysik, Universität Tübingen, Germany

To be published in: A&A

Abstract. The absolute calibration of space-borne instruments in the soft X-ray regime rests strongly on model spectra of hot white dwarfs.
We analyze the Chandra LETG+HRC-S observations of the white dwarfs HZ43 A and Sirius B and of the neutron star RX J185635-3754 in order to resolve current uncertainties in the soft X-ray spectral fluxes and photospheric parameters of the three stars. We have obtained improved parameters for which fit the observations from the optical to the soft X-ray regime. Our approach allows us to quote their absolute spectral fluxes at selected wavelengths which may aid the calibration of other space-borne instruments.

Key words: Methods: data analysis - Stars: white dwarfs - Stars: neutron - Stars: fundamental parameters - Stars: individual HZ43 A, Sirius B, RX J185635-3754 - X-rays: individual HZ43 A, Sirius B, RX J185635-3754

Preprint (407 kb PDF file including figures)
astro-ph/0608592

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