We present our analysis of new and archived observations of two candidate magnetic cataclysmic variables, namely 1RXS J174320.1−042953 and YY Sex. 1RXS J174320.1−042953 was observed in two distinctive high and low states where a phase shift was seen, which could be due to changes in the shape, size, and (or) location of the accretion region. We find that its orbital X-ray modulations only persist in the soft (0.3–2.0 keV) energy band, which could be attributed to photoelectric absorption in the accretion flow. The X-ray spectra exhibit a multi-temperature post-shock region where the hard X-rays are absorbed through a thick absorber with an equivalent hydrogen column of ∼7.5 × 1023 cm−2, which partially covers ∼56 per cent of the emission. No soft X-ray excess was found to be present; however, a soft X-ray emission with a blackbody temperature of ∼97 eV describes the spectra. Extensive Transiting Exoplanet Survey Satellite (TESS) observations of YY Sex allow us to refine its orbital period to 1.5746 ± 0.0011 h. We did not find any signature of previously reported spin or beat periods in this system. Furthermore, our new polarimetric observations show clear circular polarization modulated on the orbital period only. Finally, both systems show strong Balmer and He ii 4686 Å emission lines in the optical spectra, further indicative of their magnetic nature.
WR21 and WR31 are two WR + O binaries with short periods, quite similar to the case of V444 Cyg. The XMM-Newton observatory has monitored these two objects and clearly revealed phase-locked variations as expected from colliding winds. The changes are maximum in the soft band (0.5–2.0 keV, variations by a factor 3–4) where they are intrinsically linked to absorption effects. The increase in absorption due to the dense WR wind is confirmed by the spectral analysis. The flux maximum is however not detected exactly at conjunction with the O star in front but slightly afterwards, suggesting Coriolis deflection of the collision zone as in V444 Cyg. In the hard band (2–10 keV), the variations (by a factor of 1.5–2.0) are much more limited. Because of the lower orbital inclinations, eclipses as observed for V444 Cyg are not detected in these systems.
more » « less- NSF-PAR ID:
- 10467670
- Publisher / Repository:
- Oxford University Press
- Date Published:
- Journal Name:
- Monthly Notices of the Royal Astronomical Society
- Volume:
- 526
- Issue:
- 2
- ISSN:
- 0035-8711
- Format(s):
- Medium: X Size: p. 2167-2180
- Size(s):
- ["p. 2167-2180"]
- Sponsoring Org:
- National Science Foundation
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