How to Build the Engine of and to Provide the Fuel for Quasars

1　IntroductionDuringthelasttwodecadesdynamicalstudiesofthenucleiofgalaxiesinthelocalUniversehaveleadtotheconclusionthatsuper massiveblackholesofsome 1 0 6 ...9M⊙arecommonlypresent(Kormendy 2 0 0 1 ,andreferencestherein) .Actually,nofirmcounterexamplehasbeenfoundyet.Soonafteritsdiscovery,thequasarphenomenonwasattributedtoaccretionontosuper massiveblackholes.Accretionratesof 1 0 - 1...+1M⊙ a- 1andblackholemassesoftypically 1 0 8...11M⊙(Lynden Bell1 969)wereinferred .Inthiscontribution ,w…     

Carbon — From Space to Laboratory

In this review, the nature of carbon-containing molecules and carbonaceous solids present in meteorites, comets, and the interstellar medium is discussed. Carbon plays an active role in the lifecycle of stars and the interstellar medium. It is the basis of a rich interstellar chemistry and the main component of pre-biotic organic material in space. The aim of the review is to build a bridge between astronomical spectroscopy and laboratory studies relevant to the investigation of cosmic carbon. Special emphasis is given to the structural variety of carbon-containing species and their characterization by experimental techniques. This revised version was published online in July 2006 with corrections to the Cover Date.     

Are galaxies due to accretion?

Burnt-out Population III remnants are thought to have acted as protogalactic seeds. Once tepid pancakes have formed such seeds (≈10⁶ M⊙) could be subject to considerable growing by quasi-stationary accretion.     

Sequential solution to Kepler’s equation

Seven sequential starter values for solving Kepler’s equation are proposed for fast orbit propagation. The proposed methods have constant complexity (not iterative), do not require pre-computed data, and can be implemented in just a few lines of code. The resulting sequential orbit propagation techniques can be done at different levels of accuracy and speed, depending essentially on the value of orbit eccentricity. Accuracy and algorithmic complexity are evaluated for all the proposed approaches and compared with several existing single-point techniques to solve Kepler’s equation. The new methods obtain improved accuracy at lower computational cost as compared to the best existing methods.     

“Bumerang” Must Return to Earth

Solar System Research - The “Bumerang” space mission to the satellites of Mars is discussed. The purpose of the mission is to study the satellites and return of soil samples from Phobos...     

Sensitivity of γ-ray detectors to polarization

Previous studies have shown that the largest -ray detector to date, EGRET, does not have useful polarization sensitivity. We have explored here some improved approaches to analyzing -ray pair production events, leading to important gains in sensitivity to polarization. The performance of the next generation -ray instrument GLAST is investigated using a detailed Monte Carlo simulation of the complete detector.     

A Possible Interpretation to Venusian Rotation Evolution

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LunarEX—a proposal to cosmic vision

While the surface missions to the Moon of the 1970s achieved a great deal, scientifically much was also left unresolved. The recent plethora of lunar missions (flown or proposed) reflects a resurgence in interest in the Moon, not only in its own right, but also as a record of the early solar system including the formation of the Earth. Results from recent orbiter missions have shown evidence of ice or at least hydrogen within shadowed craters at the lunar poles.     

Are Spicules Related to Coronal Heating?

We suggest that the waxing and waning of chromospheric and coronal heating leads to a dynamic solar atmosphere which, under the right circumstances, may produce spicules. Little is known about the heating process. However, Anderson and Athay (1989a) concluded from their study of chromospheric heating that the heating rate per gram of chromospheric matter is only a small fraction of the heating rate per gram of coronal matter. We postulate that the increased heating rate in the corona is a consequence of heating charged particles as opposed to heating neutral atoms. This leads to a specific degree of hydrogen ionization at which coronal heating begins to predominate over chromospheric heating. It also introduces the likelihood that the waxing and waning of the heating rates will have relatively large consequences in the levels where hydrogen ionization is becoming significant. It is demonstrated that changes in the heating rates are capable of inducing increases and decreases in coronal mass comparable to the mass contained in a typical spicule.     

Analytical solutions to a quasilinear differential equation related to the Lane–Emden equation of the second kind

We apply the δ-expansion method to a transformed Lane–Emden equation. The results are then transformed back, and we recover analytical solutions to the Lane–Emden equation of the second kind (which describes Bonnor–Ebert gas spheres) in a special case. The rapid convergence of the method results in qualitatively accurate solutions in relatively few iterations, as we see when we compare the obtained analytical solutions to numerical results.     

