Melotte 20

(MWSC 274; Alpha Persei; Alpha Per; OCSN 218)

Click to load Aladin Lite
1.0 UTI
1.0
CN
1.0
Cdens
1.0
CC3
1.0
Clit
1.0
Cdup
Nm (P>50%) 803
Core radius and density 2.6 [pc], 8.7 [pc-2]
C3 classification AA
  • CN 1.0 Very rich
  • Cdens 1.0 Very dense
  • CC3 1.0 Very high quality
  • Clit 1.0 Very well-studied
  • Cdup 1.0 Unique
đŸ“Ĩ Members 📊 Colab đŸ”Ŧ Bayestar19 MOCAMOCA 🔍 CDS 🔍 Simbad 🔍 CDS (Îą, δ) 🔍 Simbad (Îą, δ)

Overview
ℹī¸
Melotte 20 is a very rich, very dense object of very high C3 quality. Its parallax locates it at a very close distance, near the mid-plane, affected by low extinction. It is catalogued as a massive, near-solar metallicity, young cluster, but with a large variance across recent sources for the absorption and mass parameters (see Parameters). It is very well-studied in the literature.

Yan et al. (2026)
Number of WDs: expected from single-star evolution N=2, with probability of formation through binary evolution >=0.5 N=7.

Liu et al. (2025)
Classified as primordial binary cluster 185 along with HSC_1165.

Palma et al. (2025)
Classified as tidal capture (resonant trapping pair) P416, along with HSC_1165.

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

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).

Richer et al. (2021)
The expected number of WDs is 0.72, 0 WD candidates found, and 1 WD candidate found in the wide search.

Hu et al. (2021)
Ellipticities (core, all): e_core=0.2344, e_all=0.3379.

Ahumada & Lapasset (2007)
= Alpha Persei cluster. The cluster parameters are from (1987, Lund Catalogue of Open Cluster Data). Star HD 22928 = Delta Persei (sp. B6n) is a cluster member according to its radial velocity (1969PDAO...13..329P).

Data
🔍 Search references for Melotte 20 in: SciX Simbad
ℹī¸
Reference Year RA [deg] DEC [deg] Plx [mas] pmRA [mas/yr] pmDE [mas/yr] Rv [km/s]
UCC 99999– 51.633 48.965 5.74 22.911 -25.434 -1.009
Yan et al. 2026 51.332 49.119 5.741 22.918 -25.463 –
Otto et al. 2026 51.332 49.119 – 22.86 -25.38 -0.8
Li et al. 2025 51.617 48.975 5.668 22.864 -25.378 –
Yang et al. 2025 51.332 49.119 – – – –
Wei et al. 2025 51.648 48.915 5.747 23.0 -25.462 –
Almeida et al. 2025 51.51 48.933 – – – –
Alfonso et al. 2024 51.762 48.904 5.702 22.839 -25.462 –
Zhang et al. 2024 51.332 49.119 – – – –
Swiggum et al. 2024 51.332 49.119 5.741 22.918 -25.463 -0.567
Hunt & Reffert 2024 51.332 49.119 5.741 22.918 -25.463 -0.869
Cavallo et al. 2024 51.609 48.912 5.747 – – –
Hunt & Reffert 2023 51.332 49.119 5.741 22.918 -25.463 -0.869
Qin et al. 2023 51.47 48.92 5.78 22.89 -25.55 -1.35
Just et al. 2023 51.664 48.798 – – – –
He et al. 2022 51.626 48.932 5.746 22.97 -25.431 –
Tarricq et al. 2022 51.772 49.05 5.77 23.017 -25.434 –
Jaehnig et al. 2021 51.594 48.981 5.736 22.921 -25.451 –
Netopil et al. 2022 51.079 49.861 – – – 0.72
Rain et al. 2021 51.617 48.975 5.668 22.864 -25.378 –
Richer et al. 2021 52.331 48.586 5.729 22.657 -26.014 –
Dias et al. 2021 51.51 48.933 5.695 22.845 -25.403 -0.517
Spina et al. 2021 51.617 48.964 5.69 22.863 -25.49 –
Cantat-Gaudin et al. 2020 51.617 48.975 5.668 22.864 -25.378 –
Donor et al. 2020 51.675 48.8 – 23.34 -25.8 1.0
Zhong et al. 2020 51.617 48.975 – 22.864 -25.378 -6.23
Cantat-Gaudin & Anders 2020 51.617 48.975 5.668 22.864 -25.378 –
Bossini et al. 2019 51.617 48.975 – – – –
Soubiran et al. 2018 51.617 48.975 – – – -0.1
Cantat-Gaudin et al. 2018 51.617 48.975 5.668 22.864 -25.378 –
Yen et al. 2018 51.457 49.139 5.56 22.8 -25.29 –
Dib et al. 2018 51.675 48.8 – – – –
Loktin & Popova 2017 50.145 48.167 – 22.261 -25.998 -1.4
Joshi et al. 2016 51.675 48.8 – – – –
Kharchenko et al. 2016 51.664 48.798 – – – –
Netopil et al. 2016 51.675 48.8 – – – –
Dias et al. 2014 51.079 49.862 – 0.87 -1.2 –
Kharchenko et al. 2013 51.675 48.8 – 21.49 -26.11 -1.4
Gozha et al. 2012 51.079 49.862 – – – –
Kharchenko et al. 2012 51.675 48.8 – 21.49 -26.11 -1.44
Piskunov et al. 2008 51.483 49.123 – – – –
Kharchenko et al. 2007 51.07 49.86 – 6.25 – -1.36
Piskunov et al. 2007 51.483 49.123 – – – –
Ahumada & Lapasset 2007 50.5 48.6 – – – –
van den Bergh 2006 51.5 49.117 – – – –
Kharchenko et al. 2005 51.49 49.12 – 21.98 -25.36 -2.64
Kharchenko et al. 2003 51.49 49.12 – 22.46 -25.47 –
Chen et al. 2003 50.488 48.622 – – – –
Dias et al. 2002 51.079 49.862 – 22.41 -25.87 -1.39
Dambis 1999 51.079 49.862 – – – –
Lynga 1987 50.513 48.611 – – – -2.0

