Foreground Material Research Articles

Preparation and Characterization of Anti-Microbial Wound Healing Materials from Natural Origins

Abstract Many types of polymers utilized as wound dressings, Polycaprolactone (PCL) displays high degree of biocompatibility as well as biodegradability, the mechanical strength states PCL in the foreground materials used in wound healing therapies. Current work aims to develop new types of wound plaster dressing, a multiple of natural and medical materials (aloe Vera, calendula and phenobarbital) were used to enhance the anti-microbial behavior as well as pain removal during wound healing period. Aloe Vera gels, Calendula extraction, with phenobarbital drug were precipitates on PCL layer in different percentage. Microstructure observation proves that polycaprolactone polymer is good base material supports dressing constituents, wound dressing homogeneity increased due to chemical reactions between the Aloe Vera and other materials. the main elements of dressing (carbon and oxygen) observed from chemical analysis (EDS) which is also showed that using combination of natural plants (aloe vera and Calendula) with phenobarbital medicine create wound plaster layer with wide range of active elements lead to therapeutic effects including antibacterial, In (FTIR) the results show using mixture of natural additives (aloe, calendula), medicine like phenobarbital in PCL lead to create wound plaster with high (OH) content acts to expedite the skin’s healing process by maintaining the natural level of minerals and hydration at wound area. Hydrophobicity of wound can minimized when adding some hydrophilic materials like Aloe Vera, phenobarbital and calendula, Aloe Vera gel, phenobarbital, as well as calendula decrease the contact angle value. Providing high adhesion between wound plaster and skin tissue. All prepared wound plaster has same and high resistance to Staphylococcus bacteria (40mm).

The O I fine structure line profiles in Mon R2 and M17 SW: The puzzling nature of cold foreground material identified by self-absorption

The O I fine structure line profiles in Mon R2 and M17 SW: The puzzling nature of cold foreground material identified by self-absorption

A JWST Survey for Planetary Mass Brown Dwarfs in IC 348* *Based on observations made with the NASA/ESA/CSA James Webb Space Telescope and the Gaia mission.

We have obtained images of the center of the star-forming cluster IC 348 with the James Webb Space Telescope and have identified brown dwarf candidates based on their photometry and point-like flux profiles. Low-resolution spectroscopy has been performed on four promising candidates, three of which have molecular absorption bands that indicate late spectral types. Among those late-type objects, the brightest is similar to known young L dwarfs while the other two show the so-called 3.4 μm feature that has been previously observed in the diffuse interstellar medium and in the atmospheres of Saturn and Titan, which has been attributed to an unidentified aliphatic hydrocarbon. Those two objects also exhibit features between 1.1 and 2.6 μm that we identify as the overtone and combination bands for that hydrocarbon. After accounting for the hydrocarbon bands, the remaining spectral features are consistent with youth and inconsistent with field dwarfs. Based on the low extinctions of those objects and the strengths of the overtone and combination bands, we conclude that the hydrocarbon resides in their atmospheres rather than in foreground material. Thus, our detections of the 3.4 μm feature are the first in atmospheres outside of the solar system. The presence of this hydrocarbon is not predicted by any atmospheric models of young brown dwarfs. Based on its luminosity and evolutionary models, the faintest new member of IC 348 has an estimated mass of 3–4 M Jup, making it a strong contender for the least massive free-floating brown dwarf that has been directly imaged to date.

The OH Megamaser emission in Arp 220: the rest of the story

ABSTRACT The OH Megamaser emission in the merging galaxy Arp 220 has been re-observed with the Multi-Element Radio Linked Interferometer Network (MERLIN) and the European VLBI Network (EVN). Imaging results of the OH line emission at the two nuclei are found to be consistent with earlier observations and confirm additional extended emission structures surrounding the nuclei. Detailed information about the distributed emission components around the two nuclei has been obtained using a concatenated MERLIN and EVN database with intermediate (40 mas) spatial resolution. Continuum imaging shows a relatively compact West nucleus and a more extended East nucleus in addition to an extended continuum ridge stretching below and beyond the two nuclei. Spectral line imaging show extended emission regions at both nuclei together with compact components and additional weaker components north and south of the West nucleus. Spectral line analysis indicates that the dominant OH line emission originates in foreground molecular material that is part of a large-scale molecular structure that engulfs the whole nuclear region. Compact OH components are representative of star formation regions within the two nearly edge-on nuclei and define the systemic velocities of East and West as 5425 and 5360 km s−1. The foreground material at East and West has a 100 km s−1 lower velocity at 5314 and 5254 km s−1. These emission results confirm a maser amplification scenario where the background continuum and the line emission of the star formation regions are amplified by foreground masering material that is excited by the far-infrared radiation field originating in the two nuclear regions.

