Long-term photometric behavior and orbital period variations in the supersoft X-ray source V617 Sgr

Zang, Lei; Zhao, En-Guang; Fernández-Lajús, E.; Zubairi, Ahmed Waqas; Sarotsakulchai, Nopphadon

doi:10.1016/j.newast.2023.102054

Cited by 2 publications

(1 citation statement)

References 22 publications

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“…V617 Sgr is a CBSS with primary and secondary eclipses for a period of 0.207 day. Zang et al (2023a) report 149 new eclipse times, mostly with AAVSO data. They have also collected eclipse times from Steiner et al (1999Steiner et al ( , 2006, Shi et al (2014), while about half of the eclipse times in Patterson et al (2022) are included due to the same light curves in the AAVSO database.…”

Section: Three Compact Binary Supersoft Sourcesmentioning

confidence: 99%

Evolutionary Period Changes for 52 Cataclysmic Variables, and the Failure for the Most-fundamental Prediction of the Magnetic Braking Model

Schaefer

2024

ApJ

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The evolution of cataclysmic variables (CVs) is driven by period changes ( P ̇ ), for which the long-venerable consensus is the magnetic braking model (MBM). The MBM has its only distinctive assumption being a power-law “recipe” describing the angular momentum loss (AML) in the binary, producing a single unique evolutionary track with P ̇ as a function of the orbital period. This required prediction can be used to test the most-fundamental assumption of MBM, but it has never been tested previously. In this paper, I collect P ̇ measures for 52 CVs of all types. First, 44% of the CVs have positive P ̇ , with such being impossible in MBM. Second, even among the CVs with negative P ̇ , their P ̇ measures are always more negative than required by MBM, with an average deviation of 110×. Third, three CVs have large chaotic variations in P ̇ that are impossible for MBM, proving that some unknown mechanism exists and is operating that dominates for these systems. Fourth, the MBM does not account for the long-term effects on evolution arising from the large sudden period decreases seen across many nova events, with this unaccounted effect dominating for the majority of nova systems and changing the sign of the overall evolutionary P ̇ . Fifth, three recurrent novae are observed to suddenly change P ̇ by an order of magnitude across a nova event, with this being impossible in the MBM. In all, the required MBM P ̇ predictions all fail for my 52 CVs, usually by orders of magnitude, so the MBM AML-recipe is wrong by orders of magnitude.

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Section: Three Compact Binary Supersoft Sourcesmentioning

confidence: 99%

Evolutionary Period Changes for 52 Cataclysmic Variables, and the Failure for the Most-fundamental Prediction of the Magnetic Braking Model

Schaefer

2024

ApJ

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Revised ephemeris and orbital period derivative of the supersoft X-ray source CAL 87 based on 34 yr of observations

Stecchini,

Jablonski,

Diaz

et al. 2023

Monthly Notices of the Royal Astronomical Society

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In this study, we present an analysis of over 34 yr of observational data from CAL 87, an eclipsing supersoft X-ray source. The primary aim of our study, which combines previously analysed measurements as well as unexplored publicly available data sets, is to examine the orbital period evolution of CAL 87. After meticulously and consistently determining the eclipse timings, we constructed an O − C (observed minus calculated) diagram using a total of 38 data points. Our results provide confirmation of a positive derivative in the system’s orbital period, with a determined value of $\dot{P}=+\, 8.18\pm 1.46\times 10^{-11}$ s s−1. We observe a noticeable jitter in the eclipse timings and additionally identify a systematic delay in the X-ray eclipses compared to those observed in longer wavelengths. We discuss the interplay of the pertinent factors that could contribute to a positive period derivative and the inherent variability in the eclipses.

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Long-term photometric behavior and orbital period variations in the supersoft X-ray source V617 Sgr

Cited by 2 publications

References 22 publications

Evolutionary Period Changes for 52 Cataclysmic Variables, and the Failure for the Most-fundamental Prediction of the Magnetic Braking Model

Evolutionary Period Changes for 52 Cataclysmic Variables, and the Failure for the Most-fundamental Prediction of the Magnetic Braking Model

Revised ephemeris and orbital period derivative of the supersoft X-ray source CAL 87 based on 34 yr of observations

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