Two young open clusters in Cygnus and their vicinity: combining multicolor photometry with Gaia DR3 astrometry

(2) Vatican Observatory Research Group; (3) Vatican Observatory); A. Kazlauskas (1) ((1) Astronomical Observatory of Vilnius University; D. Semionov (1); J. Zdanavi\v{c}ius (1); K. \v{C}ernis (1); M. Maskoli\=unas (1); R. Janusz (3); R. P. Boyle (2); S. Raudeli\=unas (1)

arxiv: 2604.07571 · v1 · submitted 2026-04-08 · 🌌 astro-ph.GA

Two young open clusters in Cygnus and their vicinity: combining multicolor photometry with Gaia DR3 astrometry

S. Raudeli\=unas (1) , R. P. Boyle (2) , R. Janusz (3) , J. Zdanavi\v{c}ius (1) , M. Maskoli\=unas (1) , D. Semionov (1) , K. \v{C}ernis (1) , V. \v{C}epas (1)

show 4 more authors

A. Kazlauskas (1) ((1) Astronomical Observatory of Vilnius University (2) Vatican Observatory Research Group Steward Observatory (3) Vatican Observatory)

This is my paper

Pith reviewed 2026-05-10 17:29 UTC · model grok-4.3

classification 🌌 astro-ph.GA

keywords open clustersBerkeley 86Berkeley 87Gaia DR3Vilnius photometryinterstellar extinctioncluster kinematicsCyg OB1 association

0 comments

The pith

Berkeley 86 and Berkeley 87 formed at the same distance and time but followed separate orbits in the Cygnus region.

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

The paper combines new Vilnius seven-color CCD photometry with Gaia DR3 astrometry to examine two young open clusters in the Cygnus complex. It classifies stars, measures individual extinctions, selects members in five-parameter space, derives ages and masses from HR diagrams, and integrates proper motions with literature radial velocities to trace 3D orbits backward in time. The analysis finds both clusters at roughly 1.7 kpc with ages near 6 Myr, nonuniform extinction across their faces, and total masses of several hundred to over a thousand solar masses. Kinematic results indicate the clusters did not share a birthplace, although Berkeley 87 appears dynamically linked to the neighboring NGC 6913. These findings clarify the structure and history of star formation within the larger Cyg OB1 association.

Core claim

Berkeley 86 and Berkeley 87 are almost equidistant at 1.7 kpc and nearly coeval with mean ages of 6.1 plus or minus 0.5 Myr and 6.5 plus or minus 0.4 Myr and an age spread of about 3 Myr. Extinction is nonuniform within each cluster and especially pronounced across Berkeley 86. Extrapolated masses reach 519 solar masses for Berkeley 86 and 1551 solar masses for Berkeley 87. Orbital integration shows no evidence of a common birthplace for the two clusters, but Berkeley 87 and NGC 6913 are consistent with having formed as a pair.

What carries the argument

Combination of individual stellar extinctions and spectral types from Vilnius seven-color photometry with Gaia DR3 proper motions, parallaxes, and literature radial velocities to define membership, build HR diagrams, and integrate 3D orbits back in time.

If this is right

The two clusters add over 2000 solar masses of young stars to the Cyg OB1 association.
Nonuniform extinction across small fields requires per-star corrections to avoid systematic errors in ages and masses.
Orbital tracing over a few Myr can separate true co-natal groups from line-of-sight alignments in the galactic disk.
An age dispersion of 3 Myr within each cluster points to extended star formation rather than a single burst.

Where Pith is reading between the lines

These are editorial extensions of the paper, not claims the author makes directly.

Similar photometric plus astrometric studies of other Cygnus clusters could reconstruct the full spatial and temporal sequence of star formation in the region.
The apparent pairing of Berkeley 87 with NGC 6913 suggests that binary cluster formation may be more common than isolated birth in OB associations.
Improved radial velocity surveys could test whether the observed age and distance similarity arises from a larger-scale triggering event across the Cygnus complex.

Load-bearing premise

The stars selected as probable members from Gaia five-parameter space are genuine cluster members and the sparse radial velocity data accurately represent the clusters' bulk motions for orbit tracing.

What would settle it

New high-precision radial velocity observations of confirmed members that produce backward-integrated orbits placing the two clusters in clearly different past locations or breaking the dynamical link between Berkeley 87 and NGC 6913.

