J/A+A/697/A47 Young clusters around Cas OB5 (Quintana+, 2025)
Quantifying the scale of star formation across the Perseus spiral arm using
young clusters around Cas OB5.
Quintana A.L., Negueruela I., Berlanas S.R.
<Astron. Astrophys. 697, A47 (2025)>
=2025A&A...697A..47Q 2025A&A...697A..47Q (SIMBAD/NED BibCode)
ADC_Keywords: Milky Way ; Galactic plane ; Clusters, open ; Stars, ages ;
Stars, OB; Stars, A-type ; Effective temperatures ;
Stars, distances
Keywords: stars: distances - stars: early-type -
stars: kinematics and dynamics - stars: massive - Galaxy: structure
Abstract:
Cas OB5 is an OB association located at a distance of 2.5-3kpc that
intercepts the Perseus spiral arm. It carries a moderate amount of
reddening (AV∼2-3mag) and contains several well-known open
clusters within its boundaries, such as King 12, NGC 7788, and NGC
7790. The availability of modern clustering algorithms, together with
Gaia DR3 kinematics and complementary spectroscopic data,
makes it a suitable site for studies of Galactic structure. We seek to
quantify the spatial scale of star formation in the spiral arms, using
Cas OB5 as a pilot target before extending our study to more distant
and extinguished regions of the Galaxy. We selected 129,695 candidate
OBA stars in a 6x8deg2 region around Cas OB5. We applied a
spectral energy distribution (SED) fitting process to this sample to
derive the physical parameters. Through this process, we found 56379
OBA stars, which we then clustered using HDBSCAN. We identified 17
open clusters inside this area, four of which appear to form a
coherent structure that we identify as Cas OB5. Nevertheless, our
findings suggest that these clusters belong to two different age
groups despite sharing a similar position and kinematics.
Spectroscopic observations confirm the youth of NGC 7788 (10-15Myr)
compared to NGC 7790 (110±15Myr). We have determined a spatial
scale for star formation of a few tens of pc to a few hundreds of pc,
comparing the clustered to the diffuse population of Cas OB5 across
this part of the Perseus arm. A spectroscopic analysis was required to
complement the clustering algorithm, so that we could separate younger
OCs (tracers of the spiral arm) from older ones. These results
highlight the need to combine these techniques to fully disentangle
the Milky Way structure.
Description:
Catalogue of 56379 SED-fitted OBA stars around Cas OB5 with cluster
properties and membership.
Objects:
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RA (2000) DE Designation(s)
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23 54 00.00 +61 36 00.0 Cas OB5 = Ass Cas OB 5
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
catalog.dat 317 56379 Catalog of 56379 SED-fitted OBA stars around
Cas OB5 with cluster properties and membership
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See also:
I/355 : Gaia DR3 Part 1. Main source (Gaia Collaboration, 2022)
Byte-by-byte Description of file: catalog.dat
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Bytes Format Units Label Explanations
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1- 19 I19 --- GaiaDR3 Gaia DR3 source identifier
21- 32 F12.8 deg RAdeg Barycentric right ascension (ICRS)
at Ep=2016.0
34- 45 F12.10 deg e_RAdeg Error on barycentric right ascension (ICRS)
47- 57 F11.8 deg DEdeg Barycentric declination (ICRS)
at Ep=2016.0
59- 70 F12.10 deg e_DEdeg Error on barycentric declination (ICRS)
72- 83 F12.8 deg GLON Galactic longitude of the source
85- 95 E11.8 deg GLAT Galactic latitude of the source
97-107 F11.8 mas plx Gaia DR3 corrected parallax
109-118 F10.8 mas e_plx Gaia DR3 corrected parallax uncertainty
120-126 F7.3 mas/yr pmRA Proper motion in right ascension, pmRA*cosDE,
of the source (ICRS) at Ep=2016.0
128-132 F5.3 mas/yr e_pmRA Standard error of proper motion in
right ascension direction
134-140 F7.3 mas/yr pmDE Proper motion in declination direction
of the source (ICRS) at Ep=2016.0
142-146 F5.3 mas/yr e_pmDE Standard error of proper motion
in declination direction
148-157 E10.7 mas/yr pmGLON Proper motion in Galactic longitude direction
159-167 F9.7 mas/yr e_pmGLON Error on proper motion in Galactic longitude
direction
169-178 E10.7 mas/yr pmGLAT Proper motion in Galactic latitude direction
180-188 F9.7 mas/yr e_pmGLAT Error on proper motion in Galactic latitude
190-194 F5.3 [K] logTeff Median logarithm of the SED-fitted
effective temperature
196-200 F5.3 [K] b_logTeff 16th percentile logarithm of the SED-fitted
effective temperature
202-206 F5.3 [K] B_logTeff 84th percentile logarithm of the SED-fitted
effective temperature
208-212 F5.3 [Lsun] logLum Median logarithm of the SED-fitted luminosity
214-219 F6.3 [Lsun] b_logLum 16th percentile logarithm of the SED-fitted
stellar luminosity
221-225 F5.3 [Lsun] B_logLum 84th percentile logarithm of the SED-fitted
luminosity
227-231 F5.3 [Msun] logMass Median logarithm of the SED-fitted
stellar mass
233-238 F6.3 [Msun] b_logMass 16th percentile logarithm of the SED-fitted
stellar mass
240-244 F5.3 [Msun] B_logMass 84th percentile logarithm of the SED-fitted
mass
246-253 F8.3 pc Dist Median SED-fitted distance
255-262 F8.3 pc b_Dist 16th percentile SED-fitted distance
264-271 F8.3 pc B_Dist 84th percentile SED-fitted distance
273-283 F11.8 mag AV Median extinction in the V-band
285-294 F10.8 mag b_AV ?=- 16th percentile of the extinction in
the V-band
296-306 F11.8 mag B_AV ?=- 84th percentile of the extinction in
the V-band
308-309 I2 --- Cluster [0-17] Cluster assigned to each star
(0 if not in any cluster)
311-317 F7.3 --- Prob Cluster probability membership
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Acknowledgements:
Alexis Quintana, alexis.quintana(at)ua.es
(End) Patricia Vannier [CDS] 03-Apr-2025