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Paper
IPM / Astronomy / 16581 |
School of Astronomy
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Title: |
The Isaac Newton Telescope Monitoring Survey of Local Group Dwarf Galaxies. IV. The Star Formation History of Andromeda VII Derived from Long-period Variable Stars
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Author(s): |
| 1. |
M. Navabi
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E. Saremi
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A. Javadi
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M. Noori
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J.TH. van Loon
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H. G. Khosroshahi
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I. McDonald
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M. Alizadeh
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A. Danesh
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Gh. Gozaliasl
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A. Molaeinezhad
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T. Parto
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M. Raouf
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Status: |
Published
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Journal: |
ApJ
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No.: |
2
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Vol.: |
910
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Year: |
2021
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Supported by: |
IPM
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Abstract: |
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We have examined the star formation history (SFH) of Andromeda VII (And VII), the brightest and most massive dwarf spheroidal (dSph) satellite of the Andromeda galaxy (M 31). Although M 31 is surrounded by several dSph companions with old stellar populations and low metallicity, it has a metal-rich stellar halo with an age of 6 8 Gyr. This indicates that any evolutionary association between the stellar halo of M 31 and its dSph system is frail. Therefore, the question is whether And VII (a high-metallicity dSph located 220 kpc from M 31), can be associated with M 31's young, metal-rich halo. Here, we perform the first reconstruction of the SFH of And VII employing long-period variable (LPV) stars. As the most-evolved asymptotic giant branch (AGB) and red supergiant (RSG) stars, the birth mass of LPVs can be determined by connecting their near-infrared photometry to theoretical evolutionary tracks. We found 55 LPV candidates within two half-light radii, using multi-epoch imaging with the Isaac Newton Telescope in the and bands. Based on their birth mass function, the star-formation rate (SFR) of And VII was obtained as a function of cosmic time. The main epoch of star formation occurred    Gyr ago with a SFR of           M yr  . Over the past 6 Gyr, we find slow star formation, which continued until 500 Myr ago with a SFR              M yr  . We determined And VII's stellar mass               M within a half-light radius        arcmin and metallicity        , and also derived its distance modulus of       mag.
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