Resolved Imaging of the HR 8799 Debris Disk with Herschel

We present Herschel far-infrared and submillimeter maps of the debris disk associated with the HR 8799 planetary system. We resolve the outer disk emission at 70, 100, 160 and 250 um and detect the disk at 350 and 500 um. A smooth model explains the observed disk emission well. We observe no obvious clumps or asymmetries associated with the trapping of planetesimals that is a potential consequence of planetary migration in the system. We estimate that the disk eccentricity must be <0.1. As in previous work by Su et al. (2009), we find a disk with three components: a warm inner component and two outer components, a planetesimal belt extending from 100 - 310 AU, with some flexibility (+/- 10 AU) on the inner edge, and the external halo which extends to ~2000 AU. We measure the disk inclination to be 26 +/- 3 deg from face-on at a position angle of 64 deg E of N, establishing that the disk is coplanar with the star and planets. The SED of the disk is well fit by blackbody grains whose semi-major axes lie within the planetesimal belt, suggesting an absence of small grains. The wavelength at which the spectrum steepens from blackbody, 47 +/- 30 um, however, is short compared to other A star debris disks, suggesting that there are atypically small grains likely populating the halo. The PACS longer wavelength data yield a lower disk color temperature than do MIPS data (24 and 70 um), implying two distinct halo dust grain populations.Comment: 13 pages, 8 figures (6 color), accepted for publication in the Astrophysical Journa

Herschel Observations of Debris Discs Orbiting Planet-hosting Subgiants

Debris discs are commonly detected orbiting main-sequence stars, yet little is known regarding their fate as the star evolves to become a giant. Recent observations of radial velocity detected planets orbiting giant stars highlight this population and its importance for probing, for example, the population of planetary systems orbiting intermediate mass stars. Our Herschel survey observed a subset of the Johnson et al program subgiants, finding that 4/36 exhibit excess emission thought to indicate debris, of which 3/19 are planet-hosting stars and 1/17 are stars with no current planet detections. Given the small numbers involved, there is no evidence that the disc detection rate around stars with planets is different to that around stars without planets. Our detections provide a clear indication that large quantities of dusty material can survive the stars' main-sequence lifetime and be detected on the subgiant branch, with important implications for the evolution of planetary systems and observations of polluted or dusty white dwarfs. Our detection rates also provide an important constraint that can be included in models of debris disc evolution.Comment: 12 pages, MNRAS, accepte

Spatially Resolved Images of Dust Belt(s) Around the Planet-hosting Subgiant Kappa CrB

We present Herschel spatially resolved images of the debris disc orbiting the subgiant Kappa CrB. Not only are these the first resolved images of a debris disc orbiting a subgiant, but Kappa CrB is a rare example of an intermediate mass star where a detailed study of the structure of the planetary system can be made, including both planets and planetesimal belt(s). The only way to discover planets around such stars using the radial velocity technique is to observe 'retired' A stars, which are cooler and slower rotators compared to their main-sequence counterparts. A planetary companion has already been detected orbiting the subgiant Kappa CrB, with revised parameters of m sin i = 2.1MJ and apl = 2.8AU (Johnson et al. 2008a). We present additional Keck I HIRES radial velocity measurements that provide evidence for a second planetary companion, alongside Keck II AO imaging that places an upper limit on the mass of this companion. Modelling of our Herschel images shows that the dust is broadly distributed, but cannot distinguish between a single wide belt (from 20 to 220AU) or two narrow dust belts (at around 40 and 165AU). Given the existence of a second planetary companion beyond approximately 3AU it is possible that the absence of dust within approximately 20AU is caused by dynamical depletion, although the observations are not inconsistent with depletion of these regions by collisional erosion, which occurs at higher rates closer to the star.Comment: Updated abstrac

