Redshifts of high-luminosity stars – The K effect, the Trumpler effect and mass-loss corrections

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Abstract
Many independent tests over the last 80 years have shown that the K effect is an excess redshift which O and B stars exhibit relative to other stars in the Galaxy. Trumpler reported that the most luminous O and B stars in young galactic clusters showed this excess redshift at a 10σ level of significance. The same effect is demonstrated here in B and A supergiants in h + χ Persei, as well as in other associations of young, luminous stars. It is also now possible to demonstrate the K-Trumpler effect in O, B and A supergiants in the Magellanic Clouds, as well as in nearby galaxies such as NGC 1569 and 2777 and in blue, irregular variables in M31 and M33. In addition, mass outflow in luminous stars is shown to require an average correction of about 20 km s−1 and increases the excess redshifts of the stars in the Magellanic Clouds to a significance level of 6σ. Completely empirical and independent measurements show that mass–loss corrections of this size are required on average for supergiants in both the Small and Large Magellanic Clouds and also in the Milky Way. After this correction, the K-Trumpler, intrinsic redshift is more than doubled. Recent measures by some investigators confirm that measuring lines deeper in the atmospheres of these stars, where the mass outflow is less, in fact makes the measured redshifts more positive. The supergiant, irregular variables in M31 and M33 appear to represent more extreme cases of both mass loss and the K-Trumpler effect.

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