Applied Numerical Analysis. By C.F. Gerald. Pp. xii, 340. £3·60. 1970. (Addison-Wesley.)

We present distance measurements to 71 high redshift type Ia supernovae discovered during the first year of the 5-year Supernova Legacy Survey (SNLS). These events were detected and their multi-color light-curves measured using the MegaPrime/MegaCam instrument at the Canada-France-Hawaii Telescope (CFHT), by repeatedly imaging four one-square degree fields in four bands. Follow-up spectroscopy was performed at the VLT, Gemini and Keck telescopes to confirm the nature of the supernovae and to measure their redshift. With this data set, we have built a Hubble diagram extending to z = 1, with all distance measurements involving at least two bands. Systematic uncertainties are evaluated making use of the multiband photometry obtained at CFHT. Cosmological fits to this first year SNLS Hubble diagram give the following results: {Omega}{sub M} = 0.263 {+-} 0.042 (stat) {+-} 0.032 (sys) for a flat {Lambda}CDM model; and w = -1.023 {+-} 0.090 (stat) {+-} 0.054 (sys) for a flat cosmology with constant equation of state w when combined with the constraint from the recent Sloan Digital Sky Survey measurement of baryon acoustic oscillations.

The Supernova Legacy Survey: Measurement of Omega_m, Omega_l and w from the First Year Data Set

Acknowledgements Foreword Introduction I BACKGROUND Long-term astrophysical processes Evolution theory and the future of humanity Millenial tendencies in responses to apocalyptic threats Cognitive biases potentially affecting judgement of global risks Observation selection effects and global catastrophic risks Systems-based risk analysis Catastrophes and insurance Public policy towards catastrophe II RISKS FROM NATURE Super-volcanism and other geophysical processes of catastrophic import Hazards from comets and asteroids Influence of Supernovae, gamma-ray bursts, solar flares, and cosmic rays on the terrestrial environment III RISKS FROM UNINTENDED CONSEQUENCES Climate change and global risk Plagues and pandemics: past, present, and future Artificial Intelligence as a positive and negative factor in global risk Big troubles, imagined and real IV RISKS FROM HOSTILE ACTS Catastrophe, social collapse, and and human extinction The continuing threat of nuclear war Catastrophic nuclear terrorism: a preventable peril Biotechnology and biosecurity Nanotechnology as global catastrophic risk The totalitarian threat Author's biographies Index

Global Catastrophic Risks

THIS is one of a series of books from Harvard Observatory, all of which are compiled by specialists in their own particular sphere. The present volume gives up-to-date information about the bodies in the solar system, and as it is written in language which is almost entirely free from technicalities, it will appeal to a wide circle of readers. The author devotes some space to a consideration of origins and evolution, especially to the origin of lunar craters and to the origin of the planetary system. He favours the volcanic theory of the formation of craters on the moon, but admits that meteors may be responsible for the more recent craters-those with ray systems and some of the whiter ones, and also for many of the craterlets and crater pits. In dealing with the origin and evolution of the planets in Chapter 14, he examines the arguments for and against the planetesimal hypothesis of Chamberlin and Moulton and the tidal theory, and gives his opinion in favour of a fairly rapid condensation as more probable than an accretion ; but he admits that the choice between the two processes is not conclusive as the problems are complex. Earth, Moon and Planets By Fred L. Whipple. (Harvard Books on Astronomy.) Pp. vii + 293. (London: J. and A. Churchill, Ltd., 1946.) 18s.

Earth, Moon and Planets

We determine 37 differential extinctions in 23 gravitational lens galaxies over the range 0 < z_l < 1. Only 7 of the 23 systems have spectral differences consistent with no differential extinction. The median differential extinction for the optically-selected (radio-selected) subsample is E(B-V)=0.04 (0.06) mag. The extinction is patchy and shows no correlation with impact parameter. The median total extinction of the bluest images is E(B-V)=0.08 mag, although the total extinction distribution is dominated by the uncertainties in the intrinsic colors of quasars. The directly measured extinction distributions are consistent with the mean extinction estimated by comparing the statistics of quasar and radio lens surveys, thereby confirming the need for extinction corrections when using the statistics of lensed quasars to estimate the cosmological model. A disjoint subsample of two face-on, radio-selected spiral lenses shows both high differential and total extinctions, but standard dust-to-gas ratios combined with the observed molecular gas column densities overpredict the amount of extinction by factors of 2-5. For several systems we can estimate the extinction law, ranging from R_V=1.5+/-0.2 for a z_l=0.96 elliptical, to R_V=7.2+/-0.1 for a z_l=0.68 spiral. For the four radio lenses where we can construct non-parametric extinction curves we find no evidence for gray dust over the IR-UV wavelength range. The dust can be used to estimate lens redshifts with reasonable accuracy, although we sometimes find two degenerate redshift solutions.