Stellar contributors to the hard X-ray background?

We use simple energetic arguments to estimate the contribution of massive X-ray binaries and supernova remnants to the cosmic X-ray background (XRB) at energies in excess of 2 keV. Recent surveys have shown that active galactic nuclei (AGN) probably account for most of the hard XRB ( E >2 keV), but there have been many suggestions that star-forming galaxies could emerge at fainter fluxes and perhaps account for a significant fraction of the soft and hard X-ray energy density. Assuming that the formation rate of massive X-ray binaries (MXRBs) traces the global star-formation rate, we find that their integrated contribution to the hard XRB can be estimated and is shown to be small (at less than the 1 per cent level). Similarly, the integrated flux of supernovae (SN) is also shown to be insignificant, or at most comparable to MXRBs. AGN therefore remain the most viable candidates for producing the hard XRB, unless additional processes can be shown to dominate the global hard X-ray emission in distant starburst galaxies.     

Spectrophotometry of Pluto from 3500 to 7350 Å

We have obtained spectra of Pluto on six nights during February 1979 using the Cassegrain Digicon spectrograph on the 2.1-m Struve reflector and the IDS spectrograph on the 2.7-m reflector of McDonald Observatory. These spectra, with nominal resolution of 6–7 Å, have been reduced to relative fluxes. Relative albedos were then calculated using the solar irradiances of Arvesen et al. (1969). The spectra taken in the blue show no indication of the upturn in albedo at $\text{λ < 3800}\text{A}\text{?}$ previously reported by Fix et al. (1970). The lack of a uv upturn cannot be interpreted in terms of a Rayleigh scattering atmosphere unless the albedo of the underlying surface is known. From the lack of methane absorption at the wavelength of the 6190- or 7270-Å methane bands we derive an upper limit of 1–3 m-am of gaseous CH₄. The albedo curve has a constant slope between 3500 and 7300 Å. The only other solar system body which has this feature is an S-type asteroid.     

A deeply embedded companion to LKHα198

The region around the Herbig Ae/Be star LkH198 was imaged at 10m with the CAMIRAS camera at the Canada-France-Hawaii Telescope and the Nordic Optical Telescope. We discovered a deeply embedded companion 6 north of LkH198, which may be responsible for most of the far-infrared emission in the region and for driving the molecular flow. LkH198 appears point-like at our resolution (FWHM 1.3), excluding an extended envelope of transiently heated small grains as the dominant origin of the mid-infrared excess in that star.     

Mini-inflation prior to the cosmic confinement transition?

The onset of the confinement transition in the early universe is studied within the Friedmann model. Exploiting a bag model equation of state for the deconfined matter, which is generalized to include also metastable states, the possibility of a mini-inflationary epoch is demonstrated. A criterion of metastability is derived to estimate parameters of this mini-inflation.     

Spicules: The resonant response to granular buffeting?

We propose that spicules are the direct result of a resonant buffeting of the sides of an intense (kilogauss) slender flux tube by turbulent granular motions. For a critical wavespeed, the granular motion drives a high-speed flow along the axis of the tube. We illustrate this effect by considering in detail a flux tube embedded in a uniform compressible atmosphere, thereby modelling the development of the seedflow in the photosphere that eventually manifests itself in the chromosphere as the spicule.     

A better way to reconstruct dark energy models?

To reconstruct dark energy models the redshift z _eq , marking the end of radiation era and the beginning of matter-dominated era, can play a role as important as z _t , the redshift at which deceleration parameter experiences a signature flip. To implement the idea we propose a variable equation of state for matter that can bring a smooth transition from radiation to matter-dominated era in a single model. A popular Λ∝ ρ dark energy model is chosen for demonstration but found to be unacceptable. An alternative Λ∝ ρ a ³ model is proposed and found to be more close to observation.     

Sunspots Observed to Physically Weaken in 2000–2001

The strength of a sunspot depends on its magnetic field and umbral darkness, factors which go together. The strongest field in an umbra is always found at the darkest position. We use this relationship, B=f(1/T), to demonstrate that at the maximum of cycle 22 (1990–1991) sunspots were statistically stronger than at the same phase of cycle 23 (2000–2001). Within our sample of 195 spots, cycle 23 exhibits an excess of small bright spots, and possibly, a dearth of large dark spots. This could alter the total solar irradiance (TSI)–sunspot number relationship.