The Brightest Stars in the Magellanic Clouds

Spectroscopic and photoelectric observations of individual members of the Magellanic Clouds are presented (Sections 1.7). Table II includes spectral classifications of 50 Small Cloud objects and 105 Large Cloud objects; of these 93 have been observed photoelectrically (mostly in 3 colours), and 112 have measured radial velocities. Table III also lists 103 stars proved spectroscopically to be foreground galactic stars. In Section 8 the observed colours of Cloud stars are compared with intrinsic colours of galactic supergiants by Johnson (O to A3) and Feinstein (A0 to K5). With the exception of Johnson's dip at A3 the least reddened Cloud stars agree well with these colours. Cloud stars are subject to a small amount of reddening ( $$\bar E_{\text B-\text V}=0.10$$ ) apparently arising partly in the Clouds and partly in the Galaxy. The Cloud reddening is greater for stars involved in nebulosity. In Section 9 the HR diagram shows stars at A0 to A3 brighter visually than the early B and O supergiants. Bolometrically, however, the brightest stars ( M _b ∼ −11) cover this whole range of spectral types; these brightest stars all tend to show P Cyg characteristics in their spectra and are probably at the limit of stability for massive stars (mass ∼ 100⊙). Some peculiar emission-line stars resembling Eta Car are slightly less luminous. The few red super-supergiants (visually among the brightest Large Cloud members) are probably very rare objects. Photographically, the 18th brightest known LMC member has B = 10.70. In Section 10, a detailed spectroscopic comparison between Cloud stars and galactic standards is made (together with a comparison of the gas in the Large and Small Cloud). Most of the small peculiarities noted can be attributed to very high luminosity (e.g. narrowness of the H lines) and lack of suitable galactic standards. In particular, no outstanding peculiarities are found in the 10 long-period Cloud Cepheids which have been studied. A list of 26 elements (including La II ) identified in Cloud spectra is given. In Section 11, a discussion of the UBV photometry shows that the reddening and intrinsic lines reinforce the essential similarity of stars (and dust) in both Clouds and the Galaxy. In Sections 12 and 13 evidence is presented that interstellar lines due to Cloud and galactic gas occur in spectra of stars in both Clouds. Stars showing Cloud interstellar lines tend to be involved in nebulosity; our stars of type earlier than B I are all involved in nebulosity, as in the Galaxy. The W stars and red super-supergiants also appear to be associated with nebulous regions. In Sections 14 and 15 foreground stars are briefly discussed. Details of the photometric evidence for foreground galactic absorption are presented, and spectra of 3 peculiar galactic stars are described.