Theia 828

0.15 UTI

0.0

C_N

0.08

C_dens

0.62

C_C3

0.03

C_lit

1.0

C_dup

N_m (P>50%) 21

Core radius and density 2.0 [pc], 0.4 [pc^-2]

C3 classification AC

C_N 0.0 Sparse
C_dens 0.08 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 828 is a sparse, very loose object of intermediate C3 quality. Its parallax locates it at a very close distance, near the mid-plane, affected by moderate extinction. It is catalogued as a metal-poor, 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 Moderate extinction Metal-poor Young

Palma et al. (2025)
Classified as optical pair P575, along with Theia_240.

Cavallo et al. (2024)
Gold sample.

Hunt & Reffert (2024)
Classified as moving group. CMD class: 0.70 (50th percentile).

Hunt & Reffert (2023)
Classified as open cluster. CMD class: 0.70 (50th percentile).

Data

🔍 Search references for Theia 828 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–	277.785	-21.331	2.677	2.422	-14.75	-5.824
Cavallo et al.	2024	278.322	-19.729	2.637	–	–	–
Hunt & Reffert	2023	277.651	-21.715	2.632	2.482	-14.479	-1.132
Kounkel & Covey	2019	276.71	-20.574	2.128	–	–	-12.993

💡 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–	0.36	1.12	1.49	84	-0.580	–	–	–
Cavallo et al.	2024	0.36	1.79	–	45	-0.580	–	–	–
Hunt & Reffert	2023	0.36	1.12	1.49	84	–	–	–	–
Kounkel & Covey	2019	0.47	0.62	–	418	–	–	–	–

Visualization

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