![]() Size can be indicated on the same diagram as stellar luminosity and temperature. ![]() Each dashed diagonal line corresponds to a constant stellar radius, so that stellar The points plotted here are for stars lying within about 5 pc of the Large, covering eight orders of magnitude (that is, a factor of 100 million), fromġ0 -4 to 10 4 times the luminosity of the Sun.įigure 10.13 H-R Diagram of Nearby Stars Most stars have properties within the shaded region of the H–R diagram known as the In contrast, the observed range in luminosities is very The surface temperatures of main-sequence stars range from about 3000 K (spectralĬlass M) to more than 30,000 K (spectral class O). Most stars in the solar neighborhood lie on the main sequence. Figure 10.13 is an H-R diagram for stars lying within 5 pc of the Sun. Thisīand of stars spanning the H-R diagram is known as the main sequence. To be faint (less luminous) and hot stars tend to be bright (more luminous). To bottom right (low-temperature, low-luminosity). Well-defined band stretching diagonally from top left (high-temperature, high-luminosity) Stars are not uniformly scattered across the H–R diagram. However, as Hertzsprung and Russell plotted more and more stellar temperatures and luminosities, they found The few stars plotted in Figure 10.12 give little indication of any particular connectionīetween stellar properties. The M-type star Proxima Centauri, at bottom right, has a temperature of 3000 K and a luminosity less than The B-type star Rigel, at top left, has a temperature of about 15,000 K and a luminosity more than 10,000 Its temperature, read off the bottom scale, is 5800 K-a G-type star. The Sun, of course, has a luminosity of 1 solar H-R diagram, is a useful way to compare stars. Sense of temperature increasing to the left, so that the spectral sequence O, B, A, reads left to right.įigure 10.12 H-R Diagram of Well-Known Stars A plot of luminosity against surface temperature (or spectral class), known as an Surface temperature is plotted on the horizontal axis, although in the unconventional The Sun appears right in the middle of the luminosity range, at a luminosity of Scale, expressed in units of solar luminosity (3.9 x 10 26 W) extends over a large range, from 10 -4 to 10 4. Such plots in the second decade of the twentieth century. astronomer Henry Norris Russell, who independently pioneered the use of Of this sort is called a Hertzsprung -Russell diagram, or H–R diagram, after Danish astronomer Ejnar Hertzsprung and U.S. ![]() Figure 10.12 plots luminosity versus temperature for a few well-known stars.
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