Resolved Debris Discs Around A Stars in the Herschel DEBRIS Survey

The majority of debris discs discovered so far have only been detected through infrared excess emission above stellar photospheres. While disc properties can be inferred from unresolved photometry alone under various assumptions for the physical properties of dust grains, there is a degeneracy between disc radius and dust temperature that depends on the grain size distribution and optical properties. By resolving the disc we can measure the actual location of the dust. The launch of Herschel, with an angular resolution superior to previous far-infrared telescopes, allows us to spatially resolve more discs and locate the dust directly. Here we present the nine resolved discs around A stars between 20 and 40 pc observed by the DEBRIS survey. We use these data to investigate the disc radii by fitting narrow ring models to images at 70, 100 and 160 {\mu}m and by fitting blackbodies to full spectral energy distributions. We do this with the aim of finding an improved way of estimating disc radii for unresolved systems. The ratio between the resolved and blackbody radii varies between 1 and 2.5. This ratio is inversely correlated with luminosity and any remaining discrepancies are most likely explained by differences to the minimum size of grain in the size distribution or differences in composition. We find that three of the systems are well fit by a narrow ring, two systems are borderline cases and the other four likely require wider or multiple rings to fully explain the observations, reflecting the diversity of planetary systems.Comment: 19 pages, 13 figures, 6 tables. Accepted for publication in MNRA

The debris disk around gamma Doradus resolved with Herschel

We present observations of the debris disk around gamma Doradus, an F1V star, from the Herschel Key Programme DEBRIS (Disc Emission via Bias-free Reconnaissance in the Infrared/Submillimetre). The disk is well-resolved at 70, 100 and 160 micron, resolved along its major axis at 250 micron, detected but not resolved at 350 micron, and confused with a background source at 500 micron. It is one of our best resolved targets and we find it to have a radially broad dust distribution. The modelling of the resolved images cannot distinguish between two configurations: an arrangement of a warm inner ring at several AU (best-fit 4 AU) and a cool outer belt extending from ~55 to 400 AU or an arrangement of two cool, narrow rings at ~70 AU and ~190 AU. This suggests that any configuration between these two is also possible. Both models have a total fractional luminosity of ~10^{-5} and are consistent with the disk being aligned with the stellar equator. The inner edge of either possible configuration suggests that the most likely region to find planets in this system would be within ~55 AU of the star. A transient event is not needed to explain the warm dust's fractional luminosity.Comment: 12 pages, 6 figures, accepted for publication in Ap

Spatially resolved images of dust belt(s) around the planet-hosting subgiant κ CrB

We present Herschel spatially resolved images of the debris disc orbiting the subgiant κ Coronae Borealis (κ CrB). Not only are these the first resolved images of a debris disc orbiting a subgiant, but κ CrB is a rare example of an intermediate mass star where a detailed study of the structure of the planetary system can be made, including both planets and planetesimal belt(s). The only way to discover planets using the radial velocity technique around such stars is to observe ‘retired’ A stars, which are cooler and slower rotators compared to their main-sequence counterparts. A planetary companion has already been detected orbiting the subgiant κ CrB, with revised parameters of msin i = 2.1 M_J and a_(pl) = 2.8 au (Johnson et al. 2008). We present additional Keck I HIRES (High Resolution Echelle Spectrometer) radial velocity measurements that provide evidence for a second planetary companion, alongside Keck II adaptive optics imaging that places an upper limit on the mass of this companion. Modelling of our Herschel images shows that the dust is broadly distributed, but cannot distinguish between a single wide belt (from 20 to 220 au) or two narrow dust belts (at around 40 and 165 au). Given the existence of a second planetary companion beyond ∼3 au it is possible that the absence of dust within ∼20 au is caused by dynamical depletion, although the observations are not inconsistent with depletion of these regions by collisional erosion, which occurs at higher rates closer to the star

A scientific basis for restoring fish spawning habitat in the St. Clair and Detroit Rivers of the Laurentian Great Lakes

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/110848/1/rec12159.pd

Tumor-Associated Macrophages in Glioma: Friend or Foe?

