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Topic: Interstellar dust

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Dust

Asymptotic giant branch

Vacuum

Red giant

	Interstellar dust
		The dust particles, that form only a small part of the cloud, consist mainly of silicates (sand like matter) and graphite which are often surrounded by a small layer of ice.
		The dark interstellar clouds are the most dense and are cold concentrations of interstellar gas.
		The interstellar material forms a dynamic reservoir from which stars are formed and to which they return their remnants.
	library.thinkquest.org /18188/english/universe/stars/int_dust.htm (929 words)

	cosmic dust
		Most of the dust in interstellar space comes from stars that have moved off the main sequence and entered the red giant phase of their evolution (see stars, evolution).
		Dust grains that have drifted into the general interstellar medium find their way into denser clouds and, eventually, into molecular clouds where the density is sufficiently high for more complex organic synthesis to take place (see interstellar molecules).
		Interstellar dust particles strongly absorb, scatter, and polarize visible light at wavelengths comparable to their size, reemitting the light in the far-infrared region of the spectrum.
	www.daviddarling.info /encyclopedia/C/cosmicdust.html (670 words)

	Circumstellar Debris Shells
		While the dust and gas are expected to be coupled in the interstellar medium at least on large scales, close to the heliopause the plasma flow is stopped by the solar wind.
		The variation in the dust flux along the Earth's orbit as measured from satellites was explained by the focussing effect of interstellar dust due to the gravity field of the Sun.
		Neglecting their surface charge, interstellar dust particles would form a mono-directional flux from the interstellar upstream direction relative to the Sun that is modified by solar gravity and solar radiation pressure forces.
	www.gps.caltech.edu /users/mann/webisdx.html (1243 words)

	Interstellar Dust and Extinction
		Interstellar dust is an important constituent of the Galaxy.
		There is, of course, a continuous gradation of properties from diffuse dust to inner-cloud dust, but these three designations will allow us to emphasize the rather different properties of interstellar dust in the various regions.This review is confined to diffuse dust and outer-cloud dust; for excellent reviews of inner-cloud dust, see (156, 157, 165).
		Recent general references regarding interstellar dust are the proceedings of (a) a 1985 workshop held at Wye, Maryland (123); (b) the 1987 conference ``Dust in the Universe,'' held in Manchester, England (7); and (c) IAU Symposium 135 on ``Interstellar Dust'', held in Santa Clara, California, in July, 1988 (3).
	nedwww.ipac.caltech.edu /level5/Mathis/Mathis1.html (584 words)

	Cosmic dust Information
		The study of dust is a many-faceted research topic that brings together different scientific fields: physics (solid-state, electromagnetic theory, surface physics, statistical physics, thermal physics), (fractal mathematics), chemistry (chemical reactions on grain surfaces), meteoritics, as well as every branch of astronomy and astrophysics.
		The Earth-falling dust particles are collected in the Earth's atmosphere using plate collectors under the wings of stratospheric-flying NASA airplanes and collected from surface deposits on the large Earth ice-masses (Antartica and Greenland and Arctic) and in deep-sea sediments.
		A dust particle interacts with electromagnetic radiation in a way that depends on its cross section, the wavelength of the electromagnetic radiation, and on the nature of the grain: its refractive index, size, etc. The radiation process for an individual grain is called its emissivity, dependent on the grain's efficiency factor.
	www.bookrags.com /wiki/Cosmic_dust (1868 words)

	2002 News Releases - Stardust Spacecraft Reaches for Cosmic Dust
		The mission began yesterday collecting a younger type of stardust: the free-flowing interstellar dust that was produced by the current generation of stars.
		Interstellar dust may have played a role in bringing the building blocks of life -- carbon and other organic materials -- to the young Earth.
		The interstellar dust stream differs from the solar wind in that the solar wind is made of individual atoms, while the interstellar dust is made of small particles of rocks with complex compositions.
	www.jpl.nasa.gov /releases/2002/release_2002_158.html (570 words)

