Exozodiacal dust
Encyclopedia
Exozodiacal dust is the exoplanetary analog of zodiacal dust
Zodiacal dust
The Zodiacal dust cloud is visible as a diffuse glow, known as the zodiacal light, that stretches along the zodiac, and is best seen just after sunset and before sunrise in spring and autumn when the zodiac is at a steep angle to the horizon....

, the 1-100 micrometre-sized grains of silicate dust that fill the plane of the solar system, especially interior to the asteroid belt. As for the zodiacal dust, these grains are probably produced by outgasing comets as well as by collisions among bigger parent bodies like asteroids. Exozodiacal dust clouds are often components of debris disk
Debris disk
A debris disk is a circumstellar disk of dust and debris in orbit around a star. Sometimes these disks contain prominent rings, as seen in the image of Fomalhaut on the right. Debris disks have been found around both evolved and young stars, as well as at least one debris disk in orbit around a...

s that are detected around main sequence
Main sequence
The main sequence is a continuous and distinctive band of stars that appears on plots of stellar color versus brightness. These color-magnitude plots are known as Hertzsprung–Russell diagrams after their co-developers, Ejnar Hertzsprung and Henry Norris Russell...

 stars through their excess infrared emission. By convention, exozodiacal dust refers to the innermost and hottest part of these debris disks, within a few astronomical unit
Astronomical unit
An astronomical unit is a unit of length equal to about or approximately the mean Earth–Sun distance....

s from the star. The shapes of exozodiacal dust clouds can show the dynamical influence of extrasolar planet
Extrasolar planet
An extrasolar planet, or exoplanet, is a planet outside the Solar System. A total of such planets have been identified as of . It is now known that a substantial fraction of stars have planets, including perhaps half of all Sun-like stars...

s, and potentially indicate the presence of these planets .
Because it is located near a star's habitable zone
Habitable zone
In astronomy and astrobiology, a habitable zone is an umbrella term for regions that are considered favourable to life. The concept is inferred from the empirical study of conditions favourable for Life on Earth...

, exozodiacal dust can be an important noise source for attempts to image terrestrial planets.

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