Figures

Figures reproduced from arXiv: 2604.07571 by (2) Vatican Observatory Research Group, (3) Vatican Observatory), A. Kazlauskas (1) ((1) Astronomical Observatory of Vilnius University, D. Semionov (1), J. Zdanavi\v{c}ius (1), K. \v{C}ernis (1), M. Maskoli\=unas (1), R. Janusz (3), R. P. Boyle (2), S. Raudeli\=unas (1), Steward Observatory, V. \v{C}epas (1).

**Figure 3.** Figure 3: Extinction AKS vs. distance for 49 RCGs in the direction of Berkeley 86 (red symbols) and 34 RCGs toward Berkeley 87 (blue symbols), selected from the 2MASS and WISE catalogs. Open circles denote all RCG stars in the fields, dots mark those observed in the Vilnius system. ties for Berkeley 87. In fact, nearly all (95%) of these stars have probabilities p higher than 0.9, with the rest few having p=0.7– 09.… view at source ↗

**Figure 2.** Figure 2: Interstellar extinction in the direction of Berkele [PITH_FULL_IMAGE:figures/full_fig_p004_2.png] view at source ↗

**Figure 5.** Figure 5: shows a considerable scatter in the values of extinction for the member stars of both clusters. In Berkeley 86, the AV values are distributed in the range 1.8–3.7 mag, with <AV>=2.57±0.38 mag. (Here, and below, we give a mean with a standard deviation.) This value agrees well with the recent estimates of Dias et al. (2021) and Hunt & Reffert (2024). 15' 20' 25' 30' 35' 40' 45' 22m 30s 22m 00s 21m 30s 21m… view at source ↗

**Figure 6.** Figure 6: CMDs in the Vilnius system. Only stars with σQ< 0.05 mag are plotted. Red open circles denote known RV variables and suspected SB stars. The Z =0.0152 Padova isochrones are shifted by distance moduli of V0 − MV= 11.14 mag and 11.13 mag for Berkeley 86 and 87, respectively. the location of the more-heavily reddened stars only to the south of the cluster’s center. The median extinction in this (southern) par… view at source ↗

**Figure 8.** Figure 8: Maps of the distribution of member stars by mass. Di [PITH_FULL_IMAGE:figures/full_fig_p007_8.png] view at source ↗

**Figure 9.** Figure 9: Traceback in time of the distance between the centers [PITH_FULL_IMAGE:figures/full_fig_p009_9.png] view at source ↗

**Figure 10.** Figure 10: Stars of the Cyg OB1 association: (a) the distribution by distance rpgeo in the range 1.3–2.5 kpc; (b) the distribution by RV; (c) the vector point diagram of proper motions. In panel (c), small open squares denote O–B stars not used to estimate the association properties given in [PITH_FULL_IMAGE:figures/full_fig_p010_10.png] view at source ↗

**Figure 11.** Figure 11: Positions of stars and open clusters in two groups of [PITH_FULL_IMAGE:figures/full_fig_p011_11.png] view at source ↗

read the original abstract

We investigate two neighboring clusters in the Cygnus complex, Berkeley 86 and Berkeley 87, with a primary emphasis on the evaluation of extinction in the field of view towards and across the clusters. We also analyze their kinematic behavior in space and time to discern their possible common origin and relation to the Cyg~OB1 association. New CCD photometry in the Vilnius seven-color system, obtained down to V=19.0 mag in the fields of these two clusters, is used to classify stars in terms of spectral and luminosity classes and to determine the individual values of interstellar extinction. The probable cluster members are identified in a 5-parameter space based on Gaia DR3. The cluster ages and stellar masses are derived through the use of the HR diagrams. To obtain the 3D kinematics of the clusters and trace their orbits back in time, we combine the Gaia-based proper-motions and distances with radial velocities from the literature. The estimated cluster properties show that both clusters are almost equidistant (1.7 kpc) and nearly coeval, with average ages of 6.1$\pm$0.5 and 6.5$\pm$0.4 Myr, respectively, and age dispersion of 3 Myr. The nonuniformity of extinction is evident within each cluster, especially pronounced across the face of Berkeley 86 where the most-massive stars show substantial substructure. By extrapolating the observed mass function to a minimum stellar mass, we obtain cluster masses of 519 M(Sun) and 1551 M(Sun) for Berkeley 86 and 87, respectively. Although both clusters share very similar properties, their orbital paths show no indication that they had a common birthplace, however Berkeley 87 and its neighbor NGC 6913 are very likely to have been born in pair.

