MAGRETHEA · Magnetism, rotation and evolution of Herbig Ae/Be stars
FP6 — Marie Curie Actions (Human Resources and Mobility)
- Duration
- 2007-02-01 → 2010-01-31
- EU contribution
- €182,326
- Participants
- 2
- Scheme
- OIF
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Results in brief
Final Activity Report Summary - MAGRETHEA (Magnetism, rotation and evolution of Herbig Ae/Be stars)
Magnetic fields are important components of the Universe, observed at all scales from clusters of galaxies to asteroids. In order to understand the major role of magnetic fields in the formation, evolution and structure of stars, that we believe they play, we have to learn how they form. While it is pretty well understood how solar-type stars generate their magnetic fields, through a convective dynamo, it is more difficult to understand the origin of strong magnetic fields observed in stars more massive than the sun, the so-called intermediate-mass stars (from 1.5 to 10 times the solar mass). Indeed, these stars do not possess a convective envelope favourable to solar-type magnetic field generation. We believe that the magnetic fields in intermediate-mass stars are remnants from the galactic magnetic fields threading molecular clouds in which stars form. Magnetic fields are observed in star forming regions, and in evolved stars. A convincing proof to the proposed fossil theory is detecting magnetic fields at all ages; especially at very young ages, between their birth and more evolved phases, in which observing clues are missing. This project has been mainly devoted to the detection, and characterisation of magnetic fields in very young intermediate-mass stars, the so-called Herbig Ae/Be stars. For the first time we have detected magnetic fields in a sample of Herbig Ae/Be stars, and we were able to prove that these fields are of fossil origin.
Data: CORDIS, © European Union
Project objective
This proposal is to carry out research at Royal Military College in Kingston (Canada), supervised by G. Wade. The return phase will occur at the Laboratory of Space Studies and Instrumentation in Astrophysics (LESIA) at Paris-Meudon Observatory (France), supervised by C. Catala.The scientific aim is to continue research initiated during my PhD on the magnetic and rotational properties of Herbig Ae/Be (HAeBe) stars. The origin of magnetism in main sequence A and B stars is fundamentally a mystery. The leading hypothesis is that the fields are relics from star formation. A natural consequence of this hypothesis is that some pre-main sequence (PMS) HAeBe stars, as progenitors of main sequence A and B stars, should host strong, ordered magnetic fields.The presence of magnetic field during the PMS phase will strongly influence stellar evolution, modifying accretion and mass loss, and slowing rotation via magnetic braking. A knowledge of the incidence, strength and structure of magnetic fields of HAeBe stars, characterised by a range of accretion, mass loss and rotation rates, is crucial to our understanding of the earliest phases of their evolution.It was partly in this context that the spectropolarimeter ESPaDOnS was developed by France, Canada, CFHT and ESA. During the first year of ESPaDOnS activity we achieved the initial phase of this research: we confirmed that some HAeBe stars do host strong, ordered magnetic fields. We must now explore further to understand the implications of this discovery.The next steps of my project are:- to better determine HAeBe magnetic characteristics, and to investigate relationships between accretion, mass loss, rotation and magnetism- to study the influence of age and environment on magnetism and rotation at early stages of evolution, with observations of young clusters and associations.This will involve spectropolarimetric observations of HAeBe stars using ESPaDOnS at the CFHT and the ESPaDOnS twin, Narval at Pic du Midi
Original text from CORDIS.
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Data: CORDIS, © European Union