Proyecto de Investigación: AYA2015-68012-C2-1-P
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AYA2015-68012-C2-1-P
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MONOS: Multiplicity Of Northern O-type Spectroscopic systems I. Project description and spectral classifications and visual multiplicity of previously known objects
(EDP Sciences, 2019-06-05) Maíz Apellániz, J.; Trigueros Páez, E.; Negueruela, I.; Barbá, R. H.; Simón Díaz, S.; Lorenzo, J.; Sota, A.; Gamen, R. C.; Fariña, C.; Salas, J.; Caballero, J. A.; Morrell, N. I.; Pellerín, A.; Alfaro, E. J.; Herrero, A.; Arias, J. I.; Marco, A.; Ministerio de Economía y Competitividad (MINECO); Agencia Estatal de Investigación (AEI); Cabildo de Gran Canaria; 0000-0003-0825-3443; 0000-0001-6770-1977; 0000-0003-1952-3680; 0000-0001-5358-0932; 0000-0002-9404-6952; 0000-0002-5227-9627; 0000-0002-7349-1387; 0000-0003-1887-1966; 0000-0001-8768-2179; 0000-0002-9594-1879; Centros de Excelencia Severo Ochoa, INSTITUTO DE ASTROFÍSICA DE CANARIAS (IAC), SEV-2015-0548; Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737
Context. Multiplicity in massive stars is key to understanding the chemical and dynamical evolution of galaxies. Among massive stars, those of O type play a crucial role due to their high masses and short lifetimes.
Aims. MONOS (Multiplicity Of Northern O-type Spectroscopic systems) is a project designed to collect information and study O-type spectroscopic binaries with δ > −20°. In this first paper we describe the sample and provide spectral classifications and additional information for objects with previous spectroscopic and/or eclipsing binary orbits. In future papers we will test the validity of previous solutions and calculate new spectroscopic orbits.
Methods. The spectra in this paper have two sources: the Galactic O-Star Spectroscopic Survey (GOSSS), a project that obtains blue-violet R ∼ 2500 spectroscopy of thousands of massive stars, and LiLiMaRlin, a library of libraries of high-resolution spectroscopy of massive stars obtained from four different surveys (CAFÉ-BEANS, OWN, IACOB, and NoMaDS) and additional data from our own observing programs and public archives. We have also used lucky images obtained with AstraLux.
Results. We present homogeneous spectral classifications for 92 O-type spectroscopic multiple systems and ten optical companions, many of them original. We discuss the visual multiplicity of each system with the support of AstraLux images and additional sources. For eleven O-type objects and for six B-type objects we present their first GOSSS spectral classifications. For two known eclipsing binaries we detect double absorption lines (SB2) or a single moving line (SB1) for the first time, to which we add a third system reported by us recently. For two previous SB1 systems we detect their SB2 nature for the first time and give their first separate spectral classifications, something we have also done for a third object just recently identified as a SB2. We also detect nine new astrometric companions and provide updated information on several others. We emphasize the results for two stars: for σ Ori AaAbB we provide spectral classifications for the three components with a single observation for the first time thanks to a lucky spectroscopy observation obtained close to the Aa,Ab periastron and for θ1 Ori CaCb we add it to the class of Galactic Of?p stars, raising the number of its members to six. Our sample of O-type spectroscopic binaries contains more triple- or higher-order systems than double systems.
Lucky Spectroscopy, an equivalent technique to Lucky Imaging Spatially resolved spectroscopy of massive close visual binaries using the William Herschel Telescope
(EDP Sciences, 2018-07-01) Maíz Apellániz, J.; Barbá, R. H.; Simón Díaz, S.; Sota, A.; Trigueros Páez, E.; Caballero, J. A.; Alfaro, Emilio J.; Ministerio de Economía y Competitividad (MINECO); Agencia Estatal de Investigación (AEI); Maíz Apellániz, J. [0000-0003-0825-3443]; Barbá, R. H. [0000-0003-1086-1579]; Simón Díaz, S. [0000-0003-1168-3524]; Trigueros Páez, E. [0000-0001-6770-1977]
Context. Many massive stars have nearby companions whose presence hamper their characterization through spectroscopy.
