Alessi 21

(MWSC 1137; FoF 2410; CMa00)

0.98 UTI

0.89

C_N

1.0

C_dens

1.0

C_C3

1.0

C_lit

1.0

C_dup

N₅₀ (P>50% members) 476

Stellar density (N₅₀/rad) 15.5 [N/pc²]

C3 classification AA

C_N 0.89 Rich
C_dens 1.0 Very dense
C_C3 1.0 Very 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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Alessi 21 is a rich, very dense object of very high C3 quality. Its parallax locates it at a 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.

Close Low extinction Near-solar metallicity Young

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

Cavallo et al. (2024)
Gold sample.

Data

🔍 Search references for Alessi 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–	107.663	-9.4	1.741	-5.486	2.626	38.321
Li et al.	2025	107.69	-9.363	1.72	-5.475	2.602	–
Wei et al.	2025	107.693	-9.506	1.762	-5.523	2.669	–
Almeida et al.	2025	107.711	-9.396	–	–	–	–
Alfonso et al.	2024	107.75	-9.622	1.699	-5.482	2.685	–
Hunt & Reffert	2024	107.592	-9.318	1.744	-5.501	2.653	37.491
Cavallo et al.	2024	107.723	-9.577	1.746	–	–	–
Hunt & Reffert	2023	107.592	-9.318	1.744	-5.501	2.653	37.491
Almeida et al.	2023	107.723	-9.389	–	–	–	–
Just et al.	2023	107.663	-9.298	–	–	–	–
He et al.	2022	107.685	-9.369	1.758	-5.534	2.647	–
Tarricq et al.	2022	107.725	-9.387	1.76	-5.481	2.684	–
Santos-Silva et al.	2021	107.7	-9.36	1.73	-5.52	2.59	–
Dias et al.	2021	107.711	-9.396	1.718	-5.498	2.587	41.454
Cantat-Gaudin et al.	2020	107.69	-9.363	1.72	-5.475	2.602	–
Cantat-Gaudin & Anders	2020	107.69	-9.363	1.72	-5.475	2.602	–
Liu & Pang	2019	107.671	-9.488	1.769	-5.498	2.644	–
Bossini et al.	2019	107.69	-9.363	–	–	–	–
Soubiran et al.	2018	107.69	-9.363	–	–	–	41.85
Cantat-Gaudin et al.	2018	107.69	-9.363	1.72	-5.475	2.602	–
Loktin & Popova	2017	107.7	-9.337	–	3.473	-1.3	38.8
Kharchenko et al.	2016	107.663	-9.298	–	–	–	–
Dias et al.	2014	107.696	-9.337	–	0.13	-1.09	–
Kharchenko et al.	2013	107.67	-9.3	–	-3.55	2.95	38.8
Gozha et al.	2012	107.696	-9.337	–	–	–	–
Piskunov et al.	2008	107.694	-9.341	–	–	–	–
Kharchenko et al.	2007	107.7	-9.34	–	0.5	–	38.8
Piskunov et al.	2007	107.694	-9.341	–	–	–	–
Kharchenko et al.	2005	107.7	-9.34	–	-3.65	3.04	38.8
Dias et al.	2002	107.696	-9.337	–	-4.0	2.8	38.8

💡 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–	0.57	0.26	0.75	59	0.000	279	0.48	–
Li et al.	2025	0.63	0.26	–	59	0.249	–	–	–
Wei et al.	2025	0.61	0.26	–	59	0.250	493	0.43	–
Almeida et al.	2025	0.57	0.37	–	88	–	288	–	–
Alfonso et al.	2024	0.59	0.29	–	60	-0.006	–	–	–
Hunt & Reffert	2024	–	–	–	–	–	362⁽¹⁾	–	–
Cavallo et al.	2024	0.60	0.21	–	62	0.440	–	–	–
Hunt & Reffert	2023	0.55	0.15	0.75	79	–	–	–	–
Almeida et al.	2023	0.56	0.37	–	100	-0.048	386⁽¹⁾	0.53	–
Just et al.	2023	–	–	–	50	–	36	–	–
He et al.	2022	–	0.40	–	45	–	–	–	–
Tarricq et al.	2022	0.58	–	–	69	–	–	–	–
Santos-Silva et al.	2021	0.57⁽¹⁾	0.34⁽¹⁾	–	85⁽¹⁾	0.000⁽¹⁾	–	–	–
Dias et al.	2021	0.57	0.37	–	88	-0.006	–	–	–
Cantat-Gaudin et al.	2020	0.59	0.29	–	66	–	–	–	–
Cantat-Gaudin & Anders	2020	0.57	–	–	–	–	–	–	–
Liu & Pang	2019	–	–	–	50	0.250	–	–	–
Bossini et al.	2019	0.53	0.25	–	65	0.000	–	–	–
Soubiran et al.	2018	0.57	–	–	–	–	–	–	–
Cantat-Gaudin et al.	2018	0.57	–	–	–	–	–	–	–
Loktin & Popova	2017	0.80	0.32	–	21	–	–	–	–
Kharchenko et al.	2016	0.60	0.23	–	50	–	–	–	–
Kharchenko et al.	2013	0.60	0.23	–	50	–	–	–	–
Gozha et al.	2012	0.50	–	–	30	–	257	–	–
Piskunov et al.	2008	0.50	0.22	–	30	–	270⁽¹⁾	–	–
Piskunov et al.	2007	0.50	0.22	–	30	–	134	–	–
Kharchenko et al.	2005	0.50	0.22	–	30	–	–	–	–
Dias et al.	2002	0.50	0.22	–	30	–	–	–	–

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

Visualization

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