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A Study of Contact Binaries with Large Temperature Differences between Components

Siwak M., Zola S., Koziel-Wierzbowska D.

Acta Astronomica

2010

Vol. 60, No. 4

305--336

We present an extensive analysis of new light and radial velocity (RV) curves, as well as high quality broadening function (BF) profiles of twelve binary systems for which a contact configuration with large temperature differences between components has been reported in the literature. We find that six systems (V1010 Oph, WZ Cyg, VV Cet, DO Cas, FS Lup, V747 Cen) have near contact configurations. For the remaining systems (CX Vir, FT Lup, BV Eri, FO Hya, CN And, BX And), our solutions of the new observations once again converge in a contact configuration with large temperature differences between the components. However, the bright regions discovered in the BFs for V747 Cen, CX Vir, FT Lup, BV Eri, FO Hya, and CN And, and further attributed to hot spots, shed new light on the physical processes taking place between the components and imply the possibility that the contact configurations obtained from light and RV curve modeling are a spurious result.

Giant Radio Sources as a Probe of the Cosmological Evolution of the IGM. II. The Observational Constraint on the Model of Radio-Jets Propagation through the X-ray Halo-IGM Interface

Kuligowska E., Jamrozy M., Koziel-Wierzbowska D., Machalski J.

Acta Astronomica

2009

Vol. 59, No. 4

431--455

Three limited samples of high-redshift radio sources of FRII-type are used to constrain the dynamical model for the jets' propagation through the two-media environment: the X-ray emitting halo with the power-law density profile surrounding the parent galaxy and the much hotter intergalactic medium (IGM) of a constant density. The model, originally developed by Gopal-Krishna and Wiita, is modified adopting modern values of its free parameters taken from recent X-ray measurements with the XMM-Newton and Chandra Observatories. We find that (i) giant-sized radio sources (≈1 Mpc) exist at redshifts up to z≈2, (ii) all newly identified the largest radio sources with 1