Berkeley 18

(MWSC 512; King 22; OCL 420; OCL 419; FSR 0731)

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0.95 UTI
1.0
CN
1.0
Cdens
0.75
CC3
1.0
Clit
1.0
Cdup
N50 (P>50% members) 1766
Stellar density (N50/rad) 15.6 [N/pc2]
C3 classification AB
  • CN 1.0 Very rich
  • Cdens 1.0 Very dense
  • CC3 0.75 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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Berkeley 18 is a very rich, very dense object of high C3 quality. Its parallax locates it at a large distance, above the mid-plane, affected by moderate extinction. It is catalogued as an extremely 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.

Cavallo et al. (2024)
Gold sample.

Hunt & Reffert (2024)
Classified as open cluster. CMD class: 0.20 (50th percentile).

Rain et al. (2021)
The red limit of the straggler area is BP-RP=1.31. There are several stragglers candidates with a radius larger than the apparent radius of the cluster (r=12 arcmin (Dias et al., 2002A&A...389..871D, Cat. B/ocl). Apparently, stars DR2 208498367050003072, DR2 208543824983422848, DR2 208563959789949568 are massive stragglers. This object probably suffers from differential reddening. We suggest exploring this effect in future works.

Ahumada & Lapasset (2007)
Only straggler candidates inside a radius of 3' around the centre of coordinates have been considered. The red limit of the blue straggler area is (B-V)=0.88.

Data
🔍 Search references for Berkeley 18 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– 80.54 45.44 0.17 0.776 -0.079 -2.731
Otto et al. 2026 80.554 45.468 – 0.85 -0.06 -2.6
Guerco et al. 2025 80.6 45.4 0.16 0.76 -0.09 -2.58
Hu & Soubiran 2025 80.54 45.441 – – – –
Zhang et al. 2024 80.554 45.468 – – – –
Hunt & Reffert 2024 80.554 45.468 0.162 0.782 -0.059 -5.494
Cavallo et al. 2024 80.54 45.441 0.165 – – –
Hunt & Reffert 2023 80.554 45.468 0.162 0.782 -0.059 -5.494
Just et al. 2023 80.592 45.405 – – – –
Jadhav & Subramaniam 2021 80.531 45.442 – – – –
Jaehnig et al. 2021 80.525 45.439 0.166 0.824 -0.045 –
Rain et al. 2021 80.531 45.442 0.152 0.849 -0.057 –
Spina et al. 2021 80.531 45.439 0.148 0.849 -0.044 –
Cantat-Gaudin et al. 2020 80.531 45.442 0.152 0.849 -0.057 –
Zhong et al. 2020 80.531 45.442 – 0.849 -0.057 17.51
Cantat-Gaudin & Anders 2020 80.531 45.442 0.152 0.849 -0.057 –
Soubiran et al. 2018 80.531 45.442 – – – -2.0
Bica et al. 2019 80.54 45.469 – – – –
Cantat-Gaudin et al. 2018 80.531 45.442 0.152 0.849 -0.057 –
Loktin & Popova 2017 80.55 45.4 – 0.22 -1.212 -5.5
Kharchenko et al. 2016 80.592 45.405 – – – –
Dias et al. 2014 80.55 45.4 – 0.33 -4.52 –
Kharchenko et al. 2013 80.602 45.405 – -0.37 -3.58 -5.5
Gozha et al. 2012 80.55 45.4 – – – –
Kharchenko et al. 2012 80.602 45.405 – -0.37 -3.58 –
Bukowiecki et al. 2011 80.529 45.481 – – – –
Ahumada & Lapasset 2007 80.55 45.4 – – – –
van den Bergh 2006 80.55 45.4 – – – –
Chen et al. 2003 80.541 45.397 – – – –
Dias et al. 2002 80.55 45.4 – 0.33 -4.52 -5.5

💡 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– 5.62 1.45 1.84 4266 -0.360 12274 – 32
Otto et al. 2026 – – – 4365 -0.370(15) – – –
Guerco et al. 2025 – – – 4370 -0.360 – – –
Hu & Soubiran 2025 – – – – -0.260(5) – – –
Zhang et al. 2024 – – – – -0.366(1) – – –
Hunt & Reffert 2024 – – – – – 6570(1) – –
Cavallo et al. 2024 5.22 1.57 – 3090 -0.070 – – –
Hunt & Reffert 2023 5.02 1.85 1.84 1462 – – – –
Just et al. 2023 – – – 4266 – 12274 – –
Spina et al. 2022 – – – – -0.625 – – –
Jadhav & Subramaniam 2021 5.62 1.53 – 4365 – 36420 – 22(1)
Jaehnig et al. 2021 5.83(1) – – – – – – –
Rain et al. 2021 5.52 1.45 – 4266 – – – 32
Spina et al. 2021 4.82 – – 4365 -0.621(20) – – –
Cantat-Gaudin et al. 2020 5.62 1.53 – 4365 – – – –
Kounkel et al. 2020 4.55 1.78 – 1230 – – – –
Zhong et al. 2020 5.80 1.45 – 9630 -0.372 – – –
Cantat-Gaudin & Anders 2020 5.52 – – – – – – –
Soubiran et al. 2018 5.52 – – – – – – –
Cantat-Gaudin et al. 2018 5.52 – – – – – – –
Loktin & Popova 2017 4.41 1.73 – 1445 – – – –
Kharchenko et al. 2016 5.80 1.42 – 4266 – – – –
Kharchenko et al. 2013 5.80 1.42 – 4266 0.020 – – –
Gozha et al. 2012 5.80 – – 4266 0.020 – – –
Kharchenko et al. 2012 5.80 1.42 – 4266 0.020 – – –
Bukowiecki et al. 2011 6.55(1) 1.36 – 2818 – – – –
Ahumada & Lapasset 2007 – 1.45 – 4266 – – – 126
van den Bergh 2006 5.80 1.45 – 4266 – – – –
Chen et al. 2003 5.80 1.45 – 4260 0.020(1) – – –
Dias et al. 2002 5.80 1.45 – 4266 -0.400 – – –

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

Visualization
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Berkeley 18 UCC
Berkeley 18 HUNT23
Berkeley 18 CANTAT20
Galactocentric position diagram