Interstellar dust research belongs to the young branches of astrophysics. With the establishment of sensitive observational techniques in the astronomical infrared spectroscopy in the 1960s,...
Large N-15 excesses have been measured in individual interplanetary dust particles (IDPs); TEM, in combination with spectroscopic measurements of the same IDPs, shows N concentrations within the carbonaceous material, and much of this is in organic form. The isotopic signature suggests that formation of this N-bearing carbonaceous material was in a cold, presolar molecular cloud, and it is surmised that the solid material grain embedded in the N-15-rich carbonaceous matter could be of presolar origin.
In the interstellar medium - the space between the stars in galaxies - new stars are born from material that is replenished by the debris ejected by stars when they die. This book is a comprehensive manual for studying the collisional and radiative processes observed in the interstellar medium. This second edition has been thoroughly updated and extended to cover related topics in radiation theory. It considers the chemistry of the interstellar medium both at the present epoch and in the early Universe, and discusses the physics and chemistry of shock waves. The methods of calculation of the rates of collisional excitation of interstellar molecules and atoms are explained, emphasising the quantum mechanical method. This book will be ideal for researchers involved in the interstellar medium and star formation, and physical chemists specialising in collision theory or in the measurement of the rates of collision processes.. • Comprehensive manual for studying collisional and radiative processes ...
If you have a question about this talk, please contact Stephen Walley.. Astronomers have long realised that reactions on the surface of dust grains play an important role in the formation of molecules in the interstellar medium (ISM), in particular those found frozen out as interstellar ices. To help understand the gas-grain interaction in the ISM , our group is undertaking a range of experimental and theoretical investigations of the adsorption, desorption and formation of interstellar ices.. This talk is part of the Surfaces, Microstructure and Fracture Group series.. ...
TY - JOUR. T1 - Exothermic chemical reactions can drive nonthermal crystallization of amorphous silicate grains. AU - Kaito, Chihiro. AU - Miyazaki, Yu. AU - Kumamoto, Akihito. AU - Kimura, Yuki. PY - 2007/1/1. Y1 - 2007/1/1. N2 - To explain how cometary silicates crystallize yet still preserve volatile interstellar ices in their parent comets, we experimentally demonstrate the possibility of chemical-reaction-driven crystallization, which is called non-thermal crystallization, using laboratory-synthesized amorphous Mg-bearing silicate grains. Analog silicate grains ∼50-100 nm in diameter covered with a carbonaceous layer consisting of amorphous carbon, CH 4, and other organics to a thickness of ∼10-30 nm were used as models. The analog silicate grains crystallized via the direct flow of surface reaction energy, which is produced by the graphitization of the carbonaceous layer due to oxidation at room temperature in air, into the silicates. The experimental results imply that amorphous ...
Abstract. A comparison of northern and southern hemispheric paleotemperature profiles suggests that the Bölling-Alleröd Interstadial, Younger Dryas stadial, and subsequent Preboreal warming which occurred at the end of the last ice age were characterized by temperatures that changed synchronously in various parts of the world, implying that these climatic oscillations were produced by significant changes in the Earths energy balance. These globally coordinated oscillations are not easily explained by ocean current mechanisms such as bistable flipping of ocean deep-water production or regional temperature changes involving the NW/SE migration of the North Atlantic polar front. They also are not accounted for by Earth orbital changes in seasonality or by increases in atmospheric CO2 or CH4. On the other hand, evidence of an elevated cosmic ray flux and of a major interstellar dust incursion around 15,800 years B.P. suggest that a cosmic ray wind driven incursion of interstellar dust and gas may ...
The researchers started with water and a variety of simple molecules that are known to exist in the `real` clouds, such as carbon monoxide, carbon dioxide, ammonia and hydrogen cyanide. Although these initial ingredients were not exactly the same in each experiment, both groups `cooked` them in a similar way. In specific chambers in the laboratory they reproduced the common conditions of temperature and pressure known to exist in interstellar clouds, which is, by the way, quite different from our `normal` conditions. Interstellar clouds have a temperature of 260 °C below zero, and the pressure is also very low (almost zero). Great care was taken to exclude contamination. As a result, grains analogous to those in the clouds were formed ...
