UPK 21
0.51
UTI
0.66
CN
0.43
Cdens
0.75
CC3
0.35
Clit
1.0
Cdup
Nm (P>50%)
81
Core radius and density
1.7 [pc], 2.1 [pc-2]
- CN 0.66 Moderately populated
- Cdens 0.43 Loose
- CC3 0.75 High quality
- Clit 0.35 Poorly studied
- Cdup 1.0 Unique
đĨ Members
đ Colab
đŦ Bayestar19
MOCA
đ CDS
đ Simbad
đ CDS (Îą, δ)
đ Simbad (Îą, δ)
MOCA
đ CDS
đ Simbad
đ CDS (Îą, δ)
đ Simbad (Îą, δ)
Overview
UPK 21 is a moderately populated, loose 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 poorly studied in the literature.
Data
| Reference | Year | RA [deg] | DEC [deg] | Plx [mas] | pmRA [mas/yr] | pmDE [mas/yr] | Rv [km/s] |
|---|---|---|---|---|---|---|---|
| UCC | 99999â | 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 | â |
| Almeida et al. | 2025 | 282.89 | -15.165 | â | â | â | â |
| Alfonso et al. | 2024 | 282.932 | -15.116 | 1.645 | 7.879 | 0.666 | â |
| 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 | â | â | â |
| Hunt & Reffert | 2023 | 282.92 | -15.174 | 1.679 | 7.797 | 0.694 | -23.852 |
| Almeida et al. | 2023 | 282.843 | -15.159 | â | â | â | â |
| Tarricq et al. | 2022 | 282.911 | -15.203 | 1.672 | 7.84 | 0.671 | â |
| Jadhav & Subramaniam | 2021 | 282.895 | -15.15 | â | â | â | â |
| 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 | â |
| Cantat-Gaudin & Anders | 2020 | 282.903 | -15.16 | 1.686 | 7.813 | 0.749 | â |
| Sim et al. | 2019 | 282.938 | -15.191 | â | 7.82 | 0.73 | â |
đĄ 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] | Bfrac | BSS |
|---|---|---|---|---|---|---|---|---|---|
| UCC | 99999â | 0.58 | 1.43 | 1.6 | 825 | 0.141 | 148 | 0.5 | 0 |
| Li et al. | 2025 | 0.48 | 1.21 | â | 1324 | -0.239 | â | â | â |
| Almeida et al. | 2025 | 0.59 | 1.48 | â | 731 | â | 116 | â | â |
| Alfonso et al. | 2024 | 0.58 | 0.81 | â | 1090 | 0.141 | â | â | â |
| Hunt & Reffert | 2024 | 0.56 | 1.43 | 1.60 | 467 | â | 90(1) | â | â |
| Cavallo et al. | 2024 | 0.58 | 1.93 | â | 355 | -0.170 | â | â | â |
| Hunt & Reffert | 2023 | 0.56 | 1.43 | 1.60 | 467 | â | â | â | â |
| Almeida et al. | 2023 | 0.58 | 1.45 | â | 759 | 0.198 | 195(1) | 0.50 | â |
| Tarricq et al. | 2022 | 0.57 | â | â | 1230 | â | â | â | â |
| Jadhav & Subramaniam | 2021 | 0.58 | 0.81 | â | 1148 | â | 179 | â | 0(1) |
| Dias et al. | 2021 | 0.59 | 1.48 | â | 731 | 0.141 | â | â | â |
| Cantat-Gaudin et al. | 2020 | 0.58 | 0.81 | â | 1148 | â | â | â | â |
| Cantat-Gaudin & Anders | 2020 | 0.58 | â | â | â | â | â | â | â |
| Sim et al. | 2019 | 0.59 | â | â | 891 | â | â | â | â |
(N): Indicates that there are N extra values assigned to this parameter in the corresponding reference.
Palma et al. (2025)
Classified as optical pair (not dynamically associated) P166, along with Ruprecht_145.
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: 0.99 (50th percentile).
Hunt & Reffert (2023)
Classified as open cluster. CMD class: 0.99 (50th percentile).