Alessi 31

(ASCC 92; MWSC 2723; FoF 2356)

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0.88 UTI
0.78
CN
1.0
Cdens
1.0
CC3
0.81
Clit
1.0
Cdup
N50 (P>50% members) 175
Stellar density (N50/rad) 18.5 [N/pc2]
C3 classification AA
  • CN 0.78 Rich
  • Cdens 1.0 Very dense
  • CC3 1.0 Very high quality
  • Clit 0.81 Well-studied
  • Cdup 1.0 Unique
đŸ“Ĩ Members 📊 Colab đŸ”Ŧ Bayestar19 MOCAMOCA 🔍 CDS 🔍 Simbad 🔍 CDS (Îą, δ) 🔍 Simbad (Îą, δ)

Overview
ℹī¸
Alessi 31 is a rich, very dense object of very high C3 quality. Its parallax locates it at a close 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 distance, age, metallicity, and mass parameters (see Parameters). It is well-studied in the literature.

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

Cavallo et al. (2024)
Gold sample.

Hunt & Reffert (2024)
Classified as open cluster. CMD class: 0.83 (50th percentile).

Hunt & Reffert (2023)
Classified as open cluster. CMD class: 0.83 (50th percentile).

Bica et al. (2019)
Web updates in DAML02, some were later removed (2003 to 2010). List of clusters and alike reported by B. Alessi. The Preliminary Amateur Open Cluster Catalog, Version 08/03/2003.

Data
🔍 Search references for Alessi 31 in: SciX Simbad
ℹī¸
Reference Year RA [deg] DEC [deg] Plx [mas] pmRA [mas/yr] pmDE [mas/yr] Rv [km/s]
UCC 99999– 267.715 -11.837 1.476 -1.147 -4.172 2.939
Li et al. 2025 267.698 -11.853 1.477 -1.164 -4.122 –
Wei et al. 2025 267.725 -11.842 1.475 -1.136 -4.179 –
Almeida et al. 2025 267.665 -11.882 – – – –
Alfonso et al. 2024 267.719 -11.85 1.442 -1.139 -4.178 –
Hunt & Reffert 2024 267.748 -11.857 1.473 -1.13 -4.167 3.514
Cavallo et al. 2024 267.715 -11.845 1.474 – – –
Hunt & Reffert 2023 267.748 -11.857 1.473 -1.13 -4.167 3.514
Just et al. 2023 267.772 -11.881 – – – –
He et al. 2022 267.741 -11.859 1.481 -1.136 -4.208 –
Tarricq et al. 2022 267.747 -11.87 1.503 -1.137 -4.177 –
Dias et al. 2021 267.665 -11.882 1.483 -1.189 -4.091 –
Cantat-Gaudin et al. 2020 267.698 -11.853 1.477 -1.164 -4.122 –
Cantat-Gaudin & Anders 2020 267.698 -11.853 1.477 -1.164 -4.122 –
Liu & Pang 2019 267.752 -11.835 1.474 -1.157 -4.115 –
Soubiran et al. 2018 267.698 -11.853 – – – 5.36
Bica et al. 2019 267.68 -12.002 – – – –
Cantat-Gaudin et al. 2018 267.698 -11.853 1.477 -1.164 -4.122 –
Dib et al. 2018 267.78 -11.88 – – – –
Sampedro et al. 2017 267.675 -12.002 -5.25 -2.2 – –
Joshi et al. 2016 267.78 -11.88 – – – –
Kharchenko et al. 2016 267.772 -11.881 – – – –
Dias et al. 2014 267.675 -12.002 – -5.29 -2.16 –
Kharchenko et al. 2013 267.78 -11.88 – -6.63 -5.53 –
Piskunov et al. 2008 267.774 -11.883 – – – –
Kharchenko et al. 2005 267.78 -11.88 – -7.68 -4.91 –
Dias et al. 2002 267.675 -12.002 – -5.29 -2.16 –

💡 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– 0.65 1.75 2.5 351 0.285 371 0.47 –
Li et al. 2025 0.55 1.75 – 601 0.147 – – –
Wei et al. 2025 2.10 3.31 – 28 -0.750 371 0.47 –
Almeida et al. 2025 0.65 2.15 – 113 – 557 – –
Alfonso et al. 2024 0.71 1.75 – 79 0.359 – – –
Hunt & Reffert 2024 – – – – – 668(1) – –
Cavallo et al. 2024 0.70 2.37 – 126 0.320 – – –
Hunt & Reffert 2023 0.64 2.23 2.50 150 – – – –
Just et al. 2023 – – – 1202 – 25 – –
He et al. 2022 – 2.70 – 40 – – – –
Tarricq et al. 2022 0.70 – – 251 – – – –
Dias et al. 2021 0.65 2.15 – 113 0.359 – – –
Cantat-Gaudin et al. 2020 0.71 1.75 – 240 – – – –
Kounkel et al. 2020 0.65 1.79 – 355 – – – –
Cantat-Gaudin & Anders 2020 0.66 – – – – – – –
Liu & Pang 2019 – – – 347 0.250 – – –
Soubiran et al. 2018 0.66 – – – – – – –
Cantat-Gaudin et al. 2018 0.66 – – – – – – –
Dib et al. 2018 0.64 – – 1202 – – – –
Joshi et al. 2016 0.64 0.98 – 1202 – 234 – –
Kharchenko et al. 2016 0.64 0.98 – 1202 – – – –
Kharchenko et al. 2013 0.64 0.98 – 1202 – – – –
Piskunov et al. 2008 0.65 0.79 – 1023 – – – –
Kharchenko et al. 2005 0.65 0.79 – 1023 – – – –
Dias et al. 2002 0.65 0.79 – 1023 – – – –

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

Visualization
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Alessi 31 UCC
Alessi 31 HUNT23
Alessi 31 CANTAT20
Galactocentric position diagram