GTC/CanariCam Mid-infrared Polarimetry of Magnetic Fields in Star-forming Region W51 IRS2

We present 0.″4 resolution imaging polarimetry at 8.7, 10.3, and 12.5 μm, obtained with CanariCam at the Gran Telescopio Canarias, of the central 0.11 pc × 0.28 pc (4.″2 × 10.″8) region of W51 IRS2. The polarization, as high as ∼14%, arises from silicate particles aligned by the interstellar magnetic field (B-field). We separate, or unfold, the polarization of each sightline into emission and absorption components, from which we infer the morphologies of the corresponding projected B-fields that thread the emitting- and foreground-absorbing regions. We conclude that the projected B-field in the foreground material is part of the larger-scale ambient field. The morphology of the projected B-field in the mid-infrared (mid-IR) emitting region spanning the cometary H ii region W51 IRS2W is similar to that in the absorbing region. Elsewhere, the two B-fields differ significantly with no clear relationship between them. The B-field across the W51 IRS2W cometary core appears to be an integral part of a champagne outflow of gas originating in the core and dominating the energetics there. The bipolar outflow, W51north jet, that appears to originate at or near SMA1/N1 coincides almost exactly with a clearly demarcated north–south swath of lower polarization. While speculative, comparison of mid-IR and submillimeter polarimetry on two different scales may support a picture in which SMA1/N1 plays a major role in the B-field structure across W51 IRS2.

Life cycle inventory and carbon footprint assessment of wireless ICT networks for six demographic areas

The aim of this work is to quantify, assess, and identify hotspots in the environmental sustainability of newly constructed ICT networks designed to provide internet access (4 G LTE mobile technology) to regions still lacking this service. The analysis has been carried out on six demographic areas, from high-density urban and peri‑urban to remote rural, using ISO 14,040. A Dynamic Inventory Model (DIM) relating demographic/connectivity features with foreground material and energy inventories was validated using real data from Peru. The results showed carbon footprints between 81 and 103 kg CO2 eq./subscription/year, equivalent to 1.35 – 1.73 kg CO2 eq./Gb. Most of this (between 68 and 86%) correspond to end user devices, primarily in the form of embodied emissions. Operational emissions account for about one-third of the total and derive primarily from the electricity consumed by end user devices, and to a lower extent by access networks and data centers. Linear correlations were observed between operational - embodied carbon emissions and the number of subscribers. This trend was overturned in very small ICT networks designed to serve sparsely populated rural areas, due to higher energy consumption and carbon emissions per functional unit generated by access and IP network components. The robustness of these results was studied through sensitivity and uncertainty analyses.

The β Pictoris b Hill sphere transit campaign

Aims. Photometric monitoring of β Pic in 1981 showed anomalous fluctuations of up to 4% over several days, consistent with foreground material transiting the stellar disk. The subsequent discovery of the gas giant planet β Pic b and the predicted transit of its Hill sphere to within a 0.1 au projected separation of the planet provided an opportunity to search for the transit of a circumplanetary disk (CPD) in this 21 ± 4 Myr-old planetary system. We aim to detect, or put an upper limit on, the density and nature of the material in the circumplanetary environment of the planet via the continuous photometric monitoring of the Hill sphere transit that occurred in 2017 and 2018. Methods. Continuous broadband photometric monitoring of β Pic requires ground-based observatories at multiple longitudes to provide redundancy and to provide triggers for rapid spectroscopic follow-up. These include the dedicated β Pic monitoring bRing observatories in Sutherland and Siding Springs, the ASTEP400 telescope at Concordia, and the space observatories BRITE and the Hubble Space Telescope (HST). We search the combined light curves for evidence of short-period transient events caused by rings as well as for longer-term photometric variability due to diffuse circumplanetary material. Results. We find no photometric event that matches with the event seen in November 1981, and there is no systematic photometric dimming of the star as a function of the Hill sphere radius. Conclusions. We conclude that the 1981 event was not caused by the transit of a CPD around β Pic b. The upper limit on the long-term variability of β Pic places an upper limit of 1.8 × 1022 g of dust within the Hill sphere (comparable to the ~100 km radius asteroid 16 Psyche). Circumplanetary material is either condensed into a disk that does not transit β Pic, condensed into a disk with moons that has an obliquity that does not intersect with the path of β Pic behind the Hill sphere, or is below our detection threshold. This is the first time that a dedicated international campaign has mapped the Hill sphere transit of an extrasolar gas giant planet at 10 au.