💡 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 99999– 0.18 0.28 0.61 55 0.040 3236 0.12 0
Yan et al. 2026 – – – 51 – – – –
Otto et al. 2026 – – – 51 -0.020(15) – – –
Liu et al. 2025 0.19 0.11 – 72 – – – –
Li et al. 2025 0.18 0.28 – 85 0.058 – – –
Yang et al. 2025 – – – 56 -0.080(3) – – –
Wei et al. 2025 0.22 0.65 – 41 0.000 439 0.12 –
Almeida et al. 2025 0.18 0.32 – 83 – 536 – –
Alfonso et al. 2024 0.17 0.30 – 65 0.157 – – –
Zhang et al. 2024 – – – – 0.030(1) – – –
Swiggum et al. 2024 0.17 – – 56 – 814 – –
Hunt & Reffert 2024 0.17 0.24 0.61 56 – 392(1) – –
Cavallo et al. 2024 0.17 0.74 – 42 0.120 – – –
Hunt & Reffert 2023 0.17 0.24 0.61 56 – – – –
Qin et al. 2023 0.19 0.28 – 63 – – – –
Just et al. 2023 – – – 50 – 3236 – –
He et al. 2022 – 0.55 – 63 – – – –
Spina et al. 2022 – – – – 0.010 – – –
Tarricq et al. 2022 0.17 – – 51 – – – –
Jaehnig et al. 2021 0.17(1) – – – – – – –
Netopil et al. 2022 0.17(1) – – 56 0.010(1) – – –
Rain et al. 2021 0.18 0.28 – 71 – – – 0
Richer et al. 2021 – 0.38 – 51 – – – –
Dias et al. 2021 0.18 0.32 – 83 0.158 – – –
Spina et al. 2021 0.18 – – 51 -0.013(20) – – –
Cantat-Gaudin et al. 2020 0.17 0.30 – 51 – – – –
Kounkel et al. 2020 0.19 0.30 – 55 – – – –
Donor et al. 2020 – – – – 0.010 – – –
Zhong et al. 2020 0.18(1) 0.06 – 7938 0.014 – – –
Cantat-Gaudin & Anders 2020 0.18 – – – – – – –
Bossini et al. 2019 0.15 0.06 – 87 0.140 – – –
Soubiran et al. 2018 0.18 – – – – – – –
Cantat-Gaudin et al. 2018 0.18 – – – – – – –
Yen et al. 2018 0.17 0.34 – 63 – – – –
Dib et al. 2018 0.17 – – 50 – – – –
Loktin & Popova 2017 0.18 0.28 – 71 – – – –
Joshi et al. 2016 0.17 0.28 – 50 – 7244 – –
Kharchenko et al. 2016 0.17 0.28 – 50 – – – –
Netopil et al. 2016 8.14 – – 50 0.140(2) – – –
Heiter et al. 2014 – – – – 0.140 – – –
Kharchenko et al. 2013 0.17 0.28 – 50 – – – –
Gozha et al. 2012 0.18 – – 71 0.040 7244 – –
Kharchenko et al. 2012 0.17 0.28 – 50 – – – –
Paunzen et al. 2010 – – – – 0.040 – – –
Piskunov et al. 2008 0.19 0.28 – 35 – 15346(1) – –
Piskunov et al. 2007 0.19 0.28 – 35 – 11885 – –
Ahumada & Lapasset 2007 – 0.28 – 51 – – – 1
van den Bergh 2006 0.18 0.28 – 71 – – – –
Kharchenko et al. 2005 0.19 0.28 – 35 – – – –
Kharchenko et al. 2003 0.19 0.28 – – – – – –
Chen et al. 2003 0.18 0.28 – 70 -0.050(1) – – –
Dias et al. 2002 0.18 0.28 – 71 0.040 – – –
Dambis 1999 0.15 0.31 – 25 – – – –
Lynga 1987 0.17 0.28 – 51 0.100 – – –

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

Visualization
ℹī¸
Melotte 20 UCC
Melotte 20 HUNT23
Melotte 20 CANTAT20
Galactocentric position diagram