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  2. Hertzsprung–Russell diagram - Wikipedia

    en.wikipedia.org/wiki/HertzsprungRussell_diagram

    The Hertzsprung–Russell diagram (abbreviated as H–R diagram, HR diagram or HRD) is a scatter plot of stars showing the relationship between the stars' absolute magnitudes or luminosities and their stellar classifications or effective temperatures.

  3. Stellar evolution - Wikipedia

    en.wikipedia.org/wiki/Stellar_evolution

    Representative lifetimes of stars as a function of their masses The change in size with time of a Sun-like star Artist's depiction of the life cycle of a Sun-like star, starting as a main-sequence star at lower left then expanding through the subgiant and giant phases, until its outer envelope is expelled to form a planetary nebula at upper right Chart of stellar evolution

  4. Main sequence turnoff - Wikipedia

    en.wikipedia.org/wiki/Main_sequence_turnoff

    The turnoff point for a star refers to the point on the Hertzsprung–Russell diagram where it leaves the main sequence after its main fuel is exhausted – the main sequence turnoff. By plotting the turnoff points of individual stars in a star cluster one can estimate the cluster's age .

  5. Main sequence - Wikipedia

    en.wikipedia.org/wiki/Main_sequence

    These are the most numerous true stars in the universe and include the Sun. Color-magnitude plots are known as Hertzsprung–Russell diagrams after Ejnar Hertzsprung and Henry Norris Russell. After condensation and ignition of a star, it generates thermal energy in its dense core region through nuclear fusion of hydrogen into helium. During ...

  6. Hertzsprung gap - Wikipedia

    en.wikipedia.org/wiki/Hertzsprung_gap

    The Hertzsprung gap is a feature of the Hertzsprung–Russell diagram for a star cluster. This diagram is a plot of effective temperature versus luminosity for a population of stars. The gap is named after Ejnar Hertzsprung , who first noticed the absence of stars in the region of the Hertzsprung–Russell diagram [ 1 ] between A5 and G0 ...

  7. Stellar classification - Wikipedia

    en.wikipedia.org/wiki/Stellar_classification

    The Hertzsprung–Russell diagram, which the MK system is based on, is observational in nature so these remnants cannot easily be plotted on the diagram, or cannot be placed at all. Old neutron stars are relatively small and cold, and would fall on the far right side of the diagram.

  8. Henyey track - Wikipedia

    en.wikipedia.org/wiki/Henyey_track

    The Henyey track is a path taken by pre-main-sequence stars with masses greater than 0.5 solar masses in the Hertzsprung–Russell diagram after the end of the Hayashi track. The astronomer Louis G. Henyey and his colleagues in the 1950s showed that the pre-main-sequence star can remain in radiative equilibrium throughout some period of its ...

  9. Stellar birthline - Wikipedia

    en.wikipedia.org/wiki/Stellar_birthline

    The stellar birthline is a predicted line on the Hertzsprung–Russell diagram that relates the effective temperature and luminosity of pre-main-sequence stars at the start of their contraction. [1] Prior to this point, the objects are accreting protostars , and are so deeply embedded in the cloud of dust and gas from which they are forming ...