Properties of vertically self-gravitating accretion discs with a dissipative corona     

Fazeleh Khajenabi  Peter Duffy 《Monthly notices of the Royal Astronomical Society》2008,388(4):1843-1852

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A simple model to interpret the ultraviolet, optical and infrared emission from galaxies     

Elisabete da Cunha  Stéphane Charlot  David Elbaz 《Monthly notices of the Royal Astronomical Society》2008,388(4):1595-1617

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Nekhoroshev stability at L₄ or L₅ in the elliptic-restricted three-body problem – application to Trojan asteroids     

Ch. Lhotka  C. Efthymiopoulos  R. Dvorak 《Monthly notices of the Royal Astronomical Society》2008,384(3):1165-1177

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Magnetorotational instability in protoplanetary discs: the effect of dust grains     

Raquel Salmeron  Mark Wardle 《Monthly notices of the Royal Astronomical Society》2008,388(3):1223-1238

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Observations of Low-Latitude Coronal Plumes     

Y.-M. Wang  K. Muglach 《Solar physics》2008,249(1):17-35

Using Fe ix/x 17.1 nm observations from the Extreme-Ultraviolet Imaging Telescope (EIT) on the Solar and Heliospheric Observatory (SOHO), we have identified many coronal plumes inside low-latitude coronal holes as they transited the solar limb during the late declining phase of cycle 23. These diffuse, linear features appear to be completely analogous to the familiar polar plumes. By tracking them as they rotate from the limb onto the disk (or vice versa), we confirm that EUV plumes seen against the disk appear as faint, diffuse blobs of emission surrounding a brighter core. When the EIT images are compared with near-simultaneous magnetograms from the SOHO Michelson Doppler Imager (MDI), the low-latitude, on-disk plumes are found to overlie regions of mixed polarity, where small bipoles are in contact with unipolar flux concentrations inside the coronal hole. The birth and decay of the plumes are shown to be closely related to the emergence of ephemeral regions, their dispersal in the supergranular flow field, and the cancellation of the minority-polarity flux against the dominant-polarity network elements. In addition to the faint polar and nonpolar plumes associated with ephemeral regions, we note the existence of two topologically similar coronal structures: the giant plume-like features that occur above active regions inside coronal holes, and the even larger scale “pseudostreamers” that separate coronal holes of the same polarity. In all three cases, the basic structure consists of open field lines of a given polarity overlying a photospheric region of the opposite polarity; ongoing interchange reconnection at the X-point separating the open field domains from the underlying double-arcade system appears to result in the steady evaporation of material from the closed into the open region.  相似文献   

Sources of SEP Acceleration during a Flare – CME Event     

N. J. Lehtinen  S. Pohjolainen  K. Huttunen-Heikinmaa  R. Vainio  E. Valtonen  A. E. Hillaris 《Solar physics》2008,247(1):151-169

A high-speed, halo-type coronal mass ejection (CME), associated with a GOES M4.6 soft X-ray flare in NOAA AR 0180 at S12W29 and an EIT wave and dimming, occurred on 9 November 2002. A complex radio event was observed during the same period. It included narrow-band fluctuations and frequency-drifting features in the metric wavelength range, type III burst groups at metric – hectometric wavelengths, and an interplanetary type II radio burst, which was visible in the dynamic radio spectrum below 14 MHz. To study the association of the recorded solar energetic particle (SEP) populations with the propagating CME and flaring, we perform a multi-wavelength analysis using radio spectral and imaging observations combined with white-light, EUV, hard X-ray, and magnetogram data. Velocity dispersion analysis of the particle distributions (SOHO and Wind in situ observations) provides estimates for the release times of electrons and protons. Our analysis indicates that proton acceleration was delayed compared to the electrons. The dynamics of the interplanetary type II burst identify the burst source as a bow shock created by the fast CME. The type III burst groups, with start times close to the estimated electron-release times, trace electron beams travelling along open field lines into the interplanetary space. The type III bursts seem to encounter a steep density gradient as they overtake the type II shock front, resulting in an abrupt change in the frequency drift rate of the type III burst emission. Our study presents evidence in support of a scenario in which electrons are accelerated low in the corona behind the CME shock front, while protons are accelerated later, possibly at the CME bow shock high in the corona.  相似文献   

On the evolutionary status of short-period cataclysmic variables     

S. P. Littlefair  V. S. Dhillon  T. R. Marsh  B. T. Gänsicke  John Southworth  I. Baraffe  C. A. Watson  C. Copperwheat 《Monthly notices of the Royal Astronomical Society》2008,388(4):1582-1594

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Dissipative accretion flows around a rotating black hole     

Santabrata Das  Sandip K. Chakrabarti 《Monthly notices of the Royal Astronomical Society》2008,389(1):371-378

We study the dynamical structure of a cooling dominated rotating accretion flow around a spinning black hole. We show that non-linear phenomena such as shock waves can be studied in terms of only three flow parameters, namely the specific energy     , the specific angular momentum (λ) and the accretion rate     of the flow. We present all possible accretion solutions. We find that a significant region of the parameter space in the     plane allows global accretion shock solutions. The effective area of the parameter space for which the Rankine–Hugoniot shocks are possible is maximum when the flow is dissipation-free. It decreases with the increase of cooling effects and finally disappears when the cooling is high enough. We show that shock forms further away when the black hole is rotating compared to the solution around a Schwarzschild black hole with identical flow parameters at a large distance. However, in a normalized sense, the flow parameters for which the shocks form around the rotating black holes are produced shocks closer to the black hole. The location of the shock is also dictated by the cooling efficiency in that higher the accretion rate     , the closer is the shock location. We believe that some of the high-frequency quasi-periodic oscillations may be due to the flows with higher accretion rate around the rotating black holes.  相似文献   

Radio observations of NGC 2808 and other globular clusters: constraints on intermediate-mass black holes     

Thomas J. Maccarone  Mathieu Servillat 《Monthly notices of the Royal Astronomical Society》2008,389(1):379-384

We present the results of a deep radio observation of the globular cluster NGC 2808. We show that there are no sources detected within the core of the cluster, placing constraints on both the pulsar population of the cluster and the mass of a possible intermediate-mass black hole in NGC 2808. We compare the results for this cluster with other constraints on intermediate-mass black holes derived from accretion measures. With the exception of G1 in M 31 which has previously shown radio emission, even with considerably more conservative assumptions, only the clusters with the poorest of observational constraints are consistent with falling on the   M _BH–σ  relation. This result is interpreted in terms of the fundamental differences between galaxies and globular clusters.  相似文献   

Erratum: Bulk flow and shear moments of the SFI++ survey     

《Monthly notices of the Royal Astronomical Society》2008,388(4):1904-1904

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