Context. Among the binary systems discovered by the spectroscopic monitoring of Southern Galactic O and WN stars, or the OWN Survey, several systems exhibit very different line broadening between their components. Aims. We aim to characterize these binary systems in order to understand the causes behind their markedly different spectral line widths, providing observational clues as to the physical mechanisms at play. Methods. We used new and archival multi-epoch high-resolution optical spectra for the radial velocity analysis and determined the spectroscopic orbits of both components in five systems: HD 57236, HD 93028, HD 101413, HD 151003, and HD 153426. The physical properties of the individual stellar components were determined through quantitative analysis. Using evolutionary models, we estimated the age of the systems and explored their tidal evolution. Results. The systems consist of O+O or O+B stars, with minimum masses ranging from similar to 6 M-circle dot to 21 M-circle dot, in young, wide, and fairly eccentric orbits (periods from approximately 22 to 977 d and eccentricities of e > 0.14). The primary and secondary components have a projected rotational velocity ratio of up to 1:7 (similar to 27 and similar to 193 km s(-1) in the case of HD 93028), similar to previous binary systems in this series, namely HD 93343 and HD 96264A. Conclusions. The youth and wide orbits of the systems indicate that the non-synchronous rotational nature of their components is a consequence of the stellar formation process, rather than a result of past binary interactions. While the role of binary interactions may be predominant in many cases, it is not a necessary condition to explain the entire observed population of fast rotators.

Context. Massive stars play crucial roles in galactic dynamics and chemical evolution. They are the most significant sources of ionizing UV radiation, their substantial mass-loss rates and explosions inject energy and enrich their surroundings, and their dynamical interactions eject stars and alter the evolution of stellar clusters. Consequently, the study of massive stars is essential for understanding various astrophysical phenomena, including galaxy chemical evolution, interstellar medium dynamics, gamma-ray bursts, and the reionization of the Universe. Key parameters influencing the evolution of massive stars include mass, mass-loss rate, chemical composition, and rotation. The orbits of spectroscopic binaries are particularly valuable because they provide constraints on stellar masses, and when combined with complementary data (e.g., photometry or interferometry), these masses can be fully determined. Aims. The OWN Survey was started two decades ago to study Galactic O- and WN- (hence the name) type southern spectroscopic binaries. In this paper we present the final results for single-lined (SB1) spectroscopic orbits. Methods. The OWN Survey carried out a long-term spectroscopic campaign to search for radial velocity variations indicative of orbital motion in a sample of southern Galactic O- and WN-type stars with high-resolution spectrographs in Argentina and Chile. The OWN spectra were later combined with high-resolution spectra from other sources and, in some cases, photometric time series to derive orbits and disentangled spectra, from which masses were constrained or determined and spectral classifications obtained. High-resolution optical spectra of 212 massive stars were obtained during the similar to 20 years of the OWN project, and each target was observed at least three times. Results. Among the 212 stars, 144 exhibited radial-velocity variations greater than 15 km s(-1). We present a complete and coherent compilation for the 23 systems with single-lined spectroscopic orbits identified in our sample. In Paper II we will perform a similar analysis for the systems with double-lined spectroscopic orbits.

Context. Massive stars play crucial roles in galactic dynamics and chemical evolution. They are the most significant sources of ionizing UV radiation, their substantial mass-loss rates and explosions inject energy and enrich their surroundings, and their dynamical interactions eject stars and alter the evolution of stellar clusters. Consequently, the study of massive stars is essential for understanding various astrophysical phenomena, including galaxy chemical evolution, interstellar medium dynamics, gamma-ray bursts, and the reionization of the Universe. Key parameters influencing the evolution of massive stars include mass, mass-loss rate, chemical composition, and rotation. The orbits of spectroscopic binaries are particularly valuable because they provide constraints on stellar masses, and when combined with complementary data (e.g., photometry or interferometry), these masses can be fully determined. Aims. The OWN Survey was started two decades ago to study Galactic O- and WN- (hence the name) type southern spectroscopic binaries. In this paper we present the final results for single-lined (SB1) spectroscopic orbits. Methods. The OWN Survey carried out a long-term spectroscopic campaign to search for radial velocity variations indicative of orbital motion in a sample of southern Galactic O- and WN-type stars with high-resolution spectrographs in Argentina and Chile. The OWN spectra were later combined with high-resolution spectra from other sources and, in some cases, photometric time series to derive orbits and disentangled spectra, from which masses were constrained or determined and spectral classifications obtained. High-resolution optical spectra of 212 massive stars were obtained during the ∼20 years of the OWN project, and each target was observed at least three times. Results. Among the 212 stars, 144 exhibited radial-velocity variations greater than 15 km s−1. We present a complete and coherent compilation for the 23 systems with single-lined spectroscopic orbits identified in our sample. In Paper II we will perform a similar analysis for the systems with double-lined spectroscopic orbits.

