page_title: Kappa Cassiopeiae
hierarchical_section_title: Kappa Cassiopeiae
caption_attribution_description: English: Kappa Cassiopeiae, or HD 2905 to astronomers, is a runaway star—a massive, hot supergiant gone rogue. What really makes the star stand out in this image is the surrounding, streaky red glow of material in its path. Such structures are called bow shocks, and they can often be seen in front of the fastest, most massive stars in the galaxy. Bow shocks form where the magnetic fields and wind of particles flowing off a star collide with the diffuse, and usually invisible, gas and dust that fill the space between stars. How these shocks light up tells astronomers about the conditions around the star and in space. Slow-moving stars like our sun have bow shocks that are nearly invisible at all wavelengths of light, but fast stars like Kappa Cassiopeiae create shocks that can be seen by Spitzer’s infrared detectors. Incredibly, this shock is created about 4 light-years ahead of Kappa Cassiopeiae, showing what a sizable impact this star has on its surroundings.
context_page_description: Kappa Cassiopeiae is a star in the constellation Cassiopeia.
  κ Cassiopeiae has an unusual spectrum that has anomalously weak nitrogen lines, taken as an actual nitrogen deficiency in the atmosphere. This is indicated by the modified letter C. It is also interpolated to BC0.7, being slightly hotter than a standard B1 star. It is assumed to be a member of the Cas OB14 stellar association at about 1,100 parsecs, while its distance found from the Hipparcos parallax is 1,369 parsecs.
  It is classified as an Alpha Cygni type variable star and its brightness varies by a few hundredths of a magnitude. Periods of two hours, nine days, and 2.65 days have been reported from observations at different times.
  It is a runaway star, moving at around 2.5 million mph relative to its neighbors. Its magnetic field and wind of particles creates a visible bow shock 4 light-years ahead of it, colliding with the diffuse, and usually invisible, interstellar gas and dust. This is about the same distance that Earth is from Proxima Centauri, the nearest star to the Sun. The dimensions of the bow shock are vast: around 12 light-years long and 1.8 light-years wide.
context_section_description: Kappa Cassiopeiae (κ Cas, κ Cassiopeiae) is a star in the constellation Cassiopeia.
  κ Cassiopeiae has an unusual spectrum that has anomalously weak nitrogen lines, taken as an actual nitrogen deficiency in the atmosphere.  This is indicated by the modified letter C.  It is also interpolated to BC0.7, being slightly hotter than a standard B1 star.  It is assumed to be a member of the Cas OB14 stellar association at about 1,100 parsecs, while its distance found from the Hipparcos parallax is 1,369 parsecs.
  It is classified as an Alpha Cygni type variable star and its brightness varies by a few hundredths of a magnitude.  Periods of two hours, nine days, and 2.65 days have been reported from observations at different times.
  It is a runaway star, moving at around 2.5 million mph relative to its neighbors (1,100 kilometers per second).  Its magnetic field and wind of particles creates a visible bow shock 4 light-years ahead of it, colliding with the diffuse, and usually invisible, interstellar gas and dust. This is about the same distance that Earth is from Proxima Centauri, the nearest star to the Sun. The dimensions of the bow shock are vast: around 12 light-years long and 1.8 light-years wide.
caption: Kappa Cassiopeiae and its bow shock.  Spitzer infrared image (NASA/JPL-Caltech)
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