BOSTON â President Obama signed an executive order on Monday requiring federal contractors to provide up to seven days of paid sick leave a year, even as he accused Republican congressional leaders of endangering the economy and Republican presidential candidates of undercutting American workers.OSTON â President Obama signed an executive order on Monday requiring federal contractors to provide up to seven days of paid sick leave a year, even as he accused Republican congressional leaders of endangering the economy and Republican presidential candidates of undercutting American workers.
A dwarf star is a star of relatively small size and low luminosity. 1  Most main sequence stars are dwarf stars. The term was originally coined in 1906 when the Danish astronomer Ejnar Hertzsprung noticed that the reddest starsâclassified as K and M in the Harvard scheme could be divided into two distinct groups.
The third and final group is the dim white dwarfs. These are dead stars â former giants that shed their outer layers, leaving only their hot, dense cores. They form a group thatâs below and parallel to the main sequence on the H-R diagram â a tool that depicts the lives of the stars. And weâll talk about some examples of main-sequence and giant stars tomorrow.