IC 4756

(Melotte 210; Collinder 386; MWSC 2967; Graff 1; OCL 94; FoF 2422; OCSN 207)

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1.0 UTI
1.0
CN
1.0
Cdens
1.0
CC3
1.0
Clit
1.0
Cdup
N50 (P>50% members) 643
Stellar density (N50/rad) 37.5 [N/pc2]
C3 classification AA
  • CN 1.0 Very rich
  • Cdens 1.0 Very dense
  • CC3 1.0 Very high quality
  • Clit 1.0 Very well-studied
  • Cdup 1.0 Unique
đŸ“Ĩ Members 📊 Colab đŸ”Ŧ Bayestar19 MOCAMOCA 🔍 CDS 🔍 Simbad 🔍 CDS (Îą, δ) 🔍 Simbad (Îą, δ)

Overview
ℹī¸
IC 4756 is a very rich, very dense object of very high C3 quality. Its parallax locates it at a very close distance, above the mid-plane, affected by low extinction. It is catalogued as a massive, near-solar metallicity, intermediate-age cluster, but with a large variance across recent sources for the metallicity and mass parameters (see Parameters). It is very well-studied in the literature.

Note: This object contains blue stragglers according to at least one source.

Note: This object shares a moderate percentage of members with 3 later reported entries. See table with shared members information.

Yan et al. (2026)
Number of WDs: expected from single-star evolution N=54, with probability of formation through binary evolution >=0.5 N=1.

Liu et al. (2025)
Classified as hyperbolic encounter pair 269 along with UPK_41, and of multiple system 75 along with UPK_41 and UPK_39.

Palma et al. (2025)
Part of multiple system G257, along with UPK_41 and UPK_39.

Almeida et al. (2025)
Mass determination: intermediate fit. Isochrone match: good fit. Silver sample.

Cavallo et al. (2024)
Gold sample.

Hunt & Reffert (2024)
Classified as open cluster. CMD class: 0.99 (50th percentile).

Ahumada & Lapasset (2007)
Probabilities of membership by (1975A&AS...19..211H): Star 104=HD 172012, 67%; star 120, 93%; star 1142, 62%. Stars 5 and 58 (ref. 173) appear as stragglers but they are non-members according to the same reference. Spectra from (2002AJ....124..989G): star 104, A0III+; star 279= HD 172248, B8IV; star 280=HD 172271, kB9 A2 IIIp SiSr ((shell)). Star 104 is cited as a probable blue straggler in (1978PASP...90..157S). It is suggested in (1999AN....320...35A) that the cluster member and supergiant HD 172365 is a post-blue straggler resulting from the merger of a close binary system.

Data
🔍 Search references for IC 4756 in: SciX Simbad
ℹī¸
Reference Year RA [deg] DEC [deg] Plx [mas] pmRA [mas/yr] pmDE [mas/yr] Rv [km/s]
UCC 99999– 279.661 5.445 2.107 1.265 -4.951 -24.815
Yan et al. 2026 279.627 5.437 2.108 1.284 -4.968 –
Bijavara Seshashayana et al. 2025 279.385 5.314 – – – –
Otto et al. 2026 279.627 5.437 – 1.26 -4.93 -24.6
Liu et al. 2025 279.63 5.44 2.11 1.28 -4.97 -24.88
Nizovkina et al. 2025 279.627 5.437 – – – –
Li et al. 2025 279.649 5.435 2.093 1.26 -4.927 –
Hu & Soubiran 2025 279.658 5.417 – – – –
Wei et al. 2025 279.698 5.46 2.113 1.267 -4.941 –
Almeida et al. 2025 279.633 5.42 – – – –
Alfonso et al. 2024 279.649 5.43 2.074 1.263 -4.96 –
Zhang et al. 2024 279.627 5.437 – – – –
Hunt & Reffert 2024 279.627 5.437 2.108 1.284 -4.968 -24.879
Cavallo et al. 2024 279.658 5.417 2.107 – – –
Hunt & Reffert 2023 279.627 5.437 2.108 1.284 -4.968 -24.879
Qin et al. 2023 279.67 5.43 2.1 1.27 -4.97 -24.96
Just et al. 2023 279.728 5.449 – – – –
He et al. 2022 279.66 5.435 2.109 1.278 -4.95 –
Tarricq et al. 2022 279.634 5.477 2.097 1.233 -4.954 –
Jadhav & Subramaniam 2021 279.649 5.435 – – – –
Jaehnig et al. 2021 279.646 5.427 2.126 1.257 -4.901 –
Rain et al. 2021 279.649 5.435 2.093 1.26 -4.927 –
Dias et al. 2021 279.633 5.42 2.096 1.268 -4.907 -24.563
Cantat-Gaudin et al. 2020 279.649 5.435 2.093 1.26 -4.927 –
Zhong et al. 2020 279.649 5.435 – 1.26 -4.927 -32.244
Cantat-Gaudin & Anders 2020 279.649 5.435 2.093 1.26 -4.927 –
Liu & Pang 2019 279.673 5.417 2.094 1.285 -4.899 –
Bossini et al. 2019 279.649 5.435 – – – –
Soubiran et al. 2018 279.649 5.435 – – – -24.74
Bica et al. 2019 279.626 5.422 – – – –
Cantat-Gaudin et al. 2018 279.649 5.435 2.093 1.26 -4.927 –
Loktin & Popova 2017 279.75 5.45 – -0.14 -3.4 -22.4
Kharchenko et al. 2016 279.728 5.449 – – – –
Dias et al. 2014 279.75 5.45 – -0.6 -1.69 –
Kharchenko et al. 2013 279.735 5.45 – -1.15 -3.88 -22.4
Gozha et al. 2012 279.75 5.45 – – – –
Piskunov et al. 2008 279.729 5.449 – – – –
Kharchenko et al. 2007 279.75 5.45 – 1.0 – -22.45
Piskunov et al. 2007 279.729 5.449 – – – –
Ahumada & Lapasset 2007 279.75 5.45 – – – –
van den Bergh 2006 279.63 5.49 – – – –
Kharchenko et al. 2005 279.73 5.45 – -1.11 -3.86 -22.45
Kharchenko et al. 2003 279.66 5.46 – -0.42 -3.03 –
Chen et al. 2003 279.729 5.471 – 1.06 -4.32 -25.8
Dias et al. 2002 279.75 5.45 – -0.14 -3.4 -25.8
Lynga 1987 279.729 5.448 – – – -18.0