The origin of water on our planet is not only of interest for our understanding of the evolution of our own planet and life thereon, but even more so for the increasing exploration of other planets within our solar system and the discovery of potential planetary systems in other galaxies. Having spent half a lifetime teaching his students the accepted versions of the origin of our planetary water, which increasingly did not fit the available evidence, Dr Mike Drake at the University of Arizona suggested an alternative hypothesis: that water was already present at the surfaces of interstellar dust grains when they accreted to form our planet. Although this hypothesis fitted with all available evidence, it would only be feasible if the adhesion of water to the dust grains was sufficiently strong to survive the harsh conditions in the interstellar dust clouds where planets form. Computer simulations by myself and colleagues in UCL, Arizona and Muenster on the adhesion of water to a mineral commonly ...
NASAs Cassini spacecraft has detected the faint but distinct signature of dust coming from beyond our solar system. The research, led by a team of Cassini scientists primarily from Europe,
It has been firmly established over the last quarter century that cosmic dust plays important roles in astrochemistry. The consequences of these roles affect the formation of planets, stars and even galaxies. Cosmic dust has been a controversial topic but there is now a considerable measure of agreement as to its nature and roles in astronomy, and its initiation of astrobiology. The subject has stimulated an enormous research effort, with researchers in many countries now involved in laboratory research and in |I|ab initio|/I| computations. This is the first book devoted to a study of the chemistry of cosmic dust, presenting current thinking on the subject distilled from many publications in surface and solid-state science, and in astronomy. The authors discuss the nature of dust, its formation and evolution, the chemistry it can promote on its surfaces, and the consequences of these functions. The purpose of this book is to review current understanding and to indicate where future work is required.
Context. Almost 20% of the 200 different species detected in the interstellar and circumstellar media present a carbon atom linked to nitrogen by a triple bond. Among these 37 molecules, 30 are nitrile R-CN compounds, the remaining seven belonging to the isonitrile R-NC family. How these species behave in presence of the grain surfaces is still an open question. Aims. In this contribution we investigate whether the difference between nitrile and isonitrile functional groups may induce differences in the adsorption energies of the related isomers at the surfaces of interstellar grains of different nature and morphologies. Methods. The question was addressed by means of a concerted experimental and theoretical study of the adsorption energies of CH3CN and CH3NC on the surface water ice and silica. The experimental determination of the molecule - surface interaction energies was carried out using temperature programmed desorption (TPD) under an ultra-high vacuum (UHV) between 70 and 160 K. Theoretically,
Metallic aluminum alloy foils exposed oil the forward, comet-facing surface of the aerogel tray oil the Stardust spacecraft are likely to have been impacted by the same cometary particle Population as the dedicated impact sensors and the aerogel collector. The ability of soft aluminum alloy to record hypervelocity impacts as bowl-shaped craters offers all opportunistic substrate for recognition of impacts by particles of a potentially wide size range. In contrast to impact surveys conducted oil samples from low Earth orbit, the simple encounter geometry for Stardust and Wild-2, with a known and constant spacecraft-particle relative velocity and effective surface-perpendicular impact trajectories, permits closely comparable simulation in laboratory experiments. For a detailed calibration program, we have selected a suite of spherical glass projectiles of uniform density and hardness characteristics, with well-documented particle size range from 10 mu m to nearly 100 mu m. Light gas gun buckshot ...
Many chemical models of dense interstellar clouds predict that the majority of gas-phase elemental nitrogen should be present as N2, with an abundance approximately five orders of magnitude less than that of hydrogen. As a homonuclear diatomic molecule, N2 is difficult to detect spectroscopically through infrared or millimeter-wavelength transitions. Therefore, its abundance is often inferred indirectly through its reaction product N2H+. Two main formation mechanisms, each involving two radical-radical reactions, are the source of N2 in such environments. Here we report measurements of the low temperature rate constants for one of these processes, the N + CN reaction, down to 56 K. The measured rate constants for this reaction, and those recently determined for two other reactions implicated in N2 formation, are tested using a gas-grain model employing a critically evaluated chemical network. We show that the amount of interstellar nitrogen present as N2 depends on the competition between its gas-phase
The large grains in interstellar space are probably complex, with refractory cores that condensed within stellar outflows topped by layers acquired subsequently during incursions into cold dense interstellar clouds. That cyclic process of growth and destruction outside of the clouds has been modeled[31][32] to demonstrate that the cores live much longer than the average lifetime of dust mass. Those cores mostly start with silicate particles condensing in the atmospheres of cool oxygen rich red-giant stars and carbon grains condensing in the atmospheres of cool carbon stars. The red-giant stars have evolved off the main sequence and have entered the giant phase of their evolution and are the major source of refractory dust grain cores in galaxies. Those refractory cores are also called Stardust (section above), which is a scientific term for the small fraction of cosmic dust that condensed thermally within stellar gases as they were ejected from the stars. Several percent of refractory grain ...
