Broad-band photometry and long-slit spectroscopy of the peculiar ring galaxy FM 287-14

Abstract

Aims. We report detailed morphological and kinematical insights into the disturbed galaxy FM 287-14, which is reported in the literature as a member of strongly interacting galaxies with a clear case of mergers. The main purpose of this paper is to provide a first observational study of this double-nuclei object based on photometry and spectroscopy. Methods. The study is based on BVR photometry with the 1.6-m telescope at OPD, and long-slit spectroscopy with Gemini South's GMOS spectrograph, with two-gratings centered at 5 011 Å and 6 765 Å. Image enhancement techniques were applied to the direct images, and the main lines in the spectra were used to determine the radial velocity. Line ratios and color-color diagnostic diagrams helped determine the nature of this object.Results. The external NE section is populated with well-defined H ii regions and is bluer than the SW region with less evidence of H ii regions. A double nucleus has been identified. The (B − R) × (B − V) diagram shows that the main nucleus is redder than the second one; the internal "ring-like" structure is redder than the external one. The main object redshift is z = 0.0311, corresponding to a line-of-sight velocity of 9334 km s −1 (a distance of 133.3 Mpc), and the second nucleus has a redshift of z = 0.0310, corresponding to a line-of-sight velocity of 9300 km s −1 (a distance of 132.9 Mpc). Both nuclei show characteristics of early-type galaxies, but the main one also shows modest emission evidence of the [N ii]λ6583 line.Conclusions. The peculiarities of FM 287-14 can be adequately interpreted as an ongoing merging-stage of interaction of the main object with a companion galaxy.

Estudo da Atividade Nuclear e População Estelar na Galáxia Peculiar AM 0004-413 (ESO 293-IG 037)

“…Portanto, com o objetivo de estimar a população estelar na região nuclear e remover a contribuição desta, aplicamos o código de síntese de população estelar STARLIGHT [33] no espectro nuclear calibrado da Figura 4. Este procedimento foi usado com sucesso em galáxias com redshifts semelhantes ao deste estudo (veja, por exemplo, [34][35][36][37][38][39][40][41][42]) cujo propósito foi o de medir com melhor precisão a intensidade, a largura equivalente e comprimento de onda central das linhas de emissão. O resultado da síntese espectral pode ser observada na Figura 8, envolvendo os espectros observado, modelado e o residual.…”