💡 Note: The UCC values are estimated from its identified members.

Reference Year Dist [kpc] Av [mag] DAv [mag] Age [Myr] [Fe/H] [dex] Mass [Msun] Bfrac BSS
UCC 99999– 0.48 0.6 0.64 838 -0.010 1122 0.42 1
Yan et al. 2026 – – – 1288 – – – –
Bijavara Seshashayana et al. 2025 – 0.29 – 1290 -0.050(14) – – –
Otto et al. 2026 – – – 1288 0.050(15) – – –
Liu et al. 2025 0.86 0.36 – 479 – – – –
Nizovkina et al. 2025 0.45(4) 0.95(4) – 589(4) -0.170(4) – – –
Li et al. 2025 0.47 0.60 – 1076 -0.048 – – –
Hu & Soubiran 2025 – – – – -0.220(5) – – –
Wei et al. 2025 0.50 0.28 – 891 0.500 842 0.42 –
Almeida et al. 2025 0.47 0.63 – 975 – 705 – –
Alfonso et al. 2024 0.51 0.29 – 1350 0.009 – – –
Zhang et al. 2024 – – – – 0.089(1) – – –
Hunt & Reffert 2024 – – – – – 994(1) – –
Cavallo et al. 2024 0.47 0.89 – 646 -0.010 – – –
Hunt & Reffert 2023 0.45 0.36 0.64 838 – – – –
Qin et al. 2023 0.60 0.60 – 891 – – – –
Just et al. 2023 – – – 617 – 269 – –
He et al. 2022 – 0.60 – 891 – – – –
Spina et al. 2022 – – – – -0.031 – – –
Tarricq et al. 2022 0.50 – – 1318 – – – –
Jadhav & Subramaniam 2021 0.51 0.29 – 1288 – 1352 – 1(1)
Jaehnig et al. 2021 0.47(1) – – – – – – –
Rain et al. 2021 0.47 0.60 – 490 – – – 0
Dias et al. 2021 0.47 0.63 – 975 0.006 – – –
Cantat-Gaudin et al. 2020 0.51 0.29 – 1288 – – – –
Kounkel et al. 2020 0.49 0.57 – 871 – – – –
Zhong et al. 2020 0.47(1) 0.40 – 8987 -0.160 – – –
Cantat-Gaudin & Anders 2020 0.47 – – – – – – –
Liu & Pang 2019 – – – 891 0.000 – – –
Bossini et al. 2019 0.48 0.40 – 971 0.000 – – –
Soubiran et al. 2018 0.47 – – – – – – –
Cantat-Gaudin et al. 2018 0.47 – – – – – – –
Loktin & Popova 2017 0.48 0.61 – 501 – – – –
Kharchenko et al. 2016 0.48 0.66 – 617 – – – –
Kharchenko et al. 2013 0.48 0.66 – 617 -0.150 – – –
Gozha et al. 2012 0.48 – – 500 -0.150 1288 – –
Piskunov et al. 2008 0.48 0.60 – 617 – 2679(1) – –
Piskunov et al. 2007 0.48 0.60 – 617 – 1250 – –
Ahumada & Lapasset 2007 – 0.60 – 501 – – – 6
van den Bergh 2006 0.48 0.60 – 501 – – – –
Kharchenko et al. 2005 0.48 0.60 – 617 – – – –
Kharchenko et al. 2003 0.33 0.60 – – – – – –
Chen et al. 2003 0.48 0.61 – 500 -0.060(1) – – –
Dias et al. 2002 0.48 0.61 – 500 -0.010 – – –
Lynga 1987 0.40 0.66 – 575 0.040 – – –

(N): Indicates that there are N extra values assigned to this parameter in the corresponding reference.

Cluster % RA DEC Plx pmRA pmDE Rv UTI
LISC-III 3449 26.0 279.69 5.56 2.1 1.1 -4.88 -25.01 0.02
OC 0066 6.2 279.46 5.25 2.13 1.22 -4.99 -25.29 0.0
CWNU 1168 0.3 277.75 4.9 2.3 0.77 -5.33 -25.72 0.11

💡 Note: The % column shows the percentage of members that IC 4756 shares with each listed object.

Visualization
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IC 4756 UCC
IC 4756 HUNT23
IC 4756 CANTAT20
Galactocentric position diagram