The Solar System

416 PART 4^ |^ THE SOLAR SYSTEM

Neptune’s

Visual orbit

Visual wavelength imageVisual wavelength image

Star HD 107146

hidden behind mask.

Glare of star Beta

Pictoris hidden behind

central mask.

Inclined secondary disk

located between arrows.

Size of

Neptune’s

Far-infrared image orbit

Clumps in ring of

dust may be related

to planets.

The K2V star Epsilon

Eridani is relatively faint at

far-infrared wavelengths.

■ Figure 19-13

Dust disks have been detected orbiting a number of stars;
but, in the visible part of the spectrum, the dust is at least
100 times fainter than the stars, which must be hidden
behind masks to make the dust detectable. In the far infra-
red, the stars are not as bright as the dust. Warps, clumps,
and off-center rings in these disks suggest the gravitational
infl uence of planets. (Beta Pictoris: NASA, Burrows and Krist; HD
107146: NASA; Epsilon Eridani: Joint Astronomy Center)

■ Figure 19-14

Collisions between asteroids are rare events, but they
generate lots of dust and huge numbers of fragments,
as in this artist’s conception. Further collisions
between fragments can continue to produce dust.
Because such dust is blown away quickly, astrono-
mers treat the presence of dust as evidence that
objects of asteroid size are also present. (J. Lomberg/
Gemini Observatory)