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S. Zola

Publications and source records attributed to S. Zola.

56 records · Page 4Linked to original sources
arXiv2001

HS 0705+6700: a new eclipsing sdB binary

We report the discovery of an eclipsing binary - HS 0705+6700 - being an sdB star with a faint companion. From its light curve the orbital period of 8263.87 s, the mass ratio of the system q = 0.28, the inclination of 84.4 deg and other system parameters are derived. The companion does not contribute to the optical light of the system except through a strong reflection effect. The semi-amplitude of the radial velocity curve K1 = 85.8 km/s and a mass function of f(m) = 0.00626 Msun are determined. A spectroscopic analysis of the blue spectra results in Teff = 28800K, log g = 5.40, and log n(He)/n(H) = -2.68. These characteristics are typical for sdB stars, as is its mass of 0.48 Msun. According to its mass (0.13 Msun) and radius (0.19 Rsun), the companion is an M dwarf. The primary is in a core helium burning phase of evolution, and the system must have gone through a common envelope stage when the primary was near the tip of the red giant branch.

astro-ph↗
arXiv2001

The new sample of Giant radio sources: I. Radio imaging, optical identification and spectroscopy of selected candidates

A new sample of very large angular size radio sources has been selected from the 1.4 GHz VLA surveys: FIRST and NVSS. This sample will be very useful for an observational constraint on the time evolution of double radio sources, especially their size, predicted by numerous analytical models of such evolution (cf. Introduction). In this paper we present radio and optical data for a large fraction of the sample sources. They are: high-frequency VLA maps with very weak radio cores detected, deep optical images showing the identified faint host galaxies not visible on the DSS images, and optical spectra of the identified galaxies brighter than about R ~ 18.5 mag taken with the McDonald Observatory 2.1m telescope. For 15 galaxies (of which 4 do not belong to the complete sample) the redshift has been determined. In the result, 44 per cent of galaxies in the complete sample have redshift data (with one exception all redshifts are less than 0.33), of which 70 per cent have a linear size exceeding 1 Mpc. The photometric redshift estimates for other 11 galaxies with 19 mag<R<21.7 mag (0.3<z<0.5) predict their sizes much over 1 Mpc.

astro-ph↗