The Becklin-Neugebauer object is a newly formed star within the Orion Nebula. It is substantially more luminous than the other newly formed stars in that nebula. Assuming that all these stars began the process of formation of the same time, what can you conclude about the mass of the BecklinNeugebauer object compared with those of the other newly formed stars? Does your conclusion depend on whether or not the stars have reached the main sequence? Explain your reasoning.

The luminosity of a star is related to how much energy it emits, which in turn depends on the rate at which it burns its fuel. Given that the Becklin-Neugebauer object is more luminous than the other newly formed stars, it implies that it is burning its fuel at a faster rate. The rate at which a star burns its fuel depends on its mass. This is due to the balance between gravitational forces, which are stronger for more massive stars and tend to compress the star, and the radiation pressure from the nuclear reactions in the star's core, which tends to inflate the star. So more massive stars are denser and hotter and thus burn their fuel at a higher rate.

Given that the Becklin-Neugebauer object is more luminous than the other newly formed stars, it implies that it is burning its fuel at a faster rate. According to the previous step, this indicates that it is more massive than the other stars.

The conclusion about the mass of the Becklin-Neugebauer object does not depend on whether or not the stars have reached the main sequence. The main sequence is a stage in the evolution of a star where it burns hydrogen in its core and remains stable for a long time. Stars of different masses spend different amounts of time in the main-sequence stage. Higher mass stars spend less time on the main sequence than lower mass stars because they burn through their supply of hydrogen more quickly. However, the relation between the mass and the burn rate, and consequently the luminosity, applies to all stages of a star's life, not just the main sequence. So, regardless of whether the stars are on the main sequence or not, the more luminous Becklin-Neugebauer object must be more massive than the other stars.