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J/A+A/345/419       Star formation in early-type galaxies (Longhetti+ 1999)

Star formation history of early-type galaxies in low density environments. V. Blue line-strength indices for the nuclear region Longhetti M., Bressan A., Chiosi C., Rampazzo R. <Astron. Astrophys. 345, 419 (1999)> =1999A&A...345..419L (SIMBAD/NED BibCode)
ADC_Keywords: Galaxies, spectra ; Models, evolutionary Keywords: galaxies: elliptical and lenticular, cD - Galaxies: evolution - galaxies: formation - galaxies: fundamental parameters - galaxies: interactions - galaxies: star-burst Abstract: We analyze the star formation properties of a sample of 21 shell galaxies and 30 early-type galaxies members of interacting pairs, located in low density environments (Longhetti et al., 1998, Cat. J/A+AS/130/251, 1998A&AS..130..267L). The study is based on new models developed to interpret the information coming from `blue' HδFeI, H+K(CaII) and D4000 line-strength indices proposed by Rose (1984AJ.....89.1238R; 1985AJ.....90.1927R) and Hamilton (1985ApJ...297..371H). We find that the last star forming event that occurred in the nuclear region of shell galaxies is statistically old (from 0.1 up to several Gyr) with respect to the corresponding one in the sub-sample of pair galaxies (<0.1Gyr or even ongoing star formation). If the stellar activity is somehow related to the formation of shells, as predicted by several dynamical models of galaxy interaction, shells have to be considered long lasting structures. Since pair members show evidence of very recent star formation, we suggest that either large reservoirs of gas have to be present to maintain active star formation, if these galaxies are on periodic orbits, or most of the pair members in the present sample are experiencing unbound encounters. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table2.dat 59 25 Blue indices for Simple Stellar Populations (SSP)
See also: J/A+AS/130/251 : Star Formation in Early-type galaxies. I. (Longhetti+ 1998) J/A+A/311/361 : Evolution models of elliptical galaxies. II. (Tantalo+, 1996) III/92 : A Library of Stellar Spectra (Jacoby+ 1984) Byte-by-byte Description of file: table2.dat
Bytes Format Units Label Explanations
1- 5 F5.2 [yr] Log(age) Logarithm of age 6- 11 F6.2 --- D4000a Index Δ4000 at Z=0.004 12- 17 F6.2 --- H+K(CaII)a Index H+K(CaII) at Z=0.004 18- 23 F6.2 --- Hd/FeIa Index Hδ/FeI at Z=0.004 24- 29 F6.2 --- D4000b Index Δ4000 at Z=0.02 30- 35 F6.2 --- H+K(CaII)b Index H+K(CaII) at Z=0.02 36- 41 F6.2 --- Hd/FeIb Index Hδ/FeI at Z=0.02 42- 47 F6.2 --- D4000c Index Δ4000 at Z=0.05 48- 53 F6.2 --- H+K(CaII)c Index H+K(CaII) at Z=0.05 54- 59 F6.2 --- Hd/FeIc Index Hδ/FeI at Z=0.05
Acknowledgements: Marcella Longhetti References: Longhetti et al., Paper I. 1998A&AS..130..251L, Cat. J/A+AS/130/251 Longhetti et al., Paper II. 1998A&AS..130..267L Rampazzo et al., Paper III. 1999A&A...341..357R
(End) Patricia Bauer [CDS] 26-Apr-1999
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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