Westerlund 2

0.79 UTI

0.79

C_N

1.0

C_dens

0.75

C_C3

0.7

C_lit

1.0

C_dup

N₅₀ (P>50% members) 217

Stellar density (N₅₀/rad) 122.4 [N/pc²]

C3 classification AB

C_N 0.79 Rich
C_dens 1.0 Very dense
C_C3 0.75 High quality
C_lit 0.7 Moderately studied
C_dup 1.0 Unique

📥 Members 📊 Colab 🔬 Bayestar19

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

Overview

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Westerlund 2 is a rich, very dense object of high C3 quality. Its parallax locates it at a large^* distance, near the mid-plane, affected by high extinction. It is catalogued as a massive, metal-rich, very young cluster, but with a large variance across recent sources for the age parameter (see Parameters). It is moderately studied in the literature.

(*): The parallax distance estimate (~5.09 kpc) differs significantly from the median photometric distance (~2.76 kpc).

Note: This object shares a large percentage of members with a later reported entry. See table with shared members information.

Relatively close High extinction Massive Metal-rich Very young

Palma et al. (2025)
Classified as tidal capture (resonant trapping pair) P39, along with HSC_2332.

Cavallo et al. (2024)
Silver sample.

Data

🔍 Search references for Westerlund 2 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–	156.01	-57.758	0.197	-5.32	2.871	68.86
Hunt & Reffert	2024	156.003	-57.756	0.192	-5.352	2.879	–
Celli et al.	2024	155.992	-57.764	–	–	–	–
Cavallo et al.	2024	156.008	-57.756	0.192	–	–	–
Hunt & Reffert	2023	156.003	-57.756	0.192	-5.352	2.879	–
Cantat-Gaudin et al.	2020	156.01	-57.758	0.209	-5.246	2.895	–
Cantat-Gaudin & Anders	2020	156.01	-57.758	0.209	-5.246	2.895	–
Cantat-Gaudin et al.	2018	156.01	-57.758	0.209	-5.246	2.895	–
Loktin & Popova	2017	156.015	-57.767	–	-7.5	4.22	–
Dias et al.	2014	156.008	-57.767	–	-0.89	2.45	–
Bukowiecki et al.	2011	155.996	-57.748	–	–	–	–
van den Bergh	2006	155.992	-57.764	–	–	–	–
Dias et al.	2002	156.008	-57.767	–	-6.77	4.84	–

💡 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–	2.76	4.49	3.03	17	0.760	2172	–	–
Hunt & Reffert	2024	–	–	–	–	–	2390⁽¹⁾	–	–
Celli et al.	2024	–	–	–	4	–	2172	–	–
Cavallo et al.	2024	1.86	4.46	–	174	0.760	–	–	–
Hunt & Reffert	2023	5.41	4.52	3.03	76	–	–	–	–
Cantat-Gaudin & Anders	2020	4.21	–	–	–	–	–	–	–
Cantat-Gaudin et al.	2018	4.21	–	–	–	–	–	–	–
Loktin & Popova	2017	1.92	2.32	–	21	–	–	–	–
Bukowiecki et al.	2012	–	–	–	–	–	564	–	–
Bukowiecki et al.	2011	2.67⁽¹⁾	6.20	–	7	–	–	–	–
van den Bergh	2006	1.87	2.42	–	17	–	–	–	–
Dias et al.	2002	2.85	5.12	–	2	–	–	–	–

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

Cluster	%	RA	DEC	Plx	pmRA	pmDE	Rv	UTI
Bica 417	78.8	156.01	-57.76	0.19	-5.35	2.86	–	0.03

💡 Note: The % column shows the percentage of members that Westerlund 2 shares with each listed object.

Visualization

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