Mass Transfer and Light Time Effect Studies for Au Serpentis

We utilize the PAdova and TRieste Stellar Evolution Code (PARSEC) combined with photometric observations to determine a guaranteed mass of AL Cas and re-examine its related physical parameters. Multicolor-photometric observations of AL Cas have been performed in 2016 and 2017. We use the Wilson-Devinney (W-D) code to analyze the light curves and find that AL Cas is probably an A-subtype contact binary (f = 35.7±0.9%) with a mass ratio q = 0.6399±0.0230 and an effective temperature difference ΔT = 78 K. The mass-radius relation of a higher luminosity component for AL Cas is obtained by two methods: depending on calculation of the Roche lobe (DCRL method) and depending on calculation of the W-D code (DCWD method). Using this relationship with the PARSEC model, we investigate the component masses of AL Cas as M 1 = 1.19±0.23 M ⊙ with M 2 = 0.76±0.18 M ⊙ by the DCRL method and M 1 = 1.22±0.26 M ⊙ with M 2 = 0.78±0.20 M ⊙ by the DCWD method. By means of the photometric studies, we examine the related physical properties of AL Cas with the latest findings. We update the orbital period (P orb = 0.50055593 d) of AL Cas according to six new times of light minimum together with those collected from the literature. Meanwhile, the (O – C)2 curve analysis suggests that the orbital period of AL Cas has a cyclic variation with a period of 81.25 yr and an amplitude of 0.01415 d. This cyclic change would be caused by the light-travel time effect from a third body. A similar mass of the third body (M 3 sin i′ = 0.279 M ⊙) is derived from our two methods.

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A powerful double radio relic system discovered in PSZ1 G108.18-11.53: evidence for a shock with non-uniform Mach number?

Gasperin

Intema

Weeren

et al. 2015

Mon. Not. R. Astron. Soc.

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Diffuse radio emission in the form of radio halos and relics has been found in a number of merging galaxy clusters. These structures indicate that shock and turbulence associated with the merger accelerate electrons to relativistic energies. We report the discovery of a radio relic + radio halo system in PSZ1 G108.18-11.53 (z = 0.335). This cluster hosts the second most powerful double radio relic system ever discovered. We observed PSZ1 G108.18-11.53 with the Giant Meterwave Radio Telescope (GMRT) and the Westerbork Synthesis Radio Telescope (WSRT). We obtained radio maps at 147, 323, 607 and 1380 MHz. We also observed the cluster with the Keck telescope, obtaining the spectroscopic redshift for 42 cluster members. From the injection index we obtained the Mach number of the shocks generating the two radio relics. For the southern shock we found M = 2.33 +0.19−0.26 , while the northern shock Mach number goes from M = 2.20 +0.07 −0.14 in the north part down to M = 2.00 +0.03 −0.08 in the southern region. If the relation between the injection index and the Mach number predicted by diffusive shock acceleration (DSA) theory holds, this is the first observational evidence for a gradient in the Mach number along a galaxy cluster merger shock.

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Mass Transfer and Light Time Effect Studies for Au Serpentis

Cited by 4 publications

References 36 publications

A critical review of period analyses and implications for mass exchange in W UMa eclipsing binaries: Paper 4

A critical review of period analyses and implications for mass exchange in W UMa eclipsing binaries: Paper 4

From multicolor-photometric observations to a guaranteed mass of AL Cas

A powerful double radio relic system discovered in PSZ1 G108.18-11.53: evidence for a shock with non-uniform Mach number?

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