BVRIphotometric analysis for the galaxy group NGC 4410

Abstract

We present a BVRI CCD (Charge Coupled Device) surface photometry analysis of the galaxy group NGC 4410, which contains four galaxies in interaction. Along with our photometric study, we show residual images (after subtracting isophotal models) and unsharp masked images to uncover any hidden structures in this system of galaxies; we have also performed a two-dimensional bulge-disk decomposition for NGC 4410C and D, and a major axis sector profile for NGC 4410A. We have calculated BVRI surface brightnesses and colors within regions such as galaxy centers, bridges, tails and optical knots in the NGC 4410 system, generating B− V color maps and color profiles. The information obtained was used to discover the predominant stellar populations. The colors of the galaxies imply ages of ∼2 × 10 9 to ∼2 × 10 10 years for models using a range of metallicities. The bluer knots and H II regions have colors implying ages of a minimum of 5× 10 8 years, but possibly as high as 3× 10 9 years for stellar populations formed in the interaction. These results lead us to conclude that there is a moderate star formation rate and a tranquil evolving state of the system with a long timescale for interaction, much longer than the typical dynamical timescales of 10 8 years. Although we note that NGC 4410D has a blue nucleus (possible nuclear starburst?), bulge, bar, and short spiral arms, and may be interacting with a H I gas cloud. Some observed structures in NGC 4410A are coincident with previously studied H II regions, a tidal arm and optical/radio knots found in this galaxy. An optical knot E coincident with a radio knot may be an optical synchrotron emission or an H II region. The galaxy NGC 4410B appears to be a boxy giant elliptical with a possible dusty disk embedded (similar to Cen A?) and NGC 4410C is confirmed as a lenticular galaxy.

Optical to Mid-Infrared Analysis for the Galaxy Group RSCG 44

“…Galaxies C, E have a 4 /a > 0 for about 20" indicating that these isophotes are dominated by a small disk component (the mean values of a 4 /a in disk galaxies are reported as a 4 /a > 2, see Pérez-Grana et al [21], Grutzbauch et al [7], Jerjen et al [25]) this indicative is also found in our unsharp masked images and residual images.…”

“…Along with sky subtraction we made a seeing correction to BV images applying a convolution function in order to smooth the image. The standard photometric equation used in [21] was applied in the same manner in this work. In each run observations of Landolt standard fields containing Palomar Green stars were performed during the night at a range of air-masses.…”

“…We also have produced contour maps of the group, were the lowest mapping contour corresponds to 5σ background noise levels. The intrinsic flux E n corresponding to contour n is given trough E n = 10 A(n−1) + B MJysr −1 were A and Bare constants which vary with the band and source of consideration (see [21]). The mid-infrared colors of the group will be dependent on the tem-perature of the dust, the strength of the stellar blackbody emission and polycyclic aromatic hydrocarbon emission (PAH emission) that can contribute to three of the four IRAC bands.…”

“…The mid-infrared colors of the group will be dependent on the tem-perature of the dust, the strength of the stellar blackbody emission and polycyclic aromatic hydrocarbon emission (PAH emission) that can contribute to three of the four IRAC bands. These three dominant components of the mid-infrared emission can be disentangled (to some extent) by 3.6/4.5 µm, 5.8/4.5 µm and 8/4.5 µm flux ratio mapping of the sources, a procedure similar tothe one applied in [21] and applied again in this paper. The strongest PAH contribution is expected to happen in the 8/4.5 µm flux ratio, hence, for example galaxies with emission dominated by stellar light and little dust or PAH should present low values of 8/4.5 µm flux ratio.…”

The Tidal Filament of NGC 4660

“…We note that for the 2.1m telescope data we have used Landolt standards defined in the Johnson-Kron-Cousins system while the filters used for the observations are Johnson filters, and in R and I there are significant differences between the two filter systems. Pérez-Grana et al (2008) reported no significant differences between the surface brightnesses obtained over a range of galaxy colours, using previous observations of galaxies in both systems.…”