UPK 18

0.42 UTI

0.41

C_N

0.49

C_dens

0.5

C_C3

0.35

C_lit

1.0

C_dup

N_m (P>50%) 41

Core radius and density 1.4 [pc], 2.4 [pc^-2]

C3 classification BB

C_N 0.41 Poorly populated
C_dens 0.49 Loose
C_C3 0.5 Intermediate quality
C_lit 0.35 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 18 is a poorly populated, loose object of intermediate C3 quality. Its parallax locates it at a close distance, near 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 and metallicity parameters (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. Silver sample.

Cavallo et al. (2024)
Gold sample.

Hunt & Reffert (2024)
Classified as open cluster. CMD class: 0.64 (50th percentile).

Hunt & Reffert (2023)
Classified as open cluster. CMD class: 0.64 (50th percentile).

Data

🔍 Search references for UPK 18 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–	280.784	-15.325	1.291	3.062	0.866	-20.594
Li et al.	2025	280.763	-15.325	1.28	3.112	0.98	–
Almeida et al.	2025	280.759	-15.308	–	–	–	–
Alfonso et al.	2024	280.698	-15.283	1.242	2.972	0.792	–
Hunt & Reffert	2024	280.771	-15.317	1.307	3.002	0.839	-16.58
Cavallo et al.	2024	280.754	-15.328	1.301	–	–	–
Hunt & Reffert	2023	280.771	-15.317	1.307	3.002	0.839	-16.58
Almeida et al.	2023	280.747	-15.305	–	–	–	–
Jadhav & Subramaniam	2021	280.763	-15.325	–	–	–	–
Dias et al.	2021	280.759	-15.308	1.266	3.075	0.92	–
Cantat-Gaudin et al.	2020	280.763	-15.325	1.28	3.112	0.98	–
Cantat-Gaudin & Anders	2020	280.761	-15.33	1.243	3.102	0.934	–
Sim et al.	2019	280.771	-15.304	–	3.08	0.87	–

💡 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	1.11	0.83	365	0.032	123	0.75	0
Li et al.	2025	1.02	1.26	–	665	0.040	–	–	–
Almeida et al.	2025	0.81	1.41	–	154	–	137	–	–
Alfonso et al.	2024	0.78	1.04	–	75	0.032	–	–	–
Hunt & Reffert	2024	0.74	1.11	0.83	350	–	109⁽¹⁾	–	–
Cavallo et al.	2024	0.75	1.11	–	380	-0.310	–	–	–
Hunt & Reffert	2023	0.74	1.11	0.83	350	–	–	–	–
Almeida et al.	2023	0.75	1.03	–	614	-0.228	102⁽¹⁾	0.75	–
Tarricq et al.	2022	0.76	–	–	724	–	–	–	–
Jadhav & Subramaniam	2021	0.78	1.04	–	724	–	177	–	0⁽¹⁾
Dias et al.	2021	0.81	1.41	–	154	0.032	–	–	–
Cantat-Gaudin et al.	2020	0.78	1.04	–	724	–	–	–	–
Cantat-Gaudin & Anders	2020	0.79	–	–	–	–	–	–	–
Sim et al.	2019	0.75	–	–	282	–	–	–	–

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

Visualization

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