astronomy 1 Flashcards
how old is the universe
14 billion years
what is cosmological redshift
galaxies emit light and expand into space, the wave length of light gets stretched
distant galaxies have larger redshirts then nearby galaxies
was is cosmic microwave background radiation(CMB)
leftover heat from the big bang - the early universe must have been very hot and it’s expanded since
what evidence supports he big bang theory
cosmological redshift and CMB
what does the big bang theory state
that 14 billion years ago the portion of the universe we can see today was very small and began at a point , and it has been expanding since
what does a spectrometer measure
measures all of the wavelengths of energy coming off an object , the patter is called a spectrum
what is a continuous spectra
produced by a glowing solid or liquid- a stars surface produces a continuous spectra
what is one problem that makes the big bang theory incomplete
doesn’t explain the exsistence of galaxies and large scale structure
what is the emissions spectra (bright line)
produced when a glowing gas emits energy at specific wavelengths characteristic of the elements composing the gas
what is the absorption spectra(dark line)
produced when a gas lies between the observer and the object emitting a continuous spectra
the wavelengths absorbed depends on the composition of the gas
used to classify stars
how can bright or dark line spectrums be used
can be used to determine the elemental composition of a star
each element has a distant spectral signature
what is the hubble constant (H)
rate the universe is expanding
how can u use the dark line spectra
can be used to measure an objects velocity
the change in wavelength can be used to calculate the amount of shift
what happens in a red shift
blue shift
the object is moving away
the object is moving toward us
more lines the spectra has the cooler the star
what is a galaxy
system containing billions of stars
basic building block of the universe
what are the 4 types of galaxies
spiral
barred spiral
elliptical
irregular - based on shape
characteristics of a spiral galaxy
lens shaped disks
bright nucleus - made up of millions of stars
75% are this type
youngest galaxies and could have black holes st the center
characteristics of a barred-spiral galaxy
lens shaped disks
bright nucleus
has “arms” of stars and gas
the milky way is a barred spiral
characteristics of a elliptical galaxy
lens shaped
but no bright center or “arms”
contains little or no dust and gas
20% are these type
characteristics of an irregular galaxy
small and faint lots of gas and dust stars spread unevenly least common ex: magellanic clouds
physical properties of stars -size
size can vary greatly
may be smaller than earth or way bigger than our sun
density and elements of stars
stars are mainly hydrogen and helium
most stars are the density of our sun (1.4 g/cm3
star formation
starts as a nebulae -cloud of gas and dust
protostars-glowing cloud sections
eventually hot enough to become in a stable state
then moves into a main sequence star
what is a hertzsprung-russel diagram
plots stars using surface temp in kelvin and a stars absolute magnitude(luminosity)
shows what type of star it currently is
ALL stars start out on the main sequence
