Which of these cosmic objects is not named after an arachnid?

While there is a spider called the brown recluse, there is no arachnid called a brown dwarf. In cosmology, a brown dwarf is a “failed” star. The mass of a brown dwarf is more than that of the most massive known gas giant planet but less than that of the least massive star.

Scientists classify stars according to a number of factors, including mass, age, energy, and type of light emitted. Our sun fuses hydrogen into helium and heaver elements to produce energy. It is smaller and cooler than many stars in the galaxy and produces light in the “visible (to human beings using no special equipment) spectrum”. It is classified a “yellow dwarf” on the “main sequence” of stars. Its “spectral class” is G2V.

Brown dwarfs produce all their energy by gravitational attraction, a kind of cosmic friction. A brown dwarf does not have enough mass to “go critical” and sustain the typical hydrogen fusion reaction that makes a star shine brightly.

Brown dwarfs (and red dwarfs) are very difficult to see, as they do not produce much light in the visible spectrum. Using special equipment, scientists can detect brown and red dwarfs in the infrared spectrum of light. These small, cooler dwarf stars are in the spectral classes L, T, and Y, which were specifically established to identify them.