RSG1

(Alessi 96; OCSN 255)

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0.96 UTI
0.82
CN
1.0
Cdens
1.0
CC3
1.0
Clit
1.0
Cdup
C3 classification AA
Number of members (P>50%) 297
Radius (P>50% members) 43.5 [arcmin]
  • CN 0.82 Rich
  • Cdens 1.0 Very dense
  • CC3 1.0 Very high quality
  • Clit 1.0 Very 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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RSG1 is a rich, very dense object of very high C3 quality. Its parallax locates it at a very 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 age and metallicity parameters (see Parameters). It is very well-studied in the literature.
Very close Low extinction Near-solar metallicity Intermediate age

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

Cavallo et al. (2024)
Gold sample.

Data
🔍 Search references for RSG1 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 – 75.554 37.481 3.027 0.688 -12.384 13.507
Li et al. 2025 75.508 37.475 3.001 0.77 -12.33 –
Wei et al. 2025 75.557 37.434 3.034 0.657 -12.389 –
Almeida et al. 2025 75.525 37.481 – – – –
Alfonso et al. 2024 75.483 37.525 2.997 0.75 -12.411 –
Zhang et al. 2024 75.485 37.488 – – – –
Hunt & Reffert 2024 75.485 37.488 3.053 0.971 -12.561 11.589
Cavallo et al. 2024 74.195 38.441 3.065 – – –
Hunt & Reffert 2023 75.485 37.488 3.053 0.971 -12.561 11.589
Almeida et al. 2023 75.554 37.499 – – – –
Qin et al. 2023 75.55 37.52 3.04 0.74 -12.42 14.28
He et al. 2022 75.511 37.508 3.035 0.703 -12.423 –
Tarricq et al. 2022 75.529 37.481 3.037 0.703 -12.419 –
Dias et al. 2021 75.525 37.481 3.002 0.768 -12.368 13.406
Cantat-Gaudin et al. 2020 75.508 37.475 3.001 0.77 -12.33 –
Cantat-Gaudin & Anders 2020 75.508 37.475 3.001 0.77 -12.33 –
Soubiran et al. 2018 75.508 37.475 – – – 14.69
Bica et al. 2019 75.569 37.558 – – – –
Cantat-Gaudin et al. 2018 75.508 37.475 3.001 0.77 -12.33 –
Roser et al. 2016 75.57 37.56 – 0.2 -12.32 –

💡 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
Li et al. 2025 0.32 0.68 – 106 0.042 – – –
Wei et al. 2025 0.49 1.20 – 50 -0.250 146 0.19 –
Almeida et al. 2025 0.33 0.59 – 303 – 144 – –
Alfonso et al. 2024 0.35 0.53 – 122 0.063 – – –
Zhang et al. 2024 – – – – 0.003* – – –
Hunt & Reffert 2024 – – – – – 193* – –
Cavallo et al. 2024 0.33 1.02 – 78 0.010 – – –
Hunt & Reffert 2023 0.32 0.36 1.14 207 – – – –
Almeida et al. 2023 0.31 0.74 – 242 -0.101 179* 0.50 –
Qin et al. 2023 0.45 0.78 – 79 – – – –
He et al. 2022 – 0.90 – 112 – – – –
Tarricq et al. 2022 0.34 – – 120 – – – –
Dias et al. 2021 0.33 0.59 – 303 0.063 – – –
Cantat-Gaudin et al. 2020 0.35 0.53 – 123 – – – –
Cantat-Gaudin & Anders 2020 0.33 – – – – – – –
Soubiran et al. 2018 0.33 – – – – – – –
Cantat-Gaudin et al. 2018 0.33 – – – – – – –
Roser et al. 2016 0.32 0.74* – 126* – – – –

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

Visualization
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RSG1 UCC
RSG1 HUNT23
RSG1 CANTAT20
Galactocentric position diagram