Context. The chronology of bulge and disk formation is a major unsolved issue in galaxy formation, which impacts on our global understanding of the Hubble sequence. Aims. We analyse colours of the nuclear regions of intermediate redshift disk galaxies, with the aim of obtaining empirical information of relative ages of bulges and disks at 0.1 < z < 1.3. Methods. We work with an apparent-diamete...

Contrary to traditional models of galaxy formation, recent observations suggest that some bulges form within preexisting disk galaxies. Such late-epoch bulge formation within disks seems to be linked to disk gas inflow and central star formation, caused by either internal secular processes or galaxy mergers and interactions. We identify a population of galaxies likely to be experiencing active ...

We have found that the bulge of the large, nearby Sb galaxy NGC 7331 rotates retrograde to its disk. Analysis of spectra in the region of the near-IR Ca II triplet along the major axis shows that, in the radial range between 5 and ∼20, the line of sight velocity distribution of the absorption lines has two distinct peaks, and can be decomposed into a fast-rotating component with v/σ > 3, and a ...

We have found that the bulge of the large, nearby Sb galaxy NGC 7331 rotates retrograde to its disk. Analysis of spectra in the region of the near-IR Ca II triplet along the major axis shows that, in the radial range between 5 and ∼20, the line of sight velocity distribution of the absorption lines is has two distinct peaks, and can be decomposed into a fast-rotating component with v/σ > 3, and...

air pollution is one of the most important problems in urban areas that always threaten citizen's health. photochemical smog is one of the main factors of air pollution in large cities like tehran. usually smog is not only a part of nature, but is being analyzed as an independent matter, which highly affects on the nature. it has been used as relationship between atmospheric elements such as te...