ADC/CDS Standard Document for Catalog:/journal_tables/ApJ/459/110/
ADC/CDS Standard Document for Catalog:| 1. Use the ADC Data Viewer Suite to visualize the data. |
|
| 2. Get the data files via anonymous FTP. (See Note.) |
|
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