Viṣṇu Purāṇa | Book 2 - Chapter 10
Names of the twelve Ādityas. Names of the Ṛṣis, Gandharbhas, Apsarasas, Yakṣas, Uragas, and Rākṣasas, who attend the chariot of the sun in each month of the year. Their respective functions.
PARĀŚARA.--Between the extreme northern and southern points the sun has to traverse in a year one hundred and eighty degrees, ascending and descending.
His car is presided over by divine Ādityas, Ṛṣis, heavenly singers and nymphs, Yakṣas, serpents, and Rākṣasas (one of each being placed in it in every month).
The Āditya Dhātri, the sage Pulastya, the Gandharva Tumburu, the nymph Kratusṭhalā, the Yakṣa Rathakrit, the serpent Vāsuki, and the Rākṣas Heti, always reside in the sun's car, in the month of Madhu or Chaitra, as its seven guardians.
In Vaiśākh or Mādhava the seven are Āryamat, Pulaha, Nārada, Punjikāsthalī, Rathaujas, Kachanīra, and Praheti. In Śuchi or Jyeṣṭha they are Mitra, Atri, Hāhā, Menā, Rathaswana, Takṣaka, and Paurusheya.
In the month Śukra or Āṣādha they are Varuṇa, Vaśiṣṭha, Huhu, Sahajanyā, Rathachitra, Nāga, and Budha. In the month Nabhas (or Srāvaṇa) they are Indra, Aṅgiras, Viśvāvasu, Pramlochā, Śrotas, and Elapatra (the name of both serpent and Rākṣas).
In the month Bhādrapada they are Vivaswat, Bhrigu, Ugrasena, Anumlocha, Āpūraṇa, Śankhapāla, and Vyāghra. In the month of Āśvīn they are Pūṣan, Gautama, Suruchi, Ghritāchī, Suṣeṇa, Dhananjaya, and Vāta.
In the month of Kārtik they are Parjanya, Bharadvāja, (another) Visvāvasu, Visvāchī, Senajit, Airāvata, and Chāpa. In Agrahāyana or Mārgaśīrṣa they are Ansu, Kaśyapa, Chitrasena, Urvasi, Tārkṣya, Mahāpadma, and Vidyut.
In the month of Pauṣa, Bhaga, Kratu, Urṇāyu, Purvachittī, Ariṣṭanemi, Karkoṭaka, and Sphūrja are the seven who abide in the orb of the sun, the glorious spirits who scatter light throughout the universe.
In the month of Māgha the seven who are in the sun are Tvaṣṭri, Jamadagni, Dhritarāṣṭra, Tilottamā, Ritajit, Kambala, and Brahmāpeta. Those who abide in the sun in the month Phālguna are Viṣṇu, Viśvāmitra, Sūryaverchchas, Rambhā, Satyajit, Aśvatara, and Yajnāpeta.
In this manner, Maitreya, a troop of seven celestial beings, supported by the energy of Viṣṇu, occupies during the several months the orb of the sun.
The sage celebrates his praise, and the Gandharva sings, and the nymph dances before him: the Rākṣas attends upon his steps, the serpent harnesses his steeds, and the Yakṣa trims the reins: the numerous pigmy sages, the Bālakhilyas, ever surround his chariot.
The whole troop of seven, attached to the sun's car, are the agents in the distribution of cold, heat, and rain, at their respective seasons.