Descripción del proyecto
Medición de los sistemas binarios eclipsantes
Las galaxias se alejan de nosotros, y la constante de Hubble es un parámetro fundamental que describe la relación entre sus distancias y sus velocidades de recesión. El equipo del proyecto CepBin, financiado por el Consejo Europeo de Investigación, se propone mejorar la exactitud y precisión de la constante de Hubble. Los investigadores esperan reducir la incertidumbre al 1 % y propiciar la calibración precisa de la luminosidad de las cefeidas. Las cefeidas son un tipo de estrellas variables cuyo brillo cambia de manera regular y predecible a lo largo del tiempo debido a modificaciones en su tamaño y temperatura. La relación entre el período y la luminosidad de las cefeidas permite utilizarlas como parámetro para determinar las distancias a otros objetos celestes.
Objetivo
We propose to carry out a project which will produce a decisive step towards improving the accuracy of the Hubble constant as determined from the Cepheid-SN Ia method to 1%, by using 28 extremely rare eclipsing binary systems in the LMC which offer the potential to determine their distances to 1%. To achieve this accuracy we will reduce the main error in the binary method by interferometric angular diameter measurements of a sample of red clump stars which resemble the stars in our binary systems. We will check on our calibration with similar binary systems close enough to determine their orbits from interferometry. We already showed the feasibility of our method which yielded the best-ever distance determination to the LMC of 2.2% from 8 such binary systems. With 28 systems and the improved angular diameter calibration we will push the LMC distance uncertainty down to 1% which will allow to set the zero point of the Cepheid PL relation with the same accuracy using the large available LMC Cepheid sample. We will determine the metallicity effect on Cepheid luminosities by a) determining a 2% distance to the more metal-poor SMC with our binary method, and by b) measuring the distances to LMC and SMC with an improved Baade-Wesselink (BW) method. We will achieve this improvement by analyzing 9 unique Cepheids in eclipsing binaries in the LMC our group has discovered which allow factor- of-ten improvements in the determination of all basic physical parameters of Cepheids. These studies will also increase our confidence in the Cepheid-based H0 determination. Our project bears strong synergy to the Gaia mission by providing the best checks on possible systematic uncertainties on Gaia parallaxes with 200 binary systems whose distances we will measure to 1-2%. We will provide two unique tools for 1-3 % distance determinations to individual objects in a volume of 1 Mpc, being competitive to Gaia already at a distance of 1 kpc from the Sun.
Ámbito científico
Programa(s)
Régimen de financiación
ERC-ADG - Advanced GrantInstitución de acogida
00-716 Warszawa
Polonia