Aims. We want to obtain spatially resolved spectroscopy of close massive visual binaries to derive their spectral types.
Methods. We obtained a large number of short long-slit spectroscopic exposures of five close binaries under good seeing conditions. We selected those with the best characteristics, extracted the spectra using multiple-profile fitting, and combined the results to derive spatially separated spectra.
Results. We demonstrate the usefulness of Lucky Spectroscopy by presenting the spatially resolved spectra of the components of each system, in two cases with separations of only ~0.′′3. Those are δ Ori Aa+Ab (resolved in the optical for the first time) and σ Ori AaAb+B (first time ever resolved). We also spatially resolve 15 Mon AaAb+B, ζ Ori AaAb+B (both previously resolved with GOSSS, the Galactic O-Star Spectroscopic Survey), and η Ori AaAb+B, a system with two spectroscopic B+B binaries and a fifth visual component. The systems have in common that they are composed of an inner pair of slow rotators orbited by one or more fast rotators, a characteristic that could have consequences for the theories of massive star formation.
MOS spectroscopy of protocluster candidate galaxies at z = 6.5
(Oxford Academics: Oxford University Press, 2019-08-16) Calvi, R.; Rodríguez Espinosa, J. M.; Mas hesse, J. M.; Chanchaiworawit, K.; Guzman, R.; Salvador Solé, E.; Gallego, J.; Herrero, A.; Manrique, Alberto; Marín Franch, A.; National Astronomical Research Institute of Thailand (NARIT); European Commission (EC); Ministry of Education, Culture, Sports, Science and Technology (MEXT); Agencia Estatal de Investigación (AEI); Ministerio de Economía y Competitividad (MINECO); Manríque, A. [0000-0001-5339-2659]; Gallego, J. [0000-0003-1439-7697]; Calvi, R. [0000-0002-1462-9462]; Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737; Centros de Excelencia Severo Ochoa, INSTITUTO DE ASTROFÍSICA DE CANARIAS (IAC), SEV-2015-0548; Unidad de Excelencia Científica María de Maeztu Instituto de Ciencias del Cosmos (ICCUB), MDM-2014-0369
The epoch corresponding to a redshift of z ∼ 6.5 is close to full re-ionization of the Universe, and early enough to provide an intriguing environment to observe the early stage of large-scale structure formation. It is also an epoch that can be used to verify the abundance of a large population of low luminosity star-forming galaxies that are deemed responsible for cosmic re-ionization. Here, we present the results of follow-up multi-object spectroscopy using OSIRIS at Gran Telescopio Canarias of 16 Ly α emitter (LAE) candidates discovered in the Subaru/XMM Newton Deep Survey. We have securely confirmed 10 LAEs with sufficient signal-to-noise ratio of the Ly α emission line. The inferred star formation rates of the confirmed LAEs are on the low side, within the range 0.9–4.7 M⊙ yr−1. However, they show relatively high Ly α rest frame equivalent widths. Finally we have shown that the mechanical energy released by the star formation episodes in these galaxies is enough to create holes in the neutral hydrogen medium such that Lyman continuum photons can escape to the intergalactic medium, thus contributing to the re-ionization of the Universe.