The chemistry of life may have begun shortly after the Big Bang, 13.8 billion years ago, during a habitable epoch when the Universe was only 10-17 million years old.[4][5] The first carbon-containing molecule detected in the interstellar medium was the methylidyne radical (CH) in 1937.[6] From the early 1970s it was becoming evident that interstellar dust consisted of a large component of more complex organic molecules (COMs),[7] probably polymers. Chandra Wickramasinghe proposed the existence of polymeric composition based on the molecule formaldehyde (H2CO).[8] Fred Hoyle and Chandra Wickramasinghe later proposed the identification of bicyclic aromatic compounds from an analysis of the ultraviolet extinction absorption at 2175A.,[9] thus demonstrating the existence of polycyclic aromatic hydrocarbon molecules in space. In 2004, scientists reported[10] detecting the spectral signatures of anthracene and pyrene in the ultraviolet light emitted by the Red Rectangle nebula (no other such complex ...
The chemistry of life may have begun shortly after the Big Bang, 13.8 billion years ago, during a habitable epoch when the Universe was only 10-17 million years old.[4][5]. The first carbon-containing molecule detected in the interstellar medium was the methylidyne radical (CH•) in 1937.[6] From the early 1970s it was becoming evident that interstellar dust consisted of a large component of more complex organic molecules (COMs),[7] probably polymers. Chandra Wickramasinghe proposed the existence of polymeric composition based on the molecule formaldehyde (H2CO).[8] Fred Hoyle and Chandra Wickramasinghe later proposed the identification of bicyclic aromatic compounds from an analysis of the ultraviolet extinction absorption at 2175 Å,[9] thus demonstrating the existence of polycyclic aromatic hydrocarbon molecules in space.. In 2004, scientists reported[10] detecting the spectral signatures of anthracene and pyrene in the ultraviolet light emitted by the Red Rectangle nebula (no other such ...
Abstract: Using 3D MHD simulation with the effects of radiative cooling/heating, chemical reactions, and thermal conduction, we investigate the formation of molecular cloud in the ISM. We consider the formation of molecular cloud by accretion of the HI clouds as suggested in recent observations. The simulation shows that the initial HI medium is compressed and piled up behind the shock waves induced by the accretion flows. Since the initial medium is highly inhomogeneous as a consequence of the thermal instability, the formed molecular cloud becomes very turbulent owing to the development of the Richtmyer-Meshkov instability. The structure of the post shock region is composed of dense cold gas (T,100 K) and diffuse warm gas (T,1,000 K), which are spatially well mixed owing to the turbulence. Because the energy source of the turbulence is the accretion flows, the turbulence is highly anisotropic biased toward the direction of accretion flows. The kinetic energy of the turbulence dominates the ...
Existence of dark matter depends on cosmic dust, not the shape of rotation curves!. Dark matter thought to hold galaxies together depending on the shape of rotation curves is false as ALL galaxy velocities are overstated by the redshift in cosmic dust that concentrates at the outer edges of the galaxy disk - PR12703593
Abstract : Amino acids are the essential molecular components of living organisms on Earth, but the proposed mechanisms for their spontaneous generation have been unable to account for their presence in Earths early history. The delivery of extraterrestrial organic compounds has been proposed as an alternative to generation on Earth, and some amino acids have been found in several meteorites. Here we report the detection of amino acids in the room-temperature residue of an interstellar ice analogue that was ultraviolet-irradiated in a high vacuum at 12 K. We identified 16 amino acids ; the chiral ones showed enantiomeric separation. Some of the identified amino acids are also found in meteorites. Our results demonstrate that the spontaneous generation of amino acids in the interstellar medium is possible, supporting the suggestion that prebiotic molecules could have been delivered to the early Earth by cometary dust, meteorites or interplanetary dust particles.. ...
