PROGRAMA FONDECYT INFORME FINAL ETAPA 2016 COMISIÓN NACIONAL DE INVESTIGACION CIENTÍFICA Y TECNOLÓGICA VERSION OFICIAL Nº 3 FECHA: 27/06/2017 Nº PROYECTO : 1140076 DURACIÓN : 3 años AÑO ETAPA : 2016 TÍTULO PROYECTO : INVESTIGATING THE PROPERTIES OF MASSIVE STARS THROUGH DEDICATED SPECTROSCOPIC AND IMAGING SURVEYS. DISCIPLINA PRINCIPAL : ASTRONOMIA GRUPO DE ESTUDIO : ASTRON.,COSMOL.Y PAR INVESTIGADOR(A) RESPONSABLE : RODOLFO HECTOR BARBA SUAREZ DIRECCIÓN : COMUNA : CIUDAD : La Serena REGIÓN : IV REGION FONDO NACIONAL DE DESARROLLO CIENTIFICO Y TECNOLOGICO (FONDECYT) Moneda 1375, Santiago de Chile - casilla 297-V, Santiago 21 Telefono: 2435 4350 FAX 2365 4435 Email: [email protected] INFORME FINAL PROYECTO FONDECYT REGULAR MODIFICACIONES ACADÉMICAS El informe no presenta modificaciones académicas. PROJECT RESULTS: Investigating the properties of massive stars through dedicated spectroscopic and imaging surveys. The main goals of this project were: 1. To increase the knowledge of the multiplicty among massive stars in the Milky Way and neighbour galaxies. We are providing multi-epoch RV measurements from high-resolution spectra. Specifically, we are publishing the most comprehensive and precise RV catalogue o southern massive stars, reaching a precision of about 0.5 km/s. Also, we are observing all Southern O- and WN-type stars with AstraLux Sur (a “lucky image” camera) in order to explore multiplicity at 0.1” scale. 2. To contribute to derive a comprehensive picture of the massive star population in distant parts of the Milky Way, in view of the GAIA mission. 3. To derive absolute physical parameters of a new set of massive eclipsing binaries discovered in our ongoing surveys. Some binaries are located in embedded and young massive clusters, thus, they could be close to the ZAMS, and then physical parameters derived from the light-curves will help to constrain the stellar models in a realistic way in the first stages of the evolution. 4. To derive precise astrophysical parameters for a set of double-lined spectroscopic binaries. These studies will be based in our set of high-resolution spectroscopic observations. 5. In the course of the present project, our research team will be working on observational and theoretical aspects of massive stars, thus providing an idela framework for the training of advanced students. 6. To contribute in the development of the VVV survey (the first large-scale public Chilean survey) and afterward to take advantage of the resulting science, using our NIR and stellar astrophysics expertise. It is our primarily intention to involve as many students as possible (under- and graduated) in the development of analysis tools to work with large databases, since it is crucial to transmit the new way to do astrophysics to the next generation of researchers. We have published a large number of papers based on the broad objectives of this project. Obviously, during the development has appeared new opportunities and ideas which were exploited with great success as the case of the monitoring of luminous blue variable stars and the study of magnetic properties of massive stars. In the following, results are being considerend in groups taking into account the goal item numbers. New orbits and properties of massive binaries in our Galaxy and Magellanic Clouds. “A close encounter of the massive kind” Maíz Apellániz, J., Sana, H., Barbá, R., et al. 2017, MNRAS, 464, 3561. This is a very important paper resulted from the sinergy of different monitoring surveys of O-type stars. We have used (a) HST ACS imaging and STIS spectroscopy, (b) ground-based PIONIER/VLT long-baseline interferometry, and (c) ground-based spectroscopy from different instruments to study the orbit of the extreme multiple system HD 93 129 Aa,Ab, which is composed of (at least) two very massive stars in a long-period orbit with e > 0.92 that will pass through periastron in 2017/2018. In several ways, the system is an η Car precursor. Around the time of periastron passage the two very strong winds will collide and generate an outburst of non- thermal hard X-ray emission without precedent in an O+O binary since astronomers have been able to observe above Earth’s atmosphere. A coordinated multiwavelength monitoring in the next two years will enable a breakthrough understanding of the wind interactions in such extreme close encounters. Furthermore, we have found evidence that HD 93 129 Aa may be a binary system itself. In that case, we could witness a three-body interaction that may yield a runaway star or a stellar collision close to or shortly after the periastron passage. Either of those outcomes would be unprecedented, as they are predicted to be low-frequency events in the Milky Way. After this discovery, we have started a large collaboration to monitor the event