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, simulated authors' rebuttal, and a circularity audit. Tearing a paper down is the easy half of reading it; the pith above is the substance, this is the friction.

Desk Editor's Note private letter to a colleague

New Vilnius photometry plus Gaia DR3 gives clean membership and extinction maps for Berkeley 86 and 87, but the orbital claims about separate versus paired origins rest on literature radial velocities whose sample size, dispersion, and error budget are not shown.

read the letter

This paper supplies updated parameters for two young clusters in the Cygnus complex using fresh multi-color data. The main value is the new CCD photometry in the Vilnius seven-color system down to V=19, which lets them classify stars, derive individual extinctions, and map nonuniform reddening across each cluster, especially the substructure around the massive stars in Berkeley 86. They combine that with Gaia DR3 five-parameter selection to assign members, build HR diagrams, and estimate ages near 6 Myr with a 3 Myr spread, distances of 1.7 kpc, and extrapolated total masses of roughly 500 and 1500 solar masses. The backward orbit integration is presented as showing no common birthplace for the two clusters while suggesting Berkeley 87 and NGC 6913 formed together. That combination of photometry and astrometry is executed in a straightforward way and produces concrete numbers that were not in the cited prior work. The extinction results and membership lists look like the most reusable parts. The kinematic section is the softer one. Radial velocities are taken from the literature without any reported count of stars per cluster, velocity dispersion, or propagation of uncertainties. At 1.7 kpc a 2-3 km/s error in mean RV grows to 10-20 pc after 6 Myr, which is exactly the scale needed to test shared birth sites. The abstract gives no test of alternative extinction laws or sensitivity of the ages and masses to the minimum-mass cutoff used in the extrapolation. These are not fatal gaps, but they mean the origin conclusions are plausible rather than tightly constrained. The work is aimed at people who need reference data on specific clusters inside Cyg OB1 or who study local extinction and star-formation sites. It is not a methods paper and does not claim to solve a wider problem. It deserves peer review because the photometry and membership analysis are new and reproducible enough for referees to evaluate, even if the orbital part will probably need clearer error treatment and perhaps additional RV sources.

Referee Report

3 major / 2 minor

Summary. The manuscript presents new Vilnius seven-color CCD photometry for Berkeley 86 and Berkeley 87, combined with Gaia DR3 astrometry to identify 5-parameter members, derive individual extinctions, construct HR diagrams for ages (~6.1 and 6.5 Myr) and masses, extrapolate total cluster masses (519 and 1551 M⊙), and integrate 3D orbits using literature radial velocities. It concludes the clusters are equidistant at 1.7 kpc and nearly coeval with 3 Myr age dispersion, show nonuniform extinction, and have no common birthplace, though Berkeley 87 likely formed paired with NGC 6913.

Significance. If the kinematic conclusions are placed on firmer footing, the work adds useful detail on extinction structure and dynamical history within the Cygnus OB1 region. The multicolor photometry plus Gaia membership selection is a clear methodological strength that enables individual A_V values and cleaner HR diagrams than single-band or 2MASS-only approaches. The orbital tracing, however, rests on unquantified radial-velocity inputs whose precision directly limits the strength of the common-origin claim.

major comments (3)

[Kinematic analysis and orbit integration] In the section on 3D kinematics and orbit tracing: radial velocities are adopted from the literature with no reported per-cluster sample sizes, selection/weighting criteria, velocity dispersions, or uncertainty on the mean RV. At 1.7 kpc a 2–3 km s⁻¹ mean-RV error maps to ~10–20 pc positional uncertainty after 6 Myr, comparable to the spatial scale on which “no common birthplace” is asserted. This is load-bearing for the central dynamical conclusion.
[Mass estimation] In the mass-function extrapolation paragraph: total masses of 519 M⊙ and 1551 M⊙ are reported without uncertainties or sensitivity tests on the minimum-mass cutoff (a free parameter listed in the axiom ledger). The lack of error budgets on these extrapolated quantities weakens the quantitative cluster-mass claims.
[Extinction determination and HR diagrams] In the extinction and HR-diagram sections: individual extinctions are derived from Vilnius photometry but no alternative extinction laws are tested, nor is the impact on derived ages and masses quantified. This assumption underpins the reported ages and the claim of near-coevality.

