MAGNETIC FLUX TUBES IN LATE-TYPE STARS

One of the most important and still unsolved
problems in stellar astrophysics is to identify the
basic physical processes that are responsible for
the extensive heating of the chromosphere and corona
in late-type stellar atmospheres. Two widely
accepted ways of heating are due to acoustic
wave in non-magnetic region, and MHD (magneto-
hydrodynamic) waves in the concentrated magnetic
flux tube region. Out of three different MHD tube
modes (transverse, longitudinal and torsional) this
study only involves the propagation and generation
of the transverse tube wave, which are the most
efficient means of energy transfer in the stellar
atmosphere. The current research has two components.
First, starting from the general properties of
magnetic flux tubes, propagation of stellar
transverse tube waves and corresponding cutoff
frequencies are determined analytically for the
first time for non-isothermal stellar atmospheres.
Second, the rate of transverse wave energy
generation at the stellar surface at a given height
has been calculated analytically for linear tube
wave, and numerically for nonlinear tube wave in
late-type stars for the first time.

Autorentext
Born: Dhaka, Bangladesh in Nov 10, 1978. Education: BSc in physics and mathematics from Univ of Texas at Arlington. MSc from the same university under supervision of Dr. Zdzislaw Musielak. Currently enrolled in PhD program at the Univ of Washington. Family: Youngest son of Amzad(Late) and Fahmida Hossain. Married to Mumu Mahruba Mahbub.

Klappentext
One of the most important and still unsolved problems in stellar astrophysics is to identify the basic physical processes that are responsible for the extensive heating of the chromosphere and corona in late-type stellar atmospheres. Two widely accepted ways of heating are due to acoustic wave in non-magnetic region, and MHD (magneto- hydrodynamic) waves in the concentrated magnetic flux tube region. Out of three different MHD tube modes (transverse, longitudinal and torsional) this study only involves the propagation and generation of the transverse tube wave, which are the most efficient means of energy transfer in the stellar atmosphere. The current research has two components. First, starting from the general properties of magnetic flux tubes, propagation of stellar transverse tube waves and corresponding cutoff frequencies are determined analytically for the first time for non-isothermal stellar atmospheres. Second, the rate of transverse wave energy generation at the stellar surface at a given height has been calculated analytically for linear tube wave, and numerically for nonlinear tube wave in late-type stars for the first time.