Context. Among the binary systems discovered by the spectroscopic monitoring of Southern Galactic O and WN stars, or the OWN Survey, several systems exhibit very different line broadening between their components. Aims. We aim to characterize these binary systems in order to understand the causes behind their markedly different spectral line widths, providing observational clues as to the physical mechanisms at play. Methods. We used new and archival multi-epoch high-resolution optical spectra for the radial velocity analysis and determined the spectroscopic orbits of both components in five systems: HD 57236, HD 93028, HD 101413, HD 151003, and HD 153426. The physical properties of the individual stellar components were determined through quantitative analysis. Using evolutionary models, we estimated the age of the systems and explored their tidal evolution. Results. The systems consist of O+O or O+B stars, with minimum masses ranging from ∼6 M⊙ to 21 M⊙, in young, wide, and fairly eccentric orbits (periods from approximately 22 to 977 d and eccentricities of e > 0.14). The primary and secondary components have a projected rotational velocity ratio of up to 1:7 (∼27 and ∼193 km s−1 in the case of HD 93028), similar to previous binary systems in this series, namely HD 93343 and HD 96264A. Conclusions. The youth and wide orbits of the systems indicate that the non-synchronous rotational nature of their components is a consequence of the stellar formation process, rather than a result of past binary interactions. While the role of binary interactions may be predominant in many cases, it is not a necessary condition to explain the entire observed population of fast rotators.

The study of spectral morphology is a powerful tool for understanding the fundamental properties of stars. The spectral classification scheme for O stars has been revised in the context of the Galactic O-Star Spectroscopic Survey and a new set of spectral standard stars has been proposed. Since the vast majority of the Galactic O stars are visible only in the infrared due to large interstellar absorption in the optical, it is necessary to extend this work towards those wavelengths. We are working on the construction of an atlas of Massive Galactic O-type Spectral Standards in the near-infrared (MaGOSS in the NIR), observing the standards, defined in the last installment of the Galactic O-Star Spectroscopic Survey, with high-quality spectra in the wavelength range between 0.85 μ m and 2.5 μ m. We present here an advance of the Atlas of MaGOSS in the NIR, which includes spectra of a sequence of dwarf, giant and supergiant stars. We analyze this data set to establish some spectral characteristics of such stars, with the aim of defining classification criteria in the near-infrared range, such as the ratios HeI λ 1.700 μ m/HeII λ1.692 μ m, HeI λ 1.031 μ m/HeII λ1.042 μ m, and HeI λ 2.112 μ m/HeII λ2.189 μ m.

For decades, the origin of helium enrichment in O-type stars has remained an open question. In this study, we investigate the correlation between surface helium abundance and orbital parameters for a sample of 45 O-type SB1 systems –including Cyg X-1. We find seven He-rich systems, all of which are concentrated at short orbital periods (P≲ 15 days) and are classified as runaways. In addition, four of them present relatively high eccentricities, while the other three have ellipsoidal variations. We argue that these properties are the result of binary interaction. These findings provide strong observational evidence that binary interaction is the dominant origin of helium enrichment in O-type stars. This result has important implications for the treatment of chemical mixing and surface abundances in massive-star evolutionary models, and establishes helium enrichment as a promising observational tracer for identifying post-interaction binary systems.

