Melotte 166

(Collinder 325; VDBH 218; NGC 6318; MWSC 2552; OCL 1004; vdBergh-Hagen 218; ESO 333 01)

0.90 UTI

0.81

C_N

1.0

C_dens

1.0

C_C3

0.84

C_lit

1.0

C_dup

N₅₀ (P>50% members) 268

Stellar density (N₅₀/rad) 71.0 [N/pc²]

C3 classification AA

C_N 0.81 Rich
C_dens 1.0 Very dense
C_C3 1.0 Very high quality
C_lit 0.84 Well-studied
C_dup 1.0 Unique

📥 Members 📊 Colab 🔬 Bayestar19

MOCA 🔍 CDS 🔍 Simbad 🔍 CDS (α, δ) 🔍 Simbad (α, δ)

Overview

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Melotte 166 is a rich, very dense object of very high C3 quality. Its parallax locates it at a moderate distance, near the mid-plane, affected by high extinction. It is catalogued as a massive, near-solar metallicity, very young cluster, but with a large variance across recent sources for the age and mass parameters (see Parameters). It is well-studied in the literature.

Note: This object shares a very small percentage of members with 2 later reported entries. See table with shared members information.

Relatively close High extinction Massive Near-solar metallicity Very young

Almeida et al. (2025)
Mass determination: invalid due to poor quality CMD. Isochrone match: worst fit.

Cavallo et al. (2024)
Gold sample.

Data

🔍 Search references for Melotte 166 in: SciX Simbad

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Reference	Year	RA [deg]	DEC [deg]	Plx [mas]	pmRA [mas/yr]	pmDE [mas/yr]	Rv [km/s]
UCC	99999–	259.048	-39.428	0.419	-0.753	-2.468	3.534
Almeida et al.	2025	259.042	-39.424	–	–	–	–
Hunt & Reffert	2024	259.048	-39.428	0.408	-0.764	-2.465	11.417
Celli et al.	2024	259.044	-39.424	–	–	–	–
Cavallo et al.	2024	259.046	-39.427	0.409	–	–	–
Hunt & Reffert	2023	259.048	-39.428	0.408	-0.764	-2.465	11.417
Just et al.	2023	259.036	-39.417	–	–	–	–
Dias et al.	2021	259.042	-39.424	0.409	-0.754	-2.457	–
Cantat-Gaudin et al.	2020	259.044	-39.424	0.41	-0.74	-2.451	–
Cantat-Gaudin & Anders	2020	259.044	-39.424	0.41	-0.74	-2.451	–
Bica et al.	2019	259.046	-39.428	–	–	–	–
Cantat-Gaudin et al.	2018	259.044	-39.424	0.41	-0.74	-2.451	–
Kharchenko et al.	2016	259.036	-39.417	–	–	–	–
Dias et al.	2014	259.046	-39.425	–	-0.87	-0.47	–
Kharchenko et al.	2013	259.045	-39.417	–	2.52	0.42	–
van den Bergh	2006	259.494	-39.442	–	–	–	–
Dias et al.	2002	259.046	-39.425	–	-0.87	-0.47	–

💡 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]	B_frac	BSS
UCC	99999–	2.22	3.61	2.83	10	-0.117	1944	–	–
Almeida et al.	2025	2.22	3.54	–	7	–	1684	–	–
Hunt & Reffert	2024	–	–	–	–	–	6334⁽¹⁾	–	–
Celli et al.	2024	–	–	–	10	–	2205	–	–
Cavallo et al.	2024	2.29	4.23	–	10	-0.250	–	–	–
Hunt & Reffert	2023	2.21	4.25	2.83	15	–	–	–	–
Just et al.	2023	–	–	–	63	–	185	–	–
Dias et al.	2021	2.22	3.54	–	7	0.016	–	–	–
Cantat-Gaudin et al.	2020	2.22	3.46	–	10	–	–	–	–
Cantat-Gaudin & Anders	2020	2.28	–	–	–	–	–	–	–
Cantat-Gaudin et al.	2018	2.28	–	–	–	–	–	–	–
Kharchenko et al.	2016	1.84	3.61	–	63	–	–	–	–
Kharchenko et al.	2013	1.84	3.61	–	63	–	–	–	–
van den Bergh	2006	2.30	3.72	–	2	–	–	–	–
Dias et al.	2002	2.10	3.72	–	158	–	–	–	–

(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 0679	8.6	259.06	-39.42	0.46	-0.85	-2.5	-35.87	0.04
CWWDL 13632	0.7	258.65	-39.51	0.45	-0.92	-2.59	–	0.06

💡 Note: The % column shows the percentage of members that Melotte 166 shares with each listed object.

Visualization

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