Further Photometric Observations of the Cataclysmic Variable PG 1012-029

Ashoka, B. N.; Marar, T. M. K.; Seetha, S.; Kasturirangan, K.; Rao, U. R.; Bhattacharyya, J. C.

doi:10.1007/978-94-011-2020-3_72

Cited by 3 publications

(9 citation statements)

References 5 publications

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“…The continuum shows a deep, slightly asymmetrical eclipse, the ingress being steeper than the egress, and the blue light curve having a deeper eclipse than the red, consistent with the presence of a bright spot. There is the clear signature of an orbital hump around phase 0.8 − 0.9, as also seen by Rutten et al (1992) and Ashoka et al (1994), caused by the changing aspect of the bright spot. The only other feature in the continuum light curves is the flickering seen in all CVs.…”

Section: Light Curvessupporting

confidence: 74%

“…We recorded two eclipses each of SW Sex (at T mid−ecl = HJD 2 450 503.5038±0.0004 and 2 450 503.6388±0.0004) and DW UMa (at T mid−ecl = HJD 2 450 502.4692 ± 0.0004 and 2 450 502.7424 ± 0.0004). For SW Sex, we combined these mid-eclipse timings with those of Penning et al (1984), Dhillon et al (1997), Ashoka et al (1994) and Groot et al (2001) to obtain the following ephemeris:…”

Section: Light Curvesmentioning

confidence: 99%

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The SW Sex enigma

Dhillon

Smith

Marsh

2012

Monthly Notices of the Royal Astronomical Society

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The SW Sex stars are a class of cataclysmic variables, originally identified because they shared a number of enigmatic properties -most notably, single-peaked emission lines instead of the double-peaked lines one would expect from their high-inclination accretion discs. We present high time-resolution spectrophotometry of the eclipsing nova-like variables SW Sex and DW UMa, two of the founding members of the SW Sex class. Both systems show single-peaked Balmer and He II λ4686Å emission lines that appear to originate from a region in the disc that lies close to, but downstream of, the bright spot. The emission-line light curves are consistent with the finding from X-ray and ultraviolet observations that we predominantly see the flared disc rim and the unobscured back portion of the disc in these systems. In DW UMa, the He II λ4686Å emission line originates from close to the white dwarf and exhibits flaring. Such flares have been used to argue for magnetically-channelled accretion, as in the intermediate polars, but the lack of a clear periodicity in the flares argues for a simpler model in which we are viewing the central regions of the disc through the non-uniform upper edge of a flared disc rim. We also observe narrow, blue-shifted, transient absorption features in the Balmer lines of DW UMa, which we attribute to blobs of material ejected from the system, possibly by a magnetic propeller, that happen to be passing between us and the binary. Our results suggest that the solution to the SW Sex enigma is a combination of dominant bright-spot emission and a self-occulting disc. We also propose a simplified classification scheme for nova-like variables.

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Section: Light Curvessupporting

confidence: 74%

Section: Light Curvesmentioning

confidence: 99%

The SW Sex enigma

Dhillon

Smith

Marsh

2012

Monthly Notices of the Royal Astronomical Society

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“…The blue pulses are better resolved than the red (compare, for example, the second segments of the data). In comparison, Ashoka et al (1995) found a 10.8 per cent modulation in white light. Large variability between spin cycles is visible in many cases, suggesting that the accretion pattern may be variable on very short time‐scales.…”