Explanation: Every book has a first page and every catalog a first entry. And so this lovely blue cosmic cloud begins the van den Bergh Catalog (vdB) of stars surrounded by reflection nebulae. Interstellar dust clouds reflecting the light of the nearby stars, the nebulae usually appear blue because scattering by the dust grains is more effective at shorter (bluer) wavelengths. The same type of scattering gives planet Earth its blue daytime skies. Van den Berghs 1966 list contains a total of 158 entries more easily visible from the northern hemisphere, including bright Pleiades cluster stars and other popular targets for astroimagers. Less than 5 light-years across, VdB1 lies about 1,600 light-years distant in the constellation Cassiopeia. Also on this scene, two intriguing nebulae at the right show loops and outflow features associated with the energetic process of star formation. Within are extremely young variable stars V633 Cas (top) and V376 Cas ...
Ok. Lets get some terminology down first. If a body (like the Earth) is orbiting around the Sun, we say it is closest to the Sun at perihelion and farthest from the Sun at aphelion. If a body (like the Moon) is orbiting around the Earth, its closest point to the Earth is perigee and its farthest point from the Earth is apogee. In 2000, perihelion for the Earth was on January 3, 2000, and aphelion was on July 4, 2000. The Earth was 91,405,436 miles from Sun at perihelion and 94,511,989 miles from Sun at aphelion. For the year 2001, perihelion will occur on January 3, 2001 and aphelion will occur on July 4, 2001. The actual date for perihelion and aphelion will differ from year to year. But, you can see that the Earth is closest to the Sun in January and farthest from the Sun in July!. This may not seem right. I mean its winter in the northern hemisphere in January and yet we are closest to the Sun. But, our seasons are actually determined by the tilt of the Earth and not the Earths proximity ...
Ok. Lets get some terminology down first. If a body (like the Earth) is orbiting around the Sun, we say it is closest to the Sun at perihelion and farthest from the Sun at aphelion. If a body (like the Moon) is orbiting around the Earth, its closest point to the Earth is perigee and its farthest point from the Earth is apogee. In 2000, perihelion for the Earth was on January 3, 2000, and aphelion was on July 4, 2000. The Earth was 91,405,436 miles from Sun at perihelion and 94,511,989 miles from Sun at aphelion. For the year 2001, perihelion will occur on January 3, 2001 and aphelion will occur on July 4, 2001. The actual date for perihelion and aphelion will differ from year to year. But, you can see that the Earth is closest to the Sun in January and farthest from the Sun in July!. This may not seem right. I mean its winter in the northern hemisphere in January and yet we are closest to the Sun. But, our seasons are actually determined by the tilt of the Earth and not the Earths proximity ...
Mineral evolution is a new way to look at our planets history. Its the study of the increasing diversity and characteristics of Earths near-surface minerals, from the dozen that arrived on interstellar dust particles when the Solar System was formed to the more than 4,700 types existing today. Ne
This table contains results from a survey of the Orion A and B molecular clouds undertaken with the IRAC and MIPS instruments on board Spitzer. In total, five distinct fields were mapped, covering 9 deg2 in five mid-IR bands spanning 3 - 24 microns (um). The survey includes the Orion Nebula Cluster, the Lynds 1641, 1630, and 1622 dark clouds, and the NGC 2023, 2024, 2068, and 2071 nebulae. These data are merged with the Two Micron All Sky Survey point source catalog to generate a catalog of eight-band photometry. The authors identify 3479 dusty young stellar objects (YSOs) in the Orion molecular clouds by searching for point sources with mid-IR colors indicative of reprocessed light from dusty disks or in-falling envelopes. The YSOs are subsequently classified on the basis of their mid-IR colors and their spatial distributions are presented. The authors classify 2991 of the YSOs as pre-main-sequence stars with disks and 488 as likely protostars. Most of the sources were observed with IRAC in two ...
The Astrophysics and Astrochemistry Laboratory is located in the Space Sciences and Astrophysics Branch of the Space Science and Astrobiology Division (SS) at NASAs Ames Research Center (ARC), in Mountain View, California. This laboratory supports NASAs space science missions and programs. We study the physical and chemical properties of interstellar, cometary, asteroidal, planetary and lunar materials. Among the materials studied are interstellar polycyclic aromatic hydrocarbons (PAHs, the largest carbon molecules in space), aerosols in planetary atmospheres, ice mantles on interstellar grains and surface ices on comets and on solar system planets, and laboratory samples of actual extraterrestrial materials (meteorites and cosmic dust). Extraterrestrial material analogs are produced in our laboratory under conditions realistically close to space environments and range from molecules and ions in gas-phase interstellar clouds and planetary atmospheres to interstellar, cometary, and planetary ...