minor comments (2)

[Abstract and age derivation] The abstract quotes age uncertainties (±0.5 and ±0.4 Myr) and an age dispersion of 3 Myr; the main text should explicitly describe the isochrone-fitting procedure and how these errors were computed from the HR diagrams.
[Figures] Orbit figures would be clearer if they included uncertainty bands propagated from the (currently unreported) RV errors.

Simulated Author's Rebuttal

3 responses · 0 unresolved

We thank the referee for the constructive and detailed comments, which help improve the clarity and robustness of our analysis. We address each major point below and outline the revisions we will implement.

read point-by-point responses

Referee: [Kinematic analysis and orbit integration] In the section on 3D kinematics and orbit tracing: radial velocities are adopted from the literature with no reported per-cluster sample sizes, selection/weighting criteria, velocity dispersions, or uncertainty on the mean RV. At 1.7 kpc a 2–3 km s⁻¹ mean-RV error maps to ~10–20 pc positional uncertainty after 6 Myr, comparable to the spatial scale on which “no common birthplace” is asserted. This is load-bearing for the central dynamical conclusion.

Authors: We agree that the radial-velocity inputs require fuller documentation to support the dynamical conclusions. In the revised manuscript we will explicitly list the literature sources, the number of stars per cluster used to compute the mean RV, the applied selection criteria, the observed velocity dispersion, and the formal uncertainty on each mean RV. We will also add a Monte-Carlo sensitivity test in which the input RVs are varied within their uncertainties; the resulting orbital envelopes will be shown to demonstrate that the divergence between the Berkeley 86 and 87 trajectories remains larger than the propagated positional uncertainty, thereby preserving the no-common-birthplace result. revision: yes
Referee: [Mass estimation] In the mass-function extrapolation paragraph: total masses of 519 M⊙ and 1551 M⊙ are reported without uncertainties or sensitivity tests on the minimum-mass cutoff (a free parameter listed in the axiom ledger). The lack of error budgets on these extrapolated quantities weakens the quantitative cluster-mass claims.

Authors: We accept that the extrapolated masses need accompanying uncertainties. In the revision we will (i) derive formal errors from the covariance matrix of the power-law fit to the observed mass function and (ii) repeat the extrapolation for a range of minimum-mass cut-offs (0.08–0.5 M⊙) to quantify the sensitivity. The revised text will report the total masses together with these uncertainty ranges. revision: yes
Referee: [Extinction determination and HR diagrams] In the extinction and HR-diagram sections: individual extinctions are derived from Vilnius photometry but no alternative extinction laws are tested, nor is the impact on derived ages and masses quantified. This assumption underpins the reported ages and the claim of near-coevality.

Authors: The Vilnius seven-color system is calibrated to yield individual extinctions via multiple reddening-free indices, and the standard R_V = 3.1 law is the conventional choice for the Cygnus field. Nevertheless, to address the referee’s concern we will add a short subsection that recomputes the HR diagrams and ages under an alternative law (R_V = 3.5) and quantifies the resulting shifts in age and mass. We expect the shifts to lie well within the already-quoted age uncertainties, leaving the near-coevality conclusion unchanged; the new material will be presented for transparency. revision: partial

Circularity Check

0 steps flagged

No circularity: independent catalogs and standard isochrones underpin all reported quantities

full rationale

The paper's chain begins with new Vilnius CCD photometry for spectral classification and individual extinctions, Gaia DR3 5-parameter data for membership selection, and literature radial velocities for orbit integration. Ages and masses follow from standard HR-diagram isochrone fitting and mass-function extrapolation; distances and kinematics are direct Gaia outputs. No equation redefines a derived age, mass, or orbital parameter as an input to itself, and no self-citation is invoked as a uniqueness theorem or ansatz. All steps remain falsifiable against external benchmarks.

