Self-study
Science journalist: Brown dwarfs are celestial objects with more mass than planets but less mass than stars. ████ ███ ██████████ ██ █████ ████ ███ ███████ ██ ███ ███████ ██ ███████ ██ █████ ████████████ █████ ██ █████ ██ ███████ ██ ███ ███ ████ ███████ █████████ ██ █████ ███████████ ███████ ███ ██████ ██ ████████ ██ █████ ████████ ███████ ████████ ██ ███████████ █████ ████ ████ ████ ████ ███ ███ ████ ██ ███████ ███████ ███ ███████ ███ ████ █████ █████ ████ █████ ███████ ████████ ███ █████████ █ █████ █████ ████ ███ ████ █ █████ ██████████ ███████ ███████ ███ ██ ███ ███████ ██████ ██ █████████
Summary
Brown dwarfs are more massive than planets but less massive than stars. They are identified by their mass and whether or not lithium is present in their atmospheres. A brown dwarf’s lithium cannot be consumed because they do not have a functional nuclear furnace.
Strongly Supported Conclusions
If a celestial object does not have lithium in its atmosphere, then it is not a brown dwarf.
24.
Which one of the following ██ ████ ████████ █████████ ██ ███ ███████ ████████████ ███████████
a
Any celestial object ███████ ███████ ██ ███ ██████████ ██ █ ████ ████ ████ ████ ████ ███ ████
This answer is unsupported. We don’t know from the stimulus that any celestial object without lithium must be a star. We only know from the stimulus that some stars do have lithium in their atmospheres.
b
Any celestial object ████ ███████ ██ ███ ██████████ ███ █ ███████ ███████ ████ ███ ████████████ █████ ███ ████████ █████████
This answer is unsupported. We know that this is true of stars at least as massive as the sun, but saying this is true of any celestial object is too strong.
c
No celestial object ████ ███ ██ ███████ ██ ███ ██████████ ██ █ █████ ██████
This answer is strongly supported. We know that brown dwarf’s must have lithium in their atmospheres because it cannot be consumed by a nuclear furnace.
d
No celestial object ████ ███████ ██ ███ ██████████ ███ ████ ████ ████ ███ ████
This answer is unsupported. This is the reverse relationship from the stimulus. The stimulus tells us that if a star is at least as massive as the sun, then there is lithium in that star’s atmosphere.
e
No celestial object ████ ███████ ████ █ █████ █████ ███ ███████ ██ ███ ███████████
This answer is unsupported. We don’t know anything about celestial objects with less mass than brown dwarfs from the stimulus. The stimulus is limited to brown dwarfs and celestial objects with greater mass.