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Later analysis showed that some of these were blended spectra from double stars and some were variable, and the standards have been expanded to many more stars, but many of the original stars are still considered standards of the subgiant luminosity class. O-class stars and stars cooler than K1 are rarely given subgiant luminosity classes.<ref name=garcia>{{cite journal|bibcode=1989BICDS..36...27G|title=A list of MK standard stars|journal=Bulletin d'Information du Centre de Données Stellaires|volume=36|pages=27|last1=Garcia|first1=B.|year=1989}}</ref>
==Subgiant준거성 branch가지==
[[File:Zams and tracks.png|thumb|left|upright=1.4|Stellar evolutionary tracks:{{unordered list|the {{solar mass|5}} track shows a hook and a subgiant branch crossing the [[Hertzsprung gap]]|the {{solar mass|2}} track shows a hook and pronounced subgiant branch|lower-mass tracks show very short long-lasting subgiant branches}}]]
The준거성 subgiant가지는 branch저질량에서 is중간질량 a항성의 stage진화과정에 in있는 the evolution of low to intermediate mass stars단계이다. Stars with a subgiant spectral type are not always on the evolutionary subgiant branch, and vice versa. For example, the stars [[FK Comae Berenices|FK Com]] and [[31 Comae Berenices|31 Com]] both lie in the Hertzsprung Gap and are likely evolutionary subgiants, but both are often assigned giant luminosity classes. The spectral classification can be influenced by metallicity, rotation, unusual chemical peculiarities, etc. The initial stages of the subgiant branch in a star like the sun are prolonged with little external indication of the internal changes. One approach to identifying evolutionary subgiants include chemical abundances such as Lithium which is diluted in subgiants,<ref name=lebre>{{cite journal|bibcode=1999A&A...345..936L|title=Lithium and rotation on the subgiant branch. I. Observations and spectral analysis|journal=Astronomy and Astrophysics|volume=345|pages=936|last1=Lèbre|first1=A.|last2=De Laverny|first2=P.|last3=De Medeiros|first3=J. R.|last4=Charbonnel|first4=C.|last5=Da Silva|first5=L.|year=1999}}</ref> and coronal emission strength.<ref name=ayres1998>{{cite journal|bibcode=1998ApJ...496..428A|title=The Coronae of Moderate-Mass Giants in the Hertzsprung Gap and the Clump|journal=The Astrophysical Journal|volume=496|pages=428–448|last1=Ayres|first1=Thomas R.|last2=Simon|first2=Theodore|last3=Stern|first3=Robert A.|last4=Drake|first4=Stephen A.|last5=Wood|first5=Brian E.|last6=Brown|first6=Alexander|year=1998|issue=1|doi=10.1086/305347|doi-access=free}}</ref>
As the fraction of hydrogen remaining in the core of a main sequence star decreases, the core [[virial theorem|temperature increases]] and so the rate of fusion increases. This causes stars to evolve slowly to higher luminosities as they age and broadens the main sequence band in the [[Hertzsprung–Russell diagram]].
==행성==
Planets준거성을 in돌고 orbit있는 around외계행성의 subgiant예로 stars안드로메다자리 include카파 [[Kappa Andromedae b]]b와<ref>Plait, Phil. [http://www.slate.com/blogs/bad_astronomy/2012/11/19/newly_discovered_planet_kappa_andromedae_b_seen_in_picture_of_nearby_star.html "Astronomers Take a Picture of a Planet Orbiting Another Star"]. Accessed 1 Feb. 2018</ref> and [[HD 224693 b]]를 들 수 있다.<ref>[http://exoplanet.eu/catalog/hd_224693_b/ "Planet HD 224693 b"], ''Extrasolar Planet Encyclopaedia''. Accessed 1 Feb. 2018</ref>
==각주==
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