As one moves upward and to the left on the H-R diagram, the stars become

At what stage of its evolutionary life is the Sun?

What prevents a neutron star from collapsing and becoming a black hole?

Why do astronomers seek to measure gravitational waves simultaneously with at least three detectors?

Where are the MOST massive stars to be found in the main sequence of a Hertzsprung–Russell diagram?

A star of apparent magnitude +2.1 appears _____ than a star of apparent magnitude –1.2.

In the spectral classification scheme, what designation is given to a star just a little cooler than a K5 star?

The spectrum of an ordinary main-sequence star is a

The Sun’s spectrum peaks in the green region (i.e., green is the most intense color in its spectrum). The spectrum of Rigel (the knee of Orion) peaks in the short-wavelength end of the visible spectrum. Compared with the Sun, Rigel is

A planetary nebula is a