2025AJ....169..278C


Query : 2025AJ....169..278C

2025AJ....169..278C - Astron. J., 169, 278 (2025/May-0)

The Local Ultraviolet to Infrared Treasury. II. Refining Star Formation Histories of 10 Metal-poor Dwarf Galaxies with Simultaneous UV-optical Two-CMD Fitting.

CHOI Y., GILBERT K.M., WILLIAMS B.F., WEISZ D.R., SKILLMAN E.D., DALCANTON J.J., McQUINN K.B.W., DOLPHIN A.E., PASTORELLI G., BOYER M.L., GORDON K.D., GIRARDI L. and GULL M.

Abstract (from CDS):

We present the star formation histories (SFHs) of 10 metal-poor (≲12% Z⊙), star-forming dwarf galaxies from the Local Ultraviolet to Infrared Treasury survey. The derived SFHs exhibit significant variability, consistent with the irregular star formation expected for dwarf galaxies. Using synthetic near-ultraviolet (UV) and optical color-magnitude diagrams (CMDs) with various yet targeted configurations for dust and input SFHs, we quantitatively demonstrate that simultaneous modeling of the UV and optical CMDs (“UVopt” case) improves the precision of SFH measurements in recent time bins up to ∼1 Gyr, compared to the classical single optical CMD modeling (“Opt-only” case). The UVopt case reduces uncertainties relative to the Opt-only case by ∼4%-8% over the past 10 Myr, ∼8%-20% over 100 Myr, and ∼8%-14% over 1 Gyr, across various dust configurations and input SFHs. Additionally, we demonstrate discrepancies in stellar models for blue core helium-burning (BHeB) stars at the low-metallicity regime. This discrepancy can artificially inflate star formation rate (SFR) estimates in younger age bins by misinterpreting the evolved BHeB stars as reddened upper main-sequence (MS) stars. Incorporating UV data improves BHeB-MS separation and mitigates the limitations of current low-metallicity stellar models. Comparisons of the UVopt SFHs with Hα and far-UV (FUV)-based SFRs reconfirm that Hα is an unreliable tracer over its nominal 10 Myr timescale for low-SFR galaxies, while FUV provides a more reliable tracer but yields SFRFUV values up to twice those of CMD-based 〈SFR〉_100 Myr_. Our findings underscore the importance of UV data in refining recent SFHs in low-metallicity environments.

Abstract Copyright: © 2025. The Author(s). Published by the American Astronomical Society.

Journal keyword(s): Stellar populations - Dwarf irregular galaxies - Star formation - Hertzsprung Russell diagram - Multi-color photometry

Simbad objects: 15

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Number of rows : 15
N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2026
#notes
1 M 31 AGN 00 42 44.330 +41 16 07.50 4.86 4.36 3.44     ~ 13622 1
2 MCG-04-03-019 G 00 49 49.3 -21 00 58 16.11 15.64 15.36 14.8 15.5 ~ 144 1
3 NAME SMC G 00 52 38.0 -72 48 01   2.79 2.2     ~ 12317 1
4 M 33 GiG 01 33 50.8965749232 +30 39 36.630403128 6.17 6.27 5.72     ~ 6226 1
5 NAME LMC G 05 23 34.6 -69 45 22     0.4     ~ 19090 0
6 Z 153-10 G 09 59 26.46 +30 44 47.0 14.08 13.54 13.26 13.33   ~ 652 0
7 MCG-01-26-030 H2G 10 11 00.5 -04 41 30 12.48 12.13 11.93 11.78   ~ 789 2
8 NGC 3741 AG? 11 36 05.754 +45 17 02.96 15.01 14.55 14.23 14.06   ~ 237 0
9 NGC 4163 LSB 12 12 09.34 +36 10 08.1 14.33 13.70 13.2 12.98   ~ 238 0
10 NAME CVn I dwA GiC 12 38 40.06 +32 46 00.5 16.91 16.66 16.73 16.62   ~ 242 0
11 Z 71-87 H2G 12 58 40.1930636208 +14 13 00.739589628 15.24 15.16 14.98 14.81   ~ 475 0
12 Z 271-48 EmG 13 30 44.8682655624 +54 54 38.522749824 14.72 14.25 13.90 13.75   ~ 218 0
13 Z 247-26 AG? 14 24 43.21 +44 31 41.8 14.24 13.54 13.17 13.07   ~ 217 0
14 NAME Sgr dIG G 19 29 59.0 -17 40 41   15.5 13.6     ~ 323 1
15 MCG-02-53-003 G 20 46 51.7 -12 50 54 15.75 15.18 14.83 14.46   ~ 470 1

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