Quiescent Radio Emission from Southern Late-type M Dwarfs and a Spectacular Radio Flare from the M8 Dwarf DENIS 1048-3956

We report the results of a radio monitoring program conducted at the Australia Telescope Compact Array to search for quiescent and flaring emission from seven nearby Southern late-type M and L dwarfs. Two late-type M dwarfs, the M7 V LHS 3003 and the M8 V DENIS 1048-3956, were detected in quiescent emission at 4.80 GHz. The observed emission is consistent with optically thin gyrosynchrotron emission from mildly relativistic (~1-10 keV) electrons with source densities n_e ~ 10 G magnetic fields. DENIS 1048-3956 was also detected in two spectacular, short-lived flares, one at 4.80 GHz (peak f_nu = 6.0+/-0.8 mJy) and one at 8.64 GHz (peak f_nu = 29.6+/-1.0 mJy) approximately 10 minutes later. The high brightness temperature (T_B >~ 10^13 K), short emission period (~4-5 minutes), high circular polarization (~100%), and apparently narrow spectral bandwidth of these events imply a coherent emission process in a region of high electron density (n_e ~ 10^11-10^12 cm^-3) and magnetic field strength (B ~ 1 kG). If the two flare events are related, the apparent frequency drift in the emission suggests that the emitting source either moved into regions of higher electron or magnetic flux density; or was compressed, e.g., by twisting field lines or gas motions. The quiescent fluxes from the radio-emitting M dwarfs violate the Gudel-Benz empirical radio/X-ray relations, confirming a trend previously noted by Berger et al. (abridged)Comment: 28 pages, 8 figures, accepted for publication in Ap

Trends in U.S. Public Awareness of Racial and Ethnic Health Disparities (1999-2010): 2009 General Population Toplines

Not provided

Trends in U.S. Public Awareness of Racial and Ethnic Health Disparities (1999-2010): Study Brief

None provided

Dynamics of Circumstellar Disks II: Heating and Cooling

We present a series of 2-d ($r,\phi$) hydrodynamic simulations of marginally self gravitating disks around protostars using an SPH code. We implement simple dynamical heating and we cool each location as a black body, using a photosphere temperature obtained from the local vertical structure. We synthesize SEDs from our simulations and compare them to fiducial SEDs derived from observed systems. These simulations produce less distinct spiral structure than isothermally evolved systems, especially in the inner third of the disk. Pattern are similar further from the star but do not collapse into condensed objects. The photosphere temperature is well fit to a power law in radius with index $q\sim1.1$, which is very steep. Far from the star, internal heating ($PdV$ work and shocks) are not responsible for generating a large fraction of the thermal energy contained in the disk matter. Gravitational torques responsible for such shocks cannot transport mass and angular momentum efficiently in the outer disk. Within $\sim$5--10 AU of the star, rapid break up and reformation of spiral structure causes shocks, which provide sufficient dissipation to power a larger fraction of the near IR energy output. The spatial and size distribution of grains can have marked consequences on the observed near IR SED and can lead to increased emission and variability on $\lesssim 10$ year time scales. When grains are vaporized they do not reform into a size distribution similar to that from which most opacity calculations are based. With rapid grain reformation into the original size distribution, the disk does not emit near infrared photons. With a plausible modification to the opacity, it contributes much more.Comment: Accepted by ApJ, 60pg incl 24 figure

NMR Response in quasi one-dimensional Spin-1/2 Antiferromagnets

Non-magnetic impurities break a quantum spin chain into finite segments and induce Friedel-like oscillations in the local susceptibility near the edges. The signature of these oscillations has been observed in Knight shift experiments on the high-temperature superconductor YBa$_2$Cu$_3$O$_{6.5}$ and on the spin-chain compound Sr$_2$CuO$_3$. Here we analytically calculate NMR spectra, compare with the available experimental data for Sr$_2$CuO$_3$, and show that the interchain coupling is responsible for the complicated and so far unexplained lineshape. Our results are based on a parameter-free formula for the local susceptibility of a finite spin chain obtained by bosonization which is checked by comparing with quantum Monte Carlo and density-matrix renormalization group calculations.Comment: final versio

Commission 10: Solar Activity

Commission 10 aims at the study of various forms of solar activity, including networks, plages, pores, spots, fibrils, surges, jets, filaments/prominences, coronal loops, flares, coronal mass ejections (CMEs), solar cycle, microflares, nanoflares, coronal heating etc., which are all manifestation of the interplay of magnetic fields and solar plasma. Increasingly important is the study of solar activities as sources of various disturbances in the interplanetary space and near-Earth “space weather”. Over the past three years a major component of research on the active Sun has involved data from the RHESSI spacecraft. This review starts with an update on current and planned solar observations from spacecraft. The discussion of solar flares gives emphasis to new results from RHESSI, along with updates on other aspects of flares. Recent progress on two theoretical concepts, magnetic reconnection and magnetic helicity is then summarized, followed by discussions of coronal loops and heating, the magnetic carpet and filaments. The final topic discussed is coronal mass ejections and space weather. The discussions on each topic is relatively brief, and intended as an outline to put the extensive list of references in context. The review was prepared jointly by the members of the Organizing Committee, and the names of the primary contributors to the various sections are indicated in parentheses

