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el observador de estrellas dobles n.º 2 · mayo/agosto 2009 COPYRIGHT 2005 - RICHARD YANDRICK el observador el obsevador de estrellas dobles estrellas REVISTA AMATEUR DEDICADA A LA OBSERVACIÓN, INVESTIGACIÓN Y ESTUDIO DE ESTRELLAS DOBLES año I — número 2 — mayo/agosto 2009 dobles ISSN 1989-3582 indice Editorial 3 ACTUALIDAD Noticias de actualidad del mundo de las estrellas dobles 4 por Francisco M. Rica OBSERVACIÓN Primer estudio de estrellas dobles desde el Obs. de Cantabria 10 por Francisco M. Rica Medición de estrellas dobles con una cámara Audine 15 por Florent Losse Un sistema doble con características peculiares 20 por Carlos A. Krawczenko METODOLOGÍA Misión Speckles Pic I. Julio 2008. 23 por Martine Castets y Bernard Tregon Fotometría con FoCAs II 38 por Rafael Benavides Palencia PROPUESTAS La serie de las Gammas 44 por José Luis Comellas Estrellas dobles rojas 48 por el Grupo de Estrellas Dobles del Foro de la Agrupación Astronómica Hubble Gamma Andromedae 52 por Ángel M. López Borrega HISTORIAS Jonckheere, pasión por las dobles 55 por Juan-Luis González Carballo FUERA DE FOCO El santuario de las dobles 64 por Paco Bellido condiciones de publicacion Cualquier trabajo relacionado con la astronomía de las estrellas dobles es bienvenido para ser pu- blicado en El Observador de Estrellas Dobles (OED). Los interesados deben atenerse a las siguien- tes pautas: - Se aceptará cualquier tipo de trabajo que tenga relación con las estrellas dobles, independientemente de la temática que aborde: historia de la astronomía, observación visual o fotográfica, estudios astrométricos o fotométricos, análisis y exposición de técnicas, descubrimientos, presentación de programas informáticos útiles a los doblistas, artículos de opinión, etc. - Los trabajos deberán remitirse a cualquiera de los editores a través de los correos electrónicos que figuran en la parte inferior de la página siguiente. - Se remitirán archivos de texto en formato Word o similar. Se agradece que vengan corregidos ortográfica y sintácticamente. - Se deberán adjuntar las imágenes o dibujos que se desean publicar, preferentemente insertados en el texto. - En la cabecera del artículo deberán figurar los siguientes datos: nombre y apellidos del autor, agrupación o asociación astronómica a la que pertenezca y dirección de correo electrónico. - Los artículos deberán venir precedidos por un breve resumen del contenido del mismo (4 líneas) en inglés y en castellano. - OED tendrá una periodicidad cuatrimestral. La fecha límite de recepción de trabajos para el próximo núme- ro será el 1 de agosto de 2009. editorial EL NÚMERO 2 de OED ya es una realidad. Tras la euforia del debut, siempre desbordante, y la extraordinaria acogida de la publicación por parte de la comunidad astronómica amateur, hemos renova- do fuerzas e ilusiones para componer un nuevo ejemplar. Deseamos que sea del agrado de todos vosotros. La calidad de los artículos recibidos en la redacción será, sin duda, un punto fuerte para lograrlo. Fieles a nuestra idea inicial hemos procurado ofrecer un paquete de traba- jos de los más variados niveles técnicos, desde los más avanzados hasta aquellos otros más asequibles, especialmente dirigidos a los doblistas que se inician. A des- tacar un excelente trabajo sobre interferometría de manchas, una de las técnicas de medición más precisas y modernas. Este trabajo demuestra que los astrónomos aficionados también pueden abordar con éxito este tipo de técnicas. Nuestra en- horabuena a los autores, Martine Castets y Bernard Tregón, dos doblistas franceses observando desde los Pirineos en el Observatorio Pic du Midi. Como novedades hemos introducido dos nuevas secciones. En primer lugar, la Sección Actualidad, redactada por Francisco Rica, servirá para estar al día en cuanto a los trabajos, descubrimientos, publicaciones, etc. que vayan aconteciendo en el campo de las estrellas binarias a nivel internacional. Por otro lado, a partir de este número incluiremos un apartado sobre historia de las estrellas dobles. Dare- mos cabida tanto a los aspectos biográficos sobre los principales observadores/ descubridores de estrellas dobles, como también a aquellos otros puramente obser- vacionales, técnicos e instrumentales. Creemos que el contenido histórico será muy enriquecedor y confiamos en que será seguido con gran interés por nuestros lecto- res. A instancias del USNO, os animamos a que solicitéis gratuitamente el Dou- ble Star CD 2006.5, una excelente herramienta de trabajo que incluye todos los catálogos mantenidos por el Observatorio Naval de los Estados Unidos. Aún que- dan ejemplares disponibles y pueden pedirse en http://ad.usno.navy.mil/ proj/WDS/cd_request.html Esperamos vuestros comentarios, sugerencias y críticas en el blog de la re- vista. Serán bienvenidos y nos ayudarán a mejorar. Que disfrutéis de la lectura. LOS EDITORES a director honorífico Sr. D. José Luis Comellas García-Llera editores Rafael Benavides Palencia [email protected] Juan-Luis González Carballo [email protected] Edgardo R. Masa Martín [email