Context. CO isotopologue transitions are routinely observed in molecular clouds for the purpose of probing the column density of the gas and the elemental ratios of carbon and oxygen, in addition to tracing the kinematics of the environment.Aims. Our study is aimed at estimating the abundances, excitation temperatures, velocity field, and velocity dispersions of the three main CO isotopologues towards a subset of the Orion B molecular cloud, which includes IC 434, NGC 2023, and the Horsehead pillar.Methods. We used the Cramer Rao bound (CRB) technique to analyze and estimate the precision of the physical parameters in the framework of local-thermodynamic-equilibrium (LTE) excitation and radiative transfer with added white Gaussian noise. We propose a maximum likelihood estimator to infer the physical conditions from the 1-0 and 2-1 transitions of CO isotopologues. Simulations show that this estimator is unbiased and proves efficient for a common range of excitation temperatures and column densities (Tex
What makes carbon-based organic compounds especially interesting to scientists is that life is made of them and produces them. So one source of the organics in Martian samples could be biology, Eigenbrode said. But she said there were other potential sources that might be more plausible.. Organics, for instance, can be formed through non-biological geothermal and hydrothermal processes on Earth, and presumably on Mars too. In addition, both meteorites and interstellar dust are known to contain organic compounds, and they rain down on Mars as they do on Earth.. Eigenbrode said the organics being detected could be coming from any one source, or from all of them.. Asked at the workshop what concentrations of organics were found, she replied with a grin that more light will be shed on the question at next weeks American Geophysical Union meeting.. The detection of a growing variety of organics on Mars adds to the conclusion already reached by the Curiosity team - that Mars was once much wetter, ...
For galaxy fans, you have got to point your telescope towards NGC 6946, the Fireworks Galaxy (RA 20h 34m 52.3s Dec +60 09 14). Who cares if this barred spiral galaxy 10 million light years away? This is one supernovae active baby! At one time, it was widely believed that NGC 6946 was a member of our Local Group; mainly because it could be easily resolved into stars.. There was a reddening observed in it, believed to be indicative of distance - but now know to be caused by interstellar dust. But it isnt the shrouding dust cloud that makes NGC 6946 so interesting, its the fact that so many supernova and star-forming events have sparkled in its arms in the last few years that has science puzzled! So many, in fact, that theyve been recorded every year or two for the last 60 years…. Now, for the really cool part - understanding barred structure. Thanks to the Hubble Space Telescope and a study of more than 2,000 spiral galaxies - the Cosmic Evolution Survey (COSMOS) - astronomers understand ...
Rare earths are the flotsam of a churning, restless planet - 17 oddly behaving metal oxides pushed from deep in the mantle up to the crust over countless eons. Cerium was soon put to use. Because of its inherent ability to glow in heat, it was used to treat mantles on kerosene lanterns (Welsbachs invention) and later in Victorian gas street lamps to make them glow more brightly. Like all elements heavier than iron, they were manufactured in dying stars as they undergo the supernova process - they are ejected into space and form part of the interstellar dust that condenses to form new solar systems, Long said. According to Popular Science columnist Theodore Gray, The chemistry of elements depends almost entirely on the outer shell. What makes rare earths so important are their magnetic properties, Gray said, which result when electrons are added to the inner orbits, giving each a distinct set of peculiarities. If dysprosium replaces but 6 percent of the neodymium in the electric motor magnets
Rare earths are the flotsam of a churning, restless planet - 17 oddly behaving metal oxides pushed from deep in the mantle up to the crust over countless eons. Cerium was soon put to use. Because of its inherent ability to glow in heat, it was used to treat mantles on kerosene lanterns (Welsbachs invention) and later in Victorian gas street lamps to make them glow more brightly. Like all elements heavier than iron, they were manufactured in dying stars as they undergo the supernova process - they are ejected into space and form part of the interstellar dust that condenses to form new solar systems, Long said. According to Popular Science columnist Theodore Gray, The chemistry of elements depends almost entirely on the outer shell. What makes rare earths so important are their magnetic properties, Gray said, which result when electrons are added to the inner orbits, giving each a distinct set of peculiarities. If dysprosium replaces but 6 percent of the neodymium in the electric motor magnets
You seem to want to aggravate someone into commenting on evolution. Well, I will say this: Genesis was written a long time ago. It was not written as a scientific document. It does not talk about neutrons and protons, quarks and electrons. It says nothing about the sun being a burning gas fire full of hydrogen and helium or that other stars went supernova spitting heavy elements everywhere forming interstellar dust which could form a planet such as our own. It does not mention dinosaurs, the enormous meteor that wiped them out or an ice age. In fact, its not very comprehensive from a scientific viewpoint. But then again, Genesis does not try to be from a scientific viewpoint. Genesis sets out to tell us what we need to know. God created everything. He created life. And not only that, but His Son and the Spirit were there. Gods word is powerful. He created us in His image. We then turned from Him, i.e. sinned. The Bible as a whole explains this very well. We sin and that separates us from God, ...