Dust and Extinction Curves in Galaxies with z>0: The Interstellar Medium of Gravitational Lens Galaxies

The idea that comets may be connected with the origin of life on Earth was considered heresy a few decades ago, with scientists shying away from this possibility as if from a medieval superstition. However the case that comets may have contributed at least the complex organic building blocks of life has become very strong, and mechanisms have now been identified whereby comets may incubate and transfer microbial life from one cosmic habitat to another in the Galaxy. The latter process cometary panspermia was pioneered by the late Sir Fred Hoyle and one of the present authors in the early 1980's. A theory that was once controversial is slowly gaining scientific respectability and support.The recent surge of interest in astrobiology has led to a spate of books in astrobiology - combining astronomy and biology - but in most of these, cometary panspermia is dealt with only cursorily. The present book sets out the case for cometary panspermia in a cogent way, combining evidence from space science, celestial mechanics, geology and microbiology. It should be an essential part of any university course on astrobiology, and also serve as a reference textbook for researchers in the field.

Comets and the Origin of Life

Dynamical balance arguments that involve the capture of long-period comets from the Oort cloud imply that there should be ∼ 1000 times more Halley-type objects than are actually observed. If the active comets rapidly become dormant, with albedos comparable to those of known cometary surfaces, hundreds of such bodies should by now have been detected whereas in fact only a few have been found. If, on the other hand, they disintegrate to dust, we show here that the debris would create a bright, near-spherical zodiacal cloud and ∼ 15‐30 strong annual meteor showers, also contrary to observation. Here we demonstrate that the surfaces of inactive comets, if composed of loose, fluffy organic material like cometary meteoroids, develop reflectivities that are vanishingly small in visible light. The near-Earth objects may therefore be dominated by a population of fast, multi-kilometre bodies too dark to be seen with current near-Earth object surveys. Deflection strategies that assume decades or centuries of warning before impact are inapplicable to this hazard.

/pdf/extreme-albedo-comets-and-the-impact-hazard-l2xs694gui.pdf

Extreme albedo comets and the impact hazard

The possibility of the clouds of Venus provid- ing habitats for extremophilic microorganisms has been dis- cussed for several decades. We show here that the action of the solar wind leads to erosion of parts of the atmosphere laden with aerosols and putative microorganisms, forming a comet-like tail in the antisolar direction. During inferior conjunctions that coincide with transits of the planet Venus this comet-like tail intersects the Earth's magnetopause and injects aerosol particles. Data from ESA's Venus Express spacecraft and from SOHO are used to discuss the ingress of bacteria from Venus into the Earth's atmosphere, which we estimate as ∼10 11 -10 13 cells for each transit event.

/pdf/on-the-possibility-of-microbiota-transfer-from-venus-to-6lutajj86t.pdf

On the possibility of microbiota transfer from Venus to Earth

Ices in the Martian polar caps are potential habitats for various species of microorganisms. Salts in the ice and biological anti-freeze polymers maintain liquid in cracks in the ices far below 0 xC, possibly down to the mean 220-240 K. Sub-surface microbial life is shielded from ultraviolet (UV) radiation, but could potentially be activated on south-facing slopes under the midday, midsummer Sun. Such life would be limited by low levels of vapour, little transport of nutrients, low light levels below a protective dirt-crust, frost accumulation at night and in shadows, and little if any active translocation of organisms. As in the Antarctic and in permafrost, movement to new habitats depends on geo-climatic changes, which for Mars's north polar cap occur on a 50 000 year scale, except for rare meteorite impacts. Received 2 September 2008, accepted 23 March 2009, first published online 27 April 2009

https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S1473550409004467

Mars polar cap: a habitat for elementary life

The concept of a Universe undergoing an acceleration in its expansion rate and predicating the existence of dark energy is based on observed deficits in brightness of Type 1a supernovae at high redshifts, amounting to Δ m∼0.3–0.5. We show that the effect of intergalactic graphite whiskers of radii in the general range 0.03–0.07 μm and lengths in excess of ∼5 μm will be to mimic the effects of dark energy in the redshift magnitude relation for Type 1a supernovae. The mean intergalactic density of whiskers required for such an effect is ∼3×10−34 g cm−3, about 10−5 of the critical closure density.

Apparent magnitudes of high redshift Type 1a supernovae and intergalactic graphite whiskers

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