The structured environments of embedded star-forming cores. PACS and SPIRE mapping of the enigmatic outflow source UYSO 1

The intermediate-mass star-forming core UYSO 1 has previously been found to exhibit intriguing features. While deeply embedded and previously only identified by means of its (sub-)millimeter emission, it drives two powerful, dynamically young, molecular outflows. Although the process of star formation has obviously started, the chemical composition is still pristine. We present Herschel PACS and SPIRE continuum data of this presumably very young region. The now complete coverage of the spectral energy peak allows us to precisely constrain the elevated temperature of 26 - 28 K for the main bulge of gas associated with UYSO1, which is located at the interface between the hot HII region Sh 2-297 and the cold dark nebula LDN 1657A. Furthermore, the data identify cooler compact far-infrared sources of just a few solar masses, hidden in this neighbouring dark cloud.Comment: accepted contribution for the forthcoming Herschel Special Issue of A&A, 5 pages (will appear as 4-page letter in the journal), 6 figure file

Relationship between the column density distribution and evolutionary class of molecular clouds as viewed by ATLASGAL

We present the first study of the relationship between the column density distribution of molecular clouds within nearby Galactic spiral arms and their evolutionary status as measured from their stellar content. We analyze a sample of 195 molecular clouds located at distances below 5.5 kpc, identified from the ATLASGAL 870 micron data. We define three evolutionary classes within this sample: starless clumps, star-forming clouds with associated young stellar objects, and clouds associated with HII regions. We find that the N(H2) probability density functions (N-PDFs) of these three classes of objects are clearly different: the N-PDFs of starless clumps are narrowest and close to log-normal in shape, while star-forming clouds and HII regions exhibit a power-law shape over a wide range of column densities and log-normal-like components only at low column densities. We use the N-PDFs to estimate the evolutionary time-scales of the three classes of objects based on a simple analytic model from literature. Finally, we show that the integral of the N-PDFs, the dense gas mass fraction, depends on the total mass of the regions as measured by ATLASGAL: more massive clouds contain greater relative amounts of dense gas across all evolutionary classes.Comment: Accepted for publication in A&A (25th June 15) 23 pages, 12 figures. Additional appendix figures will appear in the journal version of this pape

Dust-temperature of an isolated star-forming cloud: Herschel observations of the Bok globule CB244

We present Herschel observations of the isolated, low-mass star-forming Bok globule CB244. It contains two cold sources, a low-mass Class 0 protostar and a starless core, which is likely to be prestellar in nature, separated by 90 arcsec (~ 18000 AU). The Herschel data sample the peak of the Planck spectrum for these sources, and are therefore ideal for dust-temperature and column density modeling. With these data and a near-IR extinction map, the MIPS 70 micron mosaic, the SCUBA 850 micron map, and the IRAM 1.3 mm map, we model the dust-temperature and column density of CB244 and present the first measured dust-temperature map of an entire star-forming molecular cloud. We find that the column-averaged dust-temperature near the protostar is ~ 17.7 K, while for the starless core it is ~ 10.6K, and that the effect of external heating causes the cloud dust-temperature to rise to ~ 17 K where the hydrogen column density drops below 10^21 cm^-2. The total hydrogen mass of CB244 (assuming a distance of 200 pc) is 15 +/- 5 M_sun. The mass of the protostellar core is 1.6 +/- 0.1 M_sun and the mass of the starless core is 5 +/- 2 M_sun, indicating that ~ 45% of the mass in the globule is participating in the star-formation process.Comment: Accepted for A&A Herschel Special Issue; 5 pages, 2 figure