in different energy regimes from gamma-ray to the infrared, obtaining observing time at different ground-based (VLT, LCOGT, etc.) and space-based observatories (HST, NuStar, Fermi, Chandra, XMM, etc.). “The HD 5980 Multiple System: Masses and Evolutionary Status”, Koenigsberger et al. 2014, AJ, 148, 62. We have contributed to derive a new determination of masses and evolutionary status for the very intringuing LBV/WR system HD 5980. “Orbital and Physical Properties of the σ Ori Aa, Ab, B Triple System”, Simón-Díaz et al. 2015, ApJ, 799, 169. We have provided a complete characterization of the astrophysical properties of the σ Ori Aa, Ab, B hierarchical triple system. The combined quantitative spectroscopic analysis of the system was performed by means of the stellar atmosphere code FASTWIND. We also inferred evolutionary masses and stellar ages using the Bayesian code BONNSAI. The fastwind+bonnsai analysis showed that the Aa, Ab pair contains the hottest and most massive components of the triple system while σ Ori B is a bit cooler and less massive. The derived stellar ages of the inner pair are intriguingly younger than the one widely accepted for the σ Orionis cluster, at 3±1 Ma. “The little-studied cluster Berkeley 90. I. LS III +46 11: a very massive O3.5 If* + O3.5 If* binary”, Maíz Apellániz, J. Negueruela, I., Barbá, R. et al. 2015, A&A, 579, A108. This paper was a great discovery of a very massive system in our Galaxy composed by twin O3.5 If* + O3.5 If* stars in a very eccentric orbit. The system is located in a (at that moment) poorly known open cluster in the outer part of the Milky Way. This system is a unique example in our Galaxy. “A new massive double-lined spectroscopic binary system: The Wolf-Rayet star WR 68a” Collado, A., Gamen, R., Barbá, R., Morrell, N. 2015, A&A, 581, A49. In this paper, we have performed spectroscopic observations of the star WR 68a as part of a dedicated monitoring program of WR stars to discover new binary systems. We have discovered that WR 68a is a double- lined spectroscopic binary with an orbital period of 5.2207 days, very small or null eccentricity, and inclination ranging between 75 and 85 deg. We have classified the binary components as WN6 and O5.5-6. The WN star is less massive than the O-type star with minimum masses of 15 ± 5 Msun and 30 ± 4 Msun, respectively. The light curve constructed from available photometric data presents minima in both conjunctions of the system. “Discovery of the Massive Overcontact Binary VFTS352: Evidence for Enhanced Internal Mixing”, Almeida, L.A. et al. 2015, ApJ, 812, 102. This paper is the first of the ESO program dedicated to the monitoring spectroscopic binaries in 30 Doradus, project that I’m contributing. Here, we reported the discovery of VFTS 352, an O-type binary in the 30 Dor region, as the most massive and earliest spectral type overcontact system known to date. We derived the 3D geometry of the system, orbital period of 1.12 day, and dynamical masses M1=28.6±0.3 M⊙ and M2 =28.8±0.3 M⊙ . We ahave evidence of enhanced mixing, theoretically predicted to occur in very short-period tidally locked systems. The VFTS 352 components are two of the best candidates identified so far to undergo this so-called chemically homogeneous evolution. The future of VFTS 352 is uncertain. If the two stars merge, a very rapidly rotating star will be produced. Instead, if the stars continue to evolve homogeneously and keep shrinking within their Roche Lobes, coalescence can be avoided. In this case, tides may counteract the spin down by winds such that the VFTS 352 components may, at the end of their life, fulfill the requirements for long gamma-ray burst (GRB) progenitors in the collapsar scenario. Independently of whether the VFTS 352 components become GRB progenitors, this scenario makes VFTS 352 interesting as a progenitor of a black hole binary, hence as a potential gravitational wave source through black hole–black hole merger. “The eccentric short-period orbit of the supergiant fast X-ray transient HD 74194 (=LM Vel)”, Gamen, R. Barbá, R. et al. 2015, A&A, 583, L4. In this letter, we report the first orbital solution for the O-type supergiant star HD 74194, which is the optical counterpart of the supergiant fast X-ray transient IGR J08408-4503. We also analysed the complex Hα profile. We have determined that HD 74194 is a binary system composed of an O- type supergiant and a compact object in a short-period (P=9.54d) and high-eccentricity (e=0.63) orbit. The equivalent width of the Hα line is not modulated entirely with the orbital period, but seems to vary in a superorbital period (P=285d) nearly 30 times longer than the orbital one. “Spectroscopic and photometric analysis of early-type spectroscopic binary HD161853 in the centre of an H II”, Gamen, R., et al.