Theia 4
0.39
UTI
0.75
CN
0.35
Cdens
0.75
CC3
0.1
Clit
0.94
Cdup
Nm (P>50%)
107
Core radius and density
3.2 [pc], 1.7 [pc-2]
- CN 0.75 Rich
- Cdens 0.35 Loose
- CC3 0.75 High quality
- Clit 0.1 Rarely studied
- Cdup 0.94 Very likely 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 4 is a rich, loose object of 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, 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 is very likely a unique object, which shares a very small percentage of members with at least one previously 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 | 344.354 | 62.994 | 1.163 | -2.404 | -2.559 | -13.562 |
| Liu et al. | 2025 | 344.13 | 62.98 | 1.16 | -2.4 | -2.55 | -17.25 |
| Hunt & Reffert | 2024 | 344.129 | 62.977 | 1.156 | -2.397 | -2.547 | -17.247 |
| Cavallo et al. | 2024 | 344.419 | 63.037 | 1.154 | â | â | â |
| Hunt & Reffert | 2023 | 344.129 | 62.977 | 1.156 | -2.397 | -2.547 | -17.247 |
| Kounkel & Covey | 2019 | 344.143 | 62.985 | 1.156 | â | â | -5.405 |
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 | 0.87 | 2.03 | 1.47 | 5 | -0.140 | 175 | â | â |
| Liu et al. | 2025 | 1.39 | 0.62 | â | 17 | â | â | â | â |
| Hunt & Reffert | 2024 | 0.83 | 2.03 | 1.47 | 5 | â | 175(1) | â | â |
| Cavallo et al. | 2024 | 0.87 | 2.09 | â | 5 | -0.140 | â | â | â |
| Hunt & Reffert | 2023 | 0.83 | 2.03 | 1.47 | 5 | â | â | â | â |
| Kounkel & Covey | 2019 | 0.87 | 1.97 | â | 2 | 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 344 along with UBC_178, and as tidal capture (resonant trapping binary) 395 along with UPK_198, and of multiple system 8 along with UPK_198, UBC_178, ASCC_125 and HSC_862.
Palma et al. (2025)
Part of multiple system G82, along with FSR_0416, HSC_862, UBC_178, HSC_892, ASCC_125 and UPK_198.
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).