Spitzer and HHT observations of starless cores: masses and environments

We present Spitzer observations of a sample of 12 starless cores selected to have prominent 24 micron shadows. The Spitzer images show 8 and 24 micron shadows and in some cases 70 micron shadows; these spatially resolved absorption features trace the densest regions of the cores. We have carried out a 12CO (2-1) and 13CO (2-1) mapping survey of these cores with the Heinrich Hertz Telescope (HHT). We use the shadow features to derive optical depth maps. We derive molecular masses for the cores and the surrounding environment; we find that the 24 micron shadow masses are always greater than or equal to the molecular masses derived in the same region, a discrepancy likely caused by CO freeze--out onto dust grains. We combine this sample with two additional cores that we studied previously to bring the total sample to 14 cores. Using a simple Jeans mass criterion we find that ~ 2/3 of the cores selected to have prominent 24 micron shadows are collapsing or near collapse, a result that is supported by millimeter line observations. Of this subset at least half have indications of 70 micron shadows. All cores observed to produce absorption features at 70 micron are close to collapse. We conclude that 24 micron shadows, and even more so the 70 micron ones, are useful markers of cloud cores that are approaching collapse.Comment: 41 pages, 28 figures, 5 tables; accepted by Ap

The Earliest Phases of Star formation (EPoS): Temperature, density, and kinematic structure of the star-forming core CB 17

Context: The initial conditions for the gravitational collapse of molecular cloud cores and the subsequent birth of stars are still not well constrained. The characteristic cold temperatures (about 10 K) in such regions require observations at sub-millimetre and longer wavelengths. The Herschel Space Observatory and complementary ground-based observations presented in this paper have the unprecedented potential to reveal the structure and kinematics of a prototypical core region at the onset of stellar birth. Aims: This paper aims to determine the density, temperature, and velocity structure of the star-forming Bok globule CB 17. This isolated region is known to host (at least) two sources at different evolutionary stages: a dense core, SMM1, and a Class I protostar, IRS. Methods: We modeled the cold dust emission maps from 100 micron to 1.2 mm with both a modified blackbody technique to determine the optical depth-weighted line-of-sight temperature and column density and a ray-tracing technique to determine the core temperature and volume density structure. Furthermore, we analysed the kinematics of CB17 using the high-density gas tracer N2H+. Results: From the ray-tracing analysis, we find a temperature in the centre of SMM1 of 10.6 K, a flat density profile with radius 9500 au, and a central volume density of n(H) = 2.3x10^5 cm-3. The velocity structure of the N2H+ observations reveal global rotation with a velocity gradient of 4.3 km/s/pc. Superposed on this rotation signature we find a more complex velocity field, which may be indicative of differential motions within the dense core. Conclusions: SMM is a core in an early evolutionary stage at the verge of being bound, but the question of whether it is a starless or a protostellar core remains unanswered.Comment: published in A&

P19-53 LB. Priming with recombinant BCG expressing HIV-1 Gag or RT and boosting with recombinant MVA induces an effective immune response in mice

Mycobacterium bovis BCG (BCG) has a number of characteristics that give it great potential to act as a vehicle for the delivery of recombinant vaccines. However, its success depends on overcoming the challenges of poor antigen expression levels and genetic instability. Our studies using an optimized mycobacterial shuttle vector which utilizes the Mycobacterium tuberculosis mtrA promoter, induced upon infection of macrophages, and the M. tuberculosis 19 kDa signal sequence may overcome these issues. We have used this system to generate a recombinant BCG (rBCG) expressing HIV-1 subtype C full length Gag or reverse transcriptase (RT)

Marked influence of the nature of chemical bond on CP-violating signature in molecular ions HBr+\mathrm{HBr}^{+} and HI+\mathrm{HI}^{+}

Heavy polar molecules offer a great sensitivity to the electron Electric Dipole Moment(EDM). To guide emerging searches for EDMs with molecular ions, we estimate the EDM-induced energy corrections for hydrogen halide ions $\mathrm{HBr}^{+}$ and $\mathrm{HI}^{+}$ in their respective ground $X ^2\Pi_{3/2}$ states. We find that the energy corrections due to EDM for the two ions differ by an unexpectedly large factor of fifteen. We demonstrate that a major part of this enhancement is due to a dissimilarity in the nature of the chemical bond for the two ions: the bond that is nearly of ionic character in $\mathrm{HBr}^{+}$ exhibits predominantly covalent nature in $\mathrm{HI}^{+}$. We conclude that because of this enhancement the HI$^+$ ion may be a potentially competitive candidate for the EDM search.Comment: This manuscript has been accepted for publication in Physical Review Letters. The paper is now being prepared for publicatio