PSU ASTRO 7N COMPREHENSIVE UPDATED EXAM
QUESTIONS AND ANSWERS GRADED A+
✔✔white dwarfs - ✔✔hot, small, and dim
✔✔planetary nebula - ✔✔is the ejected envelope(the layers outside the core) of a low to
intermediate mass star
✔✔the end state of a former star's core is - ✔✔a white dwarf
✔✔Sun's history - ✔✔stellar nursery, protostar, main sequence, red giant, planetary
nebula, white dwarf
✔✔"type II" supernova - ✔✔a violent explosion with the star's core left behind; the
explosion itself creates a short-lived highly-energetic environment
✔✔if the cores mass is > than 3 solar masses it becomes a - ✔✔black hole
✔✔if the core is about 1.4-3 solar masses it becomes a - ✔✔neutron star
✔✔"onion skin" model - ✔✔concentric shells of fusion zones involving different chemical
elements, with the heaviest going on towards the core
✔✔event horizon - ✔✔a theoretical boundary around a black hole beyond which no light
or other radiation can escape.
✔✔the speed of the orbit of a star in a binary system with a black hole can be used to
measure - ✔✔the black hole's mass
✔✔singularity - ✔✔at the center of a black hole, a point of infinite density
✔✔habitable zone - ✔✔region around a star where liquid water could be present on a
planet's surface
✔✔Drake Equation - ✔✔an equation that lays out the factors that play a role in
determining the number of communicating civilizations in our galaxy (need to know
actual equation and how to use it)
✔✔Open star clusters - ✔✔•have hundreds to thousands of stars
•stars formed at the same time from the same gas cloud
•cluster only stars bound by gravity for a few million years
•lots of blue stars visible because of relatively young ages
•Pleiades is an example
, ✔✔Globular Star Cluster - ✔✔Group of tens of thousands to hundreds of thousands of
stars Highly symmetrical ball of stars
Composed of old stars that formed when the universe was younger
Located in the halo or bulge of a galaxy
No longer forming in our galaxy
The Milky Way frequently contains bright big red giants
✔✔age of a star cluster - ✔✔can be determined by seeing what spectral class of star
has most recently "turned off" of the main sequence
✔✔planetary nebulae - ✔✔what is created when a star is in the white dwarf stage and
the outer most layers of the star expand and drift away from the core
✔✔nova - ✔✔is caused by a binary star; wherein one star of the two evolves faster than
the other
✔✔Type Ia Supernova - ✔✔occur when very large amounts of material are suddenly
added to a white dwarf from a binary companion; resulting burst destroys the white
dwarf
✔✔stars form in - ✔✔molecular clouds(dark/dusty and cool areas)
✔✔the galactic center - ✔✔• towards the constellation of Sagittarius, called Sag
A*
• supermassive black hole at very center leads to faster
stellar motions there
• mass of black hole determined from Kepler's third
law as 4 million solar masses
• radius of black hole is only 100 Astronomical Units
• black hole has grown by accreting mass from other
objects
✔✔Milky Way Galaxy - ✔✔Galaxy that contains our Solar System. The name derives
from its appearance as a dim "milky" glowing band arching across the night sky, in
which the naked eye cannot distinguish individual stars.
✔✔Three components of the milky way - ✔✔bulge, disk, and halo
✔✔disk - ✔✔is 100,000 light years in diameter-spiral pattern; young blue stars dominate
✔✔bulge - ✔✔is a spherical region in the center of the disk; stars are older, so yellow
colors
✔✔halo - ✔✔is larger, spherical region around a whole galaxy; old stars, few heavy
elements
QUESTIONS AND ANSWERS GRADED A+
✔✔white dwarfs - ✔✔hot, small, and dim
✔✔planetary nebula - ✔✔is the ejected envelope(the layers outside the core) of a low to
intermediate mass star
✔✔the end state of a former star's core is - ✔✔a white dwarf
✔✔Sun's history - ✔✔stellar nursery, protostar, main sequence, red giant, planetary
nebula, white dwarf
✔✔"type II" supernova - ✔✔a violent explosion with the star's core left behind; the
explosion itself creates a short-lived highly-energetic environment
✔✔if the cores mass is > than 3 solar masses it becomes a - ✔✔black hole
✔✔if the core is about 1.4-3 solar masses it becomes a - ✔✔neutron star
✔✔"onion skin" model - ✔✔concentric shells of fusion zones involving different chemical
elements, with the heaviest going on towards the core
✔✔event horizon - ✔✔a theoretical boundary around a black hole beyond which no light
or other radiation can escape.
✔✔the speed of the orbit of a star in a binary system with a black hole can be used to
measure - ✔✔the black hole's mass
✔✔singularity - ✔✔at the center of a black hole, a point of infinite density
✔✔habitable zone - ✔✔region around a star where liquid water could be present on a
planet's surface
✔✔Drake Equation - ✔✔an equation that lays out the factors that play a role in
determining the number of communicating civilizations in our galaxy (need to know
actual equation and how to use it)
✔✔Open star clusters - ✔✔•have hundreds to thousands of stars
•stars formed at the same time from the same gas cloud
•cluster only stars bound by gravity for a few million years
•lots of blue stars visible because of relatively young ages
•Pleiades is an example
, ✔✔Globular Star Cluster - ✔✔Group of tens of thousands to hundreds of thousands of
stars Highly symmetrical ball of stars
Composed of old stars that formed when the universe was younger
Located in the halo or bulge of a galaxy
No longer forming in our galaxy
The Milky Way frequently contains bright big red giants
✔✔age of a star cluster - ✔✔can be determined by seeing what spectral class of star
has most recently "turned off" of the main sequence
✔✔planetary nebulae - ✔✔what is created when a star is in the white dwarf stage and
the outer most layers of the star expand and drift away from the core
✔✔nova - ✔✔is caused by a binary star; wherein one star of the two evolves faster than
the other
✔✔Type Ia Supernova - ✔✔occur when very large amounts of material are suddenly
added to a white dwarf from a binary companion; resulting burst destroys the white
dwarf
✔✔stars form in - ✔✔molecular clouds(dark/dusty and cool areas)
✔✔the galactic center - ✔✔• towards the constellation of Sagittarius, called Sag
A*
• supermassive black hole at very center leads to faster
stellar motions there
• mass of black hole determined from Kepler's third
law as 4 million solar masses
• radius of black hole is only 100 Astronomical Units
• black hole has grown by accreting mass from other
objects
✔✔Milky Way Galaxy - ✔✔Galaxy that contains our Solar System. The name derives
from its appearance as a dim "milky" glowing band arching across the night sky, in
which the naked eye cannot distinguish individual stars.
✔✔Three components of the milky way - ✔✔bulge, disk, and halo
✔✔disk - ✔✔is 100,000 light years in diameter-spiral pattern; young blue stars dominate
✔✔bulge - ✔✔is a spherical region in the center of the disk; stars are older, so yellow
colors
✔✔halo - ✔✔is larger, spherical region around a whole galaxy; old stars, few heavy
elements
