Ashvins or Ashwini Kumaras — are two celestial horsemen.
In the Vedic legend they are twin brothers, who were born out of the union of Sun and his wife Sanjana (daughter of Vishwakarma), when they were in the form of a stallion and a mare. These two brothers are seen as the celestial physicians in ancient Vedic texts. This is where the healing and rejuvenating aspect of this nakshatra stems from.
The Ashvini Kumaras are supposed to have knowledge of all herbs on the physical and astral plane; and are supposed to possess supernatural powers to cure any disease or fix any problem. They are particularly concerned with friction or obstacles which might come up between married couples. Ashvini Kumaras are also invoked to aid childbirth. They are also very well known in the ancient legends for curing impotence and other types of sexual disorders.
The Ashvini Kumaras are considered so powerful that they can make the old become young and even bring the dead back to life. They themselves have a youthful appearance and never age. The generosity and compassion of the Ashvini Kumaras extends to the animals as well. There are a lot of stories of them saving gentle animals like lambs from preying creatures like wolves.