Theia 3975

0.15 UTI

0.0

C_N

0.06

C_dens

0.62

C_C3

0.03

C_lit

1.0

C_dup

N_m (P>50%) 23

Core radius and density 2.1 [pc], 0.3 [pc^-2]

C3 classification AC

C_N 0.0 Sparse
C_dens 0.06 Very loose
C_C3 0.62 Intermediate quality
C_lit 0.03 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 3975 is a sparse, very loose object of intermediate C3 quality. Its parallax locates it at a relatively close distance, below the mid-plane, affected by low extinction. It is catalogued as a near-solar metallicity, young cluster (see Parameters). It was recently reported 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.

Relatively close Low extinction Near-solar metallicity Young

Palma et al. (2025)
Classified as optical pair P458, along with HSC_2076.

Cavallo et al. (2024)
Gold sample.

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

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

Data

🔍 Search references for Theia 3975 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–	122.869	-42.316	0.736	-5.378	4.446	-21.538
Hunt & Reffert	2024	122.871	-42.342	0.73	-5.351	4.469	10.963
Cavallo et al.	2024	122.875	-42.383	0.729	–	–	–
Hunt & Reffert	2023	122.871	-42.342	0.73	-5.351	4.469	10.963

💡 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–	1.3	0.49	1.12	60	0.050	110	–	–
Hunt & Reffert	2024	1.30	0.49	1.12	60	–	110⁽¹⁾	–	–
Cavallo et al.	2024	1.32	0.51	–	78	0.050	–	–	–
Hunt & Reffert	2023	1.30	0.49	1.12	60	–	–	–	–

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

Visualization

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