UPK 21

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0.76 UTI
0.66
CN
1.0
Cdens
0.75
CC3
0.7
Clit
1.0
Cdup
C3 classification AB
Number of members (P>50%) 81
Radius (P>50% members) 17.5 [arcmin]
  • CN 0.66 Moderately populated
  • Cdens 1.0 Very dense
  • CC3 0.75 High 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 21 is a moderately populated, very dense object of 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 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 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 – 282.904 -15.157 1.684 7.866 0.671 -25.045
Li et al. 2025 282.895 -15.15 1.667 7.839 0.721 –
Almeida et al. 2025 282.89 -15.165 – – – –
Alfonso et al. 2024 282.932 -15.116 1.645 7.879 0.666 –
Hunt & Reffert 2024 282.92 -15.174 1.679 7.797 0.694 -23.852
Cavallo et al. 2024 282.985 -14.911 1.682 – – –
Hunt & Reffert 2023 282.92 -15.174 1.679 7.797 0.694 -23.852
Almeida et al. 2023 282.843 -15.159 – – – –
Tarricq et al. 2022 282.911 -15.203 1.672 7.84 0.671 –
Dias et al. 2021 282.89 -15.165 1.679 7.831 0.756 -25.27
Cantat-Gaudin et al. 2020 282.895 -15.15 1.667 7.839 0.721 –
Cantat-Gaudin & Anders 2020 282.903 -15.16 1.686 7.813 0.749 –
Sim et al. 2019 282.938 -15.191 – 7.82 0.73 –

💡 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 0.48 1.21 – 1324 -0.239 – – –
Almeida et al. 2025 0.59 1.48 – 731 – 116 – –
Alfonso et al. 2024 0.58 0.81 – 1090 0.141 – – –
Hunt & Reffert 2024 – – – – – 90* – –
Cavallo et al. 2024 0.58 1.93 – 355 -0.170 – – –
Hunt & Reffert 2023 0.56 1.43 1.60 467 – – – –
Almeida et al. 2023 0.58 1.45 – 759 0.198 195* 0.50 –
Tarricq et al. 2022 0.57 – – 1230 – – – –
Dias et al. 2021 0.59 1.48 – 731 0.141 – – –
Cantat-Gaudin et al. 2020 0.58 0.81 – 1148 – – – –
Cantat-Gaudin & Anders 2020 0.58 – – – – – – –
Sim et al. 2019 0.59 – – 891 – – – –

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

Visualization
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UPK 21 UCC
UPK 21 HUNT23
UPK 21 CANTAT20
Galactocentric position diagram