Context. The presence of massive O-type stars with surfaces enriched by CNO-cycle products has been known since the early 1980s. For many years, internal rotational mixing was assumed to be the dominant mechanism responsible for this chemical contamination. However, accumulating evidence suggests that binary interaction may play an equally important, if not dominant, role. Aims. Our aim was to carry out a large-scale investigation of surface helium (He) abundances in Galactic O-type stars, based on the results from the analysis of high-quality spectroscopic data from the IACOB project. Methods. We performed a homogeneous spectroscopic analysis of 318 Galactic O-type stars with the IACOB-BROAD and FASTWIND/IACOB-GBAT tools, deriving rotational velocities, atmospheric parameters, and He abundances. We also accounted for the influence of binarity and parameter degeneracies on the abundance determinations. Results. We present homogeneously determined surface He abundances (Y-He = N-He/N-H) for the largest, statistically significant sample to date of Galactic O-type stars. About 60% of the stars show He abundances consistent with the cosmic abundance standard of Y-He = 0.098 +/- 0.002. For another 18% of the stars, we obtain anomalously low He abundance estimates, reaching values down to 0.07. These unusual He abundances might be a consequence of flux contamination of the analysed spectra by a faint companion. The remaining 22% display clear He enrichment (Y-He greater than or similar to 0.13). We provide observational evidence indicating that most of these He-enriched stars are likely the products of binary interaction. Conclusions. Our study highlights how large spectroscopic surveys are gradually opening robust observational avenues to identify the products of massive binary interaction. It also emphasises the need for caution when interpreting the spectroscopic properties of apparently single O-type stars. A significant fraction may in fact be the outcome of binary evolution rather than isolated stellar birth.

Context. In recent years, a growing amount of evidence has revealed the crucial role of binarity in massive star evolution. This additional complexity compounds the uncertainties that still affect single-star evolution models and demands a refinement of the available observational constraints. A first crucial step toward this goal involves disentangling observed stars that have evolved in isolation from those that have experienced binary interaction. Aims. We aim to investigate the possible evolutionary origins of a sample of 117 Galactic O-type stars with luminosity classes V to III and projected rotational velocities (v sin i) below ∼150 km s−1. Methods. We mostly focused on surface nitrogen and helium abundances but also considered other dynamical signatures that may help distinguish products of binary interaction from effectively single stars. We have therefore extended previous quantitative spectroscopic analyses performed within the framework of the IACOB project, and we obtained N abundance estimates. We investigated the correlations between these abundances and other stellar parameters, such as v sin i, effective temperature, surface gravity, and He abundance. As a reference, we used state-of-the-art predictions from single-star evolution models computed using different physical prescriptions. Results. We found good agreement between our N abundance estimates and previous determinations based on different analysis methodologies and stellar atmosphere codes. We identified clear differences in the N abundance distributions corresponding to three He abundance regimes, defined as He-low (YHe = N(He)/N(H)≤0.08), He-normal (0.08 < YHe ≤ 0.12), and He-rich (YHe > 0.12). We argue that the abundance estimates for the He-low group, as well as for some additional stars with abnormally low N abundances, are likely spurious determinations. For the He-normal group, the N abundance distribution peaks slightly above the expected birth value and extends up to ϵN = log(N/H)+12 ∼ 8.4 dex. For these stars, we found an overall agreement with single-star evolutionary models that include efficient internal mixing and assume moderate-to-low initial rotation (vini/vcrit ≲ 0.2). In contrast, the He-rich group exhibits a bimodal N abundance distribution, with one peak at ∼8.1 dex corresponding to mildly enriched stars and a second more enriched peak around ∼8.5 dex. None of these stars are consistent with predictions from state-of-the-art single-star evolutionary models. Conclusions. We argue that the two N abundance subgroups among the He-rich stars are most plausibly explained as binary products. Furthermore, despite the N abundance in He-normal stars with luminosity classes (LC) IV and V being reproduced by single-star evolutionary models with efficient mixing models, the same models predict a higher N abundance than observed for stars in this group with LC III. This indicates that rotational mixing alone is unable to explain the observed distribution of N abundances among stars with normal He abundances. A future comprehensive study of surface abundances in O-type supergiants (LC I and II) and fast rotators that also incorporates the abundances of additional elements is essential to further constraining the evolutionary channels of the most massive stars during the main sequence.

