2025ApJ...992..106D

Query : 2025ApJ...992..106D

2025ApJ...992..106D - Astrophys. J., 992, 106 (2025/October-2)

The HST Legacy Archival Uniform Reduction of Local Group Imaging (LAURELIN). I. Photometry and Star Formation Histories for 36 Ultra-faint Dwarf Galaxies.

DURBIN M.J., CHOI Y., SAVINO A., WEISZ D.R., DOLPHIN A.E., DALCANTON J.J., JEON M., KALLIVAYALIL N., LI T.S., PACE A.B., PATEL E., SACCHI E., SKILLMAN E.D., SOHN S.T., VAN DER MAREL R.P., WETZEL A. and WILLIAMS B.F.

Abstract (from CDS):

We present uniformly measured resolved stellar photometry and star formation histories (SFHs) for 36 nearby (≲400 kpc) ultra-faint dwarf galaxies (UFDs; -7.1 ≤ MV ≤ +0.0) from new and archival Hubble Space Telescope (HST) imaging. We measure homogeneous distances to all systems via isochrone fitting and find good agreement (≤2%) for the 18 UFDs that have literature RR Lyrae distances. From the ensemble of SFHs, we find (i) an average quenching time (here defined as the lookback time by which 80% of the stellar mass formed, τ80) of 12.48 ± 0.18 Gyr ago ($z=4.{6}_{-0.5}^{+0.6}$), which is compatible with reionization-based quenching scenarios; and (ii) modest evidence of a delay (≲800 Myr) in quenching times of UFDs thought to be satellites of the LMC or on their first infall, relative to long-term Galactic satellites, which is consistent with previous findings. We show that robust SFH measurement via the ancient main-sequence turnoff (MSTO) requires a minimum effective luminosity (i.e., luminosity within the observed field of view) of MV ≤ -2.5, which corresponds to ∼100 stars around the MSTO. We also find that increasing the signal-to-noise ratio above ∼100 at the MSTO does not improve SFH precision, which remains dominated by stochastic effects associated with the number of available stars. A main challenge driving the precision of UFD SFHs is the limitations in the accuracy of foreground dust maps. We make all photometry catalogs public as the first data release of a larger HST archival program targeting all dwarf galaxies within ∼1.3 Mpc.

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

Journal keyword(s): Dwarf galaxies - Galaxy evolution - Galaxy stellar content - Local Group - Reionization - Star formation

Status at CDS : Large table(s) will be appraised for possible ingestion in VizieR.

Simbad objects: 46

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Number of rows : 46
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 NAME Tuc IV G 00 02.9 -60 51           ~ 90 0
2 M 31 AGN 00 42 44.330 +41 16 07.50 4.86 4.36 3.44     ~ 13622 1
3 NAME SMC G 00 52 38.0 -72 48 01   2.79 2.2     ~ 12317 1
4 NAME Cetus II G 01 17.9 -17 25           ~ 56 0
5 NAME Tri II G 02 13 17.40 +36 10 42.4           ~ 164 0
6 NAME Segue 2 G 02 19 16.0 +20 10 31     15.2     ~ 299 0
7 NAME Eri III G 02 22 45.480 -52 17 04.92           ~ 79 0
8 NAME Hydrus I G 02 29 33.4 -79 18 32           ~ 80 0
9 NAME Hor I G 02 55 31.7 -54 07 08           ~ 169 0
10 NAME Horologium II G 03 16 32.1 -50 01 05           ~ 76 0
11 NAME Reticulum II G 03 35 42.1 -54 02 57           ~ 375 0
12 NAME Eridanus II G 03 44 21.1 -43 32 00           ~ 216 0
13 NAME Reticulum III G 03 45.4 -60 27           ~ 67 0
14 NAME Pic I G 04 43 47.4 -50 16 59           ~ 58 0
15 NAME LMC G 05 23 34.6 -69 45 22     0.4     ~ 19090 0
16 NAME Col I G 05 31.4 -28 02           ~ 60 0
17 NAME Carina II Dwarf Galaxy G 07 36 25.6 -57 59 57           ~ 86 0
18 NAME UMa II Galaxy G 08 51 30.0 +63 07 48     13.3     ~ 410 0
19 NAME Segue 1 G 10 07 03.2 +16 04 25     15.3     ~ 517 1
20 NAME UMa I Galaxy G 10 34 52.80 +51 55 12.0     14.4     ~ 355 1
21 NAME Carina I HII Region HII 10 43 32 -59 35.0           ~ 59 0
22 NAME Willman 1 G 10 49 21.0 +51 03 00     15.2     ~ 345 0
23 NAME Leo V LSB 11 31 09.60 +02 13 12.0     16.0     ~ 234 0
24 NAME Leo IV LSB 11 32 57.0 -00 32 00     15.1     ~ 419 1
25 NAME Vir I Dwarf Galaxy LSB 12 00 09.6 -00 40 48           ~ 40 0
26 NAME Hydra II G 12 21 42.1 -31 59 07           ~ 118 0
27 NAME Coma Dwarf Galaxy G 12 26 59.0 +23 54 15     14.1     ~ 482 1
28 NAME CVn II dSph G 12 57 09.6 +34 19 12     16.1     ~ 287 2
29 NAME Bootes II G 13 58 00.0 +12 51 00     15.4     ~ 269 0
30 NAME Bootes Dwarf Spheroidal Galaxy G 14 00 00.0 +14 30 00     12.8     ~ 491 0
31 NAME Draco II Gl? 15 52 47.6 +64 33 55           ~ 138 0
32 NAME Hercules Dwarf Galaxy G 16 31 02.0 +12 47 30     14.0     ~ 379 1
33 M 92 GlC 17 17 07.39 +43 08 09.4     6.52     ~ 2240 0
34 NAME Orphan Stream St* 19 09 -23.           ~ 281 0
35 NAME Sagittarius II Gl? 19 52 40.5 -22 04 05           ~ 97 0
36 NAME Chenab Stream St* 21 17 -59.9           ~ 45 0
37 NAME Gru II G 22 04.1 -46 26           ~ 110 0
38 NAME Pegasus III LSB 22 24 22.6 +05 25 12           ~ 69 0
39 NAME Tuc II G 22 51 55.1 -58 34 08           ~ 192 0
40 NAME Grus I G 22 56 42.4 -50 09 48           ~ 126 0
41 NAME Pisces II G 22 58 31.0 +05 57 09     16.3     ~ 283 0
42 NAME Tuc V G 23 37.4 -63 16           ~ 84 0
43 NAME Phe II G 23 39 59.4 -54 24 22           ~ 107 0
44 NAME Tuc III G 23 56.6 -59 36           ~ 229 0
45 NAME MW Group GrG ~ ~           ~ 22 0
46 NAME Local Group GrG ~ ~           ~ 9325 0

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