Recent results showed that the magnetic' field of M-dwarf RIM) stars, currently the main targets in searches for terrestrial planets is very different from the solar one, both in topology as well as in intensity. In particular, the magnetised environment surrounding a planet orbiting in the habitable zone (HZ) of dAl stars can differ substantially to the one encountered around the Earth. These extreme magnetic fields can compress planetary magnetospheres to such an extent that a significant fraction of the planet's atmosphere may be exposed to erosion by the stellar wind. Using observed surface magnetic amps for a sample of 15 (DJ stars, we investigate the minimum degree of planetary magnetospheric compression caused by the intense stellar magnetic fields. We show that hypothetical Earth-like planets with similar terrestrial magnetisation (-1 G) orbiting at the inner (outer) edge of the HZ of these stars would present magnetospheres that extend at most up to 6.1 (11.7) planetary radii. To be able to sustain an Earth-sized magnetosphere, the terrestrial planet would either need to orbit significantly farther out than the traditional limits of the HZ: or else, if it were orbiting within the life-bearing, region. it would require a minimum magnetic field ranging from a few G to up to a few thousand G.
|Title of host publication||Magnetic fields throughout stellar evolution|
|Subtitle of host publication||Proceedings of the international Astronomical Union Symposia and Colloquia|
|Editors||Pascal Petit, Moira Jardine, Hendrik Spruit|
|Place of Publication||Cambridge|
|Publisher||Cambridge University Press|
|Number of pages||2|
|Publication status||Published - 24 Aug 2014|
|Name||IAU Symposium Proceedings Series|
- stars: magnetic fields
- stars: planetary systems
- stars: rotation. astrobiologs
Vidotto, A. A., Jardine, M., Morin, J., Donati, J. -F., Lang, P., & Russell, A. J. B. (2014). Planetary protection in the extreme environments of low-mass stars. In P. Petit, M. Jardine, & H. Spruit (Eds.), Magnetic fields throughout stellar evolution: Proceedings of the international Astronomical Union Symposia and Colloquia (pp. 237-238). (IAU Symposium Proceedings Series). Cambridge University Press.