Characterizing [C ii] Line Emission in Massive Star-forming Clumps

Abstract Because the 157.74 μm [C ii] line is the dominant coolant of star-forming regions, it is often used to infer the global star formation rates of galaxies. By characterizing the [C ii] and far-infrared emission from nearby Galactic star-forming molecular clumps, it is possible to determine whether extragalactic [C ii] emission arises from a large ensemble of such clumps, and whether [C ii] is indeed a robust indicator of global star formation. We describe [C ii] and far-infrared observations using the FIFI-LS instrument on the Stratospheric Observatory For Infrared Astronomy (SOFIA) airborne observatory toward four dense, high-mass, Milky Way clumps. Despite similar far-infrared luminosities, the [C ii] to far-infrared luminosity ratio, /L FIR, varies by a factor of at least 140 among these four clumps. In particular, for AGAL313.576+0.324, no [C ii] line emission is detected despite a FIR luminosity of 24,000 . AGAL313.576+0.324 lies a factor of more than 100 below the empirical correlation curve between /L FIR and found for galaxies. AGAL313.576+0.324 may be in an early evolutionary “protostellar” phase with insufficient ultraviolet flux to ionize carbon, or in a deeply embedded “‘hypercompact” region phase where dust attenuation of UV flux limits the region of ionized carbon to undetectably small volumes. Alternatively, its apparent lack of [C ii] emission may arise from deep absorption of the [C ii] line against the 158 μm continuum, or self-absorption of brighter line emission by foreground material, which might cancel or diminish any emission within the FIFI-LS instrument’s broad spectral resolution element ( km s−1).

Decision-based territorial life cycle assessment for the management of cement concrete demolition waste.

Existing territorial life cycle assessments (LCAs) consider all activities in a given geographical area, defined as the foreground system, but cannot lead to operational decisions. In product scale LCA, the foreground system is defined as the part of the system directly controlled by an actor and is thus more adapted to compare possible scenarios within a decision perimeter. The present paper uses that concept applied to a geographical area. The developed method consists of five steps: (a) definition of the foreground material flow analysis (MFA) or LCA system corresponding to the decision perimeter; (b) territorial MFA; (c) geo-location of activities and downscaling of territorial flows to individual activities; (d) calculation of local transport distances; and (e) calculation of LCA impact indicators. The case study concerns the management of primary and secondary resources of basic quality aggregates (BQAs) in the Loire-Atlantique department (France) in 2012. Our results show that the amount of recycled cement concrete is only 7% of total consumed BQAs, although 90% of cement concrete demolition waste (CCDW) is recycled. The environmental impacts are importantly related to off-site activities. Local impacts are mainly driven by the transport of aggregates. For land planning, a concentration of fewer recycling facilities with high authorised production capacities in main cities, close to where CCDW is mainly produced, would divide transport needs in half and thus considerably reduce environmental impacts.

