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The X-Ray Nova GRO J0422+32 in Decline and Quiescence

Published online by Cambridge University Press:  12 April 2016

M. R. Garcia
Affiliation:
Smithsonian Astrophysical Observatory, Cambridge, MA, USA
P. J. Callanan
Affiliation:
Smithsonian Astrophysical Observatory, Cambridge, MA, USA
J. E. McClintock
Affiliation:
Smithsonian Astrophysical Observatory, Cambridge, MA, USA
P. Zhao
Affiliation:
Smithsonian Astrophysical Observatory, Cambridge, MA, USA

Extract

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We have followed the X-ray nova GRO J0422+32, spectroscopically and photometrically, throughout the decline to quiescence.

In the final stages of decay (days 430…880 after the outburst, see Callanan et al. (1995) for the epoch 1995), the equivalent width (EW) of the Hα emission increases monotonically and the R magnitude decreases monotonically. This suggests that the flux in the Hα line is constant, while the continuum fades. The Hα flux is the product of the R band flux (F(R), arbitrarily scaled to 100 at R = 19 mag) and the EW, and is shown in the last column of the table below. The Hα flux varies by only ~ 30% while the continuum fades by a factor of eight (from R = 19 mag to R = 21.3 mag). So, to first order, the Hα luminosity is constant in the final stages of decay. While it is generally the case that the emission line EWs in individual dwarf novae also increase during the decay, the exact behavior seen in GRO J0422+32 is not what is seen for dwarf novae (on average). Using the relation between EW[Hβ] and Mv given in figure 6 of Patterson (1984), we would expect a factor of ~ 5 variation in the Hα flux during days 430…880. The stability of the Hα flux implies that somehow the emission line region is ‘disconnected’ from the continuum (R–band) emission region.

Type
X-Ray Binaries
Copyright
Copyright © Kluwer 1996

References

Callanan, P.J., Garcia, M.R., McClintock, J.E., et al., 1995, Ap. J., 441, 786 Google Scholar
Frank, J., King, A.R., Raine, D.J., 1992, “Accretion Power In Astrophysics”, p54 Google Scholar
Patterson, J., 1984, Ap. J. Supp., 54, 443 Google Scholar
Ritter, H., 1994, A&AS, 85, 1179 Google Scholar
Williams, G., 1983, Ap. J. Supp., 53, 523 Google Scholar