Spectral Standard Stars
The revised Yerkes Atlas system (Johnson & Morgan 1953) listed 11 G-type dwarf spectral standard stars; however, not all of these have survived to this day as standards. The "anchor points" of the MK spectral classification system among the G-type main-sequence dwarf stars, i.e. those standard stars that have remained unchanged over years, are beta CVn (G0 V), the Sun (G2 V), Kappa1 Ceti (G5 V), 61 Ursae Majoris (G8 V). Other primary MK standard stars include HD 115043 (G1 V) and 16 Cygni B (G3 V). The choices of G4 and G6 dwarf standards have changed slightly over the years among expert classifiers, but often-used examples include 70 Virginis (G4 V) and 82 Eridani (G6 V). There are not yet any generally agreed upon G7 V and G9 V standards.
Read more about this topic: G-type Main-sequence Star
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