Trumpler 21

(Collinder 274; VDBH 148; MWSC 2131; OCL 903; vdBergh-Hagen 148; ESO 096 15; FoF 2099)

0.90 UTI

0.76

C_N

1.0

C_dens

0.75

C_C3

1.0

C_lit

1.0

C_dup

N₅₀ (P>50% members) 131

Stellar density (N₅₀/rad) 64.8 [N/pc²]

C3 classification AB

C_N 0.76 Rich
C_dens 1.0 Very dense
C_C3 0.75 High quality
C_lit 1.0 Very well-studied
C_dup 1.0 Unique

📥 Members 📊 Colab 🔬 Bayestar19

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

Overview

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Trumpler 21 is a rich, very dense object of high C3 quality. Its parallax locates it at a relatively close distance, near the mid-plane, affected by low extinction. It is catalogued as a near-solar metallicity, young 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.

Relatively close Low extinction Near-solar metallicity Young

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

Cavallo et al. (2024)
Gold sample.

Data

🔍 Search references for Trumpler 21 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–	203.057	-62.787	0.736	-4.708	-2.258	-13.411
Li et al.	2025	203.068	-62.787	0.722	-4.682	-2.312	–
Wei et al.	2025	203.048	-62.785	0.738	-4.707	-2.259	–
Almeida et al.	2025	203.067	-62.789	–	–	–	–
Hunt & Reffert	2024	203.055	-62.781	0.726	-4.719	-2.267	-14.672
Cavallo et al.	2024	203.048	-62.791	0.731	–	–	–
Hunt & Reffert	2023	203.055	-62.781	0.726	-4.719	-2.267	-14.672
Almeida et al.	2023	203.057	-62.792	–	–	–	–
Cordoni et al.	2023	203.067	-62.789	0.725	-4.667	-2.293	–
Just et al.	2023	203.043	-62.797	–	–	–	–
Jaehnig et al.	2021	203.073	-62.788	0.756	-4.671	-2.313	–
Rain et al.	2021	203.068	-62.787	0.722	-4.682	-2.312	–
Dias et al.	2021	203.067	-62.789	0.725	-4.667	-2.293	–
Cantat-Gaudin et al.	2020	203.068	-62.787	0.722	-4.682	-2.312	–
Cantat-Gaudin & Anders	2020	203.068	-62.787	0.722	-4.682	-2.312	–
Liu & Pang	2019	203.066	-62.787	0.728	-4.674	-2.273	–
Bossini et al.	2019	203.068	-62.787	–	–	–	–
Bica et al.	2019	203.043	-62.784	–	–	–	–
Cantat-Gaudin et al.	2018	203.068	-62.787	0.722	-4.682	-2.312	–
Loktin & Popova	2017	203.055	-62.8	–	-8.459	-2.734	-32.9
Kharchenko et al.	2016	203.043	-62.797	–	–	–	–
Dias et al.	2014	203.058	-62.8	–	-3.57	-3.34	–
Kharchenko et al.	2013	203.055	-62.8	–	-10.4	-4.5	-32.9
Piskunov et al.	2008	203.047	-62.794	–	–	–	–
van den Bergh	2006	203.05	-62.8	–	–	–	–
Kharchenko et al.	2005	203.05	-62.8	–	-10.41	-4.77	–
Kharchenko et al.	2003	203.05	-62.78	–	-11.09	-1.86	–
Dias et al.	2002	203.058	-62.8	–	-3.62	-3.36	–
Dambis	1999	203.05	-62.8	–	–	–	–

💡 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–	1.28	0.715	0.66	51	0.036	436	0.33	0.0
Li et al.	2025	1.10	0.75	–	58	-0.256	–	–	–
Wei et al.	2025	1.72	1.00	–	44	0.000	597	0.31	–
Almeida et al.	2025	1.28	0.85	–	51	–	343	–	–
Hunt & Reffert	2024	–	–	–	–	–	528⁽¹⁾	–	–
Cavallo et al.	2024	1.14	1.02	–	69	-0.450	–	–	–
Hunt & Reffert	2023	1.28	0.60	0.66	95	–	–	–	–
Almeida et al.	2023	1.26	0.83	–	63	0.073	253⁽¹⁾	0.51	–
Cordoni et al.	2023	1.28	0.85	–	51	0.138	2163	0.33	0.00
Just et al.	2023	–	–	–	71	–	81	–	–
Tarricq et al.	2022	1.29	–	–	51	–	–	–	–
Jaehnig et al.	2021	1.33⁽¹⁾	–	–	–	–	–	–	–
Rain et al.	2021	1.33	0.71	–	49	–	–	–	0
Dias et al.	2021	1.28	0.85	–	51	0.138	–	–	–
Cantat-Gaudin et al.	2020	1.32	0.58	–	49	–	–	–	–
Cantat-Gaudin & Anders	2020	1.33	–	–	–	–	–	–	–
Liu & Pang	2019	–	–	–	33	0.500	–	–	–
Bossini et al.	2019	1.29	0.72	–	49	0.000	–	–	–
Cantat-Gaudin et al.	2018	1.33	–	–	–	–	–	–	–
Loktin & Popova	2017	1.32	0.58	–	54	–	–	–	–
Kharchenko et al.	2016	1.27	0.78	–	71	–	–	–	–
Kharchenko et al.	2013	1.27	0.78	–	71	–	–	–	–
Piskunov et al.	2008	1.31	0.56	–	58	–	–	–	–
van den Bergh	2006	1.26	0.62	–	50	–	–	–	–
Kharchenko et al.	2005	1.31	0.56	–	58	–	–	–	–
Kharchenko et al.	2003	1.26	0.62	–	–	–	–	–	–
Dias et al.	2002	1.26	0.61	–	50	–	–	–	–
Dambis	1999	1.13	0.67	–	40	–	–	–	–

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

Visualization

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