protected] sitio web www.elobservadordeestrellasdobles.wordpress.com colaboradores Florent Losse (Francia), Rafael Caballero (España), Francisco Violat Bordonau (España), Juan Jordano (España), Francisco M. Rica (España), Carlos A. Krawczenko (Argentina), Martine Castets (Francia), Bernard Tregon (Francia), Ángel M. López Borrega (España), Jesús R. Sánchez (España), Paco Bellido (España) actualidad POR FRANCISCO M. RICA Interferometría Speckle desde el OBSERVACIONES EN OPTICA ADAPTATIVA Observatorio Naval de los DESDE EL OBSERVATORIO KECK: Estados Unidos PRIMERA DETERMINACIÓN DE LA MASA DINÁMICA DE UNA BINARIA DE ENANAS T Un equipo de astrofísicos com- puesto por el conocido Brian Mason junto Astrofísicos de la Universidad de Hawai, entre otras enti- con W. Hartkopf y G. L. Wycoff presenta- dades, realizaron imágenes de la binaria 2MASS J15344984- ron una nueva serie de mediciones de 2952274 AB compuesta por débiles enanas marrones de es- pectro T5.0+T5.5. Estas imágenes fueron obtenidas desde el estrellas dobles mediante el método de observatorio Keck usando una técnica llamada óptica adap• interferometría speckle (consultar el artícu- tativa (ver más abajo). Estas imágenes junto con otras de ar- lo “Técnicas de Observación. Imágenes chivo obtenidas por el telescopio Hubble cubren un 50 % del Speckle” en las páginas de esta revista) período orbital de la binaria. El análisis de los datos indicaron que el periodo orbital es de 15,1 años, la masa total es 0,056 usando el refractor de 66 centímetros del masas solares (59 masas de Júpiter) y la edad es de 0,78 Gi- Observatorio Naval de los Estados Unidos gaaños (1 Gigaaño = 1000 millones de años). Esta es la prime- (ver cuadro en la página siguiente). Sus ra binaria cuyas componentes han sido confirmadas de ser resultados fueron 2.033 observaciones subestelares y es la binaria con masa más pequeña y más fría promediadas en 1.297 posiciones relativas de entre las que tienen masas dinámicas calculadas, o sea, determinadas a través de cálculos orbitales. medias. Las separaciones de las dobles medidas oscilaban entre los 0,54" y los 58,96". Esta es la serie de medidas núme- ro XIV y cubre el período desde el 17 de ¿Óptica adaptativa? enero al 31 de diciembre de 2007. Técnica óptica que permite contrarrestar, en tiempo real, los efectos de la atmósfera de la Tierra en la formación de las imágenes astronómicas. Para lograrlo se inserta en el Órbita de dos binarias de camino óptico del telescopio un espejo deformable sostenido corto período y dos por un conjunto de actuadores controlados por computadora. binarias de largo periodo Para su utilización se necesita en el campo estelar una estre- lla de referencia: el análisis de su aspecto permite evaluar en tiempo real las perturbaciones a que está sometida la imagen. Dos astrofísicos serbios han calcu- El sistema puede utilizar también como referencia una estrella lado nuevos parámetros orbitales para artificial producida por un haz láser que atraviesa las capas de cuatro binarias. Para tres de ellas (WDS aire que provocan la mala calidad de imagen. 04340 + 1510 = CHR 17, WDS 06290 + 2013 = BTZ 1Aa y WDS 19535 + 2405 = DJU 4) ya existía una órbita calculada anteriormente y los resultados obtenidos mejoraron la órbita previa. La razón del nuevo cálculo orbital es porque las medi- das recientes muestran elevados residuos con respecto a las efemérides calculadas usando la órbita previa y los elementos orbitales del Sixth Catalog of Orbits of Visual Binary Stars (ver cuadro). Para la cuarta binaria, WDS 07106 + 1543 = J 703, esta órbita es la primera calculada. Dos de estas binarias tienen componentes tan cerradas que es necesario usar la técnica de la interferometría. Las otras dos binarias tienen largos periodos orbita- les. En el trabajo se facilitan efemérides nuevas, masas totales y para cada com- ponente (usando paralajes trigonométri- cas) y tipos espectrales. el observador n.º 2— 4 actualidad Descubrimiento de una compañera subestelar separada de una estrella cercana de baja masa Un grupo de astrofísicos de Canadá ha informado del descubrimiento de una compañera de espectro L5 separada a 125 UA de la cercana enana roja M4.5, G203-50. El descubrimiento se hizo durante una búsqueda de pares de movimiento propio común en el Sloan Digital Sky Survey (SDSS) y Two Micron All Sky Survey (2MASS). Las propiedades astrofísicas de la com- ponente primaria pueden delimitar las propiedades de la fría y nueva componente secundaria. Las evidencias indican que el proceso de formación de estrellas puede formar sistemas binarios separados y débilmente unidos por la fuerza de la gravedad cuyas componentes son estrellas de baja masa y enanas marrones. El Observatorio Naval de los Estados Unidos Este observatorio es una de las organizaciones científicas más antiguas de los Estados Uni- dos. Se encuentra en Washington D.C. y es uno de los pocos observatorios que actualmente se encuentra en zona urbana, si bien cuando se inauguró, allá por el año 1830, Washington era una pequeña ciudad que apenas le afectaba en cuanto a contaminación lumínica.
