NGC 2251

(Collinder 101; MWSC 916; OCL 499)

Click to load Aladin Lite
0.85 UTI
0.78
CN
0.73
Cdens
0.75
CC3
1.0
Clit
1.0
Cdup
Nm (P>50%) 171
Core radius and density 1.6 [pc], 3.7 [pc-2]
C3 classification AB
  • CN 0.78 Rich
  • Cdens 0.73 Moderately 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
ℹī¸
NGC 2251 is a rich, moderately dense object of high C3 quality. Its parallax locates it at a relatively close distance, near the mid-plane, affected by low extinction. It is catalogued as a near-solar metallicity, intermediate-age 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.

Palma et al. (2025)
Classified as optical pair P269, along with Basel_8.

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

Cavallo et al. (2024)
Gold sample.

Hunt & Reffert (2024)
Classified as open cluster. CMD class: 0.99 (50th percentile).

Hunt & Reffert (2023)
Classified as open cluster. CMD class: 0.99 (50th percentile).

Hu et al. (2021)
Ellipticities (core, all): e_core=0.3422, e_all=0.2852.

Ahumada & Lapasset (2007)
Stars 1=HD 259954, 4 (pg)=HD 259989, and 4 (pe)=HD 260022 are cited as blue stragglers in (1985ApJ...294L.103A) and (1982A&A...109...37M). Reference (1985ApJ...294L.103A) gives: star 1 (sp. B2IV, v.sin i<40km/s); star 34 (sp. B9.5V, v.sin i= 200km/s (approx)); star 4 (sp. A0p(Si)).

Data
🔍 Search references for NGC 2251 in: SciX Simbad
ℹī¸
Reference Year RA [deg] DEC [deg] Plx [mas] pmRA [mas/yr] pmDE [mas/yr] Rv [km/s]
UCC 99999– 98.673 8.349 0.675 0.67 -3.816 25.601
Li et al. 2025 98.68 8.337 0.658 0.697 -3.806 –
Yang et al. 2025 98.676 8.344 – – – –
Almeida et al. 2025 98.687 8.357 – – – –
Hunt & Reffert 2024 98.676 8.344 0.678 0.642 -3.795 27.096
Cavallo et al. 2024 98.684 8.366 0.679 – – –
Hunt & Reffert 2023 98.676 8.344 0.678 0.642 -3.795 27.096
Just et al. 2023 98.647 8.371 – – – –
Tarricq et al. 2022 98.67 8.349 0.667 0.659 -3.829 –
Jaehnig et al. 2021 98.671 8.352 0.697 0.701 -3.831 –
Netopil et al. 2022 98.659 8.367 – – – 25.62
Rain et al. 2021 98.68 8.337 0.658 0.697 -3.806 –
Dias et al. 2021 98.687 8.357 0.647 0.676 -3.824 26.138
Cantat-Gaudin et al. 2020 98.68 8.337 0.658 0.697 -3.806 –
Cantat-Gaudin & Anders 2020 98.68 8.337 0.658 0.697 -3.806 –
Bossini et al. 2019 98.68 8.337 – – – –
Soubiran et al. 2018 98.68 8.337 – – – 26.1
Bica et al. 2019 98.664 8.366 – – – –
Cantat-Gaudin et al. 2018 98.68 8.337 0.658 0.697 -3.806 –
Dias et al. 2018 – – – 0.34 -3.32 –
Dib et al. 2018 98.655 8.37 – – – –
Loktin & Popova 2017 98.655 8.368 – -0.526 -0.522 -16.0
Sampedro et al. 2017 98.658 8.367 – -1.42 -0.18 –
Joshi et al. 2016 98.655 8.37 – – – –
Kharchenko et al. 2016 98.647 8.371 – – – –
Netopil et al. 2016 98.658 8.367 – – – –
Dias et al. 2014 98.658 8.367 – -1.13 -0.17 –
Kharchenko et al. 2013 98.655 8.37 – -1.95 -2.34 -16.0
Gozha et al. 2012 98.658 8.367 – – – –
Bukowiecki et al. 2011 98.638 8.356 – – – –
Piskunov et al. 2008 98.65 8.37 – – – –
Kharchenko et al. 2007 98.65 8.37 – 0.2 – -16.0
Ahumada & Lapasset 2007 98.675 8.367 – – – –
van den Bergh 2006 98.65 8.367 – – – –
Kharchenko et al. 2005 98.65 8.37 – 0.67 -2.79 -16.0
Kharchenko et al. 2003 98.67 8.37 – -0.24 -2.6 –
Chen et al. 2003 98.655 8.361 – – – –
Dias et al. 2002 98.658 8.367 – -1.13 -0.17 25.33
Lynga 1987 98.691 8.357 – – – –
Sulentic et al. 1973 98.691 8.363 – – – –

