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

¹ MCTI/Laboratório Nacional de Astrofísica, Rua Estados Unidos 154, CEP 37504-364 Itajubá, MG, Brazil
e-mail: max@lna.br; mabans@lna.br; aardila@lna.br
² UEFS, Departamento de Física, Av. Transnordenstina, S/N, Novo Horizonte, CEP 44036-900 Feira de Santana, BA, Brazil
³ UEFS, Observatório Astronômico Antares, Rua da Barra, 925, Jardim Cruzeiro, CEP 44015-430 Feira de Santana, BA, Brazil
e-mail: paulopoppe1963@gmail.com; vmartin1963@gmail.com; irafbear@gmail.br
⁴ Gemini Observatory, Southern Operations Center, c/o AURA, 603 Casilla, La Serena, Chile
e-mail: ewenderoth@gemini.edu
⁵ UNIFEI, Instituto de Engenharia de Produção e Gestão, Av. BPS, 1303, Pinheirinho, CEP 37500-903 Itajubá, MG, Brazil

Received: 30 May 2013
Accepted: 21 August 2013

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.