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    Draft version June 18, 2021 Typeset using LATEX twocolumn style in AASTeX63 Stars with Photometrically Young Gaia Luminosities Around the Solar System (SPYGLASS) I: Mapping Young Stellar Structures and their Star Formation Histories Ronan Kerr,1 Aaron C. Rizzuto,1, ∗ Adam L. Kraus,1 and Stella S. R. Offner1 1Department of Astronomy, University of Texas at Austin 2515 Speedway, Stop C1400 Austin, Texas, USA 78712-1205 (Accepted May 16, 2021) ABSTRACT Young stellar associations hold a star formation record that can persist for millions of years, revealing the progression of star formation long after the dispersal of the natal cloud. To identify nearby young stellar populations that trace this progression, we have designed a comprehensive framework for the identification of young stars, and use it to identify ∼3×104 candidate young stars within a distance of 333 pc using Gaia DR2. Applying the HDBSCAN clustering algorithm to this sample, we identify 27 top-level groups, nearly half of which have little to no presence in previous literature. Ten of these groups have visible substructure, including notable young associations such as Orion, Perseus, Taurus, and Sco-Cen. We provide a complete subclustering analysis on all groups with substructure, using age estimates to reveal each region's star formation history. The patterns we reveal include an apparent star formation origin for Sco-Cen along a semicircular arc, as well as clear evidence for sequential star formation moving away from that arc with a propagation speed of ∼4 km s−1 (∼4 pc Myr−1). We also identify earlier bursts of star formation in Perseus and Taurus that predate current, kinematically identical active star-forming events, suggesting that the mechanisms that collect gas can spark multiple generations of star formation, punctuated by gas dispersal and cloud regrowth.
  • Search for Associations Containing Young Stars (SACY). V. Is

    Search for Associations Containing Young Stars (SACY). V. Is

    Astronomy & Astrophysics manuscript no. sacy˙1˙accepted˙arxiv˙2 c ESO 2018 October 2, 2018 Search for associations containing young stars (SACY) V. Is multiplicity universal? Tight multiple systems?;??;??? P. Elliott1;2, A. Bayo1;3;4, C. H. F. Melo1, C. A. O. Torres5, M. Sterzik1, and G. R. Quast5 1 European Southern Observatory, Alonso de Cordova 3107, Vitacura Casilla 19001, Santiago 19, Chile e-mail: [email protected] 2 School of Physics, University of Exeter, Stocker Road, Exeter, EX4 4QL 3 Max Planck Institut fur¨ Astronomie, Konigstuhl¨ 17, 69117, Heidelberg, Germany 4 Departamento de F´ısica y Astronom´ıa, Facultad de Ciencias, Universidad de Valpara´ıso, Av. Gran Bretana˜ 1111, 5030 Casilla, Valpara´ıso, Chile 5 Laboratorio´ Nacional de Astrof´ısica/ MCT, Rua Estados Unidos 154, 37504-364 Itajuba´ (MG), Brazil Received 21 March 2014 / Accepted 5 June 2014 ABSTRACT Context. Dynamically undisrupted, young populations of stars are crucial in studying the role of multiplicity in relation to star formation. Loose nearby associations provide us with a great sample of close (<150 pc) pre-main sequence (PMS) stars across the very important age range (≈5-70 Myr) to conduct such research. Aims. We characterize the short period multiplicity fraction of the search for associations containing young stars (SACY) sample, accounting for any identifiable bias in our techniques and present the role of multiplicity fractions of the SACY sample in the context of star formation. Methods. Using the cross-correlation technique we identified double-lined and triple-lined spectroscopic systems (SB2/SB3s), in addition to this we computed radial velocity (RV) values for our subsample of SACY targets using several epochs of fiber-fed extended range optical spectrograph (FEROS) and ultraviolet and visual echelle spectrograph (UVES) data.