Excess emission from a pointlike source coincident with the central star of the Helix Nebula is detected with Spitzer at 8, 24, and 70 μm. At 24 μm, the central source is superposed on an extended diffuse emission region. While the [O IV] 25.89 μm line contributes to the diffuse emission, a 10-35 μm spectrum of the central source shows a strong thermal continuum. The excess emission from the star most likely originates from a dust disk with blackbody temperatures of 90-130 K. Assuming a simple optically thin debris disk model, the dust is distributed in a ring between ~35 and ~150 AU from the central star, possibly arising from collisions of Kuiper Belt-like objects or the breakup of comets from an Oort-like cloud that have survived from the post-main-sequence evolution of the central star.
The Astrophysical Journal
- Pub Date:
- March 2007
- Infrared: Stars;
- stars: individual (WD 2226-210);
- Stars: White Dwarfs;
- emulateapj format, accepted for publication in ApJ Letters