	Welcome to Stardatecards - Sending Messages to the Universe!
		Approximately 99% of the interstellar medium is composed of interstellar gas, and of its mass, about 75% is in the form of hydrogen (either molecular or atomic), with the remaining 25% as helium.
		Interstellar dust is not like the dust that you might find around your house; it is made of very different substances.
		This dust is a varied mix of compounds and elements; some interstellar clouds even contain organic molecules like acetylene and acetaldehyde, known precursors of amino acids.
	www.stardatecards.com /interstellarmedium.asp (1922 words)

	Stardust@Home - About Science (Site not responding. Last check: )
		Interstellar dust was first discovered flowing across the Solar System by dust detectors aboard the Ulysses spacecraft in 1993 and was later confirmed by the Galileo mission to Jupiter.
		Interstellar dust grains form by condensation in the regions around stars that are coming to the end of their life cycle: red giants, planetary nebulae, white dwarfs, novae, and supernovae.
		The dust grains mix with the interstellar medium (the stuff between the stars) and slowly experience chemical and isotopic changes from interactions with the gas and radiation in interstellar space.
	stardustathome.ssl.berkeley.edu /a_science.php (712 words)

	Stardust@home Update,July 21, 2006What We Do \| The Planetary Society
		The central bulge of the galaxy is blocked to observation in the visible wavelengths, due to the interference by interstellar dust.
		Interstellar dust is formed through several different processes that take place during the lifetime of stars.
		Scientists could tell it came from interstellar space because it was not affected by the presence of any planet, and because it flowed from precisely the same direction as neutral interstellar gas, which had been detected before.
	planetary.org /programs/projects/stardustathome/interstellar_dust.html (2557 words)

	Earth's meteoric veil (2)
		Scientists also recognize that even smaller dust particles in the vicinity of the earth collect electrostatic charges and respond to the electric and magnetic fields in the magnetosphere, so that their motion can be influenced by electromagnetic forces.
		However, interstellar dust is thought to account for only a few per cent of the total cosmic dust influx to earth at present.
		Dust cannot be directly converted by the body into usable energy – unlike the subtler energies reaching the earth from the sun.
	ourworld.compuserve.com /homepages/dp5/dust2.htm (7836 words)

	Comets
		Interstellar dust particles can be observed as outburst on the surface of the comet and anti-tails.
		is a plasma composed of solar wind, interstellar dust, antimatter ions, dust particles, and fragments.
		Dust tails are compose of electrically charged solar wind, interstellar dust plus antimatter ions, dust and fragments.
	www.matter-antimatter.com /comets.htm (629 words)

	CSERD Resources: Applications: Interstellar Extinction
		This soot, or "dust" as it is generally called, while a tiny fraction of the galaxy, plays an extremely important role both in how we observe the heavens, and on our life on this planet.
		The surface of interstellar dust grains acts as a "rest stop" for interstellar molecules, allowing for complex chemical reactions which may have produced some of the building blocks of life on Earth.
		While it is difficult to see this dust directly, we can look at the absorption of light by stars which are partially obscured by dust, and use this information to tell us about the properties of the intervening material.
	www.shodor.org /refdesk/Resources/Applications/InterstellarExtinction/index.php (621 words)

	The Interstellar Medium
		Approximately 99% of the mass of the interstellar medium is in the form of gas with the remainder primarily in dust.
		Interstellar dust grains are typically a fraction of a micron across (approximately the wavelength of blue light), irregularly shaped, and composed of carbon and/or silicates.
		There is still some dust left from the nebula in which they formed, and light reflecting from that dust causes the blue haze around each star of the cluster (Ref).
	csep10.phys.utk.edu /astr162/lect/milkyway/ism.html (1215 words)

	Interstellar Dust
		This applies for interstellar space also and all the previously mention particles make up what is known as the "interstellar medium".
		The actual density of hydrogen as it exist in interstellar space is on the average of about 1 atom per cubic centimeter.
		It is estimated that cosmic dust is 1000 times less common than hydrogen atoms in the interstellar medium.
	www.kuhmann.com /starstuff/Dust.htm (314 words)

