Question

Which of the following stars are less bright than their temperature would predict?
neutron stars
red giants
black holes
white dwarfs

Answer 1

Among the options provided, **neutron stars** and **black holes** are less bright than their temperature would predict.

1. **Neutron Stars**: Although they can have very high surface temperatures, they are often not very luminous because their emission can be mostly in the X-ray or other non-visible wavelengths, and the size of the neutron star is quite small.

2. **Black Holes**: Black holes do not emit light themselves, so their brightness is effectively zero, regardless of their temperature. They only exhibit luminosity through accretion processes or interactions with surrounding matter, but their core itself is not bright.

**Red giants** and **white dwarfs**, on the other hand, typically do emit light in a way that corresponds more closely to their temperatures, with red giants being very luminous due to their large sizes and white dwarfs emitting visible light despite their smaller size.

So, the stars that are less bright than their temperature would predict are **neutron stars** and **black holes**.