HSC 640

0.48 UTI

0.81

C_N

1.0

C_dens

0.75

C_C3

0.25

C_lit

0.78

C_dup

N₅₀ (P>50% members) 261

Stellar density (N₅₀/rad) 25.9 [N/pc²]

C3 classification AB

C_N 0.81 Rich
C_dens 1.0 Very dense
C_C3 0.75 High quality
C_lit 0.25 Poorly studied
C_dup 0.78 Very likely unique

📥 Members 📊 Colab 🔬 Bayestar19

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

Overview

ℹ️

HSC 640 is a rich, very dense object of high C3 quality. Its parallax locates it at a relatively close distance, near the mid-plane, affected by high extinction. It is catalogued as a massive, near-solar metallicity, very young cluster, but with a large variance across recent sources for the metallicity parameter (see Parameters). It was recently reported in the literature.

Note: This is very likely a unique object, which shares a small percentage of members with at least one previously reported entry. See table with shared members information.

Relatively close High extinction Massive Near-solar metallicity Very young

Palma et al. (2025)
Classified as genetic pair P213, along with FSR_0251.

Cavallo et al. (2024)
Wood sample.

Data

🔍 Search references for HSC 640 in: SciX Simbad

ℹ️

Reference	Year	RA [deg]	DEC [deg]	Plx [mas]	pmRA [mas/yr]	pmDE [mas/yr]	Rv [km/s]
UCC	99999–	309.736	42.147	0.678	-2.319	-3.43	1.133
Zhang et al.	2024	309.774	42.12	–	–	–	–
Hunt & Reffert	2024	309.774	42.12	0.654	-2.356	-3.44	11.588
Cavallo et al.	2024	309.557	42.408	0.65	–	–	–
Hunt & Reffert	2023	309.774	42.12	0.654	-2.356	-3.44	11.588

💡 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–	1.595	4.74	3.09	15	0.259	1795	–	–
Zhang et al.	2024	–	–	–	–	-0.102⁽¹⁾	–	–	–
Hunt & Reffert	2024	–	–	–	–	–	1795⁽¹⁾	–	–
Cavallo et al.	2024	1.70	4.43	–	16	0.620	–	–	–
Hunt & Reffert	2023	1.49	5.05	3.09	14	–	–	–	–

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

Cluster	%	RA	DEC	Plx	pmRA	pmDE	Rv	UTI
DB2001 16	21.8	309.65	42.11	0.69	-2.53	-3.27	114.81	0.44
FSR 0245	9.6	309.69	42.15	0.69	-1.91	-3.61	21.62	0.52
OC 0131	6.9	309.63	42.48	0.63	-2.37	-3.34	-11.77	0.12
FSR 0249	5.0	309.63	42.49	0.62	-2.37	-3.31	-23.49	0.62

💡 Note: The % column shows the percentage of members that HSC 640 shares with each listed object.

Visualization

ℹ️

1 2