What is Hypergiant?
[[File:V382 Carinae.jpg|thumb|Hypergiant [[V382 Carinae]]]] A '''hypergiant''' (luminosity class '''0''') is a [[star]] with an enormous [[mass]] and [[luminosity]], It shows signs of a very high rate of [[mass]] loss. The exact [[definition]] is not yet settled. Hypergiants are the largest [[star]]s in the [[universe]], usually larger and brighter than [[supergiants]].<ref>However, note the definition is for huge luminosity and rapid mass loss, not simply size.</ref> The hypergiant with the largest known [[diameter]] is [[WOH G64]]<ref>{{cite journal | url=https://doi.org/10.1093%2Fmnras%2Fstx1101 | doi=10.1093/mnras/stx1101 | title=The SAGE-Spec Spitzer Legacy program: The life-cycle of dust and gas in the Large Magellanic Cloud. Point source classification – III | date=2017 | last1=Jones | first1=O. C. | last2=Woods | first2=P. M. | last3=Kemper | first3=F. | last4=Kraemer | first4=K. E. | last5=Sloan | first5=G. C. | last6=Srinivasan | first6=S. | last7=Oliveira | first7=J. M. | last8=Van Loon | first8=J. Th. | last9=Boyer | first9=M. L. | last10=Sargent | first10=B. A. | last11=McDonald | first11=I. | last12=Meixner | first12=M. | last13=Zijlstra | first13=A. A. | last14=Ruffle | first14=P. M. E. | last15=Lagadec | first15=E. | last16=Pauly | first16=T. | last17=Sewiło | first17=M. | last18=Clayton | first18=G. C. | last19=Volk | first19=K. | journal=Monthly Notices of the Royal Astronomical Society | volume=470 | issue=3 | pages=3250–3282 }}</ref> which is about 1,540 times wider than the [[Sun]]. Another large hypergiant is [[VY Canis Majoris]], about 1,420 times wider than the [[Sun]]. It is one of the extreme luminous supergiant stars. Just as supergiants evolve from massive stars that were once [[main sequence]] stars (between 8 to 22 solar masses, one solar mass being the mass of the Sun), hypergiants were once main-sequence stars that were more massive. Hypergiants are very hard to find and they have a short lifespan because of their size. While the Sun has a lifespan of around 10 billion yea