Theia 817
0.19
UTI
0.26
CN
0.24
Cdens
0.25
CC3
0.1
Clit
1.0
Cdup
Nm (P>50%)
26
Core radius and density
1.1 [pc], 1.2 [pc-2]
- CN 0.26 Poorly populated
- Cdens 0.24 Very loose
- CC3 0.25 Low quality
- Clit 0.1 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 817 is a poorly populated, very loose object of low C3 quality. Its parallax locates it at a very close distance, above 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 metallicity parameter (see Parameters). It is rarely studied in the literature.
â ī¸ Warning: the low UTI value and no obvious signs of duplication (Cdup=1.0) indicate that this is quite probably an asterism, moving group, or artifact, and not a real open cluster.
Data
| Reference | Year | RA [deg] | DEC [deg] | Plx [mas] | pmRA [mas/yr] | pmDE [mas/yr] | Rv [km/s] |
|---|---|---|---|---|---|---|---|
| UCC | 99999â | 274.892 | 24.55 | 2.744 | -2.015 | 1.194 | -25.032 |
| Yang et al. | 2025 | 274.95 | 24.606 | â | â | â | â |
| Zhang et al. | 2024 | 274.95 | 24.606 | â | â | â | â |
| Cavallo et al. | 2024 | 274.738 | 24.266 | 2.732 | â | â | â |
| Hunt & Reffert | 2023 | 274.95 | 24.606 | 2.757 | -2.018 | 1.299 | -22.438 |
| Kounkel & Covey | 2019 | 275.321 | 24.339 | 2.605 | â | â | -9.931 |
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 | 0.38 | 0.25 | 0.71 | 223 | 0.125 | â | â | â |
| Yang et al. | 2025 | â | â | â | 195 | 0.060(3) | â | â | â |
| Zhang et al. | 2024 | â | â | â | â | 0.125(1) | â | â | â |
| Cavallo et al. | 2024 | 0.38 | 0.60 | â | 251 | 0.390 | â | â | â |
| Hunt & Reffert | 2023 | 0.35 | 0.25 | 0.71 | 195 | â | â | â | â |
| Kounkel & Covey | 2019 | 0.38 | 0.20 | â | 492 | â | â | â | â |
(N): Indicates that there are N extra values assigned to this parameter in the corresponding reference.
Palma et al. (2025)
Part of multiple system G238, along with HSC_483 and Teutsch_179.
Cavallo et al. (2024)
Gold sample.
Hunt & Reffert (2024)
Classified as moving group. CMD class: 0.94 (50th percentile).
Hunt & Reffert (2023)
Classified as open cluster. CMD class: 0.94 (50th percentile).