Despite the essential role of massive stars in the evolution of the Universe, our understanding remains incomplete, particularly concerning mass loss and its influence on post-main-sequence evolution. Recognizing binary stars as ideal benchmarks for determining stellar parameters, we focused on two WR+O systems, WR 62a and WR 68a, identified as double eclipsing systems through TESS photometry. Notably, the light curve of these binaries presents a challenge to the classical modeling of photospheric eclipses, as demonstrated by the limitations of the PHysics Of Eclipsing Binaries (PHOEBE) code. To address this, we extended our approach by incorporating a model of Thomson scattering for atmospheric eclipses, complementing PHOEBE. Furthermore, a custom light curve synthesis algorithm was employed to account for binaries with extended atmospheres. This comprehensive methodology, integrating TESS data and radial velocity curves, significantly improves parameter precision, facilitating the analysis of the masses and radii of the WR and O components within the framework of massive stellar evolution.

In the pursuit of understanding the multiplicity of massive stars, the OWN Survey has undertaken spectroscopic monitoring of hundreds of targets over the past 20 yr. This effort has led to the discovery of new single-lined spectroscopic binaries. Characterizing the unseen companions of these systems is crucial to deriving precise stellar parameters, including the mass of each component, and constraining formation models for massive binary systems. In this paper, we aim to physically and evolutionarily characterize the stellar components of the massive binary HD 165246. We analyzed spectra obtained by the OWN Survey and used Kepler's second mission (K2) photometry, from which we determined the physical parameters of the system. Thanks to the high-resolution capabilities of the new echelle spectrograph Gemini/GHOST, we could directly detect spectral features of the secondary component for the first time. A very low mass ratio for the system is confirmed ( q ~ 0.16), making this binary one of the few extremely low mass ratio systems known. The primary star has a mass of M a = 22 ± 1 M ⊙ and a radius of R a = 7.0 ± 0.1 R ⊙ , while the secondary star has a mass of M b = 3.4 ± 0.1 M ⊙ and a radius of R b = 2.22 ± 0.02 R ⊙ . Stellar evolution models indicate that the system has undergone approximately two million years of evolution since its formation. Moreover, the secondary star is identified as a pre-main-sequence object, progressing toward the zero-age main sequence. This paper illustrates the power of high-resolution spectrographs such as GHOST in finding much lower mass, previously unseen stellar components of binary star systems.

Spectral morphological analysis is crucial for determining the fundamental physical properties of stars, particularly for rare and astrophysically important O-type stars. Due to heavy interstellar extinction in the optical range, most Galactic O stars remain obscured, making near-infrared (NIR) spectroscopy the only viable approach to achieve a reasonably complete sample of this stellar population and to extend current classification schemes. Our aim is to build a comprehensive spectral classification atlas of O-type stars in the NIR, providing robust morphological criteria to support and enhance future research on massive stars in heavily obscured environments. To this end, we obtained high-resolution ( R ∼ 4000–11,000) NIR spectra for the majority of standard stars from the latest installment of the Galactic O-Star Spectroscopic Survey, using spectrographs at Gemini North and Las Campanas Observatory to ensure broad spectral coverage and high data quality. We present an atlas featuring spectral sequences for nine dwarfs (O4 to B0), nine giants (O3.5 to O9.5), and 20 supergiants (O2 to B0), systematically organised and accompanied by clear morphological criteria for subtype classification across the Y , J , H , and K bands (0.930–1.115, 1.160–1.290, 1.460–1.760, and 2.050–2.200 μ m, respectively). This atlas provides a unified framework for reliable NIR classification of O-type stars and paves the way for detailed studies of massive stars in regions heavily affected by extinction.