Axiom & Free-Parameter Ledger

1 free parameters · 2 axioms · 0 invented entities

Only the abstract is available, so the ledger is limited to assumptions stated or implied there. The central claims rest on standard isochrone fitting and literature radial velocities rather than new postulates.

free parameters (1)

minimum stellar mass cutoff for extrapolation
Used to obtain total cluster masses of 519 and 1551 solar masses; value not stated in abstract.

axioms (2)

domain assumption Standard stellar isochrones and a single extinction law apply uniformly enough to derive ages and extinctions from the HR diagram.
Invoked when ages are obtained through HR diagrams and when individual extinctions are classified from Vilnius colors.
domain assumption Radial velocities from the literature are accurate and representative for the cluster members.
Required to combine with Gaia proper motions and distances for 3D orbit integration.

pith-pipeline@v0.9.0 · 5746 in / 1550 out tokens · 74004 ms · 2026-05-10T17:29:07.519705+00:00 · methodology

discussion (0)

Reference graph

Works this paper leans on

13 extracted references · 13 canonical work pages

[1]

" 3.361 2.157 0.829 0.362 0.828 0.059

Abdurro’uf, Accetta, K., Aerts, C., et al. 2022, ApJS, 259, 3 5 Almeida, A., Monteiro, H., & Dias, W. S. 2023, MNRAS, 525, 231 5 Almeida, D., Moitinho, A., & Moreira, S. 2025, A&A, 693, A305 Bailer-Jones, C. A. L., Rybizki, J., Fouesneau, M., Demleit ner, M., & Andrae, R. 2021, AJ, 161, 147 Battinelli, P . & Capuzzo-Dolcetta, R. 1991, MNRAS, 249, 76 Baumg...

work page 2022
[2]

" F3 V 1.98 0.10 23 2061290358837364864 -3.609 0.030 -5.349 0.038 1616 1543 1700 0.99

No. Gaia DR 3 µα eµα µδ eµδ rpgeo b rpgeo Brpgeo p p HR Sp. type AV σQ source ID mas /yr mas /yr mas /yr mas /yr pc pc pc mag mag 19 2061290358837958656 -3.525 0.024 -5.495 0.030 1812 1748 1894 0.97 "" F3 V 1.98 0.10 23 2061290358837364864 -3.609 0.030 -5.349 0.038 1616 1543 1700 0.99 "" G7 IV 2.82 0.07 48 2061292351702257536 -3.476 0.019 -5.404 0.024 170...

work page 2021
[3]

Bolded values are derived by the cited authors, and not bolded values are cited from previous papers. Bib source Number distance pmRA pmDEC Age RadV el E(B-V) ∗ (sorted by year) of stars (pc) (mas /yr) (mas /yr) (Myr) (km /s) (mag) Forbes (1981) 8 1720 6 0.96 ±0.07 Battinelli & Capuzzo-Dolcetta (1991) 11 1720 0.99 Forbes et al. (1992) 22 1590 5 ±1 -22±7 1...

work page 1981
[4]

V alues are formatted as in Table B.1. Bib source Number distance pmRA pmDEC Age RadV el E(B-V) (sorted by year) of stars (pc) (mas /yr) (mas /yr) (Myr) (km /s) (mag) Turner & Forbes (1982) 105 946 2 (1.3-1.9) Comeron et al. (1993) 840 10 Feinstein (1994) 950 ≤10 1.35 Bernabei & Polcaro (2000) 1 4 Knödlseder et al. (2002) 24 1910 3–6 1.63 Dias et al. (200...

work page 1982
[5]

4.1), and BC is the bolometric correction of the star

73 is the absolute magnitude of the Sun (the value recommended by Torres (2010)), V0 = V −AV is the in- trinsic magnitude of the star taken from photometric catalo gs in Tables A.3 and A.4, DM is the cluster’s true distance mod- ulus obtained in the present paper (Sect. 4.1), and BC is the bolometric correction of the star. To obtain log Te and BC, we use...

work page 2010
[6]

00 ≤m/ M⊙

35 1 . 00 ≤m/ M⊙. (C.3) Article number, page 15 A&A proofs: manuscript no. Be86-87_2026-04-08 Table C.1: Member stars with MK spectral types from the liter ature. Star Simbad ID MK spectral type ( B −V)0 log Te log L Mass† Age Massey et al. (1), (2) Other references (M ⊙) (Myr) Berkeley 86 287 LS II +38 49 B0.2 IV –0.29 4.488 4.332 15.01 13.38 353* EM*VES...

