| 1. |
- van der Wiel, M. H. D., et al.
(author)
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Signatures of warm carbon monoxide in protoplanetary discs observed with Herschel SPIRE
- 2014
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In: Monthly notices of the Royal Astronomical Society. - : Oxford University Press (OUP). - 0035-8711 .- 1365-2966. ; 444:4, s. 3911-3925
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Journal article (peer-reviewed)abstract
- Molecular gas constitutes the dominant mass component of protoplanetary discs. To date, these sources have not been studied comprehensively at the longest far-infrared and shortest submillimetre wavelengths. This paper presents Herschel SPIRE FTS spectroscopic observations towards 18 protoplanetary discs, covering the entire 450-1540 GHz (666-195 mu m) range at upsilon/Delta upsilon approximate to 400-1300. The spectra reveal clear detections of the dust continuum and, in six targets, a significant amount of spectral line emission primarily attributable to (CO)-C-12 rotational lines. Other targets exhibit little to no detectable spectral lines. Low signal-to-noise detections also include signatures from (CO)-C-13, [C I] and HCN. For completeness, we present upper limits of non-detected lines in all targets, including low-energy transitions of H2O and CH+ molecules. The 10 (CO)-C-12 lines that fall within the SPIRE FTS bands trace energy levels of similar to 50-500 K. Combined with lower and higher energy lines from the literature, we compare the CO rotational line energy distribution with detailed physical-chemical models, for sources where these are available and published. Our (CO)-C-13 line detections in the disc around Herbig Be star HD 100546 exceed, by factors of similar to 10-30, the values predicted by a model that matches a wealth of other observational constraints, including the SPIRE (CO)-C-12 ladder. To explain the observed (CO)-C-12/(CO)-C-13 ratio, it may be necessary to consider the combined effects of optical depth and isotope selective (photo) chemical processes. Considering the full sample of 18 objects, we find that the strongest line emission is observed in discs around Herbig Ae/Be stars, although not all show line emission. In addition, two of the six T Tauri objects exhibit detectable (CO)-C-12 lines in the SPIRE range.
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| 2. |
- Acke, B., et al.
(author)
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Herschel images of Fomalhaut An extrasolar Kuiper belt at the height of its dynamical activity
- 2012
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In: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 540, s. Article Number: A125 -
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Journal article (peer-reviewed)abstract
- Context. Fomalhaut is a young (2 +/- 1 x 10(8) years), nearby (7.7 pc), 2 M-circle dot star that is suspected to harbor an infant planetary system, interspersed with one or more belts of dusty debris. Aims. We present far-infrared images obtained with the Herschel Space Observatory with an angular resolution between 5.7 '' and 36.7 '' at wavelengths between 70 mu m and 500 mu m. The images show the main debris belt in great detail. Even at high spatial resolution, the belt appears smooth. The region in between the belt and the central star is not devoid of material; thermal emission is observed here as well. Also at the location of the star, excess emission is detected. We aim to construct a consistent image of the Fomalhaut system. Methods. We use a dynamical model together with radiative-transfer tools to derive the parameters of the debris disk. We include detailed models of the interaction of the dust grains with radiation, for both the radiation pressure and the temperature determination. Comparing these models to the spatially resolved temperature information contained in the images allows us to place strong constraints on the presence of grains that will be blown out of the system by radiation pressure. We use this to derive the dynamical parameters of the system. Results. The appearance of the belt points toward a remarkably active system in which dust grains are produced at a very high rate by a collisional cascade in a narrow region filled with dynamically excited planetesimals. Dust particles with sizes below the blow-out size are abundantly present. The equivalent of 2000 one-km-sized comets are destroyed every day, out of a cometary reservoir amounting to 110 Earth masses. From comparison of their scattering and thermal properties, we find evidence that the dust grains are fluffy aggregates, which indicates a cometary origin. The excess emission at the location of the star may be produced by hot dust with a range of temperatures, but may also be due to gaseous free-free emission from a stellar wind.
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| 3. |
- Greaves, J. S., et al.
(author)
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EXTREME CONDITIONS IN A CLOSE ANALOG TO THE YOUNG SOLAR SYSTEM : HERSCHEL OBSERVATIONS OF is an element of ERIDANI
- 2014
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In: Astrophysical Journal Letters. - 2041-8205 .- 2041-8213. ; 791:1, s. L11-
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Journal article (peer-reviewed)abstract
- Far-infrared Herschel images of the is an element of Eridani system, seen at a fifth of the Sun's present age, resolve two belts of debris emission. Fits to the 160 mu m PACS image yield radial spans for these belts of 12-16 and 54-68 AU. The south end of the outer belt is approximate to 10% brighter than the north end in the PACS+SPIRE images at 160, 250, and 350 mu m, indicating a pericenter glow attributable to a planet c From this asymmetry and an upper bound on the offset of the belt center, this second planet should be mildly eccentric (e(c) approximate to 0.03-0.3). Compared to the asteroid and Kuiper Belts of the young Sun, the is an element of Eri belts are intermediate in brightness and more similar to each other, with up to 20 km sized collisional fragments in the inner belt totaling approximate to 5% of an Earth mass. This reservoir may feed the hot dust close to the star and could send many impactors through the Habitable Zone, especially if it is being perturbed by the suspected planet is an element of Eri b, at semi-major axis approximate to 3 AU.
