Let’ try to understand why Sun gets exalted in Aries sign and in Ashwini Nakshatra. Let’s see what these energies represent –

Sun - Sun represents Personality, King, Government, Father, Authority, Career, Top Positions, Ego, Self Esteem, Health, Education etc.

Aries –Aries is the 1st sign of zodiac belt, so it represents the things and energy of 1st house of horoscope like Self, Personality etc. Besides that, Aries is the sign of our individuality, our aggression, our actions, our competitive ability etc. Aries is ruled by Mars and it is consisted of 2 and half Nakshatras named Ashwini, Bharani and Krittika.

Ashwini – Ashwini is 1^st nakshatra, so it comes with the nature of pro-activeness and be first everytime. It is also nakshatra of Healers or Doctors as its deity is Ashwini Kumars, the metaphysical healers. It is also nakshatra of illusion, cheating and confusion. For more info on Ashwini, please check this - https://www.astrosaxena.com/ashnaksh.

Please go through the introductory article 

- https://www.astrosaxena.com/exdeb .

Reasons behind exaltation of Sun in Aries – Basically, Sun represents our Soul or our Ego and Aries is the sign of Individuality or Self as it is the 1^st sign and represents the energy of 1^st house of Self.

Wherever Sun is placed in our chart, if we involve ourselves in the activities related with that house/sign/nakshatra then our soul feels contentment and ego gets satisfied. Now, if Sun is in Aries then it means that person’s soul will be finding contentment when person is focusing on himself and his own individuality. Sun represents Light and Sun in Aries person wants focus on himself. In other signs, Sun would have to deal with something or the other matter besides individual. Here, when Sun is in Aries, whole focus is on individual or self or his own development. As I said in introductory article, exaltation or debilitation is more about the environment a planet gets in a sign. As Sun in Aries person may focus a lot on his own development or growth or on accomplishing himself, the Sun gets the best environment in this sign for shinning the brightest. As Aries is also sign of being assertive, active and being a go-getter, it is also an indication that person may not leave any opportunity for his own personal growth.

Hence, Sun is exalted in Aries because here Sun finds the best environment to shine bright and get the best success which will bring ego satisfaction and contentment to the soul.

Reasons behind exaltation of Sun in Ashwini Nakshatra – Now, when we study about why Sun is debilitated in Swati nakshatra then one of the reasons we get is that Swati is ruled by Rahu and Rahu eclipses Sun that’s why it is debilitated in Rahu’s Nakshatra. But then it can’t be exalted in Ashwini Nakshatra because Ashwini is also ruled by Ketu and Ketu also eclipses Sun. So, there has to be some other reason behind Sun’s exaltation in Ashwini Nakshatra.

Sun gets exalted in Ashwini Nakshatra at 10 degrees which is in 4^th Pada of Ashwini Nakshatra.

Now, 1^st reason I see behind Sun getting exalted in Ashwini Nakshatra and not under remaining 1.5 nakshatras of Aries sign is that the whole mythological story of Ashwini Nakshatra is the story of Sun. It is story where Sun & his wife Sandhya make love and  twin brothers Ashwini Kumars took birth. This story not only is connected with Sun but it is also connected with the basic trait of Sun, i.e. creation. As we know that all planets came into existence from Sun itself and Sun is the source of all life. If Sun stops burning now, the human life will end in next 8 minutes. As Sun is the source of life and creation, it is apt that nakshatra which indicates about creation of Sun’s own family should be the nakshatra where Sun may feel exalted or strongest.

Then Sun is exalted at 10 degrees of Ashwini which falls into 4^th Pada of Ashwini Nakshatra and sends Sun in Cancer sign of D-9 and D-10 chart. As these two divisional charts are considered as most important divisional charts, we can get an indication as to why Sun is getting exalted at exact 10 degrees?

Again, let’s go back to the basics.

Sun represents Soul.

Ashwini Nakshatra is nakshatra of Metaphysical Healers.

At least for me, D-9 chart is chart of our righteous path in life and D-10 chart is chart of our karma in this life. Again, when we are looking at divisional charts, we have to take their higher level (Soul level or Sattva level) representations rather than generic mundane representation of marriage or job etc.

Cancer is sign of nourishing and taking care of others.

It means that no matter what we are doing in life but if we take care and nourish other people in any capacity while following our righteous life path and while doing our karma in life then our soul will find its highest contentment.

Now, it doesn’t mean that we all should become Doctors/Healers/Counsellors. As I said, “no matter what we are doing in life but if we take care and nourish other people in any capacity while following our righteous life path and while doing our karma in life then our soul will find its highest contentment”. So, even if you are an actor and you have nourished people & made them feel good with your movies then you have fulfilled the conditions here. Best example can be Sachin Tendulkar’s chart - https://www.astrosaxena.com/stendulkar who actually had Sun in Ashwini Nakshatra at 10 degrees and he nourished the cricket lovers with his game.

Conclusion – As I see, these are the reasons why I feel Sun is exalted in Aries sign and Ashwini Nakshatra at 10 degree.