NGC 6991

(FoF 2342)

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0.97 UTI
0.85
CN
1.0
Cdens
1.0
CC3
1.0
Clit
1.0
Cdup
N50 (P>50% members) 361
Stellar density (N50/rad) 18.9 [N/pc2]
C3 classification AA
  • CN 0.85 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
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NGC 6991 is a rich, very dense object of very high C3 quality. Its parallax locates it at a close distance, near the mid-plane, affected by low extinction. It is catalogued as a near-solar metallicity, old cluster (see Parameters). It is very well-studied in the literature.

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

Cavallo et al. (2024)
Gold sample.

Data
🔍 Search references for NGC 6991 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 99999– 313.61 47.379 1.769 5.616 8.422 -12.222
Li et al. 2025 313.621 47.4 1.765 5.593 8.509 –
Hu & Soubiran 2025 313.638 47.422 – – – –
Wei et al. 2025 313.582 47.345 1.771 5.564 8.397 –
Almeida et al. 2025 313.689 47.405 – – – –
Alfonso et al. 2024 313.608 47.395 1.741 5.614 8.415 –
Hunt & Reffert 2024 313.649 47.377 1.767 5.604 8.436 -12.326
Cavallo et al. 2024 313.638 47.422 1.769 – – –
Hunt & Reffert 2023 313.649 47.377 1.767 5.604 8.436 -12.326
Almeida et al. 2023 313.798 47.269 – – – –
He et al. 2022 313.655 47.395 1.771 5.622 8.402 –
Tarricq et al. 2022 313.631 47.43 1.775 5.617 8.392 –
Dias et al. 2021 313.689 47.405 1.766 5.589 8.505 -12.027
Cantat-Gaudin et al. 2020 313.621 47.4 1.765 5.593 8.509 –
Cantat-Gaudin & Anders 2020 313.621 47.4 1.765 5.593 8.509 –
Liu & Pang 2019 313.637 47.413 1.775 5.571 8.508 –
Soubiran et al. 2018 313.621 47.4 – – – -12.46
Cantat-Gaudin et al. 2018 313.621 47.4 1.765 5.593 8.509 –
Loktin & Popova 2017 313.725 47.417 – -0.272 -0.157 -21.77
Dias et al. 2014 313.725 47.417 – -1.5 1.94 –
Gozha et al. 2012 313.725 47.417 – – – –
Piskunov et al. 2008 313.634 47.445 – – – –
Kharchenko et al. 2007 313.72 47.42 – 0.42 – -6.0
Piskunov et al. 2007 313.634 47.445 – – – –
Kharchenko et al. 2005 313.63 47.45 – 7.0 9.26 -6.0

💡 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– 0.565 0.305 0.75 1429 -0.037 373 0.61 –
Li et al. 2025 0.58 0.39 – 1331 0.053 – – –
Hu & Soubiran 2025 – – – – -0.180(5) – – –
Wei et al. 2025 0.49 0.23 – 2090 0.000 795 0.63 –
Almeida et al. 2025 0.56 0.49 – 1429 – 373 – –
Alfonso et al. 2024 0.58 0.20 – 1780 -0.075 – – –
Hunt & Reffert 2024 – – – – – 307(1) – –
Cavallo et al. 2024 0.56 0.60 – 1259 0.120 – – –
Hunt & Reffert 2023 0.53 0.29 0.75 989 – – – –
Almeida et al. 2023 0.55 0.32 – 1435 0.070 672(1) 0.59 –
He et al. 2022 – 0.65 – 891 – – – –
Tarricq et al. 2022 0.57 – – 1622 – – – –
Dias et al. 2021 0.56 0.49 – 1429 -0.077 – – –
Cantat-Gaudin et al. 2020 0.58 0.20 – 1549 – – – –
Cantat-Gaudin & Anders 2020 0.56 – – – – – – –
Liu & Pang 2019 – – – 1950 -0.500 – – –
Soubiran et al. 2018 0.56 – – – – – – –
Cantat-Gaudin et al. 2018 0.56 – – – – – – –
Loktin & Popova 2017 3.10 1.20 – 1514 – – – –
Gozha et al. 2012 0.70 – – 1288 – 214 – –
Piskunov et al. 2008 0.70 0.00 – 1288 – 440(1) – –
Piskunov et al. 2007 0.70 0.00 – 1288 – 148 – –
Kharchenko et al. 2005 0.70 0.00 – 1288 – – – –

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

Visualization
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NGC 6991 UCC
NGC 6991 HUNT23
NGC 6991 CANTAT20
Galactocentric position diagram