Environmental Effects on the Properties of Spiral Galaxies: Isolated Pairs of Spirals

Abstract

We characterized isolated spiral galaxies as a reference for the properties of interacting ones: we selected all the spirals in CfA catalog with niB ≤ 13.0,δ ≥ 0, a≤ 4′ and 73° > i > 32°. The isolated ones were those having no companions in ΔD≤0.5Mpc and ΔV≤500 km/s and no satellites galaxies in their neighborhood (from Nilson catalog and Palomar charts). To select the isolated pairs of spirals we used Karachentsev’s catalog applying similar conditions for m_B, δ, a, i and the same isolation criteria. We used broad band CCD images (Johnson B,V e I), narrow band CCD images (Hα) and long slit spectra in Hα region. The BVI images analysis consisted on applying sharp-divided methods, obtaining simulated images (from bulge/disk decomposition and galaxy orientation in the sky) and Fourier analysis. From Hα images we determined total emission, size, distribution and flux of HII regions. We also obtained the rotation curves.