Optical identification of A0620-00

Boley, Forrest I.; Wolfson, R. G.; Bradt, H.; Doxsey, R.; Jernigan, G.; Hiltner, W. A.

doi:10.1086/182007

Cited by 15 publications

(14 citation statements)

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“…Within the uncertainties, the observed and expected magnitudes do not match. We note, however, that the bright sky and the high airmass also affects our estimate from the Boley et al (1976) observation and therefore its uncertainty may be even larger. We cannot therefore say with certainty if the optical maximum was reached between Boley et al's observation (∼JD 2442641) and the start of the V band measurements (∼JD 2442648), or e.g.…”

Section: X-ray Versus Other Wavelengthsmentioning

confidence: 83%

“…Since these measurements may give us an estimate of when the optical maximum was reached, we decided to study these observations more carefully. We note that Ciatti et al (1977) estimated the optical maximum to be near JD 2442650, but they used a ∼12th magnitude estimate by Boley et al (1976).…”

Section: X-ray Versus Other Wavelengthsmentioning

confidence: 91%

“…The estimate of the Boley et al (1976) observation is also plotted in Fig. 5a, together with the expected value (11.02±0.03) as extrapolated from a linear fit to the first decay phase in the V band.…”

Section: X-ray Versus Other Wavelengthsmentioning

confidence: 94%

“…But, examining their discovery image, an image tube photograph (Boley et al 1976), one can still get a rough estimate of the actual magnitude during the discovery. Comparing the magnitudes of the comparison stars in the frame with those reported by Webbink (1978) one deduces that the image tube must correspond more closely to V band than the B band.…”

Section: X-ray Versus Other Wavelengthsmentioning

confidence: 99%

“…A 0620−00 was the first X-ray transient to be identified with an optical brightening of a star, V616 Mon, at the same position (Boley & Wolfson 1975;Boley et al 1976). It was therefore also designated as Nova Mon 1975.…”

Section: Introductionmentioning

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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Section: X-ray Versus Other Wavelengthsmentioning

confidence: 83%

Section: X-ray Versus Other Wavelengthsmentioning

confidence: 91%

Section: X-ray Versus Other Wavelengthsmentioning

confidence: 94%

Section: X-ray Versus Other Wavelengthsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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