E3 Homework one
A star whose temperature is increasing but whose luminosity is roughly constant moves in what direction on the H-R diagram?
To the left
A graduate student is given the assignment to find stars with dusty disks around them. What kind of telescope would it be best for her to use for this purpose?
a large telescope that detects infrared radiation
Which of these stars will take the SHORTEST Time to go from the earliest protostar stage to the main sequence?
a star ten times the mass of our Sun
A Herbig-Haro (HH) object is
where a jet from a star in the process of being born collides with (and lights up) a nearby cloud of interstellar matter
Astronomers call a ball of matter that is contracting to become a star...
A protostar
If an astronomer wants to find and identify as many stars as possible in a cluster that has recently formed near the surface of a giant molecular cloud (such as the Trapezium cluster in the Orion Nebula), what instrument would be best for her to use?
An infrared telescope (and camera)
The big surprise about the first planet discovered around another regular star was that is
Orbited so close to its star it only took 4 days to go around
The telescope that allowed astronomers to discover most of the planets found with the transit method was called
The Kepler mission
You are an astronomy graduate student and you are observing the big Orion nebula from an airplane that has a good sized infrared telescope built into it (there is really such a plane.) On an infrared image of the nebula, what would particularly stand out?
The clouds of the nebula that have a lot of dust in them
What observations about disks of dusty material around young stars suggests that planets may be forming in such disks?
The disks show lanes that are empty of dust within them
To measure how dense a planet is (to know whether it is made of rock or gas and liquid) they must be able to measure the planet's mass from the Doppler shift and...
The planet's radius using the transit method
Why is it so difficult for astronomers to see new stars in the process of birth?
all of these
Planets in the habitable zone of their stars:
are at a temperature where water can exist as a liquid
If you want to find stars that are just being born, where are the best places to search?
giant molecular clouds
How did astronomers determine that the planet orbiting the star HD 209458 is a gas giant like Jupiter and not made mostly of rocks or metals?
it took more than one of the above measurements to figure out this problem
Astronomers believe that disks of material will form around protostars that are spinning. Which of the following observed phenomena is a good indication of the presence of a disk around a protostar?
jets and Herbig-Haro objects
In figuring out the evolutionary tracks on the H-R diagram, astronomers...
make model stars on a computer and then follow how their characteristics will change with time
What technique did astronomers use to make the first confirmed discovery of a planet around another star like the Sun?
measure the Doppler shift of the lines in the star's spectrum and look for periodic changes in this shift due to the pull of the planet as it orbits the star
Which of the following is NOT one of the reasons planets around other stars are so difficult to detect?
planets only form very late in the life of a star, just when it is ready to die, and thus last only a very short fraction of the star's life
Astronomers identify the "birth" of a real star (as opposed to the activities of a protostar) with what activity in the star?
when nuclear fusion reactions begin inside its core