The universe started 13.5 billion years ago with the Big Bang. Our earth is approximately 4.5 billion years old. As the interstellar dust coalesced to form Earth, it took approximately another billion years for the planet to cool and for the water vapor in the atmosphere to condense and form the oceans.. It was during this time that bacteriophage and bacteria evolved. They existed in this primordial earth alone for over a billion years before the evolution of eucaryotic cells. Bacteria and bacteriophage are the true senior citizens of our planet. Today, bacteriophage are ubiquitous and are the most diverse and widely distributed entities in the biosphere. One of the denses sources of phage is in sea water, where it is reported that there can be as many as one billion virions per millimeter of water. Bacteriophage give us a unique window into the past where we can imagine an even earlier period of primordial abiotic molecular self-assembly. Bacteriophage ...
The workshop will showcase a host of physics experiments that would not only exploit the environment, but might also become economically viable only by piggybacking off the stations power and navigation capabilities. These include a meteoroid-environment monitor, which would study the drifting interstellar dust that never reaches Earth owing to the planets magnetic field. A low-frequency radio observatory could be used to pick up radiation from the Universes dark ages, between 400,000 and 100 million years after the Big Bang - which is hugely challenging﻽ on Earth because of interference from human sources and the planets ionosphere, says Mark Bentum, a physicist at the University of Twente in Enschede, the Netherlands ...
3 CEN (3 Centauri). While the name, neither proper nor Greek letter, carries no panache, fourth magnitude (4.28) 3 Cen (less often k Cen) is one of the more unusual, indeed remarkable, stars of the sky. In far northern Centaurus, just below the border with Hydra and part of a small triangle made of 1, 2, and 3 Cen, the star is just barely far enough north to carry a Flamsteed number. But that is not what makes it so prominent among stellar astronomers. Its fame rests far more on its very odd chemical composition. But first, some particulars. Seen at a substantial distance of 347 light years (give or take 26), the star is binary, made of two blue-white class B stars separated by about 8 seconds of arc. The brighter, fifth magnitude (4.53) 3 Cen A is listed as a B5 giant (but see below), while 3 Cen B is a lesser sixth magnitude (6.02) B8 dwarf. The two are dimmed by about 15 percent by interstellar dust. The focus of attention is always on 3 Cen A. The adopted temperature of 17,500 Kelvin, high ...
Astronomers led by Simon Driver of Scotlands University of St. Andrews have discovered that interstellar dust shades us from as much as 50% of the light emitted by stars and galaxies. The scientists compared the number of galaxies we could see edge-on against the number which were facing us, re...
The planets residing in our solar system, just like the exoplanets of every other stellar system throughout the universe, formed when cosmic dust clumped together over billions of years. G
Originally from Korea, David Choong Lee (featured in HF Vol. 30) has been a staple of San Franciscos art scene for the past 20 years. Known for his elaborate assemblages composed of individual paintings on boxes on different depths, Lee deftly blends figuration with abstract dreamscapes, inserting realistically-rendered figures into explosions of shapes and kaleidoscopic colors. For his latest body of work, however, Lee emptied his paintings of human presence. His solo show Cosmic Dust, opening at Luna Rienne Gallery in San Francisco on September 13, will feature a series of acrylic paintings on canvas that focus on Lees intergalactic worlds - untouched and uninhabited. Honing in on the psychedelic imagery that once served as a background for his figures, he unfurls pools of liquid rainbows, mysterious glowing orbs and powerful beams of light. His new work gives the sensation of touching down on another planet.. This is Lees first abstract body of work, and one that he considers very ...
The CODITA project was designed to answer two overarching questions: how much cosmic dust enters the Earths atmosphere every day, and...
Interstellar Cycle Ultimately, stars form the interstellar medium. Stars replenish the interstellar medium at the end of their life cycle. There is a balance between the interstellar medium and stars.
