Theia 280

0.25 UTI

0.25

C_N

0.06

C_dens

0.75

C_C3

0.1

C_lit

1.0

C_dup

N_m (P>50%) 25

Core radius and density 3.5 [pc], 0.3 [pc^-2]

C3 classification AB

C_N 0.25 Poorly populated
C_dens 0.06 Very loose
C_C3 0.75 High quality
C_lit 0.1 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 280 is a poorly populated, very loose object of high C3 quality. Its parallax locates it at a close distance, below the mid-plane, affected by low extinction. It is catalogued as a low-mass, 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 significant percentage of members with a later reported entry. See table with shared members information.

Close Low extinction Low mass Near-solar metallicity Intermediate age

Palma et al. (2025)
Classified as optical pair P173, along with Theia_776.

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 280 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–	341.031	49.456	1.192	-1.756	-5.466	-12.732
Zhang et al.	2024	340.739	49.347	–	–	–	–
Hunt & Reffert	2024	340.739	49.347	1.199	-1.66	-5.312	-13.927
Cavallo et al.	2024	342.431	50.008	1.198	–	–	–
Hunt & Reffert	2023	340.739	49.347	1.199	-1.66	-5.312	-13.927
Kounkel & Covey	2019	341.71	49.787	1.232	–	–	-13.014

💡 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–	0.805	0.33	0.68	160	0.258	45	–	–
Zhang et al.	2024	–	–	–	–	-0.025⁽¹⁾	–	–	–
Hunt & Reffert	2024	0.80	0.26	0.68	160	–	45⁽¹⁾	–	–
Cavallo et al.	2024	0.83	0.43	–	191	0.540	–	–	–
Hunt & Reffert	2023	0.80	0.26	0.68	160	–	–	–	–
Kounkel & Covey	2019	0.81	0.40	–	95	–	–	–	–

(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 187	60.0	340.56	49.15	1.2	-1.82	-5.57	-14.41	0.04

💡 Note: The % column shows the percentage of members that Theia 280 shares with each listed object.

Visualization

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