.. _sphx_glr_api_gallery_astro_galactic_dynamics:

Galactic dynamics
-------------------

Oort and Lindblad's differential rotation, Rubin and Ford's flat rotation
curves, the Navarro-Frenk-White halo profile, and Chandrasekhar's dynamical
friction -- the rotation-curve and dark-matter machinery in
:mod:`physicskit.astro.galactic_dynamics`.


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  <div id='sg-tag-list' class='sphx-glr-tag-list'></div>


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    <div class="sphx-glr-thumbnails">

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    <div class="sphx-glr-thumbcontainer" tooltip="Lindblad argued the Milky Way could not rotate rigidly; Oort (1927) supplied the observational test: if the Galaxy rotates differentially, nearby stars&#x27; radial velocities and proper motions vary with Galactic longitude l in a double-sine pattern set by just two numbers,">

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  .. image:: /api/gallery/astro/galactic_dynamics/images/thumb/sphx_glr_plot_01_oort_constants_thumb.png
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  :doc:`/api/gallery/astro/galactic_dynamics/plot_01_oort_constants`

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      <div class="sphx-glr-thumbnail-title">Oort and Lindblad's differential rotation: the Oort constants</div>
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    <div class="sphx-glr-thumbcontainer" tooltip="Three results form one chain. Oort (1932) and Zwicky (1933) applied the virial theorem to stellar and galaxy-cluster velocities and found implied masses far exceeding the visible matter. Rubin and Ford (1970), confirmed and extended through the 1970s by Roberts, Whitehurst, Bosma, and others, measured spiral-galaxy rotation curves that stayed flat far beyond the visible disk rather than falling off as Keplerian motion around a centrally concentrated mass predicts. Navarro, Frenk, and White (1996-1997) found that cosmological dark-matter halos collapse onto a single near-universal density profile,">

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  .. image:: /api/gallery/astro/galactic_dynamics/images/thumb/sphx_glr_plot_02_rotation_curves_and_dark_matter_thumb.png
    :alt:

  :doc:`/api/gallery/astro/galactic_dynamics/plot_02_rotation_curves_and_dark_matter`

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      <div class="sphx-glr-thumbnail-title">Rotation curves, the NFW halo, and the dark-matter mass discrepancy</div>
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    <div class="sphx-glr-thumbcontainer" tooltip="Chandrasekhar (1943) showed that a massive body moving through a sea of much lighter field stars feels a systematic drag, built up from the cumulative small-angle gravitational deflections of every star it passes:">

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  .. image:: /api/gallery/astro/galactic_dynamics/images/thumb/sphx_glr_plot_03_dynamical_friction_thumb.png
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  :doc:`/api/gallery/astro/galactic_dynamics/plot_03_dynamical_friction`

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      <div class="sphx-glr-thumbnail-title">Chandrasekhar's dynamical friction: a satellite spiraling inward</div>
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.. toctree::
   :hidden:

   /api/gallery/astro/galactic_dynamics/plot_01_oort_constants
   /api/gallery/astro/galactic_dynamics/plot_02_rotation_curves_and_dark_matter
   /api/gallery/astro/galactic_dynamics/plot_03_dynamical_friction