Theia 139

0.21 UTI

0.31

C_N

0.19

C_dens

0.38

C_C3

0.1

C_lit

1.0

C_dup

N_m (P>50%) 31

Core radius and density 1.6 [pc], 0.9 [pc^-2]

C3 classification CB

C_N 0.31 Poorly populated
C_dens 0.19 Very loose
C_C3 0.38 Low quality
C_lit 0.1 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 139 is a poorly populated, very loose object of low C3 quality. Its parallax locates it at a very close distance, below the mid-plane, affected by low extinction. It is catalogued as a near-solar metallicity, young cluster (see Parameters). It is rarely studied in the literature.

⚠️ 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.

Very close Low extinction Near-solar metallicity Young

Palma et al. (2025)
Classified as optical pair P607, along with OCSN_64.

Cavallo et al. (2024)
Gold sample.

Hunt & Reffert (2024)
Classified as moving group. CMD class: 0.98 (50th percentile).

Hunt & Reffert (2023)
Classified as open cluster. CMD class: 0.98 (50th percentile).

Data

🔍 Search references for Theia 139 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–	82.511	-2.114	3.114	-2.783	-4.261	14.731
Yang et al.	2025	82.51	-2.11	–	–	–	–
Zhang et al.	2024	82.51	-2.11	–	–	–	–
Cavallo et al.	2024	83.403	-1.296	3.056	–	–	–
Hunt & Reffert	2023	82.51	-2.11	3.054	-2.902	-4.27	16.194
Kounkel & Covey	2019	82.658	-0.662	2.514	–	–	1.136

💡 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–	0.34	0.41	0.88	74	0.020	–	–	–
Yang et al.	2025	–	–	–	96	-0.050⁽³⁾	–	–	–
Zhang et al.	2024	–	–	–	–	0.037⁽¹⁾	–	–	–
Cavallo et al.	2024	0.34	0.46	–	35	0.020	–	–	–
Hunt & Reffert	2023	0.32	0.18	0.88	95	–	–	–	–
Kounkel & Covey	2019	0.44	0.41	–	52	–	–	–	–

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

Visualization

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