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J/ApJ/459/110      Line strengths and gradients in S0 galaxies (Fisher+ 1996)

Line strengths and line strength gradients in S0 galaxies Fisher D., Franx M., Illingworth G. <Astrophys. J. 459, 110 (1996)> =1996ApJ...459..110F
ADC_Keywords: Galaxies, spectra Keywords: galaxies: abundances - galaxies: elliptical and lenticular, cD - galaxies: stellar content Abstract: Line strengths and their gradients in Mg, Fe, and HBeta have been determined for a sample of 20 S0 galaxies in order to study the stellar populations of their bulges and disks and to investigate their relationship to elliptical galaxies. Data are also presented for the elliptical galaxy NGC 1700 and the E/S0 NGC 3585. We find that S0 galaxies generally follow a similar, though possibly steeper, relationship between central Mg_2 line strength and central velocity dispersion as found for elliptical galaxies. The S0 galaxies show no dependence between Fe line strengths and central velocity dispersion -- similar to the behavior observed in elliptical galaxies. The central Mg/Fe ratios in the luminous S0 galaxies show an overabundance of Mg to Fe with respect to solar element ratios. The magnitudes of the Mg and Fe line-strength gradients within the galaxies are found to be correlated, i.e., objects with steep Mg gradients have correspondingly large Fe gradients. We infer bulge and disk gradients for the nine most edge-on galaxies for which we have both major- and minor-axis profiles. The metal line strengths decrease with radius along the major and minor axes in the bulge-dominated central regions. At larger radii, however, the major-axis metal line strength profiles flatten while the minor-axis bulge profiles fall to lower values. Representative color maps in B-R are presented that display a separation between bulge and disk colors corresponding to the metal line strength profiles. Based on our Mg_2 profiles, the average metal gradient found in the disks of our sub-sample is Delta[Fe/H]/Delta(r/h)=-0.08±0.06, which corresponds to a reduction in the mean metallicity of the disk stellar population by ≲15% per disk scale length (h). These shallow metallicity gradients are approximately a factor of 2-3 smaller than those derived for the disks of late-type spiral galaxies from H II regions and are consistent with previous investigations that showed a trend for disk metallicity gradients to decrease toward earlier Hubble types. As inferred from our Mg and Fe line strengths, the mean size of the bulge metallicity gradients is Delta[Fe/H]/Delta(log r)=-0.7±0.4, which is steeper than typical elliptical galaxy gradients. Our findings do not support formation scenarios in which bulges formed either from heated disk material at late times after disk formation or through dissipationless stellar merging, as neither process includes mechanisms for producing the observed metallicity gradients. Our observations are better explained in terms of formation via dissipative collapse (or merging) at early times. Objects: ---------------------------------------------------------- RA (2000) DE Designation(s) ---------------------------------------------------------- 03 48.5 -16 23 NGC 1461 04 57.0 -04 52 NGC 1700 08 19.9 +20 59 NGC 2560 10 05.3 -07 44 NGC 3115 10 48.3 +12 38 NGC 3384 10 50.9 +13 25 NGC 3412 11 13.3 -26 45 NGC 3585 11 16.9 +18 03 NGC 3607 11 52.9 +36 59 NGC 3941 11 57.9 +55 27 NGC 3998 11 59.4 +50 58 NGC 4026 12 01.4 +61 54 NGC 4036 12 07.0 +43 03 NGC 4111 12 18.1 +28 11 NGC 4251 12 23.9 +16 42 NGC 4350 12 25.4 +18 11 NGC 4382 12 35.5 +12 13 NGC 4550 12 52.3 +11 19 NGC 4754 12 52.9 +11 14 NGC 4762 15 06.5 +55 45 NGC 5866 18 47.4 +45 33 NGC 6703 02 27.6 -01 10 NGC 936 ---------------------------------------------------------- File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table9 106 436 Line strength data table10 47 556 Mg2 data
Byte-by-byte Description of file: table9
Bytes Format Units Label Explanations
1- 8 A8 --- Name Object name 10- 12 A3 --- --- [PA=] Always 'PA=' 13- 15 I3 deg PA Position angle 17- 22 A6 --- n_PA Additional information on PA (1) 24- 28 A5 --- Axis Position angle axis (Minor or Major) 31- 34 F4.1 arcsec Rad Radius 36- 40 F5.2 --- Fe4668 ?=-9.99 Fe4668 line strength estimate 42- 46 F5.2 --- e_Fe4668 ?=-9.99 Fe4668 error 48- 52 F5.2 --- Hbeta ?=-9.99 Hbeta line strength estimate 54- 58 F5.2 --- e_Hbeta ?=-9.99 Hbeta error 60- 64 F5.2 --- Mgb ?=-9.99 Mg b line strength estimate 66- 70 F5.2 --- e_Mgb ?=-9.99 Mgb error 72- 76 F5.2 --- Fe5270 ?=-9.99 Fe5270 line strength estimate 78- 82 F5.2 --- e_Fe5270 ?=-9.99 Fe5270 error 84- 88 F5.2 --- Fe5335 ?=-9.99 Fe5335 line strength estimate 90- 94 F5.2 --- e_Fe5335 ?=-9.99 Fe5335 error 96-100 F5.2 --- OIII ?=-9.99 [O III] line strength estimate 102-106 F5.2 --- e_OIII ?=-9.99 OIII error
Note (1): For NGC 5866, this column contains 6" N when PA=126deg 6" N and 4.5"NW when PA= 38deg 4.5"NW
Byte-by-byte Description of file: table10
Bytes Format Units Label Explanations
1- 8 A8 --- Name Object name 10- 12 A3 --- --- Always ' PA=' 13- 15 I3 deg PA Position angle 17- 22 A6 --- n_PA Additional information on PA (1) 24- 28 A5 --- Axis Position angle axis (Minor or Major) 31- 34 F4.1 arcsec Rad Radius 37- 41 F5.3 --- Mg2 ? Mg_2 line strength estimate 44- 47 F4.3 --- e_Mg2 ? Mg2 error
Note (1): For NGC 5866, this column contains 6" N when PA=126deg 6" N and 4.5"NW when PA= 38deg 4.5"NW
Origin: AAS CD-ROM series, Volume 6, 1996 Lee Brotzman [ADS] 22-Apr-96
(End) Patricia Bauer [CDS] 06-Sep-1996
The document above follows the rules of the Standard Description for Astronomical Catalogues.From this documentation it is possible to generate f77 program to load files into arrays or line by line

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