	Cassini between Venus and Earth: Detection of interstellar dust
		We report the successful in situ measurement of interstellar dust particles inside the orbit of the Earth with the Cosmic Dust Analyzer (CDA) on the Cassini spacecraft.
		The impact ionization subsystem of the CDA is similar to the instruments on Ulysses and Galileo.
		As the heliocentric velocity and the direction of the interstellar dust flux are well known from Ulysses measurements, a combined analysis of the impact charge signals together with geometric and kinematic spacecraft data allowed us to separate interplanetary impacts from interstellar ones.
	www.agu.org /pubs/crossref/2003/2003JA009874.shtml (293 words)

	[No title] (Site not responding. Last check: )
		Instead, this relationship indicates that the dust particles must be about the same size as a wavelength of visible light: a few hundred to a few thousand nanometers in diameter.
		But if the dust grain is asymmetric -- squashed or elongated or lopsided -- the probability of interaction depends on the orientation of the light ray's electric field: if the grain's long axis lies parallel to the electric field, it is more likely to scatter the light ray.
		In fact, the surfaces of dust grains are like little factories, bringing together atoms that might otherwise rarely meet and catalyzing their reactions.
	spiff.rit.edu /classes/phys230/lectures/ism_dust/ism_dust.html (2458 words)

	Lecture: Interstellar Medium
		The interstellar medium is composed of two classes of material: gas and dust.
		Dust is made of compounds of carbon and silicon in various forms (graphite grains, silicate grains) and out of ices (such as water, carbon dioxide, ammonia).
		This is an extreme example of interstellar extinction which is the dimming of star light caused by the presence of interstellar material.
	www.astro.virginia.edu /class/hawley/astr124/ism.html (2101 words)

	Physics 7 Lecture #13(Cont'd) - The Interstellar Medium
		The interstellar medium is far too cool to excite the UV or optical transitions of hydrogen, but there is a feature at 21 cm wavelength in the radio produced by the spins (magnetic fields) of the hydrogen atom's nuclear proton and orbiting electron.
		The effect of dust is to dim the light from distant objects (interstellar extinction) in the Galaxy and redden the colors (interstellar reddening) because red light is not scattered as efficiently as blue light.
		Dust is responsible for the blue haze around the Pleiades star cluster (Messier Database, (Web Nebulae); this nebulosity is called a reflection nebula resulting from blue light from the hot B-stars being scattered toward us from dust surrounding the cluster stars.
	cassfos02.ucsd.edu /physics/ph7/ISM.html (1170 words)

	Interstellar Medium: Cold
		Maps of interstellar reddening demonstrated that the interstellar medium is composed mostly of hydrogen and helium gas (99%) and traces of dust.
		Dust is fragile because it can be broken down by UV photons, but is very important in dark nebula as sites for the formation of molecules.
		Dust particles are mostly carbon and silicate grains that are a few microns in size.
	zebu.uoregon.edu /~js/ast122/lectures/lec22.html (1441 words)

	Interstellar space dust hunted from home - space - 01 August 2006 - New Scientist
		But researchers ran into trouble focusing a microscopic scanner to study the interstellar dust because the surface of the aerogel was rougher than expected.
		Interstellar grains have only been seen on Earth before in the form of tiny inclusions within meteorites.
		That could shed light on the material from which the Sun and planets were born because it is laced with interstellar dust produced by other stars as they died.
	www.newscientist.com /article/dn9651-interstellar-space-dust-hunted-from-home.html (695 words)

	The Interstellar Medium (Site not responding. Last check: )
		Interstellar absorption lines may be distinguished from lines produced in the atmosphere of a star because:
		interstellar atoms are excited to very high levels from which they are ionized; when the ionization occurs, lines are formed in the ultraviolet.
		The principal effect(s) of interstellar dust on starlight is (are)
	nas.cl.uh.edu /blanford/ASTR3131SQIMedium.htm (459 words)