System initial mass function of the 25 Ori group from planetary-mass objects to intermediate/high-mass stars
(Oxford Academics: Oxford University Press, 2019-04-18) Suárez, G.; Downes, J. J.; Román Zúñiga, C.; Cerviño, M.; Briceño, C.; Petr Gotzens, M. G.; Vivas, K.; Consejo Nacional de Ciencia y Tecnología (CONACYT); Universidad Nacional Autónoma de México (UNAM); Agencia Estatal de Investigación (AEI); Ministerio de Economía y Competitividad (MINECO); Suárez, G. [0000-0002-2011-4924]; Downes, J. J. [0000-0001-6559-2578]; Román Zúñiga, C. [0000-0001-8600-4798]; Cerviño, M. [0000-0001-8009-231X]; Briceño, C. [0000-0001-7124-4094]; Vivas, K. [0000-0003-4341-6172]; Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737
The stellar initial mass function (IMF) is an essential input for many astrophysical studies but only in a few cases has it been determined over the whole cluster mass range, limiting the conclusions about its nature. The 25 Orionis group (25 Ori) is an excellent laboratory for investigating the IMF across the entire mass range of the population, from planetary-mass objects to intermediate/high-mass stars. We combine new deep optical photometry with optical and near-infrared data from the literature to select 1687 member candidates covering a 1.1° radius area in 25 Ori. With this sample we derived the 25 Ori system IMF from 0.012 to 13.1 M⊙. This system IMF is well described by a two-segment power law with Γ = −0.74 ± 0.04 for m < 0.4 M⊙ and Γ = 1.50 ± 0.11 for m ≥ 0.4 M⊙. It is also well described over the whole mass range by a tapered power-law function with Γ = 1.10 ± 0.09, mp = 0.31 ± 0.03 and β = 2.11 ± 0.09. The best lognormal representation of the system IMF has mc = 0.31 ± 0.04 and σ = 0.46 ± 0.05 for m < 1 M⊙. This system IMF does not present significant variations with the radii. We compared the resultant system IMF as well as the brown dwarf/star ratio of 0.16 ± 0.03 that we estimated for 25 Ori with that of other stellar regions with diverse conditions and found no significant discrepancies. These results support the idea that general star-formation mechanisms are probably not strongly dependent on environmental conditions. We found that the substellar and stellar objects in 25 Ori do not have any preferential spatial distributions and confirmed that 25 Ori is a gravitationally unbound stellar association.
Spectroscopic characterization of the known O-star population in Cygnus OB2: Evidence of multiple star-forming bursts
(EDP Sciences, 2020-10-15) Berlanas, S. R.; Herrero, A.; Comerón, F.; Simón Díaz, S.; Lennon, D. J.; Pasquali, A.; Maíz Apellániz, J.; Sota, A.; Pellerín, A.; Agencia Estatal de Investigación (AEI); Ministerio de Economía y Competitividad (MINECO); Pasquali, L. [0000-0003-2423-1826]; Centros de Excelencia Severo Ochoa, INSTITUTO DE ASTROFÍSICA DE CANARIAS (IAC), SEV-2015-0548; Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737
Context. Cygnus OB2 provides a unique insight into the high-mass stellar content in one of the largest groups of young massive stars in our Galaxy. Although several studies of its massive population have been carried out over the last decades, an extensive spectroscopic study of the whole known O-star population in the association is still lacking.
Aims. We aim to carry out a spectroscopic characterization of all the currently known O stars in Cygnus OB2, determining the distribution of rotational velocities and accurate stellar parameters to obtain an improved view of the evolutionary status of the region.
Methods. Based on existing and new optical spectroscopy, we performed a detailed quantitative spectroscopic analysis of all the known O-type stars identified in the association. For this purpose, we used the user-friendly iacob-broad and iacob-gbat automatized tools, FASTWIND stellar models, and astrometry provided by the Gaia second data release.
Results. We created the most complete spectroscopic census of O stars carried out so far in Cygnus OB2 using already existing and new spectroscopy. We present the spectra for 78 O-type stars, from which we identify new binary systems, obtain the distribution of rotational velocities, and determine the main stellar parameters for all the stars in the region that have not been detected as double-line spectroscopic binaries. We also derive radii, luminosities, and masses for those stars with reliable Gaia astrometry, in addition to creating the Hertzsprung-Russell Diagram to interpret the evolutionary status of the association. Finally, we inspect the dynamical state of the population and identify runaway candidates.
Conclusions. Our spectroscopic analysis of the O-star population in Cygnus OB2 has led to the discovery of two new binary systems and the determination of the main stellar parameters, including rotational velocities, luminosities, masses, and radii for all identified stars. This work has shown the improvement reached when using accurate spectroscopic parameters and astrometry for the interpretation of the evolutionary status of a population, revealing, in the case of Cygnus OB2, at least two star-forming bursts at ~3 and ~5 Myr. We find an apparent deficit of very fast rotators in the distribution of rotational velocities. The inspection of the dynamical distribution of the sample has allowed us to identify nine O stars with peculiar proper motions and discuss a possible dynamical ejection scenario or past supernova explosions in the region.
