Ultraviolet and Optical Observations of HDE 245770/ A 0535+26 System during an X-Ray Flare

Giovannelli, F.; Ferrari-Toniolo, M.; Giangrande, A.; Persi, P.; Bartolini, C.; Гуарниери, А.; Piccioni, A.

doi:10.1007/978-94-010-9949-3_62

Cited by 5 publications

(11 citation statements)

References 8 publications

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“…This value is in fairly agreement with that derived by Giangrande et al (1980) and by S hakhovskaya et al (1986) from optical measurements. Furthermore, Wu et al (1983) confirmed both the values of the colour excess and the spectral classification and luminosity class of H D E 245770, firstly derived by Giovannelli et al (1980) and Giangrande et al (1980). A long term photometric history of r i D E 245770 was made by Guarnieri et al (1982) in order to complete the ancient set of photographic data of the Harward collection (Stier and Liller, 1976), together with several other photoelectric measurements available (Bartolini et al, 1983).…”

Section: General Considerations On Transient X-ray Sourcessupporting

confidence: 54%

“…Thanks to Salter's observation on 17 February, 1980 at Effelsberg 100 m telescope, Giovannelli et al (1982) reported an upper limit to the radio flux density at 18 cm of 36 mJy. This value was not conflicting with the IR data, since, making an extrapolation of the IR data up to 18 cm, a value of 1.2 mJy is obtained.…”

Section: General Considerations On Transient X-ray Sourcesmentioning

confidence: 96%

“…The results did not show substantial variations with respect to those obtained, with the same satellite, during an X-ray quiescent phase . The observed IR excess and the asymmetry of the UV resonance lines of HDE 245770 supported the presence of an expanding envelope surrounding the star (Persi et al, 1979;Giovannelli et al, 1980Giovannelli et al, , 1981. The colour excess E(B -V) = 0.75 + 0.05 mag was derived by Giovannelli et al (1980) filling the observed 2200 A extinction feature and using the interstellar extinction law of Seaton (1979).…”

Section: General Considerations On Transient X-ray Sourcesmentioning

confidence: 98%

“…The proportionality of the line widths to the wavelengths suggests a Doppler origin of the broadening due to the rotation of the star (Popper, 1950;Hutchings et al, 1978). With the hypothesis of the pure rotational broadening, and for an average value of the limb darkening (/~ = 1.5), Giovannelli et al (1982) derived a rotational velocity v sin i ---230 km s-1 Persi et al (1979) derived from near IR photometry of HDE 245770 a mass loss rate of ~ 10-6 Mo yr-~, assuming a matter outflow through the envelope with uniform velocity of a few hundreds km s -~. This value is the highest never quoted for Be stars, which have usually a mass loss rate of about two orders of magnitude lower (e.g., Snow andMalborough, 1976).…”

Section: General Considerations On Transient X-ray Sourcesmentioning

confidence: 99%

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A 0535 + 26/HDE 245770: A typical X-ray/Be system

Giovannelli

Graziati

1992

Space Sci Rev

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Abstract. Among the X-ray/Be systems, A 0535 + 26/HDE 245770 has been noted, since its discovery, for its peculiar features in several respects, in a wide energy range. For this reason and for a series of concomitant favorable causes, this system has been one of the most studied among the massive X-ray binary systems. The most remarkable incident was that its optical identification with an early-type-emission-line star (O9.7IIie) has led to a deep studies on Be stars and their interactions with neutron stars, which have allowed to discover, without unbiguity, the presence of optical indicators of consequent X-ray flares, as well as that Be stars in X-ray/Be systems behave just as 'normal' Be stars. Overmore, thanks to the multifrequency coordinated observations of this system, the X-ray emissions from binary companion of the Be stars are best explained by assuming the presence of a thick equatorial disk with low expansion velocity and a thin polar region with high expansion velocity. This picture reconciled the strong discrepancy in mass loss rate evaluations coming from IR and from UV measurements, assuming that the observed regions are enterely distinct from each other, one being a high-density, low-velocity region, and the other being a low-density, very hot, rapidly-expanding disk-like zone.Since, this picture seems to be the best up-to-date frame to cuckold all the experimental panorama available on X-ray/Be systems, we would like to paint in this paper the multifrequency behaviour of A 0535 + 26/HDE 245770, which is the best studied among such systems, in order to stimulate future coordinated experimental-theoretical works on this very interesting class of objects.

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Section: General Considerations On Transient X-ray Sourcessupporting

confidence: 54%

Section: General Considerations On Transient X-ray Sourcesmentioning

confidence: 96%

Section: General Considerations On Transient X-ray Sourcesmentioning

confidence: 98%

Section: General Considerations On Transient X-ray Sourcesmentioning

confidence: 99%

See 2 more Smart Citations

A 0535 + 26/HDE 245770: A typical X-ray/Be system

Giovannelli

Graziati

1992

Space Sci Rev

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“…The best fit in with the observational data was obtained using T=30,000 K and log g=3.5 (Fig.5). The results are the same as those reported in the paper by Giovannelli et al (1980). The observed IR excess and the edge velocity allow to evaluate the mass loss rate,taking as a model an expanding envelope with an electron density ne<r-2 (Panagia and Felli 1975).…”

Section: Discussionmentioning

confidence: 70%