Alternative name of Aśvinī, 'the horse-yoker'. Colebrooke glosses the pair as 'The head of Aries'. The form survives in the Arthaśāstra's month-name Āśvayuja and in the Pali Assayuja — a genuinely pan-Indic variant.
अश्वयुक् Aśvayuj
Sheratan · β Arietis · Aries
In the living languages
Aśvayuj (Sheratan) (1 names), Seasonal and agricultural star-markers (5 names)
Attestations
Devanāgarī from Sanskrit Wikisource; the printed sandhi ऽभिजिद्श्वयुक्छतभिषजो resolves to abhijit + aśvayuj + śatabhiṣajaḥ. GRETIL's Kāśikā-derived IAST gives 'vatsaśālā-abhijid-aśvayuk-chatabhiṣajo vā'; the independent 'alt' text gives 'vatsa-śālā=abhijit=aśva-yuj=śata-hiṣaj-aḥ=vā' (with an obvious typo hiṣaj for bhiṣaj). 4.3.45 reads ४.३.४५ आश्वयुज्या वुञ् ।
Another substantial upgrade: the database currently dates Aśvayuj from the Amarakośa, but Pāṇini names it himself at 4.3.36 vatsaśālā-abhijid-aśvayuk-chatabhiṣajo vā, in a sūtra whose whole subject is asterism-derived formations, and again at 4.3.45 āśvayujyā vuñ (the full-moon night Āśvayujī). This is the ARCHAIC form: Aśvinī occurs NOWHERE in the Aṣṭādhyāyī (sandhi-tolerant search over both recensions returns zero for aśvin- and āśvin-). Vasu, translating the Kāśikā on 4.3.45, glosses Āśvayujī as 'the name of the full-moon in the Asterism of Aśvinī', which is the tradition equating the two; but the equation is the commentator's, not Pāṇini's — Pāṇini only ever says Aśvayuj. Also note 4.4.126 aśvimān aṇ, which concerns the Aśvins as deities, not the asterism.