Theia 638
0.23
UTI
0.29
CN
0.28
Cdens
0.38
CC3
0.1
Clit
1.0
Cdup
Stellar density (N50/rad)
1.4 [N/pc2]
- CN 0.29 Poorly populated
- Cdens 0.28 Loose
- CC3 0.38 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 638 is a poorly populated, loose object of low C3 quality. Its parallax locates it at a close distance, near the mid-plane, affected by low extinction. It is catalogued as a near-solar metallicity, intermediate-age cluster (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 | 48.464 | 59.403 | 1.882 | -5.789 | -1.456 | -10.958 |
| Yang et al. | 2025 | 48.398 | 59.261 | â | â | â | â |
| Zhang et al. | 2024 | 48.398 | 59.261 | â | â | â | â |
| Cavallo et al. | 2024 | 47.669 | 59.879 | 1.857 | â | â | â |
| Hunt & Reffert | 2023 | 48.398 | 59.261 | 1.86 | -5.763 | -1.504 | -13.195 |
| Kounkel & Covey | 2019 | 48.28 | 59.909 | 1.862 | â | â | -12.425 |
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 | 0.54 | 0.62 | 0.96 | 166 | -0.060 | â | â | â |
| Yang et al. | 2025 | â | â | â | 166 | -0.150(3) | â | â | â |
| Zhang et al. | 2024 | â | â | â | â | -0.060(1) | â | â | â |
| Cavallo et al. | 2024 | 0.55 | 1.14 | â | 112 | 0.140 | â | â | â |
| Hunt & Reffert | 2023 | 0.51 | 0.62 | 0.96 | 167 | â | â | â | â |
| Kounkel & Covey | 2019 | 0.54 | 0.60 | â | 252 | â | â | â | â |
(N): Indicates that there are N extra values assigned to this parameter in the corresponding reference.
Palma et al. (2025)
Classified as optical pair (not dynamically associated) P174, along with Theia_311.
Cavallo et al. (2024)
Gold sample.
Hunt & Reffert (2024)
Classified as moving group. CMD class: 1.00 (50th percentile).
Hunt & Reffert (2023)
Classified as open cluster. CMD class: 1.00 (50th percentile).