<P> In the MK system , a luminosity class is added to the spectral class using Roman numerals . This is based on the width of certain absorption lines in the star 's spectrum , which vary with the density of the atmosphere and so distinguish giant stars from dwarfs . Luminosity class 0 or Ia+ is used for hypergiants , class I for supergiants , class II for bright giants , class III for regular giants , class IV for sub-giants , class V for main - sequence stars , class sd ( or VI ) for sub-dwarfs , and class D ( or VII ) for white dwarfs . The full spectral class for the Sun is then G2V , indicating a main - sequence star with a temperature around 5,800 K . </P>
<P> In the MK system , a luminosity class is added to the spectral class using Roman numerals . This is based on the width of certain absorption lines in the star 's spectrum , which vary with the density of the atmosphere and so distinguish giant stars from dwarfs . Luminosity class 0 or Ia+ is used for hypergiants , class I for supergiants , class II for bright giants , class III for regular giants , class IV for sub-giants , class V for main - sequence stars , class sd ( or VI ) for sub-dwarfs , and class D ( or VII ) for white dwarfs . The full spectral class for the Sun is then G2V , indicating a main - sequence star with a temperature around 5,800 K . </P>
sun is classified as what type of star
sun is classified as what type of star
G2V
G2V