In this paper, we present a new multifrequency study of the giant star-forming complex RCW 122. We used molecular data obtained with the ASTE 10 m and the APEX 12 m telescopes, along with infrared observations spanning from 3.6 mu m to 870 mu m, obtained from available databases. We also incorporated a range of public datasets, including the radio continuum at 3 GHz, narrowband Ha images, and deep JHK photometry. Our analysis focuses mostly on cataloged ATLASGAL sources, showcasing a spectrum of evolutionary stages from infrared dark cloud (IRDC)/high-mass protostellar object (HMPO) to ultra-compact HII region (UCHII), as inferred from preliminary inspections of the public dataset. Based on ASTE HCO+(4-3) and CO(3-2) data, we identified five molecular clumps, designated A, B, C, D, and E, as molecular counterparts of the ATLASGAL sources. These clumps have radial velocities ranging from similar to-15 km s(-1) to -10 km s(-1), confirming their association with RCW 122. In addition, we report the detection of 20 transitions from 11 distinct molecules in the APEX spectra in the frequency ranges from 258.38 GHz to 262.38 GHz, 228.538 GHz to 232.538 GHz, and 218.3 GHz to 222.3 GHz, unveiling a diverse chemical complexity among the clumps. Utilizing CO(2-1) and (CO)-O-18(2-1) data taken from the observations with the APEX telescope, we estimated the total LTE molecular mass, ranging from 200 M-circle dot (clump A) to 4400 M-circle dot (clump B). Our mid- to far-infrared (MIR-FIR) flux density analysis yielded minimum dust temperatures of 23.7 K (clump A) to maximum temperatures of 33.9 K (clump B), indicating varying degrees of internal heating among the clumps. The bolometric luminosities span 1.7x10(3)L(circle dot) (clump A) to 2.4x10(5)L(circle dot) (clump B), while the total (dust+gas) mass ranges from 350 M-circle dot (clump A) to 3800 M-circle dot (clump B). Our analysis of the molecular line richness, L/M ratios, and CH3CCH and dust temperatures reveals an evolutionary sequence of A/E -> C -> D/B, consistent with preliminary inferences of the ATLASGAL sources. In this context, clumps A and E exhibit early stages of collapse, with clump A likely in an early HMPO phase, which is supported by identifying a candidate molecular outflow. Clump E appears to be in an intermediate stage between IRDC and HMPO. Clumps D and B show evidence of being in the UCHII phase, with clump B likely more advanced. Clump C likely represents an intermediate stage between HMPO and HMC. Our findings suggest clump B is undergoing ionization and heating by multiple stellar and protostellar members of the stellar cluster DBS 119. Meanwhile, other cluster members may be responsible for ionizing other regions of RCW 122 that have evolved into fully developed HII regions, beyond the molecular dissociation stage.

ABSTRACT We present the first spectroscopic orbit of the O-type double-lined star HD 168112 A,B. We analyse 101 high-resolution optical spectra identifying the absorption lines of both components. The orbital solution presents a relatively long period, P = 513.52 ± 0.01 d, and a high eccentricity, e = 0.743 ± 0.005. The binary system consists of two very similar stars of minimum masses of ∼25 M⊙, effective temperatures of ∼40 000 K, and surface gravities of ∼3.7 dex. The system has a minimum semimajor axis a sin i ∼ 1000 R⊙. We confirm that the A and B visual components identified via interferometry do correspond to the spectroscopic ones. We also analyse the underlying stellar groups using Gaia DR3 data and ground-based spectroscopy as part of the Villafranca project, determining that NGC 6604 is at a distance of $1942^{+38}_{-36}$ pc and giving spectral classifications for 23 massive stellar systems in Villafranca O-035 and the surrounding Ser OB2 association, for which we provide the most complete census of massive stars to date.

ABSTRACT The evolution of massive stars is not completely understood. Several phenomena affect their birth, life, and death, multiplicity being one of them. In this context, the OWN and MONOS projects are systematically observing O- and WN-type stars whose multiplicity status is unknown. Their major goal considers the necessity of determining absolute parameters of massive stars. We have collected spectra of HD 93249 A and ALS 12502 A aiming at characterizing their binary nature. For both stars, we analysed high-resolution spectra and combined them with Transiting Exoplanet Survey Satellite (TESS) observations to be compared with binary models constructed by means of the phoebe code. We discovered that the radial velocity of HD 93249 A varies with a period of 2.97968 ± 0.00001 d and that the system presents ellipsoidal light variations. We disentangled the composite spectra and classified its components as O9 III and B1.5 III, respectively. Confirmed as a spectroscopic binary, HD 93249 A can no longer be used as spectral classification standard. ALS 12502 A turned out to be a detached eclipsing binary in the TESS and Gaia data. These results enable us to determine absolute parameters for each component in the system.

