Blackbody Function Research Articles

The ALMA-CRISTAL survey: Dust temperature and physical conditions of the interstellar medium in a typical galaxy at z = 5.66

We present new λrest = 77 μm dust continuum observations from the Atