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Alpha Centauri and the solar-stellar connection
  Astronomy and astrophysics

Friday 28 October 2016
from 10:30 to 11:30
at FC61
Speaker : Rene Liseau (Onsala Space Observatory / Chalmers)
Abstract : We will be introduced to the properties and physics of the nearest stellar object to the solar system. Specifically, we will learn about chromospheres, planets and dust disks. We used the Spitzer and Herschel observatories in space and APEX and ALMA at 5000 m altitude on the ground. These top-notch and unsurpassed facilities allowed us to collect unique data in the far infrared to the millimeter regime. For the discussion of planets and debris disks we use dynamical models including, besides gravitational, also radiation pressure and Poynting-Robertson forces. alpha CenA is a solar analogue and, to interpret the data, we exploit modified theoretical models of the quiet Sun's extended atmosphere which is heated to high temperatures by as yet not well understood mechanisms. As the conditions in these layers deviate greatly from LTE, both the ionization and particle equilibria and the radiative transfer are treated in non-LTE. In the near future, also the Sun will be directly observed with ALMA and the results will provide a more comprehensive view of the physics of the outer layers of the Sun and other stars. Some of the results discussed in this talk can be found in issues of Astronomy & Astrophysics, Vol. 549, L7 (2013); 563, A102 (2014); 573, L4 (2015) and a paper in press, arXiv:1608.02384 (2016).

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