Trumpler 21

(Collinder 274; VDBH 148; MWSC 2131; OCL 903; vdBergh-Hagen 148; ESO 096 15; FoF 2099)

Click to load Aladin Lite
0.90 UTI
0.76
CN
1.0
Cdens
0.75
CC3
1.0
Clit
1.0
Cdup
N50 (P>50% members) 131
Stellar density (N50/rad) 64.8 [N/pc2]
C3 classification AB
  • CN 0.76 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
ℹī¸
Trumpler 21 is a rich, very 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, young 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.

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

Cavallo et al. (2024)
Gold sample.

Hunt & Reffert (2024)
Classified as open cluster. CMD class: 1.00 (50th percentile).

Richer et al. (2021)
The expected number of WDs is 0.45, 0 WD candidates found, and 0 WD candidates found in the wide search.

Rain et al. (2021)
This cluster was include in (Dias et al., 2002A&A...389..871D, Cat. B/ocl) however, parameters log(t)=7.690, Av=0.723, [Fe/H]=0.000 were taken from Bossini et al. (2019A&A...623A.108B, Cat. J/A+A/623/A108). The distance d=1174.4 (dmode+01) of Cantat-Gaudin et al. (2018A&A...618A..93C, Cat. J/A+A18/A93) was use 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, with submm emission not associated with the cluster.

Data
🔍 Search references for Trumpler 21 in: SciX Simbad
ℹī¸
Reference Year RA [deg] DEC [deg] Plx [mas] pmRA [mas/yr] pmDE [mas/yr] Rv [km/s]
UCC 99999– 203.057 -62.787 0.736 -4.708 -2.258 -13.411
Li et al. 2025 203.068 -62.787 0.722 -4.682 -2.312 –
Wei et al. 2025 203.048 -62.785 0.738 -4.707 -2.259 –
Almeida et al. 2025 203.067 -62.789 – – – –
Hunt & Reffert 2024 203.055 -62.781 0.726 -4.719 -2.267 -14.672
Cavallo et al. 2024 203.048 -62.791 0.731 – – –
Hunt & Reffert 2023 203.055 -62.781 0.726 -4.719 -2.267 -14.672
Almeida et al. 2023 203.057 -62.792 – – – –
Cordoni et al. 2023 203.067 -62.789 0.725 -4.667 -2.293 –
Just et al. 2023 203.043 -62.797 – – – –
Jaehnig et al. 2021 203.073 -62.788 0.756 -4.671 -2.313 –
Rain et al. 2021 203.068 -62.787 0.722 -4.682 -2.312 –
Richer et al. 2021 203.044 -62.786 0.728 -4.681 -2.302 –
Dias et al. 2021 203.067 -62.789 0.725 -4.667 -2.293 –
Cantat-Gaudin et al. 2020 203.068 -62.787 0.722 -4.682 -2.312 –
Cantat-Gaudin & Anders 2020 203.068 -62.787 0.722 -4.682 -2.312 –
Liu & Pang 2019 203.066 -62.787 0.728 -4.674 -2.273 –
Bossini et al. 2019 203.068 -62.787 – – – –
Bica et al. 2019 203.043 -62.784 – – – –
Cantat-Gaudin et al. 2018 203.068 -62.787 0.722 -4.682 -2.312 –
Loktin & Popova 2017 203.055 -62.8 – -8.459 -2.734 -32.9
Kharchenko et al. 2016 203.043 -62.797 – – – –
Dias et al. 2014 203.058 -62.8 – -3.57 -3.34 –
Kharchenko et al. 2013 203.055 -62.8 – -10.4 -4.5 -32.9
Morales et al. 2013 203.058 -62.8 – – – –
Piskunov et al. 2008 203.047 -62.794 – – – –
Ahumada & Lapasset 2007 203.05 -62.8 – – – –
van den Bergh 2006 203.05 -62.8 – – – –
Kharchenko et al. 2005 203.05 -62.8 – -10.41 -4.77 –
Kharchenko et al. 2003 203.05 -62.78 – -11.09 -1.86 –
Dias et al. 2002 203.058 -62.8 – -3.62 -3.36 –
Dambis 1999 203.05 -62.8 – – – –
Lynga 1987 203.05 -62.804 – – – –
van den Bergh & Hagen 1975 202.2 -62.533 – – – –

💡 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– 1.28 0.725 0.66 51 0.036 436 0.33 0
Li et al. 2025 1.10 0.75 – 58 -0.256 – – –
Wei et al. 2025 1.72 1.00 – 44 0.000 597 0.31 –
Almeida et al. 2025 1.28 0.85 – 51 – 343 – –
Hunt & Reffert 2024 – – – – – 528(1) – –
Cavallo et al. 2024 1.14 1.02 – 69 -0.450 – – –
Hunt & Reffert 2023 1.28 0.60 0.66 95 – – – –
Almeida et al. 2023 1.26 0.83 – 63 0.073 253(1) 0.51 –
Cordoni et al. 2023 1.28 0.85 – 51 0.138 2163 0.33 0(1)
Just et al. 2023 – – – 71 – 81 – –
Tarricq et al. 2022 1.29 – – 51 – – – –
Jaehnig et al. 2021 1.33(1) – – – – – – –
Rain et al. 2021 1.33 0.73 – 49 – – – 0
Richer et al. 2021 – 0.84 – 49 – – – –
Dias et al. 2021 1.28 0.85 – 51 0.138 – – –
Cantat-Gaudin et al. 2020 1.32 0.58 – 49 – – – –
Kounkel et al. 2020 1.30 0.86 – 72 – – – –
Cantat-Gaudin & Anders 2020 1.33 – – – – – – –
Liu & Pang 2019 – – – 33 0.500 – – –
Bossini et al. 2019 1.29 0.72 – 49 0.000 – – –
Cantat-Gaudin et al. 2018 1.33 – – – – – – –
Loktin & Popova 2017 1.32 0.59 – 54 – – – –
Kharchenko et al. 2016 1.27 0.79 – 71 – – – –
Kharchenko et al. 2013 1.27 0.79 – 71 – – – –
Morales et al. 2013 1.26 – – 50 – – – –
Piskunov et al. 2008 1.31 0.57 – 58 – – – –
Ahumada & Lapasset 2007 – 0.63 – 50 – – – 0
van den Bergh 2006 1.26 0.63 – 50 – – – –
Kharchenko et al. 2005 1.31 0.57 – 58 – – – –
Kharchenko et al. 2003 1.26 0.63 – – – – – –
Dias et al. 2002 1.26 0.62 – 50 – – – –
Dambis 1999 1.13 0.68 – 40 – – – –
Lynga 1987 1.10 0.63 – 63 – – – –

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

Visualization
ℹī¸
Trumpler 21 UCC
Trumpler 21 HUNT23
Trumpler 21 CANTAT20
Galactocentric position diagram