# 2011A&A...531A..21S

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 Query : 2011A&A...531A..21S

2011A&A...531A..21S - Astronomy and Astrophysics, volume 531A, 21-21 (2011/7-1)

Chemical abundances of the PRGs UGC 7576 and UGC 9796. I. Testing the formation scenario.

SPAVONE M., IODICE E., ARNABOLDI M., LONGO G. and GERHARD O.

Abstract (from CDS):

The study of both the chemical abundances of HII regions in polar ring galaxies and their implications for the evolutionary scenario of these systems has been a step forward both in tracing the formation history of the galaxy and giving hints toward the mechanisms at work during the building of a disk by cold accretion process. It is now important to establish whether such results are typical of the class of polar disk galaxies as a whole. The present work aims at checking the cold accretion of gas through a cosmic filament'' as a possible scenario for the formation of the polar structures in UGC 7576 and UGC 9796. If these form by cold accretion, we expect the HII regions abundances and metallicities to be lower than those of same-luminosity spiral disks, with values of Z∼1/10Z, as predicted by cosmological simulations. We used deep long-slit spectra, obtained with DOLORES@TNG in the optical wavelengths, of the brightest HII regions associated with the polar structures to derive their chemical abundances and star formation rate. We used the empirical methods, based on the intensities of easily observable lines, to derive the oxygen abundance 12+log(O/H) of both galaxies. Such values are compared with those typical of different morphological galaxy types of comparable luminosity. The average metallicity values for UGC 7576 and UGC 9796 are Z=0.4 Z and Z=0.1 Z, respectively. Both values are lower than those measured for ordinary spirals of similar luminosity, and UGC 7576 presents no metallicity gradient along the polar structure. These data, together with other observed features available for the two PRGs in previous works, are compared with the predictions of simulations of tidal accretion, cold accretion, and merging to disentangle these scenarios.

Journal keyword(s): galaxies: abundances - galaxies: evolution - galaxies: formation - galaxies: individual: UGC 7576 - galaxies: individual: UGC 9796 - galaxies: peculiar

Full paper

 Number of rows : 7
N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2022
#notes
1 UGC 7576 GiC 12 27 41.8591778952 +28 41 53.026524312   16.0       ~ 60 0
2 BD+25 2534 HS* 12 37 23.5161671712 +25 03 59.867922240 9.117 10.26 10.59 10.642 10.809 sdB1(k) 225 0
3 ESO 322-69 GiG 12 44 49.0352044176 -40 42 51.691570488   14.12 13.58 13.29 13.9 ~ 190 0
4 UGC 9562 GiP 14 51 14.3956253136 +35 32 32.932212324   14.2       ~ 153 0
5 UGC 9796 GiP 15 15 56.3061737160 +43 10 00.480168228   16.0       ~ 42 0
6 MCG+07-31-049 EmG 15 16 03.962 +43 09 36.51   15.7       ~ 32 2
7 * alf Lyr dS* 18 36 56.33635 +38 47 01.2802 0.03 0.03 0.03 0.07 0.10 A0Va 2606 0

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2022.09.26-02:58:44