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| 4. |
- Greaves, J. S., et al.
(author)
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Extreme Conditions in a Close Analog to the Young Solar System: Herschel Observations of ∈ Eridani
- 2014
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In: Astrophysical Journal Letters. - : American Astronomical Society. - 2041-8213 .- 2041-8205. ; 791:1
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Journal article (peer-reviewed)abstract
- Far-infrared Herschel images of the is an element of Eridani system, seen at a fifth of the Sun's present age, resolve two belts of debris emission. Fits to the 160 mu m PACS image yield radial spans for these belts of 12-16 and 54-68 AU. The south end of the outer belt is approximate to 10% brighter than the north end in the PACS+SPIRE images at 160, 250, and 350 mu m, indicating a pericenter glow attributable to a planet "c" From this asymmetry and an upper bound on the offset of the belt center, this second planet should be mildly eccentric (e(c) approximate to 0.03-0.3). Compared to the asteroid and Kuiper Belts of the young Sun, the is an element of Eri belts are intermediate in brightness and more similar to each other, with up to 20 km sized collisional fragments in the inner belt totaling approximate to 5% of an Earth mass. This reservoir may feed the hot dust close to the star and could send many impactors through the Habitable Zone, especially if it is being perturbed by the suspected planet is an element of Eri b, at semi-major axis approximate to 3 AU.
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| 5. |
- Levin, Malin, 1973, et al.
(author)
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Evaluation of macrophage-specific promoters using lentiviral delivery in mice.
- 2012
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In: Gene therapy. - : Springer Science and Business Media LLC. - 1476-5462 .- 0969-7128. ; 19:11, s. 1041-7
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Journal article (peer-reviewed)abstract
- In gene therapy, tissue-specific promoters are useful tools to direct transgene expression and improve efficiency and safety. Macrophage-specific promoters (MSPs) have previously been published using different delivery systems. In this study, we evaluated five different MSPs fused with green fluorescent protein (GFP) to delineate the one with highest specificity using lentiviral delivery. We compared three variants of the CD68 promoter (full length, the 343-bp proximal part and the 150-bp proximal part) and two variants (in forward and reverse orientation) of a previously characterized synthetic promoter derived from elements of transcription factor genes. We transduced a number of cell lines and primary cells in vitro. In addition, hematopoietic stem cells were transduced with MSPs and transferred into lethally irradiated recipient mice. Fluorescence activated cell sorting analysis was performed to determine the GFP expression in different cell populations both in vitro and in vivo. We showed that MSPs can efficiently be used for lentiviral gene delivery and that the 150-bp proximal part of the CD68 promoter provides primarily macrophage-specific expression of GFP. We propose that this is the best currently available MSP to use for directing transgene expression to macrophage populations in vivo using lentiviral vectors.
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| 6. |
- Sibthorpe, B., et al.
(author)
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The Vega debris disc: A view from Herschel
- 2010
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In: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 518:Article Number: L130
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Journal article (peer-reviewed)abstract
- We present five band imaging of the Vega debris disc obtained using the Herschel Space Observatory. These data span a wavelength range of 70-500 mu m with full-width half-maximum angular resolutions of 5.6-36.9 ''. The disc is well resolved in all bands, with the ring structure visible at 70 and 160 mu m. Radial profiles of the disc surface brightness are produced, and a disc radius of 11 '' (similar to 85AU) is determined. The disc is seen to have a smooth structure thoughout the entire wavelength range, suggesting that the disc is in a steady state, rather than being an ephemeral structure caused by the recent collision of two large planetesimals.
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| 7. |
- Vandenbussche, B., et al.
(author)
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The beta Pictoris disk imaged by Herschel PACS and SPIRE
- 2010
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In: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 518:Article Number: L133
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Journal article (peer-reviewed)abstract
- We obtained Herschel PACS and SPIRE images of the thermal emission of the debris disk around the A5V star beta Pic. The disk is well resolved in the PACS filters at 70, 100, and 160 mu m. The surface brightness profiles between 70 and 160 mu m show no significant asymmetries along the disk, and are compatible with 90% of the emission between 70 and 160 mu m originating in a region closer than 200 AU to the star. Although only marginally resolving the debris disk, the maps obtained in the SPIRE 250-500 mu m filters provide full-disk photometry, completing the SED over a few octaves in wavelength that had been previously inaccessible. The small far-infrared spectral index (beta = 0.34) indicates that the grain size distribution in the inner disk (
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