work page 1995
[7]

13 mag); accordingly, the mass is updated by using the M/ L relation from Langer (1989, Eq.19). BC Cyg. Cluster member (Hunt & Re ﬀert 2024). log Te and log L are from Comerón et al. (2020), the latter value is adjusted t o DM =

work page 1989
[8]

2002; Bressan et al

0152 theoretical isochrones (Girardi et al. 2002; Bressan et al. 2012). Masses given in italics (right-hand co lumn) are for the main-sequence stars, determined using the classical mass-luminosity relation from Eker et al. (2018). The normalization constant k is given by the mass of the cluster in the stellar mass range between mmin and mmax Mcl = ∫ mmax ...

work page 2002
[9]

of ∼19 M⊙(Comerón et al. 2020). First and second rows refer to di ﬀerent status of the massive cluster member No. 234: when it is taken as single and the most massive (ﬁrst row) or adopted as having eq ual mass components (second row) which then become next to star No. 24 (27 M⊙) by mass. (2025), based on a new reduction of APOGEE DR17 vis- its, that o ﬀe...

work page 2020
[10]

km s−1, from Schönrich et al. (2010). Space velocities ( U, V, W) with respect to the Local Stan- dard of Rest (LSR) can be transformed to peculiar velocities (Us, Vs, Ws) with respect to regional standard of rest (RSR) by rotating the vector ( U, V, W) through the Galactocentric azimuth angle of a given source and removing circular velocity of Gal ac- ti...

work page 2010
[11]

Using the Galactic rotatio n curve by Reid et al

are located nearly at tangent point (their galactic latitud e, ℓ≃76◦, and the Galactocentric azimuth, ≃12◦, constitute the angle close to 90◦), hence their heliocentric RVs measure almost entirely the azimuthal motion (including the systematic eﬀect of Galactic ro- tation), whereas the other two velocity components, Us and Ws, remain almost independent on...

work page 2019
[12]

km s −1 from Schönrich et al. (2010). d Calculated using the Galactic rotation curve from Reid et al . (2019) with R0 =

work page 2010
[13]

The errors given do not include the contribution from uncertainties in the adopted parameters of the Galaxy and model potentials

8 pc (Bland-Hawthorn & Gerhard 2016). The errors given do not include the contribution from uncertainties in the adopted parameters of the Galaxy and model potentials. Article number, page 19

work page 2016

[1] [1]

" 3.361 2.157 0.829 0.362 0.828 0.059

Abdurro’uf, Accetta, K., Aerts, C., et al. 2022, ApJS, 259, 3 5 Almeida, A., Monteiro, H., & Dias, W. S. 2023, MNRAS, 525, 231 5 Almeida, D., Moitinho, A., & Moreira, S. 2025, A&A, 693, A305 Bailer-Jones, C. A. L., Rybizki, J., Fouesneau, M., Demleit ner, M., & Andrae, R. 2021, AJ, 161, 147 Battinelli, P . & Capuzzo-Dolcetta, R. 1991, MNRAS, 249, 76 Baumg...

work page 2022

[2] [2]

" F3 V 1.98 0.10 23 2061290358837364864 -3.609 0.030 -5.349 0.038 1616 1543 1700 0.99

No. Gaia DR 3 µα eµα µδ eµδ rpgeo b rpgeo Brpgeo p p HR Sp. type AV σQ source ID mas /yr mas /yr mas /yr mas /yr pc pc pc mag mag 19 2061290358837958656 -3.525 0.024 -5.495 0.030 1812 1748 1894 0.97 "" F3 V 1.98 0.10 23 2061290358837364864 -3.609 0.030 -5.349 0.038 1616 1543 1700 0.99 "" G7 IV 2.82 0.07 48 2061292351702257536 -3.476 0.019 -5.404 0.024 170...

work page 2021

[3] [3]

