Theia 54

0.51 UTI

0.25

C_N

1.0

C_dens

1.0

C_C3

0.16

C_lit

1.0

C_dup

N_m (P>50%) 25

Core radius and density 0.8 [pc], 5.2 [pc^-2]

C3 classification AA

C_N 0.25 Poorly populated
C_dens 1.0 Very dense
C_C3 1.0 Very high quality
C_lit 0.16 Rarely studied
C_dup 1.0 Unique

📥 Members 📊 Colab 🔬 Bayestar19

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

Overview

ℹ️

Theia 54 is a poorly populated, very dense object of very 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 low-mass, near-solar metallicity, very young cluster, but with a large variance across recent sources for the absorption 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.

Very close Low extinction Low mass Near-solar metallicity Very young

Liu et al. (2025)
Classified as primordial binary cluster 346 along with CWNU_1129, and of multiple system 35 along with Theia_71, HSC_1438, CWNU_1129, HSC_1426 and Theia_66.

Palma et al. (2025)
Part of multiple system G31, along with Theia_66 and CWNU_1129.

Cavallo et al. (2024)
Gold sample.

Hunt & Reffert (2024)
Classified as moving group. CMD class: 0.78 (50th percentile).

Hunt & Reffert (2023)
Classified as open cluster. CMD class: 0.78 (50th percentile).

Data

🔍 Search references for Theia 54 in: SciX Simbad

ℹ️

Reference	Year	RA [deg]	DEC [deg]	Plx [mas]	pmRA [mas/yr]	pmDE [mas/yr]	Rv [km/s]
UCC	99999–	74.2	30.327	6.325	4.508	-24.66	13.89
Liu et al.	2025	74.0	30.42	6.36	4.4	-25.13	17.37
Yang et al.	2025	73.999	30.416	–	–	–	–
Swiggum et al.	2024	73.999	30.416	6.357	4.403	-25.133	15.387
Cavallo et al.	2024	75.489	30.105	6.359	–	–	–
Hunt & Reffert	2023	73.999	30.416	6.357	4.403	-25.133	17.369
He et al.	2022	74.871	29.925	6.376	4.139	-25.168	–
Kounkel & Covey	2019	75.674	30.215	6.268	–	–	0.226

💡 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–	0.15	0.42	1.1	6	0.060	30	–	–
Liu et al.	2025	0.15	0.06	–	8	–	–	–	–
Yang et al.	2025	–	–	–	4	-0.060⁽³⁾	–	–	–
Swiggum et al.	2024	0.16	–	–	4	–	30	–	–
Cavallo et al.	2024	0.15	1.08	–	13	0.180	–	–	–
Hunt & Reffert	2023	0.15	0.42	1.10	4	–	–	–	–
He et al.	2022	–	0.30	–	6	–	–	–	–
Kounkel & Covey	2019	0.16	1.56	–	22	–	–	–	–

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

Cluster	%	RA	DEC	Plx	pmRA	pmDE	Rv	UTI
OCSN 273	96.0	74.25	30.3	6.33	4.51	-24.7	13.89	0.06

💡 Note: The % column shows the percentage of members that Theia 54 shares with each listed object.

Visualization

ℹ️

1 2