Safe-life tests of refractory metals and alloys

Lyutyi, E. M.

doi:10.1007/bf00716606

Cited by 3 publications

(5 citation statements)

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“…and U−B (c.) measurements of A 0620−00. & Shugarov 1979). This indicates that in U and B the flux dropped faster to quiescence than in V, as can be seen in Fig.…”

Section: Optical Colour Behavioursupporting

confidence: 57%

“…The final optical decay started about ∼2 weeks later than the final X-ray decay, and had a fast decay time scale of ∼12 days (Tsunemi et al 1977). UBV measurements during the final decay showed B−V already near its quiescent value, whereas U−B was still at its outburst value (Lyutyi 1976; see also Lyutyi & Shugarov 1979). A ∼3.9 day modulation in the optical UBV was reported during the first part of the decay up to the glitch (Duerbeck & Walter 1976).…”

Section: Outburstmentioning

confidence: 90%

“…Lloyd et al 1977), and sometimes ∼0.1-0.2 (Hudec 1977), depending on the instrument used. In quiescence the typical uncertainties were ∼0.1-0.4 for the photoelectric UBV observations, depending on the instrument used and the wavelength band (see Ciatti et al 1977;Lyutyi & Shugarov 1979), and ∼0.2-0.5 for the photographic BV observations (Lyutyi & Shugarov 1979;Kurochkin et al 1988). The visual estimates had usual uncertainties of ∼0.1 during outburst for one observer.…”

Section: Opticalmentioning

confidence: 99%

“…At the final decline to quiescence photoelectric UBV measurements revealed a different behaviour as compared to the rest of the outburst (see Lyutyi 1976;Lyutyi & Shugarov 1979): between JD 2442856.5 and JD 2442869.3 B−V was already close to its quiescent value (∼1.3, e.g. Murdin et al 1980), while U−B was still at an outburst value of ∼−0.76 (quiescence U−B is ∼0.5, e.g.…”

Section: Optical Colour Behaviourmentioning

confidence: 99%

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A 0620 - 00 revisited: a black-hole transient case-study

Kuulkers

1998

New Astronomy Reviews

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For the first time we have performed a detailed study of the X-ray, optical and infrared light curves and an intercomparison between these wavelengths (including radio) of the 1975/1976 outburst of the famous black-hole transient A 0620−00 (Nova Mon 1975, V616 Mon). We also investigated the optical behaviour up to a year after the main outburst. This study enabled us to find some new features, which have not been discussed before.During the various stages of the outburst of A 0620−00 we found the X-rays lag the optical on the order of ∼5 to ∼20 days. Moreover, we found evidence that the activity associated with the secondary maximum started even earlier in the infrared. This suggests that most of the processes associated with the outburst occur in the outer parts of the accretion disk.Although various drops in intensity (lasting on the order of a day or more) in the optical and X-ray outburst light curves of A 0620−00 have been reported before, we identified some new ones. One such X-ray 'dip' only appeared in the soft X-rays (1.5-6 keV) whereas at higher energies ( 6 keV) the intensity slightly increases. This shows that the X-ray spectrum pivots near ∼6 keV around that time. In the optical we found evidence for another local maximum around that time (so-called 'intermediate' maximum). The 'intermediate' maximum appears ∼30 days after the secondary maximum, which is close to the viscous time scale of an irradiated accretion disk. We suggest this feature to be an 'echo' of the secondary maximum. At the end of the outburst another local maximum occurs. Since the time difference between the peak of the tertiary maximum and this local maximum is also on the order of the viscous time scale we suggest that this feature is an 'echo' of the tertiary maximum. We find that drops in the optical and X-ray intensity before and during the rise to tertiary maximum are also present in various other short period soft X-ray transients (SXTs). They always occur ∼150 days after the start of the outburst.Although the X-ray spectrum of A 0620−00 gradually softens during the decay from outburst, we find for the first time that it starts to harden again ∼100-150 days after the start of the outburst, similar to that seen in GS 2000+25 and GS 1124−68. This suggests we witness the transition from the so-called high to low state identified in black-hole X-ray binaries. We note that the time of spectral hardening in Preprint submitted to Elsevier Preprint 1 October 2018A 0620−00, GS 2000+25 and GS 1124−68 is simultaneous with the occurrence of the drops in optical and X-ray intensity.We also show that the optical outburst amplitude and the shape of the optical outburst light curve of A 0620−00 closely resembles those of the cataclysmic variable AL Com (where the compact star is a white dwarf). This strengthens the similarity in outburst and quiescent properties of the SXTs and 'Tremendous Outburst Amplitude Dwarf novae' (TOADs) or WZ Sge stars, and shows that in general the optical outburst light curves of both groups are governed...

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“…and U−B (c.) measurements of A 0620−00. & Shugarov 1979). This indicates that in U and B the flux dropped faster to quiescence than in V, as can be seen in Fig.…”

Section: Optical Colour Behavioursupporting

confidence: 57%

Section: Outburstmentioning

confidence: 90%

Section: Opticalmentioning

confidence: 99%

Section: Optical Colour Behaviourmentioning

confidence: 99%

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A 0620 - 00 revisited: a black-hole transient case-study

Kuulkers

1998

New Astronomy Reviews

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“…3a) Ñuxes observed at that point. Moreover, the last set of optical data points in Figure 3a, observed on day 232, shows that the B-band Ñux was considerably lower than both V -and U-band Ñuxes (this was originally pointed out by Lyutyi 1976 andLyutyi &Shugarov 1979), implying that perhaps the disk was becoming optically thin at this point.…”

Section: Discussionmentioning

confidence: 73%

Optical Light Curves of the Black Hole Binaries GRS 1124−68 and A0620−00 in Outburst: The Importance of Irradiation

Esin

Kuulkers

McClintock

et al. 2000

ApJ

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We test whether the model proposed by Esin et al. to explain X-ray observations of the black hole soft X-ray transient GRS 1124[68 in outburst can also explain the optical light curves of a similar object, A0620[00. We show that to reproduce the observed X-ray to optical Ñux ratio in A0620[00, we need to assume X-ray irradiation of the outer disk that is signiÐcantly in excess of what is expected for a standard planar disk. With enhanced irradiation, the Esin et al. model can reproduce the optical evolution of A0620[00 in outburst very well. Though we Ðnd that optical observations of GRS 1124[68 also imply enhanced X-ray heating of the outer disk, the irradiation appears to be a factor of D3 weaker in this system than in A0620[00. This is surprising, since GRS 1124[68 has a larger disk. We speculate that enhanced irradiation may be due to disk warping, and that the degree of warping di †ers between the two binaries.

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