Microdramas: Crucibles for Theater and Time by John H. Muse

Reviewed by: Microdramas: Crucibles for Theater and Time by John H. Muse Jill Stevenson Microdramas: Crucibles for Theater and Time. By John H. Muse. University of Michigan Press, 2017. Cloth $75.00, Paper $29.95, eBook $29.95. ix + 231 pages. In Microdramas, John H. Muse examines very short plays written between 1880 and the early twenty-first century to consider how playwrights have used brevity to experiment with theatre’s potential and, ultimately, to expose “temporal conventions that inform any theatrical performance” (2). Although Muse analyzes texts, with their length enabling him to reproduce several complete plays, he is primarily interested in what their performance reveals about the “temporal rhetoric of theater” (8). Consequently, “microdrama” is a historically contingent term defined as a play that is shorter than its audience anticipates based upon its “likely horizon of temporal expectation” (2). Shortness is always linked to how we measure time and, from the late nineteenth to early twenty-first centuries, rapid technological innovation has repeatedly reshaped experiences and understandings of time; microdramas are both responses to and manifestations of those transformations. But, as Muse demonstrates, the short play also functions as “a laboratory, a controlled space where time and action could be isolated and subjected to manipulation,” thereby exposing assumptions about dramatic form and spectatorship (5). Accordingly, this exceedingly readable book is valuable to theatre historians and makes a compelling contribution to the expanding body of scholarship on performance and temporality. In the introductory first chapter, Muse outlines his methodology, subjects, and—drawing upon recent theories of temporality and theatrical time—four concepts that will run throughout the book: “theatre’s spatialization of time, the heterogeneity of brief time, the riddle of uneventfulness, and the pace of absorption” (8). The rest of the book is organized chronologically, with each chapter focused on a specific movement or group of playwrights. Chapter 2 examines the birth of the modernist microdrama by analyzing theatrical faits-divers, a subset of the naturalist quart d’heure genre, alongside the symbolist one-act. While often situated as contrasting movements, this analysis of naturalism and symbolism’s use of brevity reveals paradoxes within these movements that expose their similarities. Muse argues that, when expressed in short form, naturalism’s concentrated verisimilitude does not foreground material specificity as much as encourage “spectators to imagine the stage as a space apart charged with symbolic meaning” (35). Likewise, a symbolist play like Maurice Maeterlinck’s Interior reveals how characters are subject to external material forces. In this respect, both genres “tend to create hollow characters overshadowed by their allegorical significance” (43). Moreover, by employing brevity the fait-divers and symbolist one-act both question what kind of experience qualifies as an event and, thus, as a play. This chapter effectively illustrates Muse’s larger project—to use microdramas as a lens to explore theatre’s core values and elements, and to show how temporal experimentation has been key to defining and challenging these. [End Page 130] Futurist short plays—sintesi, or syntheses—are the focus of chapter 3. Acknowledging the wide range of work that falls under this umbrella term, Muse sees them all sharing the characteristic of brevity. Rather than take at face value the impact of this theatrical tactic, Muse interrogates three futurist assumptions about brevity: “that it reflects modern speed and simultaneity, that it intensifies experience, and that it dismantles convention” (57). He argues that instead of a radical rejection of tradition, syntheses reveal “a set of practices far more entangled with tradition than their authors claimed” (57). This engaging, deeply researched account combines script analysis with evidence from treatises and art works to illuminate contradictions within futurist dramaturgy and “expose the movement’s conflicted relationship with theater” (89). Muse next turns to the dramaticules, or tiny dramas, by Samuel Beckett. Exploring Beckett’s “epistemology of limitation” (107), Muse shows how the playwright used extreme brevity to explore questions of narrative, language, memory, and representation, and, ultimately, to expose structures of time as mere fictions. In this way, Beckett uses theatrical reduction to ask how much time is necessary to create an event, a life, or a play. Muse ends this chapter with a discussion of duration...

First ALMA maps of HCO, an important precursor of complex organic molecules, towards IRAS 16293–2422

