Theia 391

0.36 UTI

0.69

C_N

0.1

C_dens

0.75

C_C3

0.13

C_lit

1.0

C_dup

N_m (P>50%) 88

Core radius and density 2.5 [pc], 0.5 [pc^-2]

C3 classification AB

C_N 0.69 Moderately populated
C_dens 0.1 Very loose
C_C3 0.75 High quality
C_lit 0.13 Rarely studied
C_dup 1.0 Unique

📥 Members 📊 Colab 🔬 Bayestar19

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

Overview

ℹ️

Theia 391 is a moderately populated, very loose object of high C3 quality. Its parallax locates it at a very close distance, near 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 moderate percentage of members with a later reported entry. See table with shared members information.

Close Low extinction Near-solar metallicity Intermediate age

Liu et al. (2025)
Classified as tidal capture (resonant trapping binary) 338 along with Stock_12.

Palma et al. (2025)
Classified as optical pair (not dynamically associated) P167, along with Stock_12.

Cavallo et al. (2024)
Gold sample.

Hunt & Reffert (2024)
Classified as moving group. CMD class: 0.84 (50th percentile).

Hunt & Reffert (2023)
Classified as open cluster. CMD class: 0.84 (50th percentile).

Data

🔍 Search references for Theia 391 in: SciX Simbad

ℹ️

Reference	Year	RA [deg]	DEC [deg]	Plx [mas]	pmRA [mas/yr]	pmDE [mas/yr]	Rv [km/s]
UCC	99999–	356.339	55.146	2.246	5.132	-4.41	-13.087
Yang et al.	2025	356.219	55.17	–	–	–	–
Zhang et al.	2024	356.219	55.17	–	–	–	–
Cavallo et al.	2024	356.658	55.045	2.206	–	–	–
Hunt & Reffert	2023	356.219	55.17	2.206	5.198	-4.456	-12.664
Kounkel & Covey	2019	353.952	54.537	1.718	–	–	-6.395

💡 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–	0.53	0.45	0.8	146	-0.034	–	–	–
Liu et al.	2025	0.62	0.24	–	145	–	–	–	–
Yang et al.	2025	–	–	–	144	-0.040⁽³⁾	–	–	–
Zhang et al.	2024	–	–	–	–	-0.034⁽¹⁾	–	–	–
Cavallo et al.	2024	0.46	0.71	–	170	0.510	–	–	–
Hunt & Reffert	2023	0.43	0.41	0.80	146	–	–	–	–
Kounkel & Covey	2019	0.60	0.49	–	148	–	–	–	–

(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 533	28.4	357.12	55.14	2.27	5.25	-4.46	-13.41	0.0

💡 Note: The % column shows the percentage of members that Theia 391 shares with each listed object.

Visualization

ℹ️

1 2