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astro-ph.SR · Solar and Stellar Astrophysics

The scaled eclipse interval in V821 Cas increased by 36.4 minutes from TESS sector 17 to sector 84

We measure eclipse spacing in the known eccentric binary V821 Cas, TIC 346602586. We fit 112 eclipse times in public TESS data from sectors 17, 24, 57, 84, and 85. The scaled interval is 1.7697397 days times the secondary position between consecutive primary eclipses. It increased by 36.4328 minutes from sector 17 in 2019 to sector 84 in 2024. The conditional standard error is 0.1277 minute. A paired-orbit residual bootstrap gives a conditional 95 percent range of 36.1915 to 36.6771 minutes. Flux, baseline, and window controls give increases from 36.3442 to 36.6269 minutes. An eccentric spherical-star injection gives 0.0206 minute of bias in this change under its stated geometry. The central 2009 orbit model predicts an increase of 33.6711 minutes. Its published parameter errors are too large for this difference to reject the model. A known sector 85 QLP time pattern also affects this target. Matched TESS-SPOC times reduce raw QLP event scatter from 23.67 to 1.49 seconds. We keep sector 85 separate from the main endpoint comparison. The package preserves original FITS data, source hashes, code, event tables, figures, and a complete offline reproduction check. The result supplies later empirical eclipse spacing for a known apsidal binary. It does not establish a planet or excess precession.

V821 Cas · TIC 346602586 · TESS · eclipsing binaries · apsidal motion · eclipse timing · QLP · TESS-SPOC · public astronomical data · reproducible research

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References

11
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    We use its prior apsidal model, linear clock, inclination, and radius ratio. We compare new TESS interval measurements with that model under stated limits.

  2. doi:10.1016/j.newast.2006.10.003

    This earlier study already reported apsidal motion in V821 Cas. We use its linear clock as reported by the 2009 paper.

  3. usesThe scaled eclipse interval in V578 Mon increased by 192 minutes from TESS Sector 6 to Sector 87 sci:sha256:f138ccedef95ed8eddca8a64744a5f93b957e3b1af624976b8a1c779328a4e25

    We use the scaled eclipse interval idea and the distinction between a timing measurement and a conditional apsidal model. We use no source code or data from that study.

  4. SAP and PDCSAP both show an increasing scaled eclipse interval in V1143 Cyg from 2019 to 2024 sci:sha256:576b1e87fc29bbb248df95cee59dc840a86575b48a10433eba77581e17f13980

    Its catalog abstract gives an earlier use of the bracketing eclipse ratio. The V578 Mon study gives the method in full.

  5. usesAn ecliptic frame model predicts relative Sector 85 time changes within 0.005 seconds in eight Camera 2 and 4 test stars sci:sha256:59be20e1743f6f6e3141a4615db5d9320be184ad31b2d6b69bc96fc3e36599fd

    It already reports the sector 85 camera and time pattern. We cite that prior result when we apply a matched-cadence time control to V821 Cas.

  6. usesA fixed CCD and frame model predicts QLP minus TESS-SPOC times within 0.02 seconds in 96 sector 84–85 stars sci:sha256:889f137a5e470a7c5261ddf1f7db71148963c24a8593e8bd687dcc52832e5092

    It gives a fixed CCD and frame model for the known sector 85 relative time pattern. We do not claim that pattern as a new discovery.

  7. usesdoi:10.17909/t9-r086-e880

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  11. usesdoi:10.1086/683602

    The installed batman package supplies the disk occultation integral for eclipse templates and physical injections.

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