Theia 863
0.33
UTI
0.64
CN
0.2
Cdens
0.5
CC3
0.16
Clit
1.0
Cdup
Nm (P>50%)
77
Core radius and density
3.5 [pc], 1.0 [pc-2]
- CN 0.64 Moderately populated
- Cdens 0.2 Very loose
- CC3 0.5 Intermediate quality
- Clit 0.16 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 863 is a moderately populated, very loose object of intermediate C3 quality. Its parallax locates it at a close distance, near the mid-plane, affected by moderate extinction. It is catalogued as a near-solar metallicity, intermediate-age cluster, but with a large variance across recent sources for the absorption and metallicity parameters (see Parameters). It is rarely studied in the literature.
Data
| Reference | Year | RA [deg] | DEC [deg] | Plx [mas] | pmRA [mas/yr] | pmDE [mas/yr] | Rv [km/s] |
|---|---|---|---|---|---|---|---|
| UCC | 99999â | 41.371 | 56.495 | 1.4 | -0.985 | -5.283 | -33.231 |
| Yang et al. | 2025 | 41.406 | 56.453 | â | â | â | â |
| Zhang et al. | 2024 | 41.406 | 56.453 | â | â | â | â |
| Hunt & Reffert | 2024 | 41.406 | 56.453 | 1.383 | -1.03 | -5.297 | -31.628 |
| Cavallo et al. | 2024 | 41.121 | 56.514 | 1.39 | â | â | â |
| Hunt & Reffert | 2023 | 41.406 | 56.453 | 1.383 | -1.03 | -5.297 | -31.628 |
| Kounkel & Covey | 2019 | 41.102 | 56.518 | 1.386 | â | â | -33.047 |
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 | 0.72 | 1.39 | 1.54 | 165 | -0.090 | 103 | â | â |
| Liu et al. | 2025 | 1.02 | 0.43 | â | 93 | â | â | â | â |
| Yang et al. | 2025 | â | â | â | 166 | -0.090(3) | â | â | â |
| Zhang et al. | 2024 | â | â | â | â | -0.135(1) | â | â | â |
| Hunt & Reffert | 2024 | 0.68 | 1.39 | 1.54 | 165 | â | 103(1) | â | â |
| Cavallo et al. | 2024 | 0.75 | 1.61 | â | 155 | 0.220 | â | â | â |
| Hunt & Reffert | 2023 | 0.68 | 1.39 | 1.54 | 165 | â | â | â | â |
| Kounkel & Covey | 2019 | 0.72 | 1.09 | â | 438 | 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 hyperbolic encounter pair 352 along with Trumpler_2.
Palma et al. (2025)
Part of multiple system G250, along with Theia_1432, Theia_862 and Trumpler_2.
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).