Theia 101

0.20 UTI

0.0

C_N

0.1

C_dens

0.38

C_C3

0.25

C_lit

1.0

C_dup

C3 classification CB

Number of members (P>50%) 21

Radius (P>50% members) 46.5 [arcmin]

C_N 0.0 Sparse
C_dens 0.1 Very loose
C_C3 0.38 Low quality
C_lit 0.25 Poorly studied
C_dup 1.0 Unique

📥 Members 📊 Colab 🔬 Bayestar19 🔍 CDS 🔍 Simbad 🔍 CDS (α, δ) 🔍 Simbad (α, δ)

Overview

ℹ️

Theia 101 is a sparse, very loose object of low 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 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.

Very close Low extinction Near-solar metallicity Intermediate age

Cavallo et al. (2024)
Gold sample.

Hunt & Reffert (2024)
Classified as a moving group.

Data

🔍 Search references for Theia 101 in: SciX Simbad

ℹ️

Reference	Year	RA [deg]	DEC [deg]	Plx [mas]	pmRA [mas/yr]	pmDE [mas/yr]	Rv [km/s]
UCC	–	323.246	53.072	2.113	3.189	-0.419	-26.068
Hu & Soubiran	2025	323.455	53.155	–	–	–	–
Zhang et al.	2024	323.573	53.072	–	–	–	–
Cavallo et al.	2024	323.455	53.155	2.081	–	–	–
Hunt & Reffert	2023	323.573	53.072	2.075	3.158	-0.497	-25.22

💡 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]	Bfr	BSS
Hu & Soubiran	2025	–	–	–	–	-0.150*	–	–	–
Zhang et al.	2024	–	–	–	–	0.076*	–	–	–
Cavallo et al.	2024	0.48	0.73	–	617	0.390	–	–	–
Hunt & Reffert	2023	0.45	0.74	0.98	135	–	–	–	–

(*): Indicates that this parameter is assigned more than one value in the corresponding reference.

Visualization

ℹ️

1 2