Recent content by Jamipat

On page 5 of the link http://www.maths.qmul.ac.uk/~rpn/ASTM735/Week9-powerpoint.pdf , there are 2 graphs. I'm referring to the 2nd graph (the one with the flared disk fit). What is the green plot supposed to represent?

On page 26 of http://www.maths.qmul.ac.uk/~rpn/ASTM735/Week7.pdf , it claims that the signal-noise can be improved by integrating over long time periods since the noise amplitude scales with \frac{1}{\sqrt{t}} for Gaussian statistics. Can someone explain that to me?

Page 26 of http://www.maths.qmul.ac.uk/~rpn/ASTM735/Week7.pdf claims that stellar jitter can be caused by the convective motions in the stellar photosphere. Can someone explain that to me as I don't understand it?

Tm = \frac{dj}{dt} where Tm is the torque per unit mass, and j = R2Ω(R) which is the specific angular momentum (angular momentum per unit mass) It may be shown that \frac{dj}{dt} = \frac{∂j}{∂t} + (v.\nabla)j (convective derivative) = vR\frac{∂j}{∂R} [equation (68)...

If that's the definition of the derivative, shouldn't \frac{∂}{∂R} on the expression be \frac{d}{dR}

Why does dR \rightarrow 0 makes it a correct expression?

http://www.maths.qmul.ac.uk/~rpn/ASTM735/lecture3.pdf The diagram on page 26 is the accretion disc. The torque acting on the inner edge of the ring (the one that has a thickness of dR in the diagram) is RFin = -2\piR3\nuƩ\frac{dΩ}{dR} The torque acting on the outer edge of the...

Thanks for your help guys.

At the vertical direction, shoudn't the gravitational force be -\frac{GM}{z^{2}} instead of \frac{GMz}{(R^{2} + z^{2})^{3/2}} as the gravitational force is acting in the z direction.

For an accretion disk, I thought its angular momentum was preventing the star's gravity from pulling it.

This is regarding an accretion disc orbiting a star. In the z (vertical) direction there is a hydrostatic equilibrium. \frac{1}{ρ}\frac{∂P}{∂z} = -\frac{GMz}{(R^{2} + z^{2})^{3/2}} The right hand side of the expression is the Gravitational potential energy and the left side is the pressure...