Speeding Star Shocks Interstellar Space
The red arc in this infrared image from NASA's Spitzer Space Telescope is a giant shock wave, created by a speeding star known as Kappa Cassiopeiae.
NASA/JPL-Caltech/K. Su (Univ. of Arizona)
NASA's Spitzer Space Telescope was launched 10 years ago and has since peeled back an infrared veil on the Cosmos. The mission has worked in parallel with NASA's other "Great Observatories" (Hubble and Chandra) to provide coverage of the emissions from galaxies, interstellar dust, comet tails and the solar system's planets. But some of the most striking imagery to come from the orbiting telescope has been that of nebulae. Supernova remnants, star-forming regions and planetary nebulae are some of the most iconic objects to be spotted by Spitzer. So, to celebrate a decade in space, here are Discovery News' favorite Spitzer nebulae.
First up, the Helix Nebula -- a so-called planetary nebula -- located around 700 light-years from Earth. A planetary nebula is the remnants of the death throes of a red giant star -- all that remains is a white dwarf star in the core, clouded by cometary dust.
NASA/JPL-Caltech/B. Williams (NCSU)
Spitzer will often work in tandem with other space telescopes to image a broad spectrum of light from celestial objects. Here, the supernova remnant RCW 86 is imaged by NASA's Spitzer, WISE and Chandra, and ESA's XMM-Newton.
Staring deep into the Messier 78 star-forming nebula, Spitzer sees the infrared glow of baby stars blasting cavities into the cool nebulous gas and dust.
The green-glowing infrared ring of the nebula RCW 120 is caused by tiny dust grains called polycyclic aromatic hydrocarbons -- the bubble is being shaped by the powerful stellar winds emanating from the central massive O-type star.
NASA/JPL-Caltech/J. Stauffer (SSC/Caltech)
Spitzer stares deep into the Orion nebula, imaging the infrared light generated by a star factory.
X-Ray: NASA/CXC/J.Hester (ASU); Optical: NASA/ESA/J.Hester & A.Loll (ASU); Infrared: NASA/JPL-Caltech/R.Gehrz (Univ. Minn.)
In the year 1054 A.D. a star exploded as a supernova. Today, Spitzer was helped by NASA's other "Great Observatories" (Hubble and Chandra) to image the nebula that remains. The Crab Nebula is the result; a vast cloud of gas and dust with a spinning pulsar in the center.
The Tycho supernova remnant as imaged by Spitzer (in infrared wavelengths) and Chandra (X-rays). The supernova's powerful shockwave is visible as the outer blue shell, emitting X-rays.
NASA/JPL-Caltech/E. Churchwell (University of Wisconsin - Madison)
Over 2,200 baby stars can be seen inside the bustling star-forming region RCW 49.
X-ray: NASA/CXC/Univ.Potsdam/L.Oskinova et al; Optical: NASA/STScI; Infrared: NASA/JPL-Caltech
The "Wing" of the Small Magellanic Cloud (SMC) glitters with stars and warm clouds of dust and gas. By combining observations by Spitzer, Chandra and Hubble, the complex nature of this nebulous region can be realized.
Astronomers using NASA's Spitzer Space Telescope have spotted a star ripping through space, generating a violent bow shock ahead of its relentless rampage through the interstellar medium.
Kappa Cassiopeiae (κ Cass) is a hypervelocity blue supergiant star over 40 times the size of our sun that is barreling through space at the breakneck speed of 2.5 million miles per hour (or 1,100 kilometers per second) relative to its neighboring stars. At those kinds of velocities, you'd expect to see something dramatic and κ Cass doesn't disappoint.
Spitzer's infrared optics have picked out κ Cass' huge bow shock as the star's magnetic field and stellar wind particles slam into the gases and dust filling the interstellar medium, heating it up. Bow shocks are often found in front of some of the speediest stars in our galaxy.
Bow shocks are useful as they act as a remote sensor of sorts, allowing astronomers to understand the characteristics of the environment the star is traveling through.
In this image, the red bow shock exhibits some fine structure that is possibly linked to the magnetic field that threads throughout the Milky Way shaping the gas and dust. By zooming in on these hypervelocity stars that sport bow shocks, astronomers are allowed a rare look into the structure of this normally invisible field that is thought to permeate our entire galaxy.
The wispy green clouds throughout the image are caused by polycyclic aromatic hydrocarbons illuminated by starlight that are located along Spitzer's line of sight to κ Cass.
This observation may be a valuable probe into the conditions surrounding a star 4,000 light-years away, but it also serves as a stunning example on the scale of the supergiant's sphere of influence. The distance from the star to bow shock covers a vast 4 light-years -- the approximate distance from our sun to neighboring star Proxima Centauri.