UPK 18

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0.66 UTI
0.41
CN
1.0
Cdens
0.5
CC3
0.7
Clit
1.0
Cdup
C3 classification BB
Number of members (P>50%) 41
Radius (P>50% members) 8.8 [arcmin]
  • CN 0.41 Poorly populated
  • Cdens 1.0 Very dense
  • CC3 0.5 Intermediate quality
  • Clit 0.7 Moderately studied
  • Cdup 1.0 Unique
đŸ“Ĩ Members 📊 Colab đŸ”Ŧ Bayestar19 🔍 CDS 🔍 Simbad 🔍 CDS (Îą, δ) 🔍 Simbad (Îą, δ)

Overview
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UPK 18 is a poorly populated, very dense 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 moderately 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.

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 – 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 – – – –
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] Bfr BSS
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 – – – – – 109* – –
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* 0.75 –
Tarricq et al. 2022 0.76 – – 724 – – – –
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 – – – –

(*): Indicates that this parameter is assigned more than one value in the corresponding reference.

Visualization
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UPK 18 UCC
UPK 18 HUNT23
UPK 18 CANTAT20
Galactocentric position diagram