Pismis 18

(MWSC 2142)

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0.95 UTI
0.87
CN
1.0
Cdens
1.0
CC3
0.94
Clit
1.0
Cdup
Nm (P>50%) 427
Core radius and density 0.9 [pc], 31 [pc-2]
C3 classification AA
  • CN 0.87 Rich
  • Cdens 1.0 Very dense
  • CC3 1.0 Very high quality
  • Clit 0.94 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
Pismis 18 is a rich, very dense object of very high C3 quality. Its parallax locates it at a moderate distance, near the mid-plane, affected by moderate extinction. It is catalogued as a massive, near-solar metallicity, intermediate-age cluster, but with a large variance across recent sources for the age, metallicity, and mass parameters (see Parameters). It is very well-studied in the literature.

Note: This object shares a small percentage of members with 2 later reported entries. See table with shared members information.

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 classes: 0.99 (50th percentile), true positive (human-assigned).

Hunt & Reffert (2023)
Classified as open cluster. CMD classes: 0.99 (50th percentile), true positive (human-assigned).

Hu et al. (2021)
Ellipticities (core, all): e_core=0.0762, e_all=0.0753.

Rain et al. (2021)
The distance d=2168.1 (dmode+01) of Cantat-Gaudin et al. (2018A&A...618A..93C, Cat. J/A+A18/A93) was used to fit the isochrone.

Morales et al. (2013)
Classified as morphological type 'OC2' (totally exposed cluster without correlation with ATLASGAL emission). Morphological flag: exposed cluster, without submm emission.

Ahumada & Lapasset (2007)
All the cluster parameters are from (2005, unpublished data). The diagram of stars up to 3' was examined.

Data
πŸ” Search references for Pismis 18 in: SciX Simbad
ℹ️
Reference Year RA [deg] DEC [deg] Plx [mas] pmRA [mas/yr] pmDE [mas/yr] Rv [km/s]
UCC 99999– 204.23 -62.091 0.347 -5.695 -2.27 -28.578
Li et al. 2025 204.227 -62.091 0.332 -5.658 -2.286 –
Hu & Soubiran 2025 204.213 -62.095 – – – –
Almeida et al. 2025 204.232 -62.096 – – – –
Hunt & Reffert 2024 204.227 -62.091 0.347 -5.692 -2.269 -27.593
Cavallo et al. 2024 204.213 -62.095 0.347 – – –
Hunt & Reffert 2023 204.227 -62.091 0.347 -5.692 -2.269 -27.593
Just et al. 2023 204.222 -62.062 – – – –
Jadhav & Subramaniam 2021 204.227 -62.091 – – – –
Jaehnig et al. 2021 204.227 -62.091 0.356 -5.66 -2.272 –
Rain et al. 2021 204.227 -62.091 0.332 -5.658 -2.286 –
Dias et al. 2021 204.232 -62.096 0.328 -5.672 -2.296 -28.04
Cantat-Gaudin et al. 2020 204.227 -62.091 0.332 -5.658 -2.286 –
SΓ‘nchez et al. 2020 204.229 -62.093 – -5.66 -2.336 –
Cantat-Gaudin & Anders 2020 204.227 -62.091 0.332 -5.658 -2.286 –
Soubiran et al. 2018 204.227 -62.091 – – – -28.45
Cantat-Gaudin et al. 2018 204.227 -62.091 0.332 -5.658 -2.286 –
Dias et al. 2018 – – – -6.0 -2.29 –
Sampedro et al. 2017 204.229 -62.093 – -1.92 -4.88 –
Kharchenko et al. 2016 204.222 -62.062 – – – –
Dias et al. 2014 204.229 -62.093 – -2.43 -5.11 –
Kharchenko et al. 2013 204.232 -62.065 – -8.25 -1.7 –
Morales et al. 2013 204.229 -62.093 – – – –
Bukowiecki et al. 2011 204.246 -62.062 – – – –
Ahumada & Lapasset 2007 204.225 -62.1 – – – –
van den Bergh 2006 204.225 -62.092 – – – –
Dias et al. 2002 204.229 -62.093 – -2.43 -5.11 -27.9
Lynga 1987 204.151 -62.151 – – – –
van den Bergh & Hagen 1975 203.425 -61.8 – – – –

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– 2.5 1.885 1.22 822 0.120 2514 – 0
Li et al. 2025 2.33 1.96 – 754 0.226 – – –
Hu & Soubiran 2025 – – – – -0.250(5) – – –
Almeida et al. 2025 2.19 2.17 – 679 – 1609 – –
Hunt & Reffert 2024 2.67 2.40 1.22 323 – 3543(1) – –
Cavallo et al. 2024 2.09 2.03 – 1000 0.120 – – –
Hunt & Reffert 2023 2.67 2.40 1.22 323 – – – –
Just et al. 2023 – – – 944 – 655 – –
Spina et al. 2022 – – – – 0.143 – – –
Jadhav & Subramaniam 2021 2.86 1.81 – 575 – 2514 – 0(1)
Jaehnig et al. 2021 2.78(1) – – – – – – –
Rain et al. 2021 2.77 1.58 – 1202 – – – 0
Dias et al. 2021 2.19 2.17 – 679 -0.033 – – –
Cantat-Gaudin et al. 2020 2.86 1.81 – 575 – – – –
Kounkel et al. 2020 2.78 1.97 – 646 – – – –
Cantat-Gaudin & Anders 2020 2.77 – – – – – – –
Soubiran et al. 2018 2.77 – – – – – – –
Cantat-Gaudin et al. 2018 2.77 – – – – – – –
Kharchenko et al. 2016 2.31 1.64 – 944 – – – –
Kharchenko et al. 2013 2.31 1.64 – 944 – – – –
Morales et al. 2013 2.24 – – 891 – – – –
Bukowiecki et al. 2012 – – – – – 4272 – –
Bukowiecki et al. 2011 2.25(1) 1.64 – 891 – – – –
Ahumada & Lapasset 2007 – 1.96 – 398 – – – 3
van den Bergh 2006 2.24 1.58 – 1202 – – – –
Dias et al. 2002 2.24 1.58 – 1202 – – – –

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

Cluster % RA DEC Plx pmRA pmDE Rv UTI
IC 4291 24.6 204.23 -62.09 0.35 -5.71 -2.27 -28.64 0.0
OC 0598 1.6 204.21 -62.08 0.47 -5.48 -2.16 -2.53 0.05

πŸ’‘ Note: The % column shows the percentage of members that Pismis 18 shares with each listed object.

Visualization
ℹ️
Pismis 18 UCC
Pismis 18 HUNT23
Pismis 18 CANTAT20
Galactocentric position diagram