HW 8-1: Supp. Q 1-2; (334) RQ 4; (359) RQ 9, 10
Supp Q 1: What s most likely the formation
process of elliptical galaxies?
Large elliptical galaxies are likely the result of mergers
(collisions) between several smaller, spiral galaxies.
Supp Q 2: Explain the origin of the name quasar.
These look like stars,
but aren’t really stars.
They are quasi-stellar
objects.
HW 8-1: Supp. Q 1-2; (334) RQ 4; (359) RQ 9, 10
RQ4: Contrast the motion of the disk stars
and that of the halo stars. Why do their orbits
differ?
Halo stars were formed
when the galaxy was
young and spherical.
Disk stars formed later,
after the ISM of the
galaxy had settled into
the galactic plane.
Stars take on the
motion of the gas
clouds from which they
form.
HW 8-1: Supp. Q 1-2; (334) RQ 4; (359) RQ 9, 10
RQ 9: How can collisions affect the shape of galaxies?
Collisions can create
bursts of star
formation, making
rings or big blobs of
bright stars. They
can cast off long
tentacles of stars.
They can destroy or
scramble arm
structure. Repeated
collisions can turn a
spiral galaxy into an
elliptical galaxy.
HW 8-1: Supp. Q 1-2; (334) RQ 4; (359) RQ 9, 10
RQ 10: What evidence do we have that
galactic cannibalism really happens?
The computer simulations that predict what should
happen when a larger galaxy eats a smaller galaxy
predict things actually seen in the sky, such as
casting off little tails of stars, or central regions
rotating opposite to the rest of the galaxy.