We investigate Wray 15-811, a poorly studied object of controversial nature. We present for the first time spectroscopic observations (at low, medium, and high resolution), together with deep narrow-band images. These original data are combined with data from public surveys, to infer the nature of this object. We conclude that Wray 15-811 is indeed a carbon star with an optical bow-shock nebula associated. Its spectrum displays a split Ha emission, and its SED indicates the presence of silicates features. The light curve is similar to the expected for a Mira variable with a 504-day period. Its proper motion is compatible with that of a runaway star, consistent with the presence of the observed bow-shock nebula.

We present a multi-wavelength study of the H ii region G331.03-00.15, with the aim of identifying the population of massive stars associated with it. The distributions of ionised gas and heated dust both exhibit similar spherical forms, while the bordering photo-dissociating region follows a very ring-like distribution, indicating the presence of abundant neighbouring molecular material being photo-dissociated. There is only one high-mass star catalogued in the region, namely, the WR star 1051-67L. Based on an energy analysis of the detected radio continuum emission, we deduced that additional high-mass stars could be interacting with G331.03-00.15. We conducted a search of massive star candidates by applying a series of colour criteria to a sample of highly reddened infrared (IR) point sources projected over the radio continuum morphology, with the additional condition that they be located at the same distance assumed for the region. Fourteen candidate sources were selected and classified using low-resolution, near-infrared (NIR) spectroscopic data in the H and K bands, obtained with Gemini/FLAMINGOS-2. We identified one massive star and classified it as an O7 V star. Adding the contribution from this new star to the total ionising radiation available, we concluded that it would be possible for the H ii region to be powered solely by these two massive stars. However, we do not rule out the possibility that there could be more early-type stars that remain undetected in this highly obscured part of the Galaxy. Additionally, we searched for primary tracers of star-forming activity and identified several class I and II candidate young stellar objects (YSOs), positioned over the dense clouds and clumps of molecular material found in the area. The presence of several maser species located in the densest cloud are also indicative of massive star formation taking place in the vicinity of G331.03-00.15.

ABSTRACT We present a new spectroscopic orbit of the O-type binary system HD 152147. We identify absorption lines in both components and use their radial velocities to determine the orbit, which results in a period of P = 50.2199 ± 0.0007 d, an eccentricity e = 0.738 ± 0.007, and a mean separation between the components of asin i = 151 ± 1 R⊙. Considering that the distance to the system is 1600 pc, this implies an angular separation of ∼0.44 mas, making it suitable for modern interferometric observations. In addition, we determine the fundamental stellar parameters of each component by means of a quantitative spectral analysis. We obtain Ma = 31.9−34.6 M⊙ and Ra = 17−24 R⊙ for the primary, and Mb = 14−15 M⊙ and Rb = 5−10 R⊙ for the secondary. We apply models with rotation to try to characterize the evolutionary status of the HD 152147 system. We find that the two components are compatible with a common age of 4.5 Myr. We also detect variations in the profile of Hα that are not modulated by the orbital cycle. Moreover, TESS photometry also presents intrinsic variability and was analysed for periodicities. We find a most relevant frequency of 20 times the orbital one, in a TESS data set that includes the periastron passage, and we interpret it as a tidally induced pulsation that seems to dissipate on a time-scale shorter than the orbital cycle because it is not present in another TESS data set that nearly covers the apoastron.