The formyl radical HCO has been proposed as the basic precursor of many complex organic molecules such as methanol (CH$_3$OH) or glycolaldehyde (CH$_2$OHCHO). Using ALMA, we have mapped, for the first time at high angular resolution ($\sim$1$^{\prime\prime}$, $\sim$140 au), HCO towards the Solar-type protostellar binary IRAS 16293$-$2422, where numerous complex organic molecules have been previously detected. We also detected several lines of the chemically related species H$_2$CO, CH$_3$OH and CH$_2$OHCHO. The observations revealed compact HCO emission arising from the two protostars. The line profiles also show redshifted absorption produced by foreground material of the circumbinary envelope that is infalling towards the protostars. Additionally, IRAM 30m single-dish data revealed a more extended HCO component arising from the common circumbinary envelope. The comparison between the observed molecular abundances and our chemical model suggests that whereas the extended HCO from the envelope can be formed via gas-phase reactions during the cold collapse of the natal core, the HCO in the hot corinos surrounding the protostars is predominantly formed by the hydrogenation of CO on the surface of dust grains and subsequent thermal desorption during the protostellar phase. The derived abundance of HCO in the dust grains is high enough to produce efficiently more complex species such as H$_2$CO, CH$_3$OH, and CH$_2$OHCHO by surface chemistry. We found that the main formation route of CH$_2$OHCHO is the reaction between HCO and CH$_2$OH.

Enhancement of Albedo for Solar Energy Gain with Particular Emphasis on Overcast Skies

In the absence of ground reflected radiation measured data, an average albedo value of 0.2, which describes the reflective properties of the bare ground is generally used. The variation of albedo based on different foreground surfaces and under different atmospheric conditions is an area which is under research. This paper presents an experimental investigation of albedos of different foreground materials that can be used for photovoltaic (PV) applications. Overcast skies are predominant in northerly locations and will have a high frequency of low solar altitudes, and thus ground reflection is an important contributor towards total solar energy gain. The foreground surfaces include common materials: Grass, sand, and cement slabs, and some non-conventional materials: White pebbles, white boards, white tiles, and aluminium foil. The impact of factors, such as ageing, solar elevation, rain, and cloud cover (sky conditions) is analysed to determine the changes in albedos of these materials. Each material was observed to have individual performance characteristics under these factors. It was found that the non-conventional materials were least prone to weather-related changes and have higher albedo values as compared to the conventional materials, and also have good potential to replace the conventional materials for any given PV application.

Water masers as signposts of extremely young planetary nebulae

AbstractOnly five planetary nebulae (PNe) have been confirmed to emit water masers. They seem to be very young PNe. The water emission in these objects preferentially traces circumstellar toroids, although in K 3-35 and IRAS 15103-5754, it may also trace collimated jets. We present water maser observations of these two sources at different epochs. The water maser distribution changes on timescales of months to a few years. We speculate that these changes may be due to the variation of the underlying radio continuum emission, which is amplified by the maser process in the foreground material.

η Carinae's Dusty Homunculus Nebula from Near-infrared to Submillimeter Wavelengths: Mass, Composition, and Evidence for Fading Opacity

Infrared observations of the dusty, massive Homunculus Nebula around the luminous blue variable η Carinae are crucial to characterize the mass-loss history and help constrain the mechanisms leading to the Great Eruption. We present the 2.4 - 670 μm spectral energy distribution, constructed from legacy ISO observations and new spectroscopy obtained with the Herschel Space Observatory. Using radiative transfer modeling, we find that the two best-fit dust models yield compositions which are consistent with CNO-processed material, with iron, pyroxene and other metal-rich silicates, corundum, and magnesium-iron sulfide in common. Spherical corundum grains are supported by the good match to a narrow 20.2 μm feature. Our preferred model contains nitrides AlN and Si3N4 in low abundances. Dust masses range from 0.25 to 0.44 M ʘ but M tot ≥ 45 M ʘ in both cases due to an expected high Fe gas-to-dust ratio. The bulk of dust is within a 5″ × 7″ central region. An additional compact feature is detected at 390 μm. We obtain L IR = 2.96 × 106 L ʘ, a 25% decline from an average of mid-IR photometric levels observed in 1971-1977. This indicates a reduction in circumstellar extinction in conjunction with an increase in visual brightness, allowing 25-40% of optical and UV radiation to escape from the central source. We also present an analysis of 12CO and 13CO J = 5 - 4 through 9 - 8 lines, showing that the abundances are consistent with expectations for CNO-processed material. The [12C II] line is detected in absorption, which we suspect originates in foreground material at very low excitation temperatures.