We describe observations of the (CO)-O-18 J = 2 --, 1, 3 --, 2 and C I P-3(1) --, P-3(0) lines towards the HH24-26 molecular cloud core. The (CO)-O-18 traces the north-south molecular ridge, but the dense clumps identified by previous high-resolution HCO+ and dust continuum data do not stand out. Using H-2 column densities estimated from dust continuum measurements, we find that the CO abundance may be reduced by factors of at least 10 towards three positions (two of which are Class O protostars). Depending on the assumptions employed, the reduction may be as high as similar to 50 towards the clump positions. The magnitude of the reduced abundances is in good agreement with chemical models of collapsing clouds in which molecules accrete on to dust grains. Alternative interpretations, retaining normal abundances. and relying on subtle optical depth and beam filling effects, are considered, but shown to be less likely. The contrast in C I line intensity is low across the source. The greater part ...
I have discovered a prominent light echo around the low-luminosity Type II-plateau supernova (SN) 2008bk in NGC 7793, seen in archival images obtained with the Wide Field Channel of the Advanced Camera for Surveys on board the Hubble Space Telescope (HST). The echo is a partial ring, brighter to the north and east than to the south and west. The analysis of the echo I present suggests that it is due to the SN light pulse scattered by a sheet, or sheets, of dust located Almost-Equal-To 15 pc from the SN. The composition of the dust is assumed to be of standard Galactic diffuse interstellar grains. The visual extinction of the dust responsible for the echo is A{sub V} Almost-Equal-To 0.05 mag in addition to the extinction due to the Galactic foreground toward the host galaxy. That the SN experienced much less overall extinction implies that it is seen through a less dense portion of the interstellar medium in its environment. The late-time HST photometry of SN 2008bk also clearly demonstrates that ...
The relationship between stars and the material around them -- the interstellar medium -- is complicated. Stars are born from this material -- wispy clouds of hydrogen, helium, and other elements, plus solid grains of dust. And when stars die, they expel much of their material back into the interstellar medium, enriching it with elements forged in the hearts of the stars themselves.. And between birth and death, a star can have a powerful influence on the interstellar medium around it.. An example is the star known as Alpha Camelopardalis. Its one of the brightest stars of the faint constellation Camelopardalis, the giraffe, which is high in the north on January evenings.. Alpha Cam is probably 25 to 30 times as massive as the Sun. That great heft makes its surface extremely hot, driving a strong wind of gas off the surface and into space, forming a big bubble around Alpha Cam.. The star is racing through space at more than a hundred thousand miles an hour. As it plows through the ...
Space is not empty, as the ancients believed when admiring the depth of the sky on starry nights. Space is occupied by material, although it is rarefied and with a non-uniform distribution between stars, planets and galaxies.The interstellar material (5) of our galaxy and perhaps of the entire universe is composed of hydrogen (70%) and helium (28%) in the gaseous state. Only a very small part (2%) is formed of tiny solid particles, called cosmic dust or interstellar grains. Among these elements like O, C, N, Ni, S, Al and Fe and also various organic and inorganic molecules have been identified.An important role in the evolution of the interstellar material is played by these grains, responsible for the absorption and diffraction of radiation, grain/grain collisions, absorption of various substances on their surfaces and electrical conductance. These latter properties allow electrical charge transfer inside the molecular clouds, regulating the ion/molecule interaction, in turn a source of further ...
Interplanetary dust particle collected from the stratosphere over south-western USA, probably from Comet 26P/Grigg-Skjellerup Link to MinDat.org Location Data ...
The uncertainties reported by the DIRBE team were dominated by systematic uncertainties in the foreground determination. This met the mission objective of searching for the CIB to the limits imposed by our astrophysical environment. Major sources of uncertainty were the stellar foreground model (1.2-3.5 µm), the interplanetary dust model (1.25-100 µm), and the interstellar medium model (100-240 µm). Because DIRBE data can yield improved measurements of the CIB as the foregrounds are better determined, it is worth summarizing how the DIRBE team analysis was done. The interplanetary dust contribution presents the most difficult problem except at the longest wavelengths, since it dominates the measured sky brightness from 1-140 µm even at high galactic and ecliptic latitude (see Figure 2, Hauser et al. 1998). The contribution from the IPD was determined by fitting a parameterized model of the spatial distribution and scattering and radiative properties of the dust cloud to the apparent annual ...
