Interstellar Dust#

Introduction

Topics



Introduction

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Core

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Ice Mantle

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Are we all made of star dust ? Carl Sagan

Note

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Structure#

../../../_images/Dust_grain.jpg

Fig. 13 Interstellar Dust Grain. Source#

Origin#

Star outer shelves

Ice crust#

Investigation tools#

Interstellar dust extinction curves (IEC)#

Starlight extinction by dust is a combined effect from absorption and scattering. It is a wavelength-dependent process that can be described by an extinction curve

-> gives information about the properties of the interstellar dust: the continuum shape contains details about the size distribution of the grains, while extinction features reveal the composition of the dust grains

  • 2 main methods to obtain IEC: those using individual sight lines and those using an ensemble of stars.

Type 1#

  • Pair method: the observed SED of a reddened star is compared to (i.e., divided by) the observed SED of an unreddened comparison star with similar stellar properties. The difference in their SEDs is then attributed to the dust in the line of sight toward the reddened star.

Type 2#