A sub-percent distance scale from binaries and Cepheids

Información del proyecto

CepBin

Identificador del acuerdo de subvención: 695099

DOI

10.3030/695099

Proyecto cerrado

Fecha de la firma de la CE 6 Octubre 2016

Fecha de inicio 1 Noviembre 2016

Fecha de finalización 31 Octubre 2021

Financiado con arreglo a

• EXCELLENT SCIENCE - European Research Council (ERC)

Coste total

€ 2 360 500,00

Aportación de la UE

€ 2 360 500,00

Coordinado por

CENTRUM ASTRONOMICZNE IM. MIKOLAJA KOPERNIKA POLSKIEJ AKADEMII NAUK
Poland

Periodic Reporting for period 4 - CepBin (A sub-percent distance scale from binaries and Cepheids)

Período documentado: 2021-05-01 hasta 2021-10-31

Resumen del contexto y de los objetivos generales del proyecto

We aim at improving the accuracy of the determination of the Hubble constant, that is a measure of the rate of expansion of the universe. We will achieve this goal through a very accurate measurement of the distances to the Magellanic Clouds (two nearby galaxies), using eclipsing binary systems (pairs of stars that periodically pass in front of each other). This will in turn allow us to calibrate the Period-Luminosity relation (the Leavitt law) of Cepheids present in these two galaxies. Cepheids are of prime importance to determine extragalactic distances and calibrate the Hubble constant.

Our results will not only pave the road for 1 % H0 determination, but will also will provide the opportunity to
improve the calibration of a number of secondary methods for distance determination, and as a result
provide a homogeneous catalog of precise distances to nearby galaxies which will be important for many
fields of modern astrophysics. The unique catalog of precise (1-2 %) physical parameters for some 200
binary systems (e.g. 400 red giant stars) emerging from this project, including 20 classical Cepheids, will
lead to an improved understanding of stellar evolution at late stages, and of stellar pulsation theory. Our
much improved understanding of the basic physics of Cepheids will also boost our confidence in the
calibration of the extragalactic distance scale we will achieve in this project.

Trabajo realizado desde el comienzo del proyecto hasta el final del período abarcado por el informe y los principales resultados hasta la fecha

We already measured precision stellar parameters for several eclipsing binary systems in the Large Magellanic Cloud and in the Milky Way.
Based on these data we measured very accurate distanced to the studied systems. We also measured the effect of metal content on the brightness
of Classical Cepheids. We demonstrated that this effect is very small and does not affect cosmic distance determinations with Cepheids.
We also improved calibration of the Baade - Wesselink method for distance determination with classical Cepheids.
We also measured precision distances to several nearby galaxies.

Avances que van más allá del estado de la técnica e impacto potencial esperado (incluida la repercusión socioeconómica y las implicaciones sociales más amplias del proyecto hasta la fecha)

Our distance determinations are the most accurate measurements reported so far. The form strong basis for
trully accurate determination of the Hubble constant.

artist's vision of the LMC distance determination