Presentation
Magnetic fields are at the base of star formation and stellar structure and evolution. Our Sun has magnetic fields that give rise to such spectacular activity that impacts the climate on Earth. The magnetic activity in other stars is, in some cases, of orders of magnitude more intense than the solar one, influencing – often drastically – the transport of chemical species and angular momentum, as well as affecting the possible planetary systems around them.
The empirical study of stellar magnetism is a rather unexplored field. The reason is that spectropolarimetry – the unique tool to obtain quantitative information of magnetic fields – has been little exploited since it is a photon starving technique and the data are difficult to interpret.
This project will exploit spectropolarimetric techniques to reach three general objectives that will allow us to advance in the knowledge of stellar magnetism:
(1) The empirical study the magnetism of stellar chromospheres and the magnetic coupling of atmospheric layers.
(2) The empirical study of the magnetism of prominences in (solar-type) stars.
(3) Constraining the magnetism fields in hot central stars of planetary nebulae.
AYA2014-60833-P is a research project funded by the Spanish Ministerio de Economía y Competitividad.
Stellar chromospheres are a critical transition layer where the relatively cool photosphere gives way to the million-degree corona and to the stellar environment in which planets are embedded.
Despite their importance, the magnetic mapping of stellar chromospheres has never been attempted. One of the main object ives of this project is to build a synthesis code of the radiative transfer of polarised light in cool stars photosphere and chromosphere for an empirical investigation of the magnetism of stellar chromospheres and its coupling to other atmospheric layers. This will help us solving one of the long lasting problems in stellar physics: the heating of the outer atmospheres, in which we know that magnetic fields play an important role.
Prominences are cool chromospheric material magnetically levitating in the hot coronae of the Sun and of other stars harbouring similar magnetic activity. The magnetic field plays a fundamental role in the formation, support, and eruption of stellar prominences yet, the magnetism of these structures has not been reliably measured. This project has the challenge to measure the polarisation signals of stellar prominences and the study of the magnetic fields in these structures
Stars similar to our Sun end their lives as a planetary nebulae (PNe) with a hot star in its centre.
One would expect that a star loses its atmosphere isotropically, but about 80% PNe are bipolar or very asymmetric. The reason for this is not yet understood. The presence of magnetic fields would nicely explain these complicated shapes, as the ejected matter is trapped along the field lines. Magnetic fields in PNe have been elusive and this project aims its detection in the central stars of PNe and proto-PNe.
The Mid-resolution InfRAreD Astronomical Spectrograph (MIRADAS) is an instrument to be installed at the 10.4m Gran Telescopio Canarias in 2020.
MIRADAS will open a completely unexplored window into stellar magnetism, hence the aim of this project is to develop numerical techniques for the interpretation of the wealth of data that this instrument will offer attached to the largest telescope in the world.