The two components of Pismis 24-1NE cannot be detected separately, but analysis of their eclipses shows that they are almost identical, with temperatures around 42,000 K.  The pair combined is nearly 800,000 times as luminous as the sun, making each individual star likely to be under 400,000 L☉.
 The spectral type of the combined object is O3.5 If* indicating an expanded star with strong emission lines of highly ionised nitrogen.
 Separate spectral signatures cannot be detected so it is assumed that both stars have similar spectra.
 The mass as a single object has been calculated to be 74 M☉ but each star would have a smaller mass.
 Hard x-ray radiation from the vicinity of Pismis 24-1 is assumed to be caused by the colliding winds of these two supergiants.

Pismis 24-1SW is apparently a single star with a spectral type of O4 III(f⁺), indicating a temperature around 40,000 K and emission lines of ionised nitrogen, silicon, and helium.
 The luminosity is around 650,000 L☉, the radius 17 R☉, and the mass 66 M☉.
 It is classified as a giant star on the basis of its spectrum, but the hottest O stars develop these spectral features while still burning hydrogen in their cores, as a result of vigorous convection and powerful stellar winds.

When first modelled, Pismis 24-1 was thought to be a single star with a mass of 300 M☉ or more, higher than expected to be theoretically possible.
 This has been steadily reduced as the star was discovered to be double, then triple, and as newer models of stellar atmospheres have been developed.
 The latest mass estimates are well within theoretical expectations for star formation without exotic explanations.
The two components of Pismis 24-1NE cannot be detected separately, but analysis of their eclipses shows that they are almost identical, with temperatures around 42,000 K.  The pair combined is nearly 800,000 times as luminous as the sun, making each individual star likely to be under 400,000 L☉.  The spectral type of the combined object is O3.5 If* indicating an expanded star with strong emission lines of highly ionised nitrogen.  Separate spectral signatures cannot be detected so it is assumed that both stars have similar spectra.  The mass as a single object has been calculated to be 74 M☉ but each star would have a smaller mass.  Hard x-ray radiation from the vicinity of Pismis 24-1 is assumed to be caused by the colliding winds of these two supergiants.
Pismis 24-1SW is apparently a single star with a spectral type of O4 III(f⁺), indicating a temperature around 40,000 K and emission lines of ionised nitrogen, silicon, and helium.  The luminosity is around 650,000 L☉, the radius 17 R☉, and the mass 66 M☉.  It is classified as a giant star on the basis of its spectrum, but the hottest O stars develop these spectral features while still burning hydrogen in their cores, as a result of vigorous convection and powerful stellar winds.
When first modelled, Pismis 24-1 was thought to be a single star with a mass of 300 M☉ or more, higher than expected to be theoretically possible.  This has been steadily reduced as the star was discovered to be double, then triple, and as newer models of stellar atmospheres have been developed.  The latest mass estimates are well within theoretical expectations for star formation without exotic explanations.
Pismis 24-1