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Stars

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Encyclopedia of Astrobiology

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Definition

Stars are spheres of plasma in hydrostatic equilibrium, where the inward force of gravity is balanced by the outward gas pressure. The energy source for the gas is gravitation, sustained and prolonged by nuclear energy resulting from thermonuclear fusion reactions in the hot stellar interior. Stars form by contraction of a portion of a molecular cloud.

Overview

Stars are spheres of gas that can most of the time be considered as in hydrostatic and radiative equilibrium. They form during the contraction of cold molecular clouds. In the process of star formation, a part of the original matter of the cloud may form a disk around the star, and in such a disk, planets could be built.

At the center of the collapsing cloud, the temperature rises until it is sufficient for nuclear reactions to take place; thus, a new star is born. Through these reactions, new chemical elements are synthesized (➔ nucleosynthesis) accompanied by a production of energy. The energy release sustains the...

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Authors and Affiliations

  1. Observatoire de Genève, Université de Genève, Geneva, Versoix, Switzerland

    Patrick Eggenberger & Sylvia Ekström

Authors
  1. Patrick Eggenberger
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  2. Sylvia Ekström
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Corresponding author

Correspondence to Patrick Eggenberger .

Editor information

Editors and Affiliations

  1. Labo. d'Astrophysique de Bordeaux (LAB), Observatoire Aquitain des Sciences de l'Univers (OASU), Floirac CX, France

    Muriel Gargaud

  2. Astronomy Department, University of Massachusetts, Amherst, MA, USA

    William M. Irvine

  3. Centro de Biología Molecular, Universidad Autónoma de Madrid, Madrid, Spain

    Ricardo Amils

  4. Geophysical Lab., Carnegie Institution of Washington, Washington, DC, USA

    Henderson James Cleaves

  5. Dépt. Sc. de la Terre et de l’Atmosphère, Université du Québec, Montréal, Montreal, QC, Canada

    Daniele Pinti

  6. Centro de Astrobiología (CAB), Inst. Nacional de Técnica Aeroespacial, Torrejón de Ardoz, Madrid, Spain

    José Cernicharo Quintanilla

  7. Centre National d'Etudes Spatiale (CNES) DPI/E2U, Paris CX, France

    Michel Viso

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Eggenberger, P., Ekström, S. (2021). Stars. In: Gargaud, M., et al. Encyclopedia of Astrobiology. Springer, Berlin, Heidelberg. https://doi.org/10.1007/978-3-642-27833-4_1503-6

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  • DOI: https://doi.org/10.1007/978-3-642-27833-4_1503-6

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  • Publisher Name: Springer, Berlin, Heidelberg

  • Print ISBN: 978-3-642-27833-4

  • Online ISBN: 978-3-642-27833-4

  • eBook Packages: Living Reference Physics and AstronomyReference Module Physical and Materials ScienceReference Module Chemistry, Materials and Physics

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Chapter history

  1. Latest

    Stars
    Published:
    08 July 2021

    DOI: https://doi.org/10.1007/978-3-642-27833-4_1503-6

  2. Original

    Star
    Published:
    04 May 2015

    DOI: https://doi.org/10.1007/978-3-642-27833-4_1503-5