Properties of massive stars in Galactic binary systems

En el marco del proyecto OWN, usamos datos espectroscópicos de alta resolución de la binaria masiva HD 54662 para medir velocidades radiales y desentramar los espectros de las dos componentes del sistema, que hemos clasificado como O6.5 Vz(n) y O7.5 Vz. Obtenemos una nueva solución orbital espectroscópica para el sistema, con un periodo de 5.50 ± 0.02 años. Usamos datos astrométricos publicados para calcular masas estelares absolutas de 24 ± 1 y 20 ± 1 M para las componentes A y B, respectivamente. Analizamos cuantitativamente los espectros desentramados con modelos fastwind de atmósferas estelares y calculamos masas evolutivas actuales usando la herramienta bonnsai. Obtenemos masas evolutivas demasiado altas, lo cual podría estar relacionado con el problema de discrepancia de masas.Within the OWN project, we use high resolution spectroscopic data of the massive binary system HD54662 to measure accurate radial velocities and disentangle the spectra of the two components, which we classify as O6.5Vz(n) and O7.5Vz. We obtain a new spectroscopic orbital solution of the system, with a period of P=5.500.02yr. We use published astrometric data to derive absolute stellar masses of 241 and 201M for components A and B, respectively. We analyze quantitatively the disentangled spectra using fastwind stellar atmosphere models and infer current evolutionary masses using the bonnsai tool. We find too high evolutionary masses, which could be related to the mass discrepancy problem.Fil: Sabín Sanjulián, C.. Universidad de La Serena; ChileFil: Barba, Rodolfo Héctor. Universidad de La Serena; ChileFil: Gamen, Roberto Claudio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Astrofísica La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas. Instituto de Astrofísica La Plata; ArgentinaFil: Arias, J. A.. Universidad de La Serena; ChileSegunda Reunión Binacional de Asociación Argentina de Astronomía y Sociedad Chilena de AstronomíaLa SerenaChileUniversidad de La SerenaSociedad Chilena de Astronomí

A new spectroscopic analysis of the massive O + O type binary HD 54662 AB

HD 54662 AB is one of the three O + OB binaries known so far with orbital period longer than 1000 d, offering the opportunity to test scenarios of massive star formation and models of single stellar evolution. Here, we present a detailed study of this system based on new high-resolution spectra and data. A disentangling method is used to recover the individual spectra of the primary and secondary components, which are classified as O6.5 V(n)z and O7.5 Vz, respectively. Combining radial velocity measurements and astrometric data, a new absolute orbit with a period of 2113 ± 9 d and an eccentricity of 0.062 ± 0.008 is determined, confirming previous findings. However, absolute masses of 23.8 ± 1.1 M for the primary and 20.3 ± 1.1 M for the secondary are obtained, differing from previous determinations but in reasonable agreement with the spectral types of the stars. Primary and secondary components show remarkably different projected rotational velocities (160 and 40 km s−1 , respectively), which is probably related to the formation process of the binary. Contrary to previously interpretations, the star with broader spectral features is the most massive object in the system. Stellar and wind parameters of both stars are derived through quantitative spectroscopic analysis of the disentangled spectra using FASTWIND models, and they are consistent with the current calibrations for O-type stars. Evolutionary masses and ages are also computed with the BONNSAI tool. Ages below 2.5 Ma are obtained, in agreement with the youth expected from their Vz nature.Fil: Barba, Rodolfo Héctor. Universidad de La Serena; ChileFil: Sabín Sanjulián, C. Universidad de La Serena; ChileFil: Arias, J. I.. Universidad de La Serena; ChileFil: Gamen, Roberto Claudio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Astrofísica La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas. Instituto de Astrofísica La Plata; ArgentinaFil: Morrell, Nidia Irene. Observatorio Las Campanas, Carnegie Institution; ChileFil: Ferrero, G. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Astrofísica La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas. Instituto de Astrofísica La Plata; ArgentinaFil: Maíz Apellániz, Jesús. Csic-Inta. Centro de Astrobiología; EspañaFil: Putkuri, C.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Astrofísica La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas. Instituto de Astrofísica La Plata; ArgentinaFil: Simón Díaz, S.. Instituto de Astrofísica de Canarias; EspañaFil: Boyajian, T. S.. Louisiana State University; Estados UnidosFil: Fullerton, A. W.. Space Telescope Science Institute; Estados UnidosFil: McSwain, M. V.. Lehigh University; Estados Unido

