Examinando por Autor "Sota, A."

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Acceso Abierto
Lucky spectroscopy, an equivalent technique to lucky imaging II. Spatially resolved intermediate-resolution blue-violet spectroscopy of 19 close massive binaries using the William Herschel Telescope
(EDP Sciences, 2021-06-29) Maíz Apellániz, J.; Barbá, R. H.; Fariña, C.; Sota, A.; Pantaleoni González, M.; Holgado, G.; Negueruela, I.; Simón Díaz, S.; European Commission (EC); Agencia Estatal de Investigación (AEI); Canary Islands Government; Agencia Canaria de Investigación, Innovación y Sociedad de la Información (ACIIS); Ministerio de Economía y Competitividad (MINECO); Maíz Apellániz, J. [0000-0003-0825-3443]; Barbá, R. H. [0000-0003-1086-1579]; Fariña, C. [0000-0003-4940-3751]; Sota, A. [0000-0002-9404-6952]; Pantaleoni González, M. [0000-0001-9933-1229]; Holgado, G. [0000-0002-9296-8259]; Negueruela, I. [0000-0003-1952-3680]; Centro de Excelencia Científica Severo Ochoa Instituto de Astrofísica de Andalucía CSIC, SEV-2015-0548
Context. Many massive stars have nearby companions. These hamper a characterization of massive stars through spectroscopy. Aims. We continue to obtain spatially resolved spectroscopy of close massive visual binaries to derive their spectral types. Methods. We used the lucky spectroscopy technique to obtain a large number of short long-slit spectroscopic exposures of 19 close visual 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. The results were analyzed in combination with data from lucky imaging, regular intermediate-resolution single-order spectroscopy, and échelle high-resolution spectroscopy. Results. The new application of lucky spectroscopy has allowed us (among other results) to [a] spatially disentangle two O stars (FN CMa B and 6 Cas B) with brighter BA supergiant companions for the first time; [b] determine that two B stars (α Sco B and HD 164 492 B) with close and more massive companions are fast rotators (in the second case, solving a case of mistaken identity); [c] extend the technique to cases with extreme magnitude differences (the previous two cases plus CS Cam A,B), shorter separations (HD 193 443 A,B), and fainter primary magnitudes down to B = 11 (HD 219 460 A,B); [d] spatially disentangle the spectra of stars with companions as diverse as an A supergiant (6 Cas A), a Wolf-Rayet star (HD 219 460 B = WR 157), and an M supergiant (α Sco A); [e] discover the unexpected identity of some targets such as two previously unknown bright O stars (HD 51 756 B and BD +60 544) and a new member of the rare OC category (HD 8768 A); and [f] identify and classify (in some cases for the first time) which of the components of four visual binaries (σ Ori, HD 219 460, HD 194 649, and HD 191 201) is a double-lined spectroscopic binary. For another seven systems (FN CMa, σ Sco, HD 51 756, HD 218 195, HD 17 520, HD 24 431, and HD 164 492), we detect signs of spectroscopic binarity using high-spectral-resolution spectroscopy. We also determine the limits of the technique.
Acceso Abierto
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.
Acceso Abierto
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.
Acceso Abierto
Search for Galactic runaway stars using Gaia Data Release 1 and HIPPARCOS proper motions (Corrigendum)
(EDP Sciences, 2019-09-04) Maíz Apellániz, J.; Pantaleoni González, M.; Barbá, R. H.; Simón Díaz, S.; Negueruela, I.; Lennon, D. J.; Sota, A.; Trigueros Páez, E.; Maíz Apellániz, J. [0000-0003-0825-3443]; Pantaleoni González, M. [0000-0001-9933-1229]; Barbá, R. [0000-0003-1086-1579]; Simón Díaz, S. [0000-0003-1168-3524]; Trigueros Páez, E. [0000-0001-6770-1977]
Erratum for: A&A, 616, A149 (2018), https://doi.org/10.1051/0004-6361/201832787
Acceso Abierto
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.
Acceso Abierto
The Villafranca catalog of Galactic OB groups I. Systems with O2–O3.5 stars
(EDP Sciences, 2020-11-16) Maíz Apellániz, J.; Crespo Bellido, P.; Barbá, R. H.; Fernández Aranda, R.; Sota, A.; Agencia Estatal de Investigación (AEI); Fernández Aranda, R. [0000-0002-7714-688X]; Maíz Apellániz, J. [0000-0003-0825-3443]; Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737
Context. The spectral classifications of the Galactic O-Star Spectroscopic Survey (GOSSS) and the astrometric and photometric data from Gaia have significantly improved our ability to measure distances and determine memberships of stellar groups (clusters, associations, or parts thereof) with OB stars. In the near future, the situation will be further improved thanks to subsequent Gaia data releases and new photometric and spectroscopic surveys. Aims. We initiated a program to identify and determine the membership of Galactic stellar groups with OB stars and measure distances to them. Given the data currently available, we started with the identification and distance determinations of groups with O stars. In this paper, we concentrate on groups that contain stars with the earliest spectral subtypes. Methods. We used GOSSS to select Galactic stellar groups with O2–O3.5 stars and the method described in paper 0 of this series, which combines Gaia DR2 G + GBP + GRP photometry, positions, proper motions, and parallaxes to assign robust memberships and measure distances. We also included Collinder 419 and NGC 2264, the clusters cited in that paper, to generate our first list of 16 O-type Galactic stellar groups. Results. We derived distances, determined the membership, and analyzed the structure of sixteen Galactic stellar groups with O stars, Villafranca O-001 to Villafranca O-016, including the fourteen groups with the earliest-O-type optically accessible stars known in the Milky Way. We compared our distance with previous results from the literature and establish that the best consistency is with (the small number of) VLBI parallaxes and the worst is with kinematic distances. Our results indicate that very massive stars can form in relatively low-mass clusters or even in near-isolation, as is the case for the Bajamar star in the North America nebula. This lends support to the hierarchical scenario of star formation, where some stars are born in well-defined bound clusters but others are born in associations that are unbound from the beginning: groups of newborn stars come in many shapes and sizes. We propose that HD 64 568 and HD 64 315 AB could have been ejected simultaneously from Haffner 18 (Villafranca O-012 S). Our results are consistent with a difference of ≈20 μas in the Gaia DR2 parallax zero point between bright and faint stars.