	Spaceflight Now \| Breaking News \| Stardust raises hand to catch interstellar dust
		The direction of the interstellar dust is opposite to the motion of the sun, which drags the planets with it, relative to the particle media.
		Thus the dust motion is small relative to the solar system motion that is controlling the direction of interstellar dust passing through our solar system.
		The interstellar dust stream was detected many years ago by earth orbiting spacecraft and information on this stream has been improved by early Pioneer and Voyager spacecraft.
	spaceflightnow.com /news/0002/24stardustcollection (633 words)

	Reconsidering Interstellar Dust And Heavy Elements
		Because it is diffucult to measure the composition of the dust directly, astronomers generally have assumed that the overall ratios of the elements and the general constituents of the mixture of dust grains were largely the same from one interstellar cloud to another.
		In interstellar clouds in the Milky Way, both iron and silicon are generally largely absent from the gas, and thus are thought to be major constituents of the dust.
		The possibility that the dust in the Small Magellanic Cloud is made primarily of iron, with little silicon, might in principle affect the abundance of molecular hydrogen, which is thought to form on the dust grains.
	unisci.com /stories/20012/0605013.htm (915 words)

	LAMBDA - FIRAS Galactic Dust Spectra and Interstellar Dust Parameters
		The remaining signal is dominated by thermal continuum emission from Galactic interstellar dust.
		Maps of the interstellar dust temperature and the 167 micron (1800 GHz) optical depth are included in the high-frequency Line Emission Map file.
		A single-temperature dust model was used to make these maps and the far-infrared dust emissivity was assumed to have a power law spectral index of 2.0.
	lambda.gsfc.nasa.gov /product/cobe/firas_dust.cfm (138 words)

	Cool Cosmos
		Most of this interstellar gas and dust originates from the death of stars which either exploded (supernova) or blew off their outer layers, returning their material to interstellar space.
		Dust grains absorb visible and ultraviolet light which causes them to heat up and radiate in the infrared.
		A surprise discovery from the IRAS mission was that space is filled with faint wisps of dust which cannot be seen in visible light.
	coolcosmos.ipac.caltech.edu /cosmic_classroom/cosmic_reference/dust.html (459 words)

	Interstellar space dust hunted from home - space - 01 August 2006 - New Scientist Space
		But researchers ran into trouble focusing a microscopic scanner to study the interstellar dust because the surface of the aerogel was rougher than expected.
		Interstellar grains have only been seen on Earth before in the form of tiny inclusions within meteorites.
		That could shed light on the material from which the Sun and planets were born because it is laced with interstellar dust produced by other stars as they died.
	space.newscientist.com /article.ns?id=dn9651&feedId=space_rss20 (709 words)

	[No title]
		Interstellar dust is produced in the envelopes around red supergiant stars.
		Dust particles are mostly carbon and silicate grains that are a few microns in size.
		Continuum reddening by interstellar dust in the general ISM has been measured by a number of investigators who compared opticaVinfrared colors of reddened luminous stars with the intrinsic colors exhibited by their unreddened counterparts (Sneden et al.
	www.lycos.com /info/interstellar--molecules.html (615 words)

	01.10.2006 - Public to look for dust grains in Stardust detectors
		Though Stardust's main mission was to capture dust from the tail of comet Wild 2 - dust dating from the origins of the solar system some 4.5 billion years ago - it also captured a sprinkling of dust from distant stars, perhaps created in supernova explosions less than 10 million years ago.
		Based on previous measurements of interstellar dust by both the Ulysses and Galileo spacecrafts, Westphal expects to find approximately 45 grains of submicroscopic dust in the collector, a mosaic of tiles of lightweight aerogel forming a disk about 16 inches in diameter - nearly a square foot in area - and half an inch thick.
		The dust grains were collected in two phases during the Stardust spacecraft's seven-year journey to and from Wild 2 as the spacecraft turned its Stardust Interstellar Dust Collector (SIDC) into the interstellar dust stream, which courses through the solar system at a speed of about 20 kilometers (12 miles) per second.
	www.berkeley.edu /news/media/releases/2006/01/10_dust.shtml (1333 words)

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