Melotte 18

(Collinder 38; NGC 1245; MWSC 264; OCL 389; FSR 0648; FoF 27)

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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) 1163
Stellar density (N50/rad) 40.6 [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¸
Melotte 18 is a very rich, very dense object of very high C3 quality. Its parallax locates it at a moderate distance, below the mid-plane, affected by low extinction. It is catalogued as a massive, near-solar metallicity, old cluster, but with a large variance across recent sources for the mass parameter (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 very small percentage of members with 3 later reported entries. See table with shared members information.

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

Cavallo et al. (2024)
Gold sample.

Data
🔍 Search references for Melotte 18 in: SciX Simbad
ℹī¸
Reference Year RA [deg] DEC [deg] Plx [mas] pmRA [mas/yr] pmDE [mas/yr] Rv [km/s]
UCC 99999– 48.694 47.23 0.299 0.474 -1.648 -29.767
Li et al. 2025 48.691 47.235 0.289 0.504 -1.579 –
Hu & Soubiran 2025 48.685 47.233 – – – –
Carrasco-Varela et al. 2025 48.967 47.261 – – – –
Almeida et al. 2025 48.684 47.236 – – – –
Zhang et al. 2024 48.711 47.235 – – – –
Hunt & Reffert 2024 48.711 47.235 0.297 0.47 -1.66 -32.844
Cavallo et al. 2024 48.685 47.233 0.297 – – –
Hunt & Reffert 2023 48.711 47.235 0.297 0.47 -1.66 -32.844
Cordoni et al. 2023 48.684 47.236 0.289 0.512 -1.568 –
Just et al. 2023 48.69 47.252 – – – –
Jaehnig et al. 2021 48.693 47.236 0.314 0.499 -1.582 –
Rain et al. 2021 48.691 47.235 0.289 0.504 -1.579 –
Dias et al. 2021 48.684 47.236 0.289 0.512 -1.568 -30.377
Cantat-Gaudin et al. 2020 48.691 47.235 0.289 0.504 -1.579 –
Donor et al. 2020 48.7 47.253 – 0.51 -1.63 -29.0
Cantat-Gaudin & Anders 2020 48.691 47.235 0.289 0.504 -1.579 –
Liu & Pang 2019 48.673 47.237 0.295 0.504 -1.544 –
Soubiran et al. 2018 48.691 47.235 – – – -29.6
Bica et al. 2019 48.691 47.231 – – – –
Cantat-Gaudin et al. 2018 48.691 47.235 0.289 0.504 -1.579 –
Loktin & Popova 2017 48.675 47.237 – -1.897 1.699 -29.5
Kharchenko et al. 2016 48.69 47.252 – – – –
Dias et al. 2014 48.675 47.237 – 1.83 -1.92 –
Kharchenko et al. 2013 48.7 47.253 – -2.06 1.66 -29.5
Gozha et al. 2012 48.675 47.237 – – – –
Kharchenko et al. 2012 48.7 47.253 – -1.93 1.74 –
van den Bergh 2006 48.675 47.25 – – – –
Chen et al. 2003 48.674 47.25 – – – –
Dias et al. 2002 48.675 47.237 – 1.83 -1.92 -29.7

💡 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– 2.92 0.82 0.36 1059 -0.001 4346 0.36 0.06
Li et al. 2025 2.88 0.81 – 1204 -0.059 – – –
Hu & Soubiran 2025 – – – – -0.100(5) – – –
Carrasco-Varela et al. 2025 2.76 0.83 – 1199 -0.100 – – 0.06(1)
Almeida et al. 2025 2.76 0.83 – 1199 – 1557 – –
Zhang et al. 2024 – – – – -0.106(1) – – –
Hunt & Reffert 2024 – – – – – 5337(1) – –
Cavallo et al. 2024 2.81 1.00 – 891 0.080 – – –
Hunt & Reffert 2023 3.38 0.55 0.36 979 – – – –
Cordoni et al. 2023 2.76 0.83 – 1199 -0.001 3356 0.36 0.03
Just et al. 2023 – – – 1059 – 6012 – –
Jaehnig et al. 2021 3.21(1) – – – – – – –
Rain et al. 2021 3.15 0.74 – 1072 – – – 5
Dias et al. 2021 2.76 0.83 – 1199 -0.001 – – –
Cantat-Gaudin et al. 2020 3.21 0.50 – 1202 – – – –
Donor et al. 2020 – – – – -0.080 – – –
Cantat-Gaudin & Anders 2020 3.15 – – – – – – –
Liu & Pang 2019 – – – 1020 0.500 – – –
Soubiran et al. 2018 3.15 – – – – – – –
Cantat-Gaudin et al. 2018 3.15 – – – – – – –
Loktin & Popova 2017 2.92 0.95 – 509 – – – –
Kharchenko et al. 2016 3.00 0.78 – 1059 – – – –
Kharchenko et al. 2013 3.00 0.78 – 1059 0.100 – – –
Gozha et al. 2012 2.80 – – 1047 0.100 – – –
Kharchenko et al. 2012 3.00 0.78 – 1059 0.100 – – –
van den Bergh 2006 2.88 0.93 – 501 – – – –
Chen et al. 2003 2.88 0.93 – 500 0.100(1) – – –
Dias et al. 2002 2.82 0.74 – 1072 -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
OC 0271 3.4 48.68 47.23 0.24 0.44 -1.66 -31.19 0.0
OC 0272 2.1 48.68 47.24 0.41 0.57 -1.67 -31.83 0.0
CWNU 1783 0.5 48.46 47.18 0.34 0.48 -0.98 -16.24 0.03

💡 Note: The % column shows the percentage of members that Melotte 18 shares with each listed object.

Visualization
ℹī¸
Melotte 18 UCC
Melotte 18 HUNT23
Melotte 18 CANTAT20
Galactocentric position diagram