J/A+A/704/A322 Low metallicity evolutionary synt. mod. (Millan-Irigoyen+, 2025)
HR-pyPopStar II. High spectral resolution evolutionary synthesis models low
metallicity expansion, and the properties of the stellar populations of
dwarf galaxies.
Millan-Irigoyen I., Molla M., Cervino M., Garcia-Vargas M.L.
<Astron. Astrophys. 704, A322 (2025)>
=2025A&A...704A.322M 2025A&A...704A.322M (SIMBAD/NED BibCode)
ADC_Keywords: Models, atmosphere ; Galaxies ; Associations, stellar ;
Energy distributions
Keywords: stars: atmospheres - stars: evolution - galaxies: evolution -
galaxies: stars clusters - galaxies: stellar content
Abstract:
Low metallicity stellar populations are very abundant in the Universe,
either as the remnants of the past history of the Milky Way or similar
spiral galaxies, or the young low metallicity stellar populations that
are being observed in the local dwarf galaxies or in the high-z
objects with low metal content recently found with JWST.
Our goal is to develop new high-spectral-resolution models tailored
for low-metallicity environments and apply them to analyze stellar
population data, particularly in cases where a significant portion of
the stellar content exhibits low metallicity.
We used the state-of-the-art stellar population synthesis code
HR-pyPopStar with available stellar libraries to create a new set of
models focused on low metallicity stellar populations.
We have compared the new spectral energy distributions with the
previous models of HR-pyPopStar for solar metallicity. Once we
verified that the spectra, except for the oldest ages that show some
differences in the molecular bands of the TiO and G band, are similar,
we reanalyzed the high resolution data from the globular cluster M 15
by finding a better estimate of its age and metallicity. Finally, we
analyzed a subsample of mostly star-forming dwarf galaxies from the
MaNGA survey we found similar stellar mass-mean stellar metallicity
weighted by light to other studies that studied star forming dwarf
galaxies and slightly higher mean stellar metallicity than the other
works that analysed all types of dwarf galaxies at the same time, but
are within error bars.
Description:
We have made a new set of HR-PYPOPSTAR models with a wider range of
metallicities, basically reaching lower metallicities than in our
first version of the models.
We also computed some magnitudes in bands that are within our
wavelength range: U, B, V, and R in the Johnson system and u, g, r, i,
and z in the SDSS system. In Table 4 we give these magnitudes for all
ages, metallicities, and IMFs.
Table 5 contains the properties of the stellar populations of the
sample obtained by FADO using the new SSP models.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table4.dat 240 1908 Magnitudes in broad-band filters of the SSPs
models
table5.dat 79 31 Properties of the stellar populations of the
sample obtained by FADO using the new SSP models
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See also:
J/MNRAS/506/4781 : HR-PYPOPSTAR model (Millan-irigoyen+, 2021)
Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
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1- 3 A3 --- IMF IMF: CHA, KRO, FER or SAL (G1)
5- 10 F6.4 --- Z Metallicity: 0.0001,0.0004,0.004,0.008,0.02,0.05
12- 16 F5.2 [yr] logtau Logarithm of the age in yr
18- 39 F22.19 mag Umag Magnitude in Johnson-Cousins band U
41- 63 F23.20 mag Bmag Magnitude in Johnson-Cousins band B
65- 86 F22.19 mag Vmag Magnitude in Johnson-Cousins band V
88-109 F22.19 mag Rmag Magnitude in Johnson-Cousins band R
111-131 F21.18 mag Imag Magnitude in Johnson-Cousins band I
133-154 F22.19 mag umag Magnitude in SDSS-SLOAN band u
156-176 F21.18 mag gmag Magnitude in SDSS-SLOAN band g
178-197 F20.17 mag rmag Magnitude in SDSS-SLOAN band r
199-219 F21.18 mag imag Magnitude in SDSS-SLOAN band i
221-240 F20.17 mag zmag Magnitude in SDSS-SLOAN band z
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Byte-by-byte Description of file: table5.dat
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Bytes Format Units Label Explanations
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1- 11 A11 --- PlateId Plate Id from MaNGA
13- 21 F9.7 [Msun] logMstar Log10 of the current stellar mass
of the galaxy
23- 29 F7.5 [yr] meanlogAgeM Mean of the log10 of the age weighted
by light
31- 37 F7.5 [yr] meanlogAgeL Mean of the log10 of the age weighted
by mass
39- 58 F20.17 [Sun] logmeanZL Log10 of the mean of the metallicity
weighted by light
60- 79 F20.17 [Sun] logmeanZM Log10 of the mean of the metallicity
weighted by light
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Global notes:
Note (G1): IMF as follows:
SAL = Salpeter (1955ApJ...121..161S 1955ApJ...121..161S)
FER = Ferrini, Penco & Palla (1990A&A...231..391F 1990A&A...231..391F)
KRO = Kroupa (2002Sci...295...82K 2002Sci...295...82K) with exponent -2.7 for the massive
star range
CHA = Chabrier (2003ApJ...586L.133C 2003ApJ...586L.133C)
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Acknowledgements:
Iker Millan-Irigoyen, millaniker(at)gmail.com
References:
Millan-Irigoyen et al., Paper I 2021MNRAS.506.4781M 2021MNRAS.506.4781M, Cat. J/MNRAS/506/4781
(End) Patricia Vannier [CDS] 30-Sep-2025