Symbiotics - Astrophotography and Spectroscopy

Astro-Imaging and Spectroscopy

Star Party  St Michel  Haute Provence (France)

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Symbiotic stars

Many, perhaps even most stars, are members of binaries  -- two stars that orbit each other. Symbiotic stars are a small subset  of binaries with an attitude: they display characteristic, dramatic,  episodic changes in the spectra of their light because (it is thought)  one star of pair is a very hot, small star while the other is a cool  giant (from                                          
Most red giants are placid and calm, but  some pulsate with periods between 80 and 1,000 days like the star Mira  and undergo large changes in brightness.
This subset of red giants is called 'Mira variables.' The  red giant in R Aqr is a Mira variable and undergoes steady changes in  brightness by a factor of 250 as it pulsates, unlike its white dwarf  companion that does not pulsate. There are other striking differences between the two stars. The white dwarf is about ten thousand times brighter than the red giant.
The white dwarf has a surface temperature of some 20,000 K while the Mira variable has a temperature of about 3,000 K.

Chandra's image shows Mira A (right), a highly evolved red giant star,  and Mira B (left), a white dwarf. To the right of the image is an  artist's conception of this interacting star system. Mira A is losing  gas rapidly from its upper atmosphere via a stellar wind. Mira B exerts a  gravitational tug that creates a gaseous bridge between the two stars.  Gas from the wind and bridge accumulates in an accretion disk around  Mira B and collisions between rapidly moving particles in the disk  produce X-rays.
CH Cyg
  • 2018-08-15
  • Alpy600
  • 8" Newton f/4
  • Atik 414
  • Site: Berlin Germany
CH Cyg H-alpha
  • 2018-06-30
  • L200 Spectrograph 1800 grating 29ยต slit
  • ASI1600 MM 2x2 bin
  • Site: Berlin, Germany
CI Cyg
  • 2019-08-05
  • Alpy600
  • 8" f/4 Newton
  • Atik 414
  • Site: Berlin , Germany
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Copyright  Matthias Kiehl

March 2024
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