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Infrared photometry and polarimetry of Cygnus X-3We present photometry and linear polarimetry of Cygnus X-3 at K (2.2 micrometers) obtained over a 5 yr period. Photometry and polarimetry at J, H, and K of nearby field stars is also presented. From an analysis of these data we find: (1) Using the x-ray ephemeris of Kitamoto et al. (ApJ, 384, 263 (1992), including the first and second derivatives of the period, the leading edge of the decline to minimum in the quiescent K light curve has not changed in phase since 1974. The duration of the minimum in the light curve has changed significantly between different epochs, becoming much broader in 1993 than it was previously. (2) In addition to an interstellar polarization component, it is likely Cyg X-3 has an intrinsic polarization component that is variable. The variations in the polarization do not show any diagnostic pattern with orbital phase. A crude analysis of the polarization suggests the intrinsic polarization of Cyg X-3 has a mean position angle of approximately 12 deg, nearly the same as the direction of the expanding radio lobes. This is consistent with circumstellar electrons scattering in an equatorial disk that is perpendicular to the lobe axis. (3) The mean position angle for the interstellar polarization in the direction of Cyg X-3 is 150 deg. This is nearly perpendicular to the axis of interstellar radio scattering seen in the extended (Very Long Baseline Inteferometry (VLBI) images. Since the position angle of interstellar polarization is the same as the projected magnetic field direction, this suggests the interstellar (not circumstellar) scattering must be taking place perpendicular to the interstellar magnetic field lines. (4) Cyg X-3 was observed at K during a flare on 1992 September 30 with a temporal resolution of 6 s. The flaring had rise and fall times of approximately 50 s with peak intensities up to 80 mJy. The flux between individual flare events never dropped to quiescent levels for the duration of our observations (approximately 2000 s).
Document ID
19950028677
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Jones, Terry Jay
(Univ. of Minnesota, Minneapolis, MN United States)
Gehrz, Robert D.
(Univ. of Minnesota, Minneapolis, MN United States)
Kobulnicky, Henry A.
(Univ. of Minnesota, Minneapolis, MN United States)
Molnar, Lawrence A.
(Univ. of Iowa, Iowa, IA United States)
Howard, Eric M.
(Univ. of Rochester, Rochester, NY United States)
Date Acquired
August 16, 2013
Publication Date
August 1, 1994
Publication Information
Publication: The Astronomical Journal
Volume: 108
Issue: 2
ISSN: 0004-6256
Subject Category
Astrophysics
Accession Number
95A60276
Distribution Limits
Public
Copyright
Other

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