Numerous nitrile/isonitrile pairs have been detected in the interstellar medium; the isonitriles are suggested to be generated by nonthermal processes. Benzonitrile (C$_{6}$H$_{5}$CN) was recently detected in Taurus Molecular Cloud 1 (TMC-1) by radioastronomy. Herein, we report the analysis of benzoisonitrile (C$_{6}$H$_{5}$NC, $\mu$$_{a}$ = 4.0 D) ground vibrational state and its two lowest-energy vibrational states, \nub{22} (141 \wn, calculated at the B3LYP/6-311+G(2d,p) level of theory) and \nub{33} (155 \wn), in the 135 - 375 GHz frequency region. Over 4500 new rotational transitions have been measured in the ground vibrational state, main isotopologue. The rotational and distortion constants determined in this work may be used to search for benzoisonitrile in the interstellar medium. The Coriolis-coupled dyad reported herein, containing over 3000 new transitions for each vibrational state, has been analyzed for the first time, including resonances and several nominal interstate ...
We present continuum data from the Submillimetre Common-User Bolometer Array (SCUBA) on the James Clerk Maxwell Telescope (JCMT), and the multiband imaging Photometer for Spitzer (MIPS) on the Spitzer Space Telescope, at submillimetre and infrared wavelengths, respectively. We study the Taurus molecular cloud 1 (TMC1) and, in particular, the region of the Taurus Molecular Ring (TMR). In the continuum data, we see no real evidence for a ring, but rather we see one side of it only, appearing as a filament. We name the filament the bulls tail. The filament is seen in emission at 850, 450 and 160 μm, and in absorption at 70 μm.We compare the data with archive data from the Infrared Astronomical Satellite (IRAS) at 12, 25, 60, 100 μm, in which the filament is also seen in absorption. We find that the emission from the filament consists of two components: a narrow, cold (∼8 K), central core, and a broader, slightly warmer (∼12 K), shoulder of emission. We use a radiative transfer code to ...
My thesis built on the work by Biesecker et al. (2002) who studied the Kreutz comets which arrived from 1996-1998. Biesecker et al. showed that Kreutz comets behave in a characteristic fashion: brightening as they approach the Sun, reaching a peak in brightness prior to perihelion, then fading as they continue to approach perihelion. They also found that the brightening followed two universal curves which peaked at slightly different heliocentric distances. I have updated and improved their photometric routines (presented at DPS in 2004) and have calculated the photometry for all SOHO comets which were discovered by February 2006 (approximately 1100 comets and more than 20,000 images). From this much larger sample of light curves (the original two universal curves model was derived from only the 56 brightest comets seen from 1996-1998), it appears that the two universal curves are smeared out and become part of a broader distribution of peaks in the brightness which occur from 10-14 solar ...
The first of these missions was DEEP IMPACT which encountered comet 9P/Temel 1 and, at about 05h45 UTC on 4 July 2005, intentionally impacted a 370 kg projectile onto the comet resulting in an ejecta plume that was observed by fly-by spacecraft and by ground-based observatories. Observations of the plume within one second after the impact were subsequently explained in terms of a cloud of expanding, incandescent, liquid droplets cooling from ≈ 3500 K to 1000 K in less than half a second. The total mass of the droplets was about ten times that of the impactor. Spitzer Space Telescope observations of the comet dust coma before impact show a rather smooth, featureless spectrum indicative of large (radius , 100 μm), optically thick, silicate emission grains. After the impact the scattering produced by the coma increased enormously, indicating the presence of large amounts of sub-micron sized particles, dust much smaller than in the pre-impact coma. These observations can be explained by the ...
A series of reports focus on comet Hale-Bopp, including its extreme brightness, its increasing activity, and its flair for variable, dusty outbursts as it approaches the sun (see the Perspective by Cruikshank, p. 1895). Detailed images from the Hubble Space Telescope (Weaver et al.,p. 1900) indicate that the comet nucleus is very large (between 27 to 42 kilometers in diameter). Thermal infrared observations from the Earth-orbiting Infrared Satellite Observatory (Crovisier et al.,p. 1904) and ground-based telescopes (Hayward and Hanner, p. 1907) indicate that the dust grains coming off the nucleus as the comet moved inside of Mars orbit are probably crystalline and amorphous silicates. Optical observations (Rauer et al., p. 1909), see cover, and Wagner and Schleicher, p. 1918) showed high rates of sublimation of icy, dust grains, dominated by water and cyanide even at large distances from the sun. Photometric observations (Schleicher et al., p. 1913) also indicated that the gas production rates ...