Theia 651

0.22 UTI

0.0

C_N

0.22

C_dens

0.75

C_C3

0.06

C_lit

1.0

C_dup

N_m (P>50%) 24

Core radius and density 1.5 [pc], 1.1 [pc^-2]

C3 classification AB

C_N 0.0 Sparse
C_dens 0.22 Very loose
C_C3 0.75 High quality
C_lit 0.06 Rarely studied
C_dup 1.0 Unique

📥 Members 📊 Colab 🔬 Bayestar19

MOCA 🔍 CDS 🔍 Simbad 🔍 CDS (α, δ) 🔍 Simbad (α, δ)

Overview

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Theia 651 is a sparse, very loose object of high C3 quality. Its parallax locates it at a 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.

Note: This object shares a large percentage of members with a later reported entry. See table with shared members information.

⚠️ Warning: the low UTI value and no obvious signs of duplication (C_dup=1.0) indicate that this is quite probably an asterism, moving group, or artifact, and not a real open cluster.

Close Low extinction Near-solar metallicity Intermediate age

Palma et al. (2025)
Classified as optical pair P373, along with CWNU_384.

Cavallo et al. (2024)
Gold sample.

Hunt & Reffert (2024)
Classified as moving group. CMD class: 0.99 (50th percentile).

Hunt & Reffert (2023)
Classified as open cluster. CMD class: 0.99 (50th percentile).

Data

🔍 Search references for Theia 651 in: SciX Simbad

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Reference	Year	RA [deg]	DEC [deg]	Plx [mas]	pmRA [mas/yr]	pmDE [mas/yr]	Rv [km/s]
UCC	99999–	130.945	-30.721	1.361	-2.537	-0.606	3.222
Hu & Soubiran	2025	130.833	-30.747	–	–	–	–
Cavallo et al.	2024	130.833	-30.747	1.36	–	–	–
Hunt & Reffert	2023	130.957	-30.737	1.356	-2.59	-0.554	3.95
Kounkel & Covey	2019	131.321	-31.41	1.467	–	–	-3.803

💡 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]	B_frac	BSS
UCC	99999–	0.69	0.19	0.3	575	-0.065	–	–	–
Hu & Soubiran	2025	–	–	–	–	-0.270⁽⁵⁾	–	–	–
Cavallo et al.	2024	0.69	0.19	–	575	0.140	–	–	–
Hunt & Reffert	2023	0.69	0.09	0.30	689	–	–	–	–
Kounkel & Covey	2019	0.68	0.27	–	282	–	–	–	–

(N): Indicates that there are N extra values assigned to this parameter in the corresponding reference.

Cluster	%	RA	DEC	Plx	pmRA	pmDE	Rv	UTI
CWNU 417	96.0	130.89	-30.71	1.36	-2.56	-0.55	2.96	0.08

💡 Note: The % column shows the percentage of members that Theia 651 shares with each listed object.

Visualization

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