UPK 4

0.52 UTI

0.7

C_N

0.26

C_dens

1.0

C_C3

0.32

C_lit

1.0

C_dup

N_m (P>50%) 91

Core radius and density 2.4 [pc], 1.3 [pc^-2]

C3 classification AA

C_N 0.7 Moderately populated
C_dens 0.26 Loose
C_C3 1.0 Very high quality
C_lit 0.32 Poorly studied
C_dup 1.0 Unique

📥 Members 📊 Colab 🔬 Bayestar19

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

Overview

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UPK 4 is a moderately populated, loose object of very high C3 quality. Its parallax locates it at a close distance, below the mid-plane, affected by moderate extinction. It is catalogued as a near-solar metallicity, intermediate-age cluster, but with a large variance across recent sources for the age parameter (see Parameters). It is poorly studied in the literature.

Close Moderate extinction Near-solar metallicity Intermediate age

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

Cavallo et al. (2024)
Gold sample.

Hunt & Reffert (2024)
Classified as open cluster. CMD class: 1.00 (50th percentile).

Hunt & Reffert (2023)
Classified as open cluster. CMD class: 1.00 (50th percentile).

Data

🔍 Search references for UPK 4 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–	281.349	-23.776	1.257	-2.009	-6.408	10.208
Li et al.	2025	281.361	-23.764	1.239	-2.009	-6.373	–
Almeida et al.	2025	281.355	-23.783	–	–	–	–
Alfonso et al.	2024	281.35	-23.777	1.222	-2.022	-6.418	–
Hunt & Reffert	2024	281.387	-23.766	1.265	-2.028	-6.408	9.351
Cavallo et al.	2024	281.335	-23.812	1.266	–	–	–
Hunt & Reffert	2023	281.387	-23.766	1.265	-2.028	-6.408	9.351
He et al.	2022	281.401	-23.704	1.243	-2.022	-6.425	–
Tarricq et al.	2022	281.321	-23.827	1.236	-2.021	-6.401	–
Dias et al.	2021	281.355	-23.783	1.24	-2.021	-6.391	–
Cantat-Gaudin et al.	2020	281.361	-23.764	1.239	-2.009	-6.373	–
Cantat-Gaudin & Anders	2020	281.357	-23.768	1.245	-2.023	-6.384	–
Sim et al.	2019	281.373	-23.744	–	-2.03	-6.4	–

💡 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–	0.78	1.25	1.54	275	0.038	296	–	–
Li et al.	2025	0.70	1.25	–	535	0.042	–	–	–
Almeida et al.	2025	0.77	1.39	–	252	–	236	–	–
Alfonso et al.	2024	0.83	1.04	–	467	0.035	–	–	–
Hunt & Reffert	2024	0.75	1.24	1.54	157	–	355⁽¹⁾	–	–
Cavallo et al.	2024	0.79	1.39	–	347	0.270	–	–	–
Hunt & Reffert	2023	0.75	1.24	1.54	157	–	–	–	–
He et al.	2022	–	1.85	–	50	–	–	–	–
Tarricq et al.	2022	0.81	–	–	288	–	–	–	–
Dias et al.	2021	0.77	1.39	–	252	0.035	–	–	–
Cantat-Gaudin et al.	2020	0.83	1.04	–	275	–	–	–	–
Cantat-Gaudin & Anders	2020	0.79	–	–	–	–	–	–	–
Sim et al.	2019	0.78	–	–	282	–	–	–	–

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

Visualization

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