Count: 0. No stars meet the strict criterion of having an IAU‑approved or well‑established proper name that begins with the letter Y. Consult the IAU Name List, SIMBAD, the Bright Star Catalogue, Gaia EDR3 distance data, and NASA name pages and you will find no matches; the search term “Stars with proper names that start with Y” therefore returns zero confirmed entries. Note that many traditional star names come from Arabic, Greek, or Latin roots and are standardized in English spellings that rarely begin with Y, so the absence is not a data error but an outcome of naming history and modern catalog rules.

Explain why this criterion produces no results. Observe that the IAU prioritizes established historical names and approved modern names, and it avoids approving ad hoc or regionally varied transliterations. Recognize that transliteration from Arabic or other languages seldom produces initial Y in the canonical forms used by catalogues, and that many stars are known by Bayer, Flamsteed, or variable‑star designations (letters and numbers) rather than unique proper names. Consider related categories instead: many variable‑star names begin with the letter Y as a designation (for example in variable‑star catalogs), and a few regional or archaic names may start with y‑sound transliterations but lack IAU approval. Consult authoritative sources and the proposed A–Z index if you want nearby alternatives or to verify borderline cases, and do not accept unverified or informal spellings as official proper names.