Transcript lecture 15

spectrum of Sun
stellar spectra
d
1
p
• The HertzsprungRussel diagram
• a.k.a. HR diagram
• Vertical axis: L*
• Horiz. axis: Ts*
color of the star
cartoon showing current idea for how a star forms:
(a) denser
“cores”
form in
dense
molecular
clouds
(c)
outflows
shoot out
of poles of
the
star/disk
system
(b) the
center of a
“core”
collapses
(due to its
gravity) to
form
“proto-star”
and disk
(d) After
clearing:
protostar
and protoplanetary
disk
stage c (almost d): a protostar with disk and jet
infrared image
optical image
stage “a”: a dense molecular cloud core