💡 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– 1.34 0.6 1.03 285 -0.090 251 – 2
Li et al. 2025 1.33 0.78 – 365 -0.052 – – –
Yang et al. 2025 – – – 490 -0.060(3) – – –
Almeida et al. 2025 1.31 0.92 – 325 – 365 – –
Hunt & Reffert 2024 1.39 0.58 1.03 491 – 736(1) – –
Cavallo et al. 2024 1.43 0.75 – 363 0.260 – – –
Hunt & Reffert 2023 1.39 0.58 1.03 491 – – – –
Just et al. 2023 – – – 285 – 101 – –
Tarricq et al. 2022 1.46 – – 275 – – – –
Jaehnig et al. 2021 1.44(1) – – – – – – –
Netopil et al. 2022 1.39(1) – – 309 -0.090(1) – – –
Rain et al. 2021 1.45 0.57 – 263 – – – 0
Dias et al. 2021 1.31 0.92 – 325 -0.092 – – –
Cantat-Gaudin et al. 2020 1.52 0.85 – 275 – – – –
Kounkel et al. 2020 1.45 0.93 – 302 – – – –
Cantat-Gaudin & Anders 2020 1.45 – – – – – – –
Bossini et al. 2019 1.39 0.72 – 308 -0.090 – – –
Soubiran et al. 2018 1.45 – – – – – – –
Cantat-Gaudin et al. 2018 1.45 – – – – – – –
Dib et al. 2018 1.33 – – 285 – – – –
Loktin & Popova 2017 1.34 0.59 – 273 – – – –
Joshi et al. 2016 1.33 0.60 – 285 – 251 – –
Kharchenko et al. 2016 1.33 0.60 – 285 – – – –
Netopil et al. 2016 9.26 – – 250 -0.090(2) – – –
Heiter et al. 2014 – – – – -0.090 – – –
Kharchenko et al. 2013 1.33 0.60 – 285 0.250 – – –
Bukowiecki et al. 2012 – – – – – 170 – –
Gozha et al. 2012 1.33 – – 267 0.250 251 – –
Bukowiecki et al. 2011 1.26(1) 0.66 – 224 – – – –
Paunzen et al. 2010 – – – – -0.210 – – –
Piskunov et al. 2008 1.33 0.60 – 269 – – – –
Ahumada & Lapasset 2007 – 0.60 – 269 – – – 3
van den Bergh 2006 1.33 0.60 – 269 – – – –
Kharchenko et al. 2005 1.33 0.60 – 269 – – – –
Kharchenko et al. 2003 1.33 0.60 – – – – – –
Chen et al. 2003 1.33 0.59 – 260 -0.080(1) – – –
Dias et al. 2002 1.33 0.59 – 267 -0.100 – – –
Lynga 1987 1.55 0.73 – 302 – – – –

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

Visualization
ℹī¸
NGC 2251 UCC
NGC 2251 HUNT23
NGC 2251 CANTAT20
Galactocentric position diagram