Rotation profile for radiative zone of Sun - convection

In summary, the conversation is focused on the rotation profile of the radiative zone in Stellar Physics. It is noted that the rotation in this zone is solid, unlike the convective zone where it varies mainly in latitude. The shape of the rotation profile is discussed, with the options being flat, Keplerian, or circular. It is mentioned that the current understanding is that it is a flat profile. The discussion then moves on to the physical processes that maintain this rotation profile. It is noted that convection occurs when the temperature gradient is greater than the adiabatic gradient, and this leads to instability in one scheme and stability in another. The Schwarzschild criterion is also mentioned in relation to this. The effect of a molecular weight gradient
  • #1
fab13
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6
I am exercising on Stellar Physics topics and in particular the questions below:

gYyR2.png


1) First of all on the rotation profile for the radiative zone: I know that unlike the convective zone, where the rotation varies mainly in latitude (faster at the equator than at the poles), the radiative zone has a solid rotation, that is to say that it rotates in a single block.

What is the shape rotation profile for the radiative area?

Is it flat ? , "Keplerian" (I mean velocity equals ##V = \sqrt{\dfrac {GM}{R}}## ) ?, or just circular (##V = R \Omega## and thus the profile would be linearly increasing according to the radius ##R##)?

From what I have seen on web, it seems to be a flat profile but I am not sure.

2) Then, what physical processes occur to keep this profile with this form?

3) Regarding the question with the 2 schemes: I know that convection occurs when the temperature gradient is greater than the adiabatic gradient. So there is instability for the scheme a) and stability for scheme b) towards the convection: is this correct?

The Schwarzschild criterion would be on the adiabatic gradient ?

for example, if ##\bigg(\dfrac{\text{d}\,\text{ln} T}{\text{d}\,\text{ln} P}\bigg)_{m}> 2/5##, Then there is convection?

3) For question 3.b), how does a molecular weight gradient change this criterion?

I would say a priori that the molecular weight prevents the penetration of the radiative zone in the convective zone because the archimedes thrust would be counter-balanced by gravity but I'm not sure?

or would its effect be in the other direction, that is, a penetration of the convective zone into the radiative zone?

4) Finally, does thermohaline convection correspond to a penetration of convection in the radiative zone (perhaps because of this molecular weight gradient) or the opposite (penetration of the radiative zone into the convective zone)?

In what case then does it occur?

Thank you in advance for your help, it will be precious
 

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  • #2
UPDATE : I think that I made an error about the interpretation on the stability and instability situation towards convection. This should be the contrary, i.e stability for schema a) and instability for schema b). This is because the slope of temperature gradient and adiabatic gradient are computed with inversion of (x) and (y) coordinates (##\alpha## slope becomes ##1/\alpha##, so the situation is inverted).

Anyone could confirm me this error of interpretation towards my first explanation ?

Regards
 

FAQ: Rotation profile for radiative zone of Sun - convection

1. What is the significance of the rotation profile for the radiative zone of the Sun?

The rotation profile for the radiative zone of the Sun is important because it helps us understand how energy is transferred within the Sun. The rotation of the radiative zone plays a crucial role in the formation and maintenance of the solar magnetic field, which influences solar activity and space weather.

2. How is the rotation profile for the radiative zone of the Sun measured?

The rotation profile for the radiative zone of the Sun can be measured using helioseismology, which involves studying the oscillations of the Sun's surface caused by sound waves traveling through the interior. By analyzing these oscillations, scientists can determine the rotation rate at different depths within the Sun.

3. What factors influence the rotation profile for the radiative zone of the Sun?

The rotation profile for the radiative zone of the Sun is influenced by a combination of factors, including the Sun's initial angular momentum, the effects of magnetic fields, and the transfer of angular momentum through convection and other processes. These factors can vary over time and contribute to the complex rotation profile observed in the Sun.

4. How does the rotation profile for the radiative zone of the Sun differ from that of the convection zone?

The rotation profile for the radiative zone of the Sun differs from that of the convection zone in terms of the speed and direction of rotation. In the radiative zone, the rotation rate is slower and more uniform compared to the convection zone where there are large-scale flows that cause variations in rotation speed and direction.

5. Can the rotation profile for the radiative zone of the Sun change over time?

Yes, the rotation profile for the radiative zone of the Sun can change over time due to the influence of various factors such as solar activity and magnetic fields. In fact, recent studies have shown that the rotation rate of the radiative zone has changed significantly over the past few decades, suggesting that it is a dynamic and evolving component of the Sun.

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