Theia 66
0.53
UTI
0.51
CN
0.74
Cdens
1.0
CC3
0.19
Clit
1.0
Cdup
Nm (P>50%)
52
Core radius and density
1.5 [pc], 3.7 [pc-2]
- CN 0.51 Moderately populated
- Cdens 0.74 Moderately dense
- CC3 1.0 Very high quality
- Clit 0.19 Rarely studied
- Cdup 1.0 Unique
đĨ Members
đ Colab
đŦ Bayestar19
MOCA
đ CDS
đ Simbad
đ CDS (Îą, δ)
đ Simbad (Îą, δ)
MOCA
đ CDS
đ Simbad
đ CDS (Îą, δ)
đ Simbad (Îą, δ)
Overview
Theia 66 is a moderately populated, moderately 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 low-mass, near-solar metallicity, very young cluster, but with a large variance across recent sources for the absorption parameter (see Parameters). It is rarely studied in the literature.
Note: This object shares a large percentage of members with a later reported entry. See table with shared members information.
Data
| Reference | Year | RA [deg] | DEC [deg] | Plx [mas] | pmRA [mas/yr] | pmDE [mas/yr] | Rv [km/s] |
|---|---|---|---|---|---|---|---|
| UCC | 99999â | 68.304 | 18.009 | 6.883 | 12.083 | -18.994 | 17.869 |
| Liu et al. | 2025 | 68.14 | 18.1 | 6.88 | 12.2 | -18.93 | 18.99 |
| Yang et al. | 2025 | 68.144 | 18.103 | â | â | â | â |
| Zhang et al. | 2024 | 68.144 | 18.103 | â | â | â | â |
| Swiggum et al. | 2024 | 68.144 | 18.103 | 6.88 | 12.202 | -18.932 | 18.788 |
| Cavallo et al. | 2024 | 68.85 | 17.804 | 6.88 | â | â | â |
| Hunt & Reffert | 2023 | 68.144 | 18.103 | 6.88 | 12.202 | -18.932 | 18.989 |
| He et al. | 2022 | 68.245 | 18.01 | 6.874 | 12.278 | -18.898 | â |
| Kounkel & Covey | 2019 | 68.478 | 17.775 | 6.807 | â | â | 3.075 |
đĄ 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 | 99999â | 0.15 | 0.23 | 1.47 | 6 | -0.001 | 35 | â | â |
| Liu et al. | 2025 | 0.15 | 0.11 | â | 5 | â | â | â | â |
| Yang et al. | 2025 | â | â | â | 6 | -0.220(3) | â | â | â |
| Zhang et al. | 2024 | â | â | â | â | -0.001(1) | â | â | â |
| Swiggum et al. | 2024 | 0.14 | â | â | 6 | â | 35 | â | â |
| Cavallo et al. | 2024 | 0.15 | 1.80 | â | 19 | 0.080 | â | â | â |
| Hunt & Reffert | 2023 | 0.14 | 0.44 | 1.47 | 6 | â | â | â | â |
| He et al. | 2022 | â | 0.15 | â | 4 | â | â | â | â |
| Kounkel & Covey | 2019 | 0.15 | 0.23 | â | 27 | â | â | â | â |
(N): Indicates that there are N extra values assigned to this parameter in the corresponding reference.
Liu et al. (2025)
Classified as primordial binary cluster 96 along with CWNU_1129, and as tidal capture (resonant trapping binary) 195 along with HSC_1438, and of multiple system 35 along with Theia_71, HSC_1438, CWNU_1129, Theia_54 and HSC_1426.
Palma et al. (2025)
Part of multiple system G31, along with Theia_54 and CWNU_1129.
Cavallo et al. (2024)
Bronze sample.
Hunt & Reffert (2024)
Classified as moving group. CMD class: 0.77 (50th percentile).
Hunt & Reffert (2023)
Classified as open cluster. CMD class: 0.77 (50th percentile).