The HARPS search for southern extra-solar planets. XXVII. Up to seven planets orbiting HD 10180: probing the architecture of low-mass planetary systems

Context. Low-mass extrasolar planets are presently being discovered at an increased pace by radial velocity and transit surveys, opening a new window on planetary systems. Aims. We are conducting a high-precision radial velocity survey with the HARPS spectrograph which aims at characterizing the population of ice giants and super-Earths around nearby solar-type stars. This will lead to a better understanding of their formation and evolution, and yield a global picture of planetary systems from gas giants down to telluric planets. Methods. Progress has been possible in this field thanks in particular to the sub-m/s radial velocity precision achieved by HARPS. We present here new high-quality measurements from this instrument. Results. We report the discovery of a planetary system comprising at least five Neptune-like planets with minimum masses ranging from 12 to 25 M_Earth, orbiting the solar-type star HD 10180 at separations between 0.06 and 1.4 AU. A sixth radial velocity signal is present at a longer period, probably due to a 65-M_Earth object. Moreover, another body with a minimum mass as low as 1.4 M_Earth may be present at 0.02 AU from the star. This is the most populated exoplanetary system known to date. The planets are in a dense but still well-separated configuration, with significant secular interactions. Some of the orbital period ratios are fairly close to integer or half-integer values, but the system does not exhibit any mean-motion resonances. General relativity effects and tidal dissipation play an important role to stabilize the innermost planet and the system as a whole. Numerical integrations show long-term dynamical stability provided true masses are within a factor ~3 from minimum masses. We further note that several low-mass planetary systems exhibit a rather "packed" orbital architecture with little or no space left for additional planets. (Abridged)Comment: 20 pages, 15 figures, accepted for publication in A&

The HARPS search for southern extra-solar planets. XXIV. Companions to HD 85390, HD 90156 and HD 103197: A Neptune analogue and two intermediate mass planets

We report the detection of three new extrasolar planets orbiting the solar type stars HD 85390, HD 90156 and HD 103197 with the HARPS spectrograph mounted on the ESO 3.6-m telescope at La Silla observatory. HD 85390 has a planetary companion with a projected intermediate mass (42.0 Earth masses) on a 788-day orbit (a=1.52 AU) with an eccentricity of 0.41, for which there is no analogue in the solar system. A drift in the data indicates the presence of another companion on a long period orbit, which is however not covered by our measurements. HD 90156 is orbited by a warm Neptune analogue with a minimum mass of 17.98 Earth masses (1.05 Neptune masses), a period of 49.8 days (a=0.25 AU) and an eccentricity of 0.31. HD 103197 has an intermediate mass planet on a circular orbit (P=47.8 d, Msini=31.2 Earth masses). We discuss the formation of planets of intermediate mass (about 30-100 Earth masses) which should be rare inside a few AU according to core accretion formation models.Comment: 9 pages, 5 figures. Accepted to A&

The regulatory and transcriptional landscape associated with carbon utilization in a filamentous fungus.

Filamentous fungi, such as Neurospora crassa, are very efficient in deconstructing plant biomass by the secretion of an arsenal of plant cell wall-degrading enzymes, by remodeling metabolism to accommodate production of secreted enzymes, and by enabling transport and intracellular utilization of plant biomass components. Although a number of enzymes and transcriptional regulators involved in plant biomass utilization have been identified, how filamentous fungi sense and integrate nutritional information encoded in the plant cell wall into a regulatory hierarchy for optimal utilization of complex carbon sources is not understood. Here, we performed transcriptional profiling of N. crassa on 40 different carbon sources, including plant biomass, to provide data on how fungi sense simple to complex carbohydrates. From these data, we identified regulatory factors in N. crassa and characterized one (PDR-2) associated with pectin utilization and one with pectin/hemicellulose utilization (ARA-1). Using in vitro DNA affinity purification sequencing (DAP-seq), we identified direct targets of transcription factors involved in regulating genes encoding plant cell wall-degrading enzymes. In particular, our data clarified the role of the transcription factor VIB-1 in the regulation of genes encoding plant cell wall-degrading enzymes and nutrient scavenging and revealed a major role of the carbon catabolite repressor CRE-1 in regulating the expression of major facilitator transporter genes. These data contribute to a more complete understanding of cross talk between transcription factors and their target genes, which are involved in regulating nutrient sensing and plant biomass utilization on a global level