Ruprecht 42

(Berkeley 41; MWSC 1388; OCL 669; ESO 494 08)

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0.85 UTI
0.75
CN
1.0
Cdens
0.75
CC3
0.86
Clit
1.0
Cdup
C3 classification AB
Number of members (P>50%) 111
Radius (P>50% members) 1.4 [arcmin]
  • CN 0.75 Rich
  • Cdens 1.0 Very dense
  • CC3 0.75 High quality
  • Clit 0.86 Well-studied
  • Cdup 1.0 Unique
đŸ“Ĩ Members 📊 Colab đŸ”Ŧ Bayestar19 🔍 CDS 🔍 Simbad 🔍 CDS (Îą, δ) 🔍 Simbad (Îą, δ)

Overview
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Ruprecht 42 is a 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 a near-solar metallicity, intermediate-age cluster, but with a large variance across recent sources for the age and mass parameters (see Parameters). It is well-studied in the literature.

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

Very distant Moderate extinction Near-solar metallicity Intermediate age

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

Cavallo et al. (2024)
Gold sample.

Data
🔍 Search references for Ruprecht 42 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 – 119.404 -25.922 0.155 -1.892 2.219 81.646
Hu & Soubiran 2025 119.4 -25.92 – – – –
Almeida et al. 2025 119.399 -25.919 – – – –
Hunt & Reffert 2024 119.404 -25.925 0.156 -1.884 2.213 81.617
Cavallo et al. 2024 119.4 -25.92 0.158 – – –
Hunt & Reffert 2023 119.404 -25.925 0.156 -1.884 2.213 81.617
Almeida et al. 2023 119.398 -25.92 – – – –
Just et al. 2023 119.406 -25.933 – – – –
Dias et al. 2021 119.399 -25.919 0.116 -1.92 2.187 –
Cantat-Gaudin et al. 2020 119.407 -25.92 0.121 -1.911 2.191 –
Cantat-Gaudin & Anders 2020 119.407 -25.92 0.121 -1.911 2.191 –
Bica et al. 2019 119.388 -25.916 – – – –
Cantat-Gaudin et al. 2018 119.407 -25.92 0.121 -1.911 2.191 –
Kharchenko et al. 2016 119.406 -25.933 – – – –
Dias et al. 2014 119.4 -25.917 – -2.67 3.41 –
Kharchenko et al. 2013 119.412 -25.935 – -4.22 2.56 –
Dias et al. 2002 119.4 -25.917 – -2.67 3.41 –

💡 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] Bfr BSS
Hu & Soubiran 2025 – – – – -0.250* – – –
Almeida et al. 2025 4.92 1.40 – 438 – 418 – –
Hunt & Reffert 2024 – – – – – 679* – –
Cavallo et al. 2024 4.29 1.02 – 955 -0.260 – – –
Hunt & Reffert 2023 5.23 1.01 2.21 558 – – – –
Almeida et al. 2023 5.21 1.55 – 283 -0.236 689* 0.60 –
Just et al. 2023 – – – 501 – 111 – –
Dias et al. 2021 4.92 1.40 – 438 -0.262 – – –
Cantat-Gaudin et al. 2020 6.55 0.96 – 339 – – – –
Cantat-Gaudin & Anders 2020 6.68 – – – – – – –
Cantat-Gaudin et al. 2018 6.68 – – – – – – –
Kharchenko et al. 2016 1.96 1.29 – 501 – – – –
Kharchenko et al. 2013 1.96 1.29 – 501 – – – –
Dias et al. 2002 5.46 1.20 – 398 0.330 – – –

(*): Indicates that this parameter is assigned more than one value in the corresponding reference.

Cluster % RA DEC Plx pmRA pmDE Rv UTI
OC 0421 22.5 119.41 -25.92 0.16 -1.91 2.22 – 0.0

💡 Note: The % column shows the percentage of members that Ruprecht 42 shares with each listed object.

Visualization
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Ruprecht 42 UCC
Ruprecht 42 HUNT23
Ruprecht 42 CANTAT20
Galactocentric position diagram