ABSTRACT We present a multiwavelength investigation of the H ii region G347.600+00.211, located at a distance of 7.9 kpc. We analyse the gas and dust properties aiming to disentangle the origin of the region as well as its role in the formation of new stars. G347.600 + 00.211 is very conspicuous at 1420 MHz and infrared wavelengths, showing an incomplete shell-like structure with two distinct zones of very intense emission. The infrared bubble S8 is part of the shell structure. The spatial distribution of the molecular gas shows the presence of six clouds located around the ionized region and showing a good morphological correlation with the 8-$\mu$m emission. Cold dust is coincident with the dense gas shown in the CO measurements. As for the origin of the region, we found that the massive cluster [DBS2003]179 and two Wolf–Rayet (WR) stars are located at the same distance than the ionized gas. Based on a stellar density analysis, we inferred that one of the WR stars, 1181-81L, is also a probable member of the cluster. Both the cluster and the WR stars are not only within the ring-like structure, but are also located near the two spots of very heightened emission, suggesting they may be responsible for this bright emission. Finally, as expanding H ii regions are hypothesized to trigger star formation, we used different infrared point source catalogues to search for young stellar object candidates (cYSOs). A total of 33 cYSOs and 4 CH ii regions were identified projected on to the photodissociation regions and molecular clouds.

ABSTRACT The Cygnus region harbours a vast diversity of rich stellar complexes. Hence, it is ideal for studying recently formed stellar clusters, and investigate how the feedback effect and radiation emitted by its massive stars modifies the interstellar medium giving place to induced star forming processes. This is the case of the small and poorly studied cluster DB2001-22. We focus our attention at analysing the cluster and its encompassing region, to distinguish different stellar populations and study their relationship with the surrounding environment. We gleaned literature and data bases for optical and IR photometry, astrometry provided by Gaia eDR3 and spectroscopy, and obtained new infrared Gemini spectra of three young stellar objects candidates (cYSOs). Furthermore, we detected two new massive stars: O7 V and B3 V, in the LAMOST data base, pointing out that DB2001–22 belongs to a much larger complex that involves an entire bubble structure and houses a richer massive population at a distance of 3.0 kpc. In this sense, DB2001–22 and the H ii region G82.6+0.4 are clearly related. Some observed gas and dust structures seem to have been sculpted by these massive stars. Infrared emission is compatible with a hot ionized gas mixed with warm dust surrounded by a structured photo-dissociation region (PDR) scenario. We found nine Class I and 56 Class II cYSOs, whose distribution along the PDR and the tips of pillar structures suggests that their formation may have been induced by the action of the earliest stars in the cluster on to their environment.

Context. The OWN Survey has detected several O-type stars with composite spectra whose individual components show very different line broadening. Some of these stars have been revealed as binary systems whose components are asynchronous. This fact may be related to the processes acting in these systems (e.g., angular-momentum transfer, tidal forces, etc.) or to the origin of the binaries themselves. Aims. We aim to determine the orbital and physical parameters of the massive star HD 96264A in order to confirm its binary nature and to constrain the evolutionary status of its stellar components. Methods. We computed the spectroscopic orbit of the system based on the radial velocity analysis of 37 high-resolution, high-S/N, multi-epoch optical spectra. We disentangled the composite spectrum and determined the physical properties of the individual stellar components using FASTWIND models incorporated to the IACOB-GBAT tool. We also computed a set of evolutionary models to estimate the age of the system and explore its tidal evolution. Results. HD 96264A is a binary system composed of an O9.2 IV primary and a B0 V(n) secondary, with minimum masses of 15.0 ± 0.5 M ⊙ and 9.9 ± 0.4 M ⊙ , respectively, in a wide and eccentric orbit ( P = 124.336 ± 0.008 d; e = 0.265 ± 0.005). The primary and secondary components have different projected rotational velocities (∼40 and ∼215 km s −1 respectively), and the physical properties derived through quantitative spectroscopic analyses include masses of ∼20.5 M ⊙ and 16.8 M ⊙ , respectively. The evolutionary models indicate an approximate age of 4.5 Myr for both stars in the pair, corresponding to current masses and radii of 26.0 M ⊙ and 10.8 R ⊙ for the primary, and 17.9 M ⊙ and 7.0 R ⊙ for the secondary. Conclusions. The youth and wide orbit of the system indicate that the non-synchronous rotational nature of its components is a consequence of the stellar formation process rather than tidal evolution. This circumstance should be accounted for in theories of binary star formation.