Optical Variations of the Be Star HDE 245770/A 0535+26

Гуарниери, А.; Bartolini, C.; Piccioni, A.; Giangrande, A.; Giovannelli, F.

doi:10.1007/978-94-009-8565-0_14

Cited by 3 publications

(6 citation statements)

References 11 publications

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“…(iv) From all these data a diverging trend of colour indices was also evident: the star had B-V= +0.45mag and U- B=-0.54mag in the fifties (Hiltner, 1956;Lenouvel and Flogere, 1957), while in the seventies and early eighties had mean values B -V = + 0.56 mag and U -B = -0.60 mag (Rossiger, 1976;Guarnieri et al, 1982).…”

Section: General Considerations On Transient X-ray Sourcesmentioning

confidence: 94%

“…From this history, Guarnieri et al (1982) noted that: (i) The star was in 1981 at its highest luminosity level.…”

Section: General Considerations On Transient X-ray Sourcesmentioning

confidence: 98%

“…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 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 Sourcesmentioning

confidence: 94%

“…From this history, Guarnieri et al (1982) noted that: (i) The star was in 1981 at its highest luminosity level.…”

Section: General Considerations On Transient X-ray Sourcesmentioning

confidence: 98%

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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“…Fatkhullin et al (2003), , Greiner et al (2003b), Guarnieri et al (2003), Maiorano et al (2003), Nysewander et al (2003), Price & Warren (2003), Rumyantsev et al (2003a,b), Semkov (2003) and Von Braun et al (2003). The distribution of these 27 photometric data points is N(B, V, R, I) = (2, 4, 19, 2).…”

Section: Optical Observations and Calibrationsmentioning

confidence: 97%

Early optical and millimeter observations of GRB 030226 afterglow

Sagar

Anupama

Bhattacharya

et al. 2004

A&A

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Abstract. The CCD magnitudes in Johnson UBV and Cousins RI photometric passbands for the afterglow of the long duration GRB 030226 are presented. Upper limits of a few mJy to millimeter wave emission at the location of optical are obtained over the first two weeks. The optical data presented here, in combination with other published data on this afterglow, show an early R band flux decay slope of 0.77 ± 0.04, steepening to 2.05 ± 0.04 about 0.65 ± 0.03 day after the burst. Interpreted as the "jet break", this indicates a half opening angle of ∼3.2 degree for the initial ejection, for an assumed ambient density of ∼1 cm −3 . Broadband spectra show no appreciable evolution during the observations, and indicate the presence of synchrotron cooling frequency ν c near the upper edge of the optical band. From the broadband spectra we derive an electron energy distribution index p = 2.07 ± 0.06 and an intrinsic extinction E(B − V) ∼ 0.17. Millimeter upper limits are consistent with these derived parameters.

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“…Some years later and based on a very similar dataset, Hutchings (1984) found a 112 day period. Guarnieri et al (1982) noted at first possible 32, 63 or 77 day periods in their photometric data, but later (Guarnieri et al 1985) found modulation in the V band photometry with the proposed orbital period of 110 days. Gnedin et al (1988) made a Fourier analysis of V band photometry obtained during [1981][1982][1983][1984][1985] and marked out periods of 1100, 103 and 28 days, but found no periodicity corresponding to the X-ray period.…”

Section: Introductionmentioning

confidence: 98%

X-ray and optical periodicities in X-ray binaries I. A0535+26

Larionov

Lyuty²,

Зайцева³

2001

A&A

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Abstract.A homogeneous set of UBV photometry (354 data points obtained between 1983 and 1998) for the Be/X-ray binary A0535+26 = V725 Tau is analysed, aiming to look for possible periodic component(s). After subtraction of the long-term variation it was found that only a ≈103 d periodic component remains in the power spectra in both the V and B colour bands. The probability of chance occurrence of such a peak is less than 0.1%. There are no signs of optical variability at the X-ray period (≈111 d ). We discuss possible reasons for a 103-day modulation and suggest that it corresponds to a beat frequency of the orbital period of the neutron star and the precession period (≈1400 d ) either of an accretion disc around the neutron star or a warped decretion disc around the Be star.

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Optical Variations of the Be Star HDE 245770/A 0535+26

Cited by 3 publications

References 11 publications

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

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

Early optical and millimeter observations of GRB 030226 afterglow

X-ray and optical periodicities in X-ray binaries I. A0535+26

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