WL 17: A Young Embedded Transition Disk

Abstract We present the highest spatial resolution ALMA observations to date of the Class I protostar WL 17 in the ρ Ophiuchus L1688 molecular cloud complex, which show that it has a 12 au hole in the center of its disk. We consider whether WL 17 is actually a Class II disk being extincted by foreground material, but find that such models do not provide a good fit to the broadband spectral energy distribution (SED) and also require such high extinction that it would presumably arise from dense material close to the source, such as a remnant envelope. Self-consistent models of a disk embedded in a rotating collapsing envelope can nicely reproduce both the ALMA 3 mm observations and the broadband SED of WL 17. This suggests that WL 17 is a disk in the early stages of its formation, and yet even at this young age the inner disk has been depleted. Although there are multiple pathways for such a hole to be created in a disk, if this hole was produced by the formation of planets it could place constraints on the timescale for the growth of planets in protoplanetary disks.

TRACING THE MILKY WAY NUCLEAR WIND WITH 21 cm ATOMIC HYDROGEN EMISSION

ABSTRACT There is evidence in 21 cm H i emission for voids several kiloparsecs in size centered approximately on the Galactic center, both above and below the Galactic plane. These appear to map the boundaries of the Galactic nuclear wind. An analysis of H i at the tangent points, where the distance to the gas can be estimated with reasonable accuracy, shows a sharp transition at Galactic radii R ≲ 2.4 kpc from the extended neutral gas layer characteristic of much of the Galactic disk, to a thin Gaussian layer with FWHM ∼ 125 pc. An anti-correlation between H i and γ-ray emission at latitudes suggests that the boundary of the extended H i layer marks the walls of the Fermi Bubbles. With H i, we are able to trace the edges of the voids from down to z ≈ 0, where they have a radius ∼2 kpc. The extended Hi layer likely results from star formation in the disk, which is limited largely to R ≳ 3 kpc, so the wind may be expanding into an area of relatively little H i. Because the H i kinematics can discriminate between gas in the Galactic center and foreground material, 21 cm H i emission may be the best probe of the extent of the nuclear wind near the Galactic plane.

SODIUM ABSORPTION SYSTEMS TOWARD SN Ia 2014J ORIGINATE ON INTERSTELLAR SCALES*

ABSTRACT Na i D absorbing systems toward Type Ia supernovae (SNe Ia) have been intensively studied over the last decade with the aim of finding circumstellar material (CSM), which is an indirect probe of the progenitor system. However, it is difficult to deconvolve CSM components from non-variable, and often dominant, components created by interstellar material (ISM). We present a series of high-resolution spectra of SN Ia 2014J from before maximum brightness to ≳250 days after maximum brightness. The late-time spectrum provides unique information for determining the origin of the Na i D absorption systems. The deep late-time observation allows us to probe the environment around the SN at a large scale, extending to ≳40 pc. We find that a spectrum of diffuse light in the vicinity, but not directly in the line of sight, of the SN has absorbing systems nearly identical to those obtained for the “pure” SN line of sight. Therefore, basically all Na i D systems seen toward SN 2014J must originate from foreground material that extends to at least ∼40 pc in projection and none at the CSM scale. A fluctuation in the column densities at a scale of ∼20 pc is also identified. After subtracting the diffuse, “background” spectrum, the late-time Na i D profile along the SN line of sight is consistent with profiles near maximum brightness. The lack of variability on a ∼1 year timescale is consistent with the ISM interpretation for the gas.

Evidence for a toroidal magnetic-field component in 5C 4.114 on kiloparsec scales

