J/A+A/703/A113 Euclid obs. of extragalactic star clusters (Larsen+, 2025)
Euclid: Star clusters in IC 342, NGC 2403, and Holmberg II.
Larsen S.S., Ferguson A.M.N., Howell J.M., Annibali F., Cuillandre J.-C.,
Hunt L.K., Lancon A., Saifollahi T., Massari D., Le M.N., Aghanim N.,
Altieri B., Amara A., Andreon S., Auricchio N., Baccigalupi C., Baldi M.,
Balestra A., Bardelli S., Battaglia P., Biviano A., Branchini E.,
Brescia M., Brinchmann J., Camera S., Capobianco V., Carbone C.,
Carretero J., Casas S., Castellano M., Castignani G., Cavuoti S.,
Chambers K.C., Cimatti A., Colodro-Conde C., Congedo G., Conselice C.J.,
Conversi L., Copin Y., Courbin F., Courtois H.M., Cropper M., Da Silva A.,
Degaudenzi H., De Lucia G., Dole H., Douspis M., Dubath F., Dupac X.,
Dusini S., Escoffier S., Fabricius M., Farina M., Faustini F., Ferriol S.,
Fotopoulou S., Frailis M., Franceschi E., Galeotta S., George K., Gillis B.,
Giocoli C., Gomez-Alvarez P., Gracia-Carpio J., Grazian A., Grupp F.,
Haugan S.V.H., Hoekstra H., Holmes W., Hormuth F., Hornstrup A., Jahnke K.,
Jhabvala M., Keihaenen E., Kermiche S., Kiessling A., Kohley R., Kubik B.,
Kuijken K., Kuemmel M., Kunz M., Kurki-Suonio H., Le Brun A.M.C., Ligori S.,
Lilje P.B., Lindholm V., Lloro I., Maino D., Maiorano E., Mansutti O.,
Marggraf O., Markovic K., Martinelli M., Martinet N., Marulli F., Massey R.,
Medinaceli E., Mei S., Mellier Y., Meneghetti M., Meylan G., Mora A.,
Moresco M., Moscardini L., Neissner C., Niemi S.-M., Padilla C., Paltani S.,
Pasian F., Pedersen K., Percival W.J., Pettorino V., Pires S., Polenta G.,
Poncet M., Popa L.A., Pozzetti L., Raison F., Renzi A., Rhodes J.,
Riccio G., Romelli E., Roncarelli M., Saglia R., Sakr Z., Sapone D.,
Sartoris B., Schewtschenko J.A., Schirmer M., Schneider P., Secroun A.,
Seidel G., Seiffert M., Serrano S., Simon P., Sirignano C., Sirri G.,
Skottfelt J., Stanco L., Steinwagner J., Tallada-Crespi P., Taylor A.N.,
Tereno I., Toledo-Moreo R., Torradeflot F., Tsyganov A., Tutusaus I.,
Valenziano L., Valiviita J., Vassallo T., Verdoes Kleijn G., Veropalumbo A.,
Wang Y., Weller J., Zamorani G., Zerbi F.M., Zucca E., Martin-Fleitas J.,
Scottez V.
<Astron. Astrophys. 703, A113 (2025)>
=2025A&A...703A.113L 2025A&A...703A.113L (SIMBAD/NED BibCode)
ADC_Keywords: Galaxies, nearby ; Clusters, globular ; Photometry, infrared ;
Optical
Keywords: galaxies: individual: IC 342 - galaxies: individual: NGC 2403 -
galaxies: individual: Holmberg II - galaxies: spiral -
galaxies: star clusters: general
Abstract:
We examine the star cluster populations in the three nearby
(3.20-3.45Mpc) galaxies IC 342, NGC 2403, and Holmberg II, observed as
part of the Euclid Early Release Observations programme. Our main
focus in this paper is on old globular clusters (GCs), for which the
wide field-of-view and excellent image quality of Euclid offer
substantial advantages over previous work. For IC 342, in particular,
this is the first study of stellar clusters other than its nuclear
cluster. After selection based on size and magnitude criteria,
followed by visual inspection, we identify 111 old (>1Gyr) GC
candidates in IC 342, 49 in NGC 2403 (of which 15 were previously
known), and 7 in Holmberg II. In addition, a number of younger and/or
intermediate-age candidates are identified. The colour distributions
of GC candidates in the two larger galaxies show hints of bimodality
with peaks at (IE-HE)=0.36 and 0.79 in both IC 342 and NGC 2403,
corresponding to metallicities of [Fe/H]=-1.5 and [Fe/H]=-0.5, similar
to those found for the metal-poor and metal-rich GC subpopulations in
the Milky Way. The luminosity functions of our GC candidates exhibit
an excess of relatively faint objects, relative to a canonical,
approximately Gaussian GC luminosity function (GCLF). Although some
contamination from background galaxies and younger clusters may be
present in our GC samples, we argue that the excess may be partly
real, particularly in IC 342 where the excess objects may be similar
to those previously identified in galaxies such as M101 and NGC 6946.
