Nota de prensa
AJUSTES A LA ROTACIÓN DE LA VÍA LÁCTEA
19 de Septiembre de 2008
Nuevas mediciones de gran precisión han revelado que la rotación de la Vía Láctea es más simple de lo que anteriormente se pensaba. El instrumento de ESO más exitoso, HARPS, logró demostrar que la debatida“caída“ aparente de estrellas Cefeidas vecinas hacia nuestro Sol responde a una propiedad intrínseca de las Cefeidas.
Desde que Henrietta Leavitt descubrió sus propiedades únicas en 1912, las estrellas brillantes y pulsantes conocidas como Cefeidas se han utilizado como indicadores de distancias. Combinadas con mediciones de velocidad, las propiedades de las Cefeidas son también una herramienta extremadamente valiosa en la determinación de la rotación de nuestra galaxia, la Vía Láctea.
"El movimiento de las Cefeidas de la Vía Láctea es confuso y ha llevado a desacuerdo entre los investigadores", dice Nardetto. "Si se toma en cuenta la rotación de la galaxia, las Cefeidas parecen 'caer' hacia el Sol con una velocidad media de aproximadamente 2 km/s".
Durante décadas se ha debatido intensamente si este fenómeno estaba verdaderamente relacionado con el movimiento real de las Cefeidas y, por consiguiente, con un complejo modelo de rotación de nuestra galaxia, o si era el resultado de los efectos dentro de la atmósfera de las Cefeidas.
Nardetto y sus colegas observaron ocho Cefeidas con el espectrógrafo HARPS de alta precisión, instalado en el telescopio de 3,6 metros de ESO en La Silla, a 2.400 metros de altitud en el Desierto de Atacama Chileno. El Buscador de Planetas con Velocidad Radial de Alta Precisión (HARPS) es mundialmente conocido como un exitoso cazador de planetas, pero también puede ser utilizado para resolver casos complejos que requieren la insuperable capacidad de HARPS para determinar velocidades radiales (la velocidad con que un objeto se aleja o se acerca a nosotros). "Nuestras observaciones demuestran que este movimiento aparente hacia nosotros casi ciertamente proviene de una propiedad intrínseca de las Cefeidas", dice Nardetto.
Los astrónomos detectaron que las desviaciones en la velocidad medida de las Cefeidas estaban vinculadas a los elementos químicos en las atmósferas de las Cefeidas estudiadas. "Este resultado, si se generaliza a todas las Cefeidas, implica que la rotación de la Vía Láctea es más simple de lo que anteriormente se pensó, y ciertamente es simétrica sobre un eje", concluye Nardetto.
Los resultados completos de esta investigación aparecen en el artículo “High resolution spectroscopy for Cepheids distance determination. III. A relation between γ-velocities and γ-asymmetries", de Nardetto, N., Stoekl, A., Bersier, D. & Barnes, T. G., que será publicado en la prestigiosa revista Astronomy & Astrophysics.
Nicolas Nardetto pertenecía al Instituto Max-Planck de Radioastronomía (Bonn, Alemania) al momento de realizar esta investigación.
Contactos
Nicolas Nardetto
Departamento de Astronomia
Chile, Chile
Teléfono: + 56 41 220 33 66
Correo electrónico: nnardetto@astro-udec.cl
Francisco Rodríguez (Contacto para medios de comunicación en Chile)
Red de Difusión Científica de ESO
y European Southern Observatory
Teléfono: +56-2-463-3151
Correo electrónico: eson-chile@eso.org
Acerca de la nota de prensa
| Nota de prensa No.: | eso0830es-cl |
| Legacy ID: | PR 30/08 |
| Nombre: | Milky Way |
| Tipo: | Milky Way : Star : Type : Variable |
| Facility: | ESO 3.6-metre telescope |
| Instruments: | HARPS |
| Science data: | 2008A&A...489.1255N |
Imágenes
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