EDP Sciences
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Volume 369, Number 2, April II 2001
Page(s) 421 - 431
Section Extragalactic astronomy
DOI http://dx.doi.org/10.1051/0004-6361:20010107

A&A 369, 421-431 (2001)
DOI: 10.1051/0004-6361:20010107

The ultraviolet visibility and quantitative morphology of galactic disks at low and high redshift

D. Burgarella, V. Buat, J. Donas, B. Milliard and S. Chapelon

Observatoire Astronomique Marseille-Provence, Laboratoire d'Astrophysique de Marseille, BP 8, 13376 Marseille Cedex 12, France

(Received 20 June 2000 / Accepted 12 January 2001)

We have used ultraviolet (200 nm) images of the local spiral galaxies M33, M51, M81, M100, M101 to compute morphological parameters of galactic disks at this wavelength: half-light radius $r_{\rm hl}$, surface brightness distributions, asymmetries (A) and concentrations ($C_{\rm A}$). The visibility and the evolution of the morphological parameters are studied as a function of the redshift. The main results are: local spiral galaxies would be hardly observed and classified if projected at high redshifts ($z \ge 1$) unless a strong luminosity evolution is assumed. Consequently, the non-detection of large galactic disks cannot be used without caution as a constraint on the evolution of galatic disks. Spiral galaxies observed in ultraviolet appear more irregular since the contribution from the young stellar population becomes predominent. When these galaxies are put in a (log A vs. log $C_{\rm A}$) diagram, they move to the irregular sector defined at visible wavelengths. Moreover, the log A parameter is degenerate and cannot be used for an efficient classification of morphological ultraviolet types. The analysis of high redshift galaxies cannot be carried out in a reliable way so far and a multi-wavelength approach is required if one does not want to misinterpret the data.

Key words: galaxies: evolution -- galaxies: fundamental parameters -- ultraviolet: galaxies -- galaxies: spiral

Offprint request: D. Burgarella, denis.burgarella@astrsp-mrs.fr

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