HSC 1840

0.14 UTI

0.25

C_N

0.2

C_dens

0.25

C_C3

0.0

C_lit

1.0

C_dup

N₅₀ (P>50% members) 25

Stellar density (N₅₀/rad) 1.0 [N/pc²]

C3 classification DB

C_N 0.25 Poorly populated
C_dens 0.2 Very loose
C_C3 0.25 Low quality
C_lit 0.0 Rarely studied
C_dup 1.0 Unique

📥 Members 📊 Colab 🔬 Bayestar19

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

Overview

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HSC 1840 is a poorly populated, 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 absorption 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

Liu et al. (2025)
Classified as tidal capture (resonant trapping binary) 208 along with HSC_1849, and of multiple system 59 along with HSC_1849 and Theia_118.

Cavallo et al. (2024)
Gold sample.

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

Data

🔍 Search references for HSC 1840 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–	100.994	-23.85	3.615	-6.978	2.105	13.426
Liu et al.	2025	100.91	-22.9	3.66	-6.83	2.07	13.9
Cavallo et al.	2024	100.536	-24.408	3.661	–	–	–
Hunt & Reffert	2023	100.906	-22.902	3.658	-6.827	2.068	13.899

💡 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–	0.27	0.08	0.37	163	0.380	–	–	–
Liu et al.	2025	0.25	0.01	–	102	–	–	–	–
Cavallo et al.	2024	0.28	0.45	–	234	0.380	–	–	–
Hunt & Reffert	2023	0.27	0.08	0.37	163	–	–	–	–

Visualization

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