NASA/IPAC EXTRAGALACTIC DATABASE
Date and Time of the Query: 2019-04-20 T17:29:43 PDT
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For refcode 1991A&AS...91...61v:
Retrieve 95 NED objects in this reference.
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Copyright by European Southern Observatory (ESO). Reproduced by permission
1991A&AS...91...61v A study of southern extreme IRAS galaxies. I. Optical observations A. C. van den Broek, W. van Driel, T. de Jong, J. Lub, M.H.K de Grijp and P. Goudfrooij Astronomical Institute `Anton Pannekoek", University of Amsterdam, Kruislaan 403, NL-1098 51 Amsterdam, The Netherlands Sterrewacht Leiden, Postbus 9513, NL-2300 RA, The Netherlands Received October 4, 1990; accepted April 3, 1991 Abstract. - In order to study the processes that (strongly) enhance the star formation rate in some galaxies we have selected 62 galaxies from the IRAS point source catalogue with far-infrared to blue luminosity ratios (L_FIR_/L^0^_B_) of three or larger. These galaxies form a subset of a far-infrared complete sample of 254 sources in two fields covering in total 1500 square degrees of the southern sky (10^h^ <= {alpha} <= 14^h^ and -40^deg^ <= {delta} <= -20^deg^; 20^h^ <= {alpha} <= 22^h^ and -40^deg^ <= {delta} <= -20^deg^).The sources in the far-infrared complete sample all have flux densities larger than 1 and 2.5 Jy at 60 and 100 microns, respectively, to ensure completeness. Furthermore, in order to select mainly galaxies, for all sources the flux densities at 60 and 100 microns are larger than at 12 and 25 microns. We initially used B-band magnitudes estimated from ESO/SRC and POSS sky survey plates to estimate L_FIR_/LB ratios for all galaxies in the far-infrared complete sample, and we selected only those galaxies for the optical observations that have L_FIR_/L^0^_B_ >= 4.3, thus obtaining a sample of 62 galaxies. Comparison of the estimated with the observed, corrected CCD B-band magnitudes later revealed that the actual L_FIR_/L^0^_B_ selection criterium is less sharp and corresponds to L_FIR_/L_B_ >~3. For these 62 sources we also obtained far-infrared co-added flux-densities, so that 100%, 95%, and 70% of the sources are detected at 60 and 100, 25 and 12 microns, respectively. Due to the L_FIR_/L_B_ selection criterion and the correlation between L_FIR_/L_B_ and the S_100_/S_60_ flux density ratio the subsample of 62 galaxies consists only of warm sources with log (S_100_/S_60_) <= 0.4. The optical observations comprise long-slit CCD spectra in the 4800-7300 A wavelength range, broad-band B, V and R, and narrow-band H{alpha} CCD images. In this paper we present the optical observations and show spectra, and broad-band, colour and continuum-subtracted H{alpha} CCD images for more than 50 galaxies. The spectra are mostly H II-types although some 25% are AGN-types. The broad-band images show, among other things, that our sample predominantly consists of barred spirals and distorded interacting system, while the H{alpha} images show in most cases small compact sources. From the spectra we derived redshifts, line- ratios, equivalent widths, and extinction determinations from the H{beta}/H{alpha} line ratios. We also derived integrated magnitudes, colours, H{alpha} fluxes, diameters and luminosities of the galaxies from the CCD images. We determined average luminosity profiles of all early- type galaxies and all possible merger candidates in our sample, and we found that all these galaxies have exponential disks except two objects that follow a de `Vaucouleurs r^1/4^ law: a merger candidate, and an elliptical galaxy in a close interacting pair (the latter is not an IRAS galaxy, however). Key words: galaxies: general - galaxies: structure of- galaxies: redshifts - galaxies: active.
Retrieve 95 NED objects in this reference.
Please click here for ADS abstract

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