Section: The Time Seriesmentioning

confidence: 79%

The emission-line pulse pattern in the intermediate polar RX J0558+53

Harlaftis

Horne

1999

Monthly Notices of the Royal Astronomical Society

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We observed the intermediate polar RX J0558+53 with the 4.2‐m William Herschel Telescope (WHT) and find a `corkscrew' pattern in the pulsed emission lines, which indicates a two‐pole white dwarf accretion. The `corkscrew' pattern consists of two emission‐line pulses, separated by half the white dwarf spin period, and moving from red to blue velocities. The detected emission‐line pulsations have an amplitude of 1.1‐‐2.7 per cent in the He II and Balmer emission lines at the 545‐s spin period of the white dwarf compared with 3.5‐‐4.8 per cent for the continuum double‐peak pulsations. We image the emission‐line pulse pattern and it is shown to lag the continuum pulse by 0.12 spin cycles. We interpret the pattern by invoking an accretion curtain from the disrupted, inner disc to the two poles of the magnetic white dwarf. The semi‐amplitude of the He II pulse of 408 ± 35 km s‐1 can be used to constrain the size of the magnetosphere, R ∼ 4.1 × 104 km, and the magnetic moment of the white dwarf (∼ 2.4 × 1032 G cm3). Power spectra show dominant frequencies at 2 ο and 2(ο ‐ Ο) which suggest reprocessing of the illuminating beams of the white dwarf in the accretion disc. Finally, the steady He II emission line shows a strong sinusoidal component moving from red to blue at binary phase 0.5, with a width similar to that expected from irradiation of the secondary star. Imaging of the emission lines indicates illuminated locations at the inner side of the red star and the back side of the accretion disc.

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“…The phase dependent absorption features observed by Honeycutt, Schlegel & Kaitchuck (1986) were studied in greater detail by Szkody & Piché (1990), but they were unable to account for the behaviour with a simple model. High-speed photometry by Rutten, van Paradijs & Tinbergen (1992) revealed a prominent bright spot in SW Sex (also seen by Ashoka et al 1994) and the resulting eclipse maps showed a flatter run of effective temperature with radial distance from disc centre than that predicted by steadystate disc theory. Despite the more recent efforts of Still (1995), who presented a high signal-to-noise but relatively low spectral-resolution study of SW Sex, no real progress has been made in unravelling the SW Sex phenomenon, a situation which we hope to redress in the present paper.…”

Section: Introductionmentioning

confidence: 91%

“…We derived an ephemeris for SW Sex by adding the 9 times of mid-eclipse observed by René Rutten (private communication; see Table 1) to the 6 eclipse timings of Penning et al (1984) and the 6 of Ashoka et al (1994). A linear leastsquares fit to these data yields the following ephemeris:…”

Section: Ephemerismentioning

confidence: 99%

On the nature of SW Sex

Dhillon

Marsh

Jones

1997

Monthly Notices of the Royal Astronomical Society

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We present spectrophotometry of the eclipsing nova-like variable SW Sex. The continuum is deeply eclipsed and shows asymmetries due to the presence of a bright spot. We derive a new ephemeris and, by measuring the eclipse width, we are able to constrain the inclination to i > 75 • and the disc radius to R D > 0.6L 1 . In common with other members of its class (of which it is the proto-type), SW Sex shows single-peaked emission lines which show transient absorption features and large phase shifts in their radial velocity curves. In addition, the light curves of the emission lines show a reduction in flux around phase 0.5 and asymmetric eclipse profiles which are not as deep as the continuum eclipse. Using Doppler tomography, we find that most of the line emission in SW Sex appears to originate from three sources: the secondary star, the accretion disc and an extended bright spot. The detection of the red star allows us to constrain the radial-velocity semi-amplitude of the secondary to K R > 180 km s −1 and hence the component masses toThe Doppler maps suggest a simple new model for SW Sex in which the dominance of single-peaked line emission from the bright spot over the weak double-peaked disc emission gives SW Sex its single-peaked profiles and forces the radial-velocity curves to follow the motion of the bright spot and thus exhibit large phase shifts. The transient absorption features in the Balmer-line profiles are mostly artifacts of the complex intertwining of the emission components from the secondary star, bright spot and accretion disc and involve little true absorption. While the accretion disc and secondary star components of this model appear to be secure, the dominant bright-spot component fails in one important area -its inconsistency with the Balmer-line light curves. The eclipse profile requires the material emitting the Balmer lines to be eclipsed as early as phase 0.8, but which is not as deeply eclipsed as the continuum, exhibits a flat bottomed eclipse and then comes out of eclipse very sharply around phase 0.05. Although it is possible to explain the early ingress with a raised disc rim downstream from the bright-spot, the rapid egress is difficult to account for without speculating that either there are regions of strong Balmer absorption in the disc whose changing visibility during eclipse alters the shape of the light curve or that there is Balmer emission from above the orbital plane which shares the velocity of the bright-spot.

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Further Photometric Observations of the Cataclysmic Variable PG 1012-029

Cited by 3 publications

References 5 publications

The SW Sex enigma

The SW Sex enigma

The emission-line pulse pattern in the intermediate polar RX J0558+53

On the nature of SW Sex

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