The specific frequency of classical old GCs in IC 342, as determined
based on the brighter half of the GCLF, appears to be unusually low
with SN = 0.2-0.3. The combined luminosity function of young and
intermediate-age clusters in all three galaxies is consistent with a
power-law distribution, dN/dL proportional to L(-2.3±0.1).
Description:
We present our analysis of the star cluster populations in three
nearby galaxies, IC 342, NGC 2403, and Holmberg II, observed as part
of the Euclid Early Release Observations programme. The table contains
the lists of cluster candidates, including photometry, size
measurements, and classification.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tablea1.dat 162 797 Catalogue of cluster candidates
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Byte-by-byte Description of file: tablea1.dat
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Bytes Format Units Label Explanations
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1- 16 A16 --- ID Cluster ID (ESCC-IC342-NNN, ESCC-NGC2403-NNN
or ESCC-HoII-NNN)
18- 23 I6 --- MasterID ID in master catalogue
25- 30 A6 --- OtherID Other ID (1)
32- 42 F11.7 deg RAdeg Right ascension (J2000)
44- 54 F11.7 deg DEdeg Declination (J2000)
56- 60 F5.2 mag IEmag Euclid IE (550-900nm) magnitude
62- 66 F5.2 mag e_IEmag Uncertainty on Euclid IE magnitude
68- 72 F5.2 mag YEmag Euclid YE (10866.24Å) magnitude
74- 78 F5.2 mag e_YEmag Uncertainty on Euclid YE magnitude
80- 84 F5.2 mag JEmag Euclid JE (13766.64Å) magnitude
86- 90 F5.2 mag e_JEmag Uncertainty on Euclid JE magnitude
92- 96 F5.2 mag HEmag Euclid HE (17825.15Å) magnitude
98-102 F5.2 mag e_HEmag Uncertainty on Euclid HE magnitude
104-108 F5.2 mag umag ?=99.99 u magnitude
110-114 F5.2 mag e_umag ?=99.99 Uncertainty on u magnitude
116-120 F5.2 mag gmag ?=99.99 g magnitude
122-126 F5.2 mag e_gmag ?=99.99 Uncertainty on g magnitude
128-132 F5.2 mag rmag ?=99.99 r magnitude
134-138 F5.2 mag e_rmag ?=99.99 Uncertainty on r magnitude
140-145 F6.2 pix FWHM ?=-99 PSF-corrected FWHM in Euclid VIS
pixels (2)
147-153 F7.2 --- B/A ?=-99 Minor/major axis ratio (2)
156-157 I2 --- Class [1/10] Visual classification (3)
160-162 A3 --- Age Age group (4)
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Note (1): Other IDs as follows:
ESCC* = Sources from Hunt et al., 2025A&A...697A...9H 2025A&A...697A...9H
D* = Sources from Davidge, 2007ApJ...664..820D 2007ApJ...664..820D,
D6 = [D2007] J073505.9+654527.5 in Simbad
F* = Sources from Battistini et al., 1984A&A...130..162B 1984A&A...130..162B,
[BBF84] FNN in Simbad
C* = Sources from Tammann & Sandage, 1968ApJ...151..825T 1968ApJ...151..825T,
TS CN in Simbad
DRI* = Sources from Drissen et al., 1999AJ....117.1249D 1999AJ....117.1249D,
[DRM99] 5-NN in Simbad
JC15, JD1 = Sources from Forbes et al. 2022MNRAS.512..802F 2022MNRAS.512..802F
L* = Sources from LEGUS, Cook et al., 2019MNRAS.484.4897C 2019MNRAS.484.4897C
A* = Sources from ANGST, Cook et al., 2012ApJ...751..100C 2012ApJ...751..100C
B* = Sources from Billet et al., 2002AJ....123.1454B 2002AJ....123.1454B,
[BHE2002] DDO 50 N in Simbad
Note (2): A value of -99.00 indicates that no measurement could be made.
Note (3): A numerical value indicating the outcome of visual classification by
three authors (AMNF, JH, SSL) as follows::
1 = Source classified as Likely cluster by all
2 = Source with 2 Likely and 1 Maybe classification
3 = Source with 1 Likely classification
4 = Source classified as Maybe by all
10 = Source with at least one Young classification
Note (4): Rough indication of likely age as follows:
YC = young cluster, from morphology (less than about 10Myr)
IAC = intermediate-age cluster, from ugr colours (about 10Myr-1Gyr)
GCC = old globular cluster candidate, from ugr colours (about 1-14Gyr)
NC = objects with missing/ambiguous colours
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Acknowledgements:
Soeren Larsen, s.larsen(at)astro.ru.nl
(End) Soeren Larsen [Radboud University], Patricia Vannier [CDS] 12-Aug-2025