The dictionary meaning of Ṛkṣa (Riksha) is ‘star’ or a constellation. In Mahābhārata (Mahabharata), we have the term mentioned several times, in this sense. At one place in Anuśāsanaparva (Anusasanaparva), when Kṛṣṇa (Krishna)was about to go to Himālaya (Himalaya) for tapasyā (tapasya; ascetic practice), Jāmvavatī (Jamvavati), his wife, prayed so that he might have a safe journey, and the gods might protect him. At the same time, she also prayed to the Ṛkṣa, along with gods and goddesses, rivers, oṣadhi (oshadhi; medicinal herbs). This Ṛkṣa obviously refer to the stars like Śravaṇā (Sravana), Bhadrā (Bhadra) and so on. The prayer contained the idea that these stars, the zodiac constellations like Meṣa and the others, the Saptarṣimaṇḍala(Saptarshimandala; the constellation of seven stars named after the seven iconic sages) — all these might be favourably disposed to Kṛṣṇa.
The meaning of the term ‘Ṛkṣa’ in the sense of star or stars , become clearer in the utterance of Brahmā (Brahma). He describes that in the beginning of Creation, at first day and night were created, then came māsa (masa; month) and pakṣa (paksha; fortnight), and then there was a birth of stars like Śravaṇā (Sravana) and Bhadrā (Bhadra) —
ahaḥ pūrvaṁ tato rātrirmāsā śuklādayaḥ smṛtāḥ
śravaṇādīni ṛkṣāṇi ṛtavaḥ śiśirādayaḥ.