J/A+A/463/455 Nearby early-type gal. with ionized gas. III. (Annibali+, 2007)
Nearby early-type galaxies with ionized gas.
III. Analysis of line-strength indices with new stellar population models.
Annibali F., Bressan A., Rampazzo R., Zeilinger W.W., Danese L.
<Astron. Astrophys. 463, 455 (2007)>
=2007A&A...463..455A 2007A&A...463..455A
ADC_Keywords: Galaxies, nearby ; Abundances ; Models, evolutionary
Keywords: galaxies: elliptical and lenticular, cD -
galaxies: fundamental parameters - galaxies: formation -
galaxies: evolution
Abstract:
The paper is devoted to the study of the underlying stellar population
of a sample of 62 nearby early-type galaxies, predominantly located in
low density environments, a large fraction of which showing emission
lines. Ages, metallicities and [α/Fe] ratios have been derived
through the comparison of Lick indices measured at different
galacto-centric distances (7 apertures and 4 gradients) with new
Simple Stellar Population (SSP) models which account for the presence
of alpha/Fe-enhancement. The SSPs cover a wide range of ages
(108-16x109yr), metallicities (0.0004≤Z≤0.05) and
[α/Fe] ratios (0-0.8). To derive the stellar population
parameters we use an algorithm that provides, together with the most
likely solution in the (age, Z, [α/Fe]) space, also the
probability density function along the age-metallicity degeneracy. We
derive a large spread in age, with SSP-equivalent ages ranging from a
few to 15Gyrs. Age does not show any significant trend with central
velocity dispersion sigmac but E galaxies appear on average older
than lenticulars.
Description:
Ages, metallicities and [α/Fe] ratios derived for all the
apertures and gradients of the total sample of 62 galaxies are
presented. Each table presents the results obtained with one
particular choice of the line strength index triplets: (Hβ, Mgb,
and <Fe>), (Hγ_F, Mgb, and <Fe>) and (Hδ_F, Mgb, and
<Fe>). From 0 to 6, the apertures correspond to regions of increasing
radii: 1.5" (0), 2.5" (1), 10" (2), re/10 (3), re/8 (4),
re/4 (5) and re/2 (6). From 0 to 3 the gradients correspond to
adjacent annulii of increasing radii: 0≤r≤re/16 (0),
re/16≤r≤re/8 (1), re/8≤r≤re/4 (2) and
re/4≤r≤re/2 (3).
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
galaxies.dat 50 62 Galaxy positions (From Simbad)
table5.dat 61 415 Apertures: ages, metallicities and [α/Fe]
ratios from (Hβ, Mgb, and <Fe>)
table6.dat 61 415 Apertures: ages, metallicities and [α/Fe]
ratios from (HγF, Mgb, and <Fe>)
table7.dat 61 415 Apertures: ages, metallicities and [α/Fe]
ratios from (HδF, Mgb, and <Fe>)
table9.dat 61 227 Gradients: ages, metallicities and [α/Fe]
ratios from (Hβ, Mgb, and <Fe>)
table10.dat 61 227 Gradients: ages, metallicities and [α/Fe]
ratios from (HγF, Mgb, and <Fe>)
table11.dat 61 227 Gradients: ages, metallicities and [α/Fe]
ratios from (HδF, Mgb, and <Fe>)
table12.dat 61 224 Gradients: final ages, metallicities and
[α/Fe] ratios
--------------------------------------------------------------------------------
See also:
J/A+A/433/497 : Nearby early-type gal. with ionized gas. I. (Rampazzo+, 2005)
J/A+A/445/79 : Nearby early-type gal. with ionized gas. II. (Annibali+, 2006)
J/A+A/519/A40 : Nearby early-type gal. with ionized gas. IV (Annibali+, 2010)
Byte-by-byte Description of file: galaxies.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 8 A8 --- Galaxy Simbad name
11- 12 I2 h RAh Simbad Hour of Right Ascension (J2000.0)
14- 15 I2 min RAm Simbad Minute of Right Ascension (J2000.0)
17- 20 F4.1 s RAs Simbad Second of Right Ascension (J2000.0)
22 A1 --- DE- Simbad Sign of the Declination (J2000.0)
23- 24 I2 deg DEd Simbad Degree of Declination (J2000.0)
26- 27 I2 arcmin DEm Simbad Arcminute of Declination (J2000.0)
29- 30 I2 arcsec DEs Simbad Arcsecond of Declination (J2000.0)
34- 38 F5.2 mag Bmag Simbad B band magnitude
40- 44 F5.2 mag Vmag ? Simbad V band magnitude
46- 50 A5 --- MType Simbad morphological type
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table[567].dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 8 A8 --- Galaxy Galaxy designation
11 I1 --- Aperture [0/6] Aperture number (1)
16- 19 F4.1 Gyr Age Age
22- 25 F4.1 Gyr e_Age Error on age
32- 36 F5.3 --- Z Metallicity mass fraction
39- 43 F5.3 --- e_Z Error on metallicity
50- 54 F5.3 --- a/Fe α/Fe ratio
57- 61 F5.3 --- e_a/Fe Error on α/Fe ratio
--------------------------------------------------------------------------------
Note (1): Aperture numbers as follows:
0 = 1.5"
1 = 2.5"
2 = 10"
3 = re/10
4 = re/8
5 = re/4
6 = re/2
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table9.dat table1?.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 8 A8 --- Galaxy Galaxy designation
11 I1 --- Gradient [0/3] Gradient number (1)
16- 19 F4.1 Gyr Age Age
22- 25 F4.1 Gyr e_Age Error on age
32- 36 F5.3 --- Z Metallicity mass fraction
39- 43 F5.3 --- e_Z Error on metallicity
50- 54 F5.3 --- a/Fe α/Fe ratio
57- 61 F5.3 --- e_a/Fe Error on α/Fe ratio
--------------------------------------------------------------------------------
Note (1): Gradient numbers as follows:
0 = 0 ≤ r ≤ re/16
1 = re/16 ≤ r ≤ re/8
2 = re/8 ≤ r ≤ re/4
3 = re/4 ≤ r ≤ re/2
--------------------------------------------------------------------------------
Acknowledgements:
Francesca Annibali, annibali(at)stsci.edu
(End) Patricia Vannier [CDS] 28-Sep-2006