Astro 7 Unit 3 Review Flashcards
How do LOW mass stars live their lives?
longest lifetime (billions, trillions of years), fusion creates low mass elements, remnant is roughly earth sized
our sun is a low mass star
How do INTERMEDIATE mass stars live their lives?
tens - hundreds of millions of years lifetime, fusion creates elements between low and high mass, remnant is size of a large city, a few times bigger than our sun
How do HIGH mass stars live their lives?
couple million year life, fusion creates elements up to iron, remnant is immensely small hole, 30-40 times mass of sun
What is the end state of a LOW mass star?
becomes planetary nebulae, leaves behind a white dwarf
What is the end state of a INTERMEDIATE mass star?
becomes a type 2 supernova, leaves behind a neutron star
What is the end state of a HIGH mass star?
becomes type 2 supernova, leaves behind a black hole
What is the H-R Diagram and how is it used?
Horizontal Axis: left to right is hottest to coldest. spectral class is o - b - a - f - g - k - m which is determined using absorption lines
What is the main sequence?
main-sequence stars located on H-R diagram in a band from lower right across to upper left — around the slightly-wavy red line in the example H-R Diagram
How are different properties of stars related to stars on the main sequence?
when on the main-sequence stars are burning Hydrogen into Helium in their cores, higher temp = higher luminosity, more massive stars burn out faster
How are extrasolar planets detected?
found using ‘transit’ method, the brightness of the star decreases regularly due to the planet passing right in front of it
How does the habitable zone change depending on the mass of a star?
a less-massive star would have habitable zone closer to the star and a more-massive star would have habitable zone farther from the star
What is a habitable zone?
region around a star where liquid water could be present on a planet’s surface
What are black holes?
the end state of the highest-mass stars, left behind after supernova explosion, gravity is so great light cannot escape, infinite density and infinitely small
What is a type 2 supernova?
a violent explosion with the star’s core left behind
What is a neuron star?
if the remaining core is about 1.4 – 3 solar masses, about city sized
What types of stars are not on the main sequence?
red giants and super giants (most luminous) white dwarfs
Nuclear Fusion
a long-lasting source of energy 4 protons combine to make helium-4 (2 protons and 2 neutrons) and release energy in gamma rays
The Sun
mostly gas, hydrogen (73 %, by mass) and helium (25 %, by mass), 99.9% of all mass in solar system is sun
Possibly layers of the sun?
Parralax method
D = 1/p
ex: a star with measured parallax angle of 0.1 arcsec is 1 / 0.1 = 10 parsecs away
ex: a star with a parallax angle of 0.02 arcsec is 1 / 0.02 = 50 parsecs away
Look at HR Diagram
Drake equation - maybe the variables and their meaning?
