Poster Version
This image from NASA's Spitzer Space Telescope (left panel) shows the "bow
shock" of a dying star named R Hydrae, or R Hya, in the constellation
Hydra.
Bow shocks are formed where the stellar wind from a star are pushed into a
bow shape (illustration, right panel) as the star plunges through the gas
and dust between stars. Our own Sun has a bow shock, but prior to this
image one had never been observed around this particular class of red
giant star.
R Hya moves through space at approximately 50 kilometers per second. As it
does so, it discharges dust and gas into space. Because the star is
relatively cool, that ejecta quickly assumes a solid state and collides
with the interstellar medium. The resulting dusty nebula is invisible to
the naked eye but can be detected using an infrared telescope.
This bow shock is 16,295 astronomical units from the star to the apex and
6,188 astronomical units thick (an astronomical unit is the distance
between the sun and Earth). The mass of the bow shock is about 400 times
the mass of the Earth.
The false-color Spitzer image shows infrared emissions at 70 microns.
Brighter colors represent greater intensities of infrared light at that
wavelength. The location of the star itself is drawn onto the picture in
the black "unobserved" region in the center.