A monotonic, statistically significant gradient in the observed Faraday Rotation Measure (RM) across the jet of an Active Galactic Nucleus (AGN) reflects a corresponding gradient in the electron density and/or line-of-sight magnetic (B) field. Such gradients may indicate the presence of a toroidal B field component, possibly associated with a helical jet B field. Although transverse RM gradients have been reported across a number of parsec-scale AGN jets, the same is not true on kiloparsec scales, suggesting that other (e.g. random) B-field components usually dominate on these larger scales. We have identified an extended, monotonic transverse RM gradient across the Northern lobe of a previously published Very Large Array (kiloparsec-scale) RM image of 5C4.114. We reanalyzed these VLA data in order to determine the significance of this RM gradient. The RM gradient across the Northern kiloparsec-scale lobe structure of 5C4.114 has a statistical significance of about 4sigma. There is also a somewhat less prominent monotonic transverse RM gradient across the Southern jet/lobe (significance ~ 3sigma). Other parts of the RM distribution observed across the source are patchy and show no obvious order.This suggests that we are observing a random RM component associated with the foreground material in the cluster in which the radio source is located and through which it is viewed, superposed on a more ordered RM component that arises in the immediate vicinity of the AGN jets. We interpret the transverse RM gradient as reflecting the systematic variations of the line-of-sight component of a helical or toroidal B field associated with the jets of 5C4.114. These results suggest that the helical field that arises due to the joint action of the rotation of the central black hole and its accretion disc and the jet outflow can survive to distances of thousands of parsec from the central engine.

First detection of [N II] 205μm absorption in interstellar gas

We present high resolution [N ii] 205 μm (3P1 − 3P0) spectra obtained with Herschel-HIFI towards a small sample of far-infrared bright star forming regions in the Galactic plane: W 31C (G10.6−0.4), W 49N (G43.2−0.1), W 51 (G49.5−0.4), and G34.3+0.1. All sources display an emission line profile associated directly with the H ii regions themselves. For the first time we also detect absorption of the [N ii] 205 μm line by extended low-density foreground material towards W 31C and W 49N over a wide range of velocities. We attribute this absorption to the warm ionised medium (WIM) and find N(N+) ≈ 1.5 × 1017 cm-2 towards both sources. This is in agreement with recent Herschel-HIFI observations of [C ii] 158 μm, also observed in absorption in the same sight-lines, if ≈7–10% of all C+ ions exist in the WIM on average. Using an abundance ratio of [N] / [H] = 6.76 × 10-5 in the gas phase we find that the mean electron and proton volume densities are ~0.1–0.3 cm-3 assuming a WIM volume filling fraction of 0.1–0.4 with a corresponding line-of-sight filling fraction of 0.46–0.74. A low density and a high WIM filling fraction are also supported by RADEX modelling of the [N ii] 205 μm absorption and emission together with visible emission lines attributed mainly to the WIM. The detection of the 205 μm line in absorption emphasises the importance of a high spectral resolution, and also offers a new tool for investigation of the WIM.

SN 2007uy – metamorphosis of an aspheric Type Ib explosion

The supernovae of Type Ibc are rare and the detailed characteristics of these explosions have been studied only for a few events. Unlike Type II SNe, the progenitors of Type Ibc have never been detected in pre-explosion images. So, to understand the nature of their progenitors and the characteristics of the explosions, investigation of proximate events are necessary. Here we present the results of multi-wavelength observations of Type Ib SN 2007uy in the nearby ($\sim$ 29.5 Mpc) galaxy NGC 2770. Analysis of the photometric observations revealed this explosion as an energetic event with peak absolute R band magnitude $-18.5\pm0.16$, which is about one mag brighter than the mean value ($-17.6\pm0.6$) derived for well observed Type Ibc events. The SN is highly extinguished, E(B-V) = 0.63$\pm$0.15 mag, mainly due to foreground material present in the host galaxy. From optical light curve modeling we determine that about 0.3 M$_{\odot}$ radioactive $^{56}$Ni is produced and roughly 4.4 M$_{\odot}$ material is ejected during this explosion with liberated energy $\sim 15\times10^{51}$ erg, indicating the event to be an energetic one. Through optical spectroscopy, we have noticed a clear aspheric evolution of several line forming regions, but no dependency of asymmetry is seen on the distribution of $^{56}$Ni inside the ejecta. The SN shock interaction with the circumburst material is clearly noticeable in radio follow-up, presenting a Synchrotron Self Absorption (SSA) dominated light curve with a contribution of Free Free Absorption (FFA) during the early phases. Assuming a WR star, with wind velocity $\ga 10^3 {\rm km s}^{-1}$, as a progenitor, we derive a lower limit to the mass loss rate inferred from the radio data as $\dot{M} \ga 2.4\times10^{-5}$ M$_{\odot}$, yr$^{-1}$, which is consistent with the results obtained for other Type Ibc SNe bright at radio frequencies.