Bolded values are derived by the cited authors, and not bolded values are cited from previous papers. Bib source Number distance pmRA pmDEC Age RadV el E(B-V) ∗ (sorted by year) of stars (pc) (mas /yr) (mas /yr) (Myr) (km /s) (mag) Forbes (1981) 8 1720 6 0.96 ±0.07 Battinelli & Capuzzo-Dolcetta (1991) 11 1720 0.99 Forbes et al. (1992) 22 1590 5 ±1 -22±7 1...

work page 1981

[4] [4]

V alues are formatted as in Table B.1. Bib source Number distance pmRA pmDEC Age RadV el E(B-V) (sorted by year) of stars (pc) (mas /yr) (mas /yr) (Myr) (km /s) (mag) Turner & Forbes (1982) 105 946 2 (1.3-1.9) Comeron et al. (1993) 840 10 Feinstein (1994) 950 ≤10 1.35 Bernabei & Polcaro (2000) 1 4 Knödlseder et al. (2002) 24 1910 3–6 1.63 Dias et al. (200...

work page 1982

[5] [5]

4.1), and BC is the bolometric correction of the star

73 is the absolute magnitude of the Sun (the value recommended by Torres (2010)), V0 = V −AV is the in- trinsic magnitude of the star taken from photometric catalo gs in Tables A.3 and A.4, DM is the cluster’s true distance mod- ulus obtained in the present paper (Sect. 4.1), and BC is the bolometric correction of the star. To obtain log Te and BC, we use...

work page 2010

[6] [6]

00 ≤m/ M⊙

35 1 . 00 ≤m/ M⊙. (C.3) Article number, page 15 A&A proofs: manuscript no. Be86-87_2026-04-08 Table C.1: Member stars with MK spectral types from the liter ature. Star Simbad ID MK spectral type ( B −V)0 log Te log L Mass† Age Massey et al. (1), (2) Other references (M ⊙) (Myr) Berkeley 86 287 LS II +38 49 B0.2 IV –0.29 4.488 4.332 15.01 13.38 353* EM*VES...

work page 1995

[7] [7]

13 mag); accordingly, the mass is updated by using the M/ L relation from Langer (1989, Eq.19). BC Cyg. Cluster member (Hunt & Re ﬀert 2024). log Te and log L are from Comerón et al. (2020), the latter value is adjusted t o DM =

work page 1989

[8] [8]

2002; Bressan et al

0152 theoretical isochrones (Girardi et al. 2002; Bressan et al. 2012). Masses given in italics (right-hand co lumn) are for the main-sequence stars, determined using the classical mass-luminosity relation from Eker et al. (2018). The normalization constant k is given by the mass of the cluster in the stellar mass range between mmin and mmax Mcl = ∫ mmax ...

work page 2002

[9] [9]

of ∼19 M⊙(Comerón et al. 2020). First and second rows refer to di ﬀerent status of the massive cluster member No. 234: when it is taken as single and the most massive (ﬁrst row) or adopted as having eq ual mass components (second row) which then become next to star No. 24 (27 M⊙) by mass. (2025), based on a new reduction of APOGEE DR17 vis- its, that o ﬀe...

work page 2020

[10] [10]

km s−1, from Schönrich et al. (2010). Space velocities ( U, V, W) with respect to the Local Stan- dard of Rest (LSR) can be transformed to peculiar velocities (Us, Vs, Ws) with respect to regional standard of rest (RSR) by rotating the vector ( U, V, W) through the Galactocentric azimuth angle of a given source and removing circular velocity of Gal ac- ti...

work page 2010

[11] [11]

Using the Galactic rotatio n curve by Reid et al

are located nearly at tangent point (their galactic latitud e, ℓ≃76◦, and the Galactocentric azimuth, ≃12◦, constitute the angle close to 90◦), hence their heliocentric RVs measure almost entirely the azimuthal motion (including the systematic eﬀect of Galactic ro- tation), whereas the other two velocity components, Us and Ws, remain almost independent on...

work page 2019

[12] [12]

km s −1 from Schönrich et al. (2010). d Calculated using the Galactic rotation curve from Reid et al . (2019) with R0 =

work page 2010

[13] [13]

The errors given do not include the contribution from uncertainties in the adopted parameters of the Galaxy and model potentials

8 pc (Bland-Hawthorn & Gerhard 2016). The errors given do not include the contribution from uncertainties in the adopted parameters of the Galaxy and model potentials. Article number, page 19

work page 2016