Spectroscopic study of the extremely young O-type triple system Herschel 36 A in the Hourglass nebula - I. Orbital properties

We present a detailed spectroscopic study of Herschel 36 A (H36A), the main stellar component of the massive multiple system Herschel 36 in the Hourglass nebula, based on high-resolution optical spectra obtained along an 11 yr span. The three stellar components present in the spectrum of H36A are separated by means of a spectral disentangling technique. Individual spectral classifications are improved, and high-precision orbital solutions for the inner and outer orbits are calculated. H36A is confirmed to be a hierarchical triple system composed of a close massive binary (Ab1 + Ab2, O9.5 V + B0.7 V) in wide orbit around a third O-type star (Aa, O7.5 Vz). The inner-pair orbit is characterized by a period of 1.54157 ± 0.00006 d, and semi-amplitudes of 181.2 ± 0.7 and 295.4 ± 1.7 km s−1. The outer orbit has a period of 492.81 ± 0.69 d, and semi-amplitudes of 62.0 ± 0.6 and 42.4 ± 0.8 km s−1. The inner and outer orbits are not coplanar, having a relative inclination of at least 20◦. Dynamical minimum masses of 20.6 ± 0.8 M☉, 18.7 ± 1.1 M☉, and 11.5 ± 1.1 M☉ are derived for the Aa, Ab1, and Ab2 components, respectively, in reasonable agreement with the theoretical calibrations.Fil: Campillay, Abdo R.. Universidad de La Serena; ChileFil: Arias, Julia Ines. Universidad de La Serena; Chile. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Barba, Rodolfo Héctor. Universidad de La Serena; Chile. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Morrell, Nidia Irene. Observatorio Las Campanas, Carnegie Institution; Chile. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Gamen, Roberto Claudio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Astrofísica La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas. Instituto de Astrofísica La Plata; ArgentinaFil: Maíz Apellániz, Jesús. Consejo Superior de Investigaciones Científicas; Españ

A remarkable change of the spectrum of the magnetic Of?p star HD148937 reveals evidence of an eccentric, high-mass binary

We report newspectroscopic observations of themagnetic Of?p starHD148937 obtained since 2015 that differ qualitatively from its extensive historical record of weak, periodic spectral variations. This remarkable behaviour represents clear evidence for an unprecedented change in the character of variability of the star. In this paper, we describe the new spectral properties and compare them to the previous line profiles. Based on measurements of the radial velocities of the C III/N III emission lines near 4640 Å and the CIV absorption lines near 5800 Å, we infer that HD148937 is likely a high-mass, double-lined spectroscopic binary. Combining the spectroscopic orbit with an archival interferometric measurement of the apparent separation of the equal brightness components, we tentatively conclude that HD148937 consists of two O-type stars with masses of approximately 34 and 49 Mo, orbiting in an eccentric (e = 0.75), long-period (Porb 26 yr) orbit. We discuss the potential relationship of the binary system to the peculiar properties of HD148937, and propose future observations to refine the orbital and stellar properties.Fil: Wade, G. A.. Royal Military College of Canada; CanadáFil: Smoker, J. V.. European Southern Observatory Chile; ChileFil: Evans, C. J.. Uk Astronomy Technology Centre, Royal Observatory; Reino UnidoFil: Howarth, I. D.. Colegio Universitario de Londres; Reino UnidoFil: Barba, Rodolfo Héctor. Universidad de La Serena; Chile. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Juan. Instituto de Ciencias Astronómicas, de la Tierra y del Espacio. Universidad Nacional de San Juan. Instituto de Ciencias Astronómicas, de la Tierra y del Espacio; ArgentinaFil: Cox, N. L. J.. University of Amsterdam; Países BajosFil: Morrell, Nidia Irene. Las Campanas Observatory, Carnegie Observatories; Chile. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Nazé, Yaël. Université de Liège; BélgicaFil: Cami, J.. The University of Western Ontario; Reino Unido. SETI Institute; Estados UnidosFil: Farhang, A.. The University of Western Ontario; Reino Unido. Institute for Research in Fundamental Sciences; IránFil: Walborn, Nolan Revere. Space Telescope Science Institute; Estados UnidosFil: Arias, J.. Universidad de La Serena; ChileFil: Gamen, Roberto Claudio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Astrofísica La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas. Instituto de Astrofísica La Plata; Argentin