1,723,084 research outputs found
A search for new variable stars in NGC 6231
No full textNGC 6231 is a well-studied young open cluster hosting several variable stars.
In the field six β Cephei stars, several eclipsing binaries and one δ Scuti star are
known (as well as a foreground δ Scuti star). In an ongoing effort to map and study
the variability in NGC 6231, we present new results based on CCD time-series data
optimised for the bright β Cephei stars as well as data optimised for much
fainter stars. We detect 17 new variable stars in the cluster,
including three δ Scuti stars, three γ Doradus candidates, three Slowly Pulsating
B star candidates and one, or possibly two, new β Cephei stars
Comentarios adicionales sobre la estrella Sanduleak-Seggewiss (NGC 6231-92)
Get PDFLa estrella extremadamente enrojecida NGC 6231-92, parece ser F5 Ia. Si está más distante que el cúmulo abierto NGC 6231, se trata entonces de un objeto muy brillante con Mᵥ= -8 o -9. Esta estrella muestra, además, E(U-B)/E(B-V)= 0.95, y E(B-V)/E(R-I)= 2.22, lo que aparta de las relaciones normales. La emisión que muestran algunas de sus líneas espectrales, así como el enrojecimiento anormal, apuntan a la posibilidad de que esta estrella esté rodeada por una envoltura.Asociación Argentina de Astronomí
Linked collectors and determiners for: Umbrageocoris Kondorosyi: A New Genus And Species Of Big-Eyed Bugs From New Guinea (Heteroptera: Lygaeoidea: Geocoridae).
No full textNatural history specimen data linked to collectors and determiners held within, "Umbrageocoris Kondorosyi: A New Genus And Species Of Big-Eyed Bugs From New Guinea (Heteroptera: Lygaeoidea: Geocoridae)". Claims or attributions were made on Bionomia by volunteer Scribes, <a href="http://bionomia.net/dataset/dedc13e2-6231-4a23-bf04-b37b23379c97">https://bionomia.net/dataset/dedc13e2-6231-4a23-bf04-b37b23379c97</a> using specimen data from the dataset aggregated by the Global Biodiversity Information Facility, <a href="https://gbif.org/dataset/dedc13e2-6231-4a23-bf04-b37b23379c97">https://gbif.org/dataset/dedc13e2-6231-4a23-bf04-b37b23379c97</a>. Formatted as a Frictionless Data package
The young open cluster NGC 6231: five years of investigations
Get PDFIn this contribution, we present an overview of the main results obtained by the Liège multiwavelength (in the X-ray and optical domains) campaign on the young open cluster NGC 6231. We probe the distribution of the O star properties, and especially their binary nature. In this regard, we revise the O-type binary fraction and we briefly discuss the distribution of the binary parameters. We then present the latest developments of the canonical L[SUB]X[/SUB]-L[SUB]bol[/SUB] relation. We discuss the causes of the observed deviations from this relation and of the X-ray variability among O-type stars. Probing the population of low mass pre-main sequence stars detected in the X-ray domain, we propose a scenario for the star formation history in NGC 6231
Clasificación espectral en el cúmulo abierto NGC 6231
No full textContinuando con el programa sistemático iniciado hace varios años para estudiar espectroscópicamente cúmulos y asociaciones australes, nos hemos ocupado en esta oportunidad de NGC 6231. Con espectros en dos dispersiones (125 y 39 Å mm⁻¹) todos de 1.2 mm de ancho se clasificaron los objetos del cúmulo en el sistema MAT. Se discute el diagrama HR y algunas estrellas interesantes.Asociación Argentina de Astronomí
NGC 6231 et la structure d'amas ouverts abordés par l'observation
No full textLe but de ce travail est de mieux comprendre l'histoire de l'évolution dynamique des amas ouverts, en comparant la structure de quelques objets afin d'en révéler les ressemblances et les dissemblances.
Des travaux d'observations sur un très jeune amas (NGC 6231) sont tout d'abord présentés. Les analyses de la structure de cet objet, ainsi que de celles des Pléiades et de Praesepe sont ensuite décrites.
Afin de pouvoir comparer les divers amas entre eux, les signatures importantes de leur évolution sont définies le plus précisément possible. L'étude d'un amas aussi jeune que NGC 6231 permet également de mettre au jour les résultats récents de la formation stellaire.
Ce travail est ainsi utile pour fixer les conditions "initiales" de l'évolution des amas, qui devront être explicables par les scénarios décrivant les processus de formation de ces objets et prises en compte par les modèles qui tentent de reproduire leurs évolutions ultérieures</p
Reducing mesh; (a) 499994Tri#, (b): 71659 Tri#, (c): 17913Tri#, (d): 6231 Tri#, (e): 202 Tri#.
No full textReducing mesh; (a) 499994Tri#, (b): 71659 Tri#, (c): 17913Tri#, (d): 6231 Tri#, (e): 202 Tri#.</p
THE INITIAL MASS FUNCTION AND THE SURFACE DENSITY PROFILE OF NGC 6231
No full textWe have performed new wide-field photometry of the young open cluster NGC 6231 to study the shape of the initial mass function (IMF) and mass segregation. We also investigated the reddening law toward NGC 6231 from optical to mid-infrared color excess ratios, and found that the total-to-selective extinction ratio is RV = 3.2, which is very close to the normal value. But many early-type stars in the cluster center show large color excess ratios. We derived the surface density profiles of four member groups, and found that they reach the surface density of field stars at about 10', regardless of stellar mass. The IMF of NGC 6231 is derived for the mass range 0.8-45 M ⊙. The slope of the IMF of NGC 6231 (Γ = -1.1 ± 0.1) is slightly shallower than the canonical value, but the difference is marginal. In addition, the mass function varies systematically, and is a strong function of radius—it is very shallow at the center, and very steep at the outer ring suggesting the cluster is mass segregated. We confirm the mass segregation for the massive stars (m >~ 8 M ⊙) by a minimum spanning tree analysis. Using a Monte Carlo method, we estimate the total mass of NGC 6231 to be about 2.6 (± 0.6) × 103 M ⊙. We constrain the age of NGC 6231 by comparison with evolutionary isochrones. The age of the low-mass stars ranges from 1 to 7 Myr with a slight peak at 3 Myr. However, the age of the high-mass stars depends on the adopted models and is 3.5 ± 0.5 Myr from the non-rotating or moderately rotating models of Brott et al. as well as the non-rotating models of Ekström et al. But the age is 4.0-7.0 Myr if the rotating models of Ekström et al. are adopted. This latter age is in excellent agreement with the timescale of ejection of the high-mass runaway star HD 153919 from NGC 6231, albeit the younger age cannot be entirely excluded.sponsorship: The authors thank the anonymous referee for many insightful comments. H. Sung acknowledges the support of the National Research Foundation of Korea (NRF) funded by the Korea Government (MEST, grant No. 20120005318). H. Sung expresses his thanks to Professor Harvey Butcher, the director of Research School of Astronomy and Astrophysics, ANU for hosting him as a Visiting Fellow. (National Research Foundation of Korea (NRF), Korea Government (MEST)|20120005318)status: Publishe
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