Naked Science Forum

Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: chris on 30/01/2016 00:20:45

Title: What is the hottest part of the Sun?
Post by: chris on 30/01/2016 00:20:45
The centre of the Sun is millions of degrees, but is this the hottest area, or is the surface hotter?
Title: Re: What is the hottest part of the Sun?
Post by: evan_au on 30/01/2016 00:49:40
The visible surface of the Sun is around 5800K (around 5500C).
The Sun's corona (only visible during eclipses) is heated by flares on the visible surface to around 5,000,000K.
The center of the Sun, where the nuclear energy is created is estimated to be about 16,000,000K. This is the hottest part.

The temperature of the surface and the corona can be measured directly via their visible spectrum.
The center temperature must be estimated from the observed rate of heat production, the rates of nuclear fusion reactions at different temperatures, and the thermal conductivity of the Sun.

See: http://en.wikipedia.org/wiki/Sun
Corrected: Conversion of temperature: K to C
Title: Re: What is the hottest part of the Sun?
Post by: chris on 30/01/2016 09:10:15
Why is the visible surface cooler than the corona?
Title: Re: What is the hottest part of the Sun?
Post by: alysdexia on 30/01/2016 09:29:15
Wouldn't PmbPhys tell you to google it?
Title: Re: What is the hottest part of the Sun?
Post by: evan_au on 30/01/2016 22:17:23
Quote from: chris
Why is the visible surface cooler than the corona?
I'm afraid that this is one of the outstanding open questions in physics.
All the more frustrating because it is right in front of our eyes!
http://en.wikipedia.org/wiki/Corona#Coronal_heating_problem

Some recent work with an X-Ray telescope (http://en.wikipedia.org/wiki/High_Resolution_Coronal_Imager) that can monitor very rapid events on the surface of the Sun revealed unraveling magnetic "braids", which may be part of the answer.