J/A+A/497/41 Average Early-type galaxies NIR spectrum (Cesetti+, 2009)
Early-type galaxies in the near-infrared: 1.5-2.4µm spectroscopy.
Cesetti M., Ivanov V.D., Morelli L., Pizzella A., Buson L., Corsini E.M.,
Dalla Bonta E., Stiavelli M., Bertola F.
<Astron. Astrophys. 497, 41 (2009)>
=2009A&A...497...41C 2009A&A...497...41C
ADC_Keywords: Galaxies, IR ; Galaxies, spectra
Keywords: infrared: galaxies - Galaxy: abundances -
galaxies: elliptical and lenticular, cD - galaxies: spiral -
galaxies: stellar content
Abstract:
Near-infrared (hereafter NIR) data may provide complementary
information to the traditional optical population synthesis analysis
of unresolved stellar populations because the spectral energy
distribution of the galaxies in the 1-2.5um range is dominated
by different types of stars than at optical wavelengths. Furthermore,
NIR data are less affected by dust absorption and hence could
constrain the stellar populations in dust-obscured galaxies.
We attempt to develop observational constraints on the stellar
populations of unresolved stellar systems in the NIR.
Description:
Studies of composite stellar systems (i.e. galaxies hosting an AGN)
often need to subtract the contribution of the underlying galaxy).
This prompted us to create an average spectrum of the galaxies in our
sample.
We used a homogenized subset of eight galaxies observed with SofI at
NTT, with high signal-to-noise ratio and excluding the objects with
young populations to create an average spectrum of the galaxies in our
sample. The average age of the galaxies used to create the composite
spectrum is 9±2Gyr (the median is 9.5Gyr) and the average [Fe/H] is
0.17±0.13 (the median is 0.16). The values of the spectrum are in
arbitrary units and normalized to unity at 22000Å. The regions with
zero r.m.s. values per Angstrom at the beginning and the at the and
are covered only by one or two spectra.
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table5.dat 21 9908 Average spectrum of the sample galaxies
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table5.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 5 I5 0.1nm Lambda [14944,24851] Spectrum Wavelengh
9- 13 F5.3 --- Flux Avarage spectrum in arbitrary units and
normalized to unity at 22000Å (2.2µm)
17- 21 F5.3 --- rms r.m.s. values per Angstroem
--------------------------------------------------------------------------------
Acknowledgements:
Mary Cesetti, anna.marino(at)unipd.it
(End) Mary Cesetti [ESO, Chile], Patricia Vannier [CDS] 04-Sep-2008