J/A+A/709/A10 Magellanic Bridge photometric catalogue - STEP (Ficara+, 2026)
STEP survey. III. STEPping stones between the clouds:
the star formation history of the Magellanic Bridge.
Ficara F., Ripepi V., Cignoni M., Gatto M., Marconi M., Tosi M.,
Bellazzini M, Grebel E. K., Cioni M.-R., Tortora C., Mercurio A.
<Astron. Astrophys. 709, A10 (2026)>
=2026A&A...709A..10F 2026A&A...709A..10F (SIMBAD/NED BibCode)
ADC_Keywords: Magellanic Clouds ; Surveys ; Photometry ; Optical
Keywords: Hertzsprung-Russell and C-M diagrams - galaxies: dwarf -
galaxies: interactions - galaxies: irregular - Magellanic Clouds -
galaxies: star formation
Abstract:
The Magellanic Clouds (MCs) offer a unique laboratory for studying
galaxy interaction and the evolution of dwarf galaxies. The star
formation history (SFH), which traces when and how stars formed,
provides powerful constraints for the dynamical modelling of the
system's past interactions and the processes of stripping and
triggered star formation in tidally influenced environments. We aim to
reconstruct the SFH of the Magellanic Bridge, the gaseous and stellar
stream connecting the Magellanic Clouds. We used data from the deep
optical STEP survey, which covers 54deg2 across the Small Magellanic
Cloud (SMC) and the Bridge, reaching stars below the oldest
main-sequence turnoff at the distance of the MCs. We applied the
synthetic colour-magnitude diagram technique to 14deg2 of STEP data.
We constructed two libraries of synthetic stellar populations based on
the PARSEC-COLIBRI and BaSTI stellar evolutionary models, with
metallicities in the range -2.0≤[Fe/H]≤0 across the whole Hubble
time. We find a clear peak of recent star formation ∼100Myr ago in the
Magellanic Bridge, which becomes increasingly pronounced towards the
SMC. The low metallicity of this population suggests that it formed
from gas stripped from the SMC during its most recent close encounter
with the LMC. In the eastern part of the Bridge (LMC side), star
formation peaks at earlier times, around 10Gyr and 2Gyr ago. We
estimate a total stellar mass in the Bridge of
(5.1±0.2)x105M☉ and a present-day stellar metallicity of
[$Fe/H]~-0.6dex, close to SMC value.
Description:
The data used in this work were obtained with the VLT Survey Telescope
(VST) in the context of the STEP (Small Magellanic Cloud in Time:
Evolution of a Prototype interacting late-type dwarf galaxy) survey.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 91 538813 Magellanic Bridge photometric catalogue
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Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 24 A24 --- Id Source ID, STEP-JHHMMSS.ss+DDMMSS.s
26- 33 F8.5 deg RAdeg Right ascension (J2000.0)
35- 43 F9.5 deg DEdeg Declination (J2000.0)
45- 51 F7.4 mag gmag Calibrated magnitude in the g-filter
53- 60 F8.4 mag e_gmag ?=99 Uncertainty of the magnitude in the g-filter
62- 69 F8.4 mag imag Calibrated magnitude in the i-filter
71- 78 F8.4 mag e_imag ?=99 Uncertainty of the magnitude in the i-filter
80- 84 F5.2 --- chi CHI output parameter of DAOPHOTIV/ALLSTAR
86- 91 F6.3 --- sharp SHARP output parameter of DAOPHOTIV/ALLSTAR
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Acknowledgements:
Francesco Ficara, francesco.ficara(at)inaf.it
License: CC-BY-4.0 [see https://spdx.org/licenses/]
(End) Patricia Vannier [CDS] 31-Mar-2026