Tumor-associated macrophages (TAMs) contribute substantially to the tumor mass of gliomas and have been shown to play a major role in the creation of a tumor microenvironment that promotes tumor progression. Shortcomings of attempts at antiglioma immunotherapy may result from a failure to adequately address these effects. Emerging evidence supports an independent categorization of glioma TAMs as alternatively activated M2-type macrophages, in contrast to classically activated proinflammatory M1-type macrophages. These M2-type macrophages exert glioma-supportive effects through reduced anti-tumor functions, increased expression of immunosuppressive mediators, and nonimmune tumor promotion through expression of trophic and invasion-facilitating substances. Much of our work has demonstrated these features of glioma TAMs, and together with the supporting literature will be reviewed here. Additionally, the dynamics of glioma cell-TAM interaction over the course of tumor development remain poorly understood; our efforts to elucidate glioma cell-TAM dynamics are summarized. Finally, the molecular pathways which underlie M2-type TAM polarization and gene expression similarly require further investigation, and may present the most potent targets for immunotherapeutic intervention. Highlighting recent evidence implicating the transcription factor STAT3 in immunosuppressive tumorigenic glioma TAMs, we advocate for gene array-based approaches to identify yet unappreciated expression regulators and effector molecules important to M2-type glioma TAMs polarization and function within the glioma tumor microenvironment

Niche-breadth of freshwater macrophytes occurring in tropical southern African rivers predicts species global latitudinal range

The study tested the hypothesis that measurement, using multivariate Principal Components Analy-sis (PCA), of the niche-breadth of river macrophyte species in southern tropical Africa, may predicttheir larger-scale biogeographical range. Two measures of niche-breadth were calculated for 44 riverinemacrophyte species, from 20 families commonly occurring in Zambia, using an approach based on PCAordination with 16 bio-physico-chemical input variables. These included altitude, stream order, streamflow, pH, conductivity and soluble reactive phosphate concentration (SRP). In the absence of additionalchemical water quality data for Zambian rivers, invertebrate-based measures of general water qualitywere also used. These were benthic macroinvertebrate Average Score per Taxon (ASPT), and individualabundance of nine macroinvertebrate families with differing water quality tolerance, indicated by theirSensitivity Weightings within the Zambian Invertebrate Scoring System (ZISS). Macrophyte large-scalelatitudinal range was derived from world geopositional records held by online databases, and additionalrecords held by the authors. The two niche-breadth metrics divided the species into narrow-niche andintermediate/broad-niche categories, showing significant variation (from one or both of correlation andANOVA test outcomes) in altitude, stream flow, conductivity, SRP, pH and ASPT, but not stream order.Macrophyte alpha-diversity (as a measure of number of individual niches co-existing per habitat) showedno significant relationship with individual species niche-breadth. Narrow-niche species included a higherproportion of Afrotropical endemics than did species with broader niche size. There were significant pre-dictive relationships between macrophyte niche-breadth and latitudinal range of the target species atglobal and Afrotropical scales, but not for the Neotropics.Fil: Kennedy, Michael. University Of Aberdeen; Reino UnidoFil: Lang, Pauline. University of Glasgow; Reino UnidoFil: Tapia Grimaldo, Julissa. University of Glasgow; Reino UnidoFil: Varandas Martins, Sara. University of Glasgow; Reino UnidoFil: Bruce, Alannah. University of Glasgow; Reino UnidoFil: Moore, Isabel. University of Glasgow; Reino UnidoFil: Taubert, Rebeca. University of Glasgow; Reino UnidoFil: Macleod-Nolan, Chantal. University of Glasgow; Reino UnidoFil: McWaters, Stephanie. University of Glasgow; Reino UnidoFil: Briggs, John. University of Glasgow; Reino UnidoFil: Lowe, Steve. University of Glasgow; Reino UnidoFil: Saili, Kochelani. University Of Zambia;Fil: SICHINGABULA, Henry. University Of Zambia;Fil: Dallas, Helen. Nelson Mandela Metropolitan University, Sudafrica; SudáfricaFil: Morrison, Sean. University of Glasgow; Reino UnidoFil: Franceschini, Maria Celeste. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Centro de Ecología Aplicada del Litoral. Universidad Nacional del Nordeste. Centro de Ecología Aplicada del Litoral; ArgentinaFil: Willems, Frank. The Kasanka Trust; ZambiaFil: Bottino, Flavia. Universidad Federal de San Carlos; BrasilFil: MURPHY Kevin. University of Glasgow; Reino Unid