Melotte 66

(Collinder 147; MWSC 1222; OCL 739; ESO 208 12; FSR 1396; FoF 4)

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1.0 UTI
1.0
CN
1.0
Cdens
1.0
CC3
1.0
Clit
1.0
Cdup
Nm (P>50%) 1800
Core radius and density 3.8 [pc], 8.0 [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
πŸ“₯ Members πŸ“Š Colab πŸ”¬ Bayestar19 MOCAMOCA πŸ” CDS πŸ” Simbad πŸ” CDS (Ξ±, Ξ΄) πŸ” Simbad (Ξ±, Ξ΄)

Overview
ℹ️
Melotte 66 is a very rich, very dense object of very high C3 quality. Its parallax locates it at a large distance, well below the mid-plane, affected by low extinction. It is catalogued as a very massive, near-solar metallicity, old cluster, but with a large variance across recent sources for the metallicity and mass parameters (see Parameters). It is very well-studied in the literature.

Note: This object contains blue stragglers according to at least one source.

Note: This object shares a very small percentage of members with a later reported entry. See table with shared members information.

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

Cavallo et al. (2024)
Gold sample.

Hunt & Reffert (2024)
Classified as open cluster. CMD class: 0.50 (50th percentile).

Rain et al. (2024)
BSSs appear in two distinct, parallel sequences, both well aligned with binary evolution tracks of different donor masses. This resembles double BSS sequences seen in other clusters. Existing evidence suggests mass transfer may contribute to both sequences, but the detailed origin remains uncertain.

Hunt & Reffert (2023)
Classified as open cluster. CMD class: 0.50 (50th percentile).

Hu et al. (2021)
Ellipticities (core, all): e_core=0.0699, e_all=0.0287.

Rain et al. (2021)
This object probably suffers from differential reddening. We suggest exploring this effect in future works.

Ahumada & Lapasset (2007)
The red limit of the straggler area is (V-I)=0.76. In (1964ApJS....8..352L) it is suggested that a spread in the metal abundances may account for the observed dispersion around the turnoff in the colour- magnitude diagram. In that case, several stars that appear as blue stragglers would not be such.

Data
πŸ” Search references for Melotte 66 in: SciX Simbad
ℹ️
Reference Year RA [deg] DEC [deg] Plx [mas] pmRA [mas/yr] pmDE [mas/yr] Rv [km/s]
UCC 99999– 111.581 -47.684 0.193 -1.431 2.772 21.659
Li et al. 2025 111.573 -47.685 0.183 -1.474 2.745 –
Hu & Soubiran 2025 111.577 -47.684 – – – –
Carrasco-Varela et al. 2025 111.701 -47.749 – – – –
Almeida et al. 2025 111.567 -47.682 – – – –
Hunt & Reffert 2024 111.583 -47.693 0.195 -1.435 2.775 21.411
Cavallo et al. 2024 111.577 -47.684 0.193 – – –
Rain et al. 2024 111.582 -47.684 0.193 -1.431 2.771 –
Hunt & Reffert 2023 111.583 -47.693 0.195 -1.435 2.775 21.411
Just et al. 2023 111.547 -47.666 – – – –
Jadhav & Subramaniam 2021 111.573 -47.685 – – – –
Jaehnig et al. 2021 111.572 -47.682 0.211 -1.486 2.739 –
Netopil et al. 2022 111.595 -47.667 – – – 18.5
Rain et al. 2021 111.573 -47.685 0.183 -1.474 2.745 –
Dias et al. 2021 111.567 -47.682 0.189 -1.485 2.735 18.295
Cantat-Gaudin et al. 2020 111.573 -47.685 0.183 -1.474 2.745 –
SΓ‘nchez et al. 2020 111.596 -47.667 – -1.273 2.531 –
Cantat-Gaudin & Anders 2020 111.573 -47.685 0.183 -1.474 2.745 –
Liu & Pang 2019 111.558 -47.694 0.258 -1.476 2.74 –
Soubiran et al. 2018 111.573 -47.685 – – – 21.94
Bica et al. 2019 111.601 -47.666 – – – –
Cantat-Gaudin et al. 2018 111.573 -47.685 0.183 -1.474 2.745 –
Dias et al. 2018 – – – -1.7 2.9 –
Loktin & Popova 2017 111.555 -47.666 – -5.385 3.903 23.5
Sampedro et al. 2017 111.596 -47.667 – -2.59 3.61 –
Kharchenko et al. 2016 111.547 -47.666 – – – –
Netopil et al. 2016 111.596 -47.667 – – – –
Dias et al. 2014 111.596 -47.667 – -3.09 3.26 –
Kharchenko et al. 2013 111.55 -47.668 – -4.37 6.78 23.5
Gozha et al. 2012 111.596 -47.667 – – – –
Bukowiecki et al. 2011 111.583 -47.677 – – – –
Kharchenko et al. 2007 111.6 -47.67 – 0.12 – –
Ahumada & Lapasset 2007 111.6 -47.667 – – – –
van den Bergh 2006 111.596 -47.667 – – – –
Chen et al. 2003 111.595 -47.657 – – – –
Dias et al. 2002 111.596 -47.667 – -3.09 3.26 22.1
Lynga 1987 111.564 -47.731 – – – –

πŸ’‘ 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– 4.69 0.45 1.05 3275 -0.330 8876 0.34 14
Li et al. 2025 4.76 0.59 – 3790 -0.366 – – –
Hu & Soubiran 2025 – – – – -0.400(5) – – –
Carrasco-Varela et al. 2025 4.69 0.58 – 4487 -0.400 – – 14(1)
Almeida et al. 2025 4.69 0.58 – 4487 – 8876 – –
Hunt & Reffert 2024 4.70 0.21 1.05 2473 – 5794(1) – –
Cavallo et al. 2024 3.70 0.66 – 7244 -0.630 – – –
Rain et al. 2024 4.68 0.34 – 4757 – 20958 0.34 –
Hunt & Reffert 2023 4.70 0.21 1.05 2472 – – – –
Just et al. 2023 – – – 2317 – 3828 – –
Jadhav & Subramaniam 2021 4.83 0.25 – 4266 – 18163 – 10(1)
Jaehnig et al. 2021 4.78(1) – – – – – – –
Netopil et al. 2022 4.68(1) – – 3981 -0.330(1) – – –
Rain et al. 2021 4.72 0.47 – 3388 – – – 14
Dias et al. 2021 4.69 0.58 – 4487 -0.325 – – –
Cantat-Gaudin et al. 2020 4.83 0.25 – 4266 – – – –
Kounkel et al. 2020 4.33 0.60 – 2138 – – – –
Cantat-Gaudin & Anders 2020 4.72 – – – – – – –
Liu & Pang 2019 – – – 2690 0.000 – – –
Soubiran et al. 2018 4.72 – – – – – – –
Cantat-Gaudin et al. 2018 4.72 – – – – – – –
Loktin & Popova 2017 4.30 0.45 – 2897 – – – –
Kharchenko et al. 2016 4.49 0.39 – 2317 – – – –
Netopil et al. 2016 9.57 – – 3930 -0.320(2) – – –
Heiter et al. 2014 – – – – -0.320 – – –
Kharchenko et al. 2013 4.49 0.39 – 2317 -0.330 – – –
Gozha et al. 2012 4.31 – – 2786 -0.330 – – –
Bukowiecki et al. 2011 4.95(1) 0.19 – 3162 – – – –
Paunzen et al. 2010 – – – – -0.430 – – –
Ahumada & Lapasset 2007 – 0.44 – 2818 – – – 35
van den Bergh 2006 4.31 0.44 – 2754 – – – –
Chen et al. 2003 4.31 0.45 – 2780 -0.350(1) – – –
Dias et al. 2002 4.70 0.47 – 3388 -0.330 – – –
Lynga 1987 3.95 0.50 – 6026 -0.360 – – –

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

Cluster % RA DEC Plx pmRA pmDE Rv UTI
OC 0462 1.4 111.58 -47.71 0.26 -1.42 2.77 22.1 0.0

πŸ’‘ Note: The % column shows the percentage of members that Melotte 66 shares with each listed object.

Visualization
ℹ️
Melotte 66 UCC
Melotte 66 HUNT23
Melotte 66 CANTAT20
Galactocentric position diagram