ASCC 20

(MWSC 556)

0.87 UTI

0.8

C_N

1.0

C_dens

1.0

C_C3

0.78

C_lit

1.0

C_dup

N₅₀ (P>50% members) 244

Stellar density (N₅₀/rad) 10.1 [N/pc²]

C3 classification AA

C_N 0.8 Rich
C_dens 1.0 Very dense
C_C3 1.0 Very high quality
C_lit 0.78 Well-studied
C_dup 1.0 Unique

📥 Members 📊 Colab 🔬 Bayestar19

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

Overview

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ASCC 20 is a rich, very dense object of very high C3 quality. Its parallax locates it at a very close distance, below 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 absorption parameter (see Parameters). It is well-studied in the literature.

Note: This object shares a large percentage of members with 3 later reported entries. See table with shared members information.

Very close Low extinction Near-solar metallicity Young

Liu et al. (2025)
Classified as primordial binary cluster 6 along with Briceno_1, and of multiple system 5 along with ASCC_21 and Briceno_1.

Palma et al. (2025)
Part of multiple system G10, along with ASCC_19, OC_0339, OCSN_61 and UBC_17a.

Cavallo et al. (2024)
Gold sample.

Data

🔍 Search references for ASCC 20 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–	82.08	1.656	2.75	-0.556	0.778	29.188
Liu et al.	2025	82.19	1.72	2.73	-0.57	0.76	27.89
Zhang et al.	2024	82.194	1.721	–	–	–	–
Hunt & Reffert	2024	82.194	1.721	2.73	-0.569	0.759	27.886
Cavallo et al.	2024	82.006	1.698	2.731	–	–	–
Hunt & Reffert	2023	82.194	1.721	2.73	-0.569	0.759	27.886
Donor et al.	2020	82.189	1.64	–	1.42	-1.9	19.4
Kharchenko et al.	2016	82.183	1.64	–	–	–	–
Dias et al.	2014	82.183	1.63	–	1.85	-3.36	–
Kharchenko et al.	2013	82.189	1.64	–	0.59	0.33	23.0
Gozha et al.	2012	82.183	1.63	–	–	–	–
Piskunov et al.	2008	82.181	1.627	–	–	–	–
Kharchenko et al.	2007	82.18	1.63	–	0.75	–	22.97
Piskunov et al.	2007	82.181	1.627	–	–	–	–
Kharchenko et al.	2005	82.18	1.63	–	-0.09	0.51	17.62

💡 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–	0.39	0.12	0.47	22	0.030	649	–	–
Liu et al.	2025	0.38	0.06	–	25	–	–	–	–
Zhang et al.	2024	–	–	–	–	0.050⁽¹⁾	–	–	–
Hunt & Reffert	2024	–	–	–	–	–	105⁽¹⁾	–	–
Cavallo et al.	2024	0.37	0.53	–	13	0.030	–	–	–
Hunt & Reffert	2023	0.36	0.11	0.47	13	–	–	–	–
Donor et al.	2020	–	–	–	–	0.020	–	–	–
Kharchenko et al.	2016	0.39	0.19	–	10	–	–	–	–
Kharchenko et al.	2013	0.39	0.19	–	10	–	–	–	–
Gozha et al.	2012	0.45	–	–	22	–	676	–	–
Piskunov et al.	2008	0.45	0.12	–	22	–	1186⁽¹⁾	–	–
Piskunov et al.	2007	0.45	0.12	–	22	–	622	–	–
Kharchenko et al.	2005	0.45	0.12	–	22	–	–	–	–

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

Cluster	%	RA	DEC	Plx	pmRA	pmDE	Rv	UTI
OCSN 57	97.1	82.08	1.67	2.74	-0.52	0.79	29.19	0.1
FoF 2371	37.7	82.39	2.02	2.69	-0.68	0.69	29.78	0.13
OCSN 56	17.2	82.64	2.37	2.53	-0.82	0.53	31.28	0.2

💡 Note: The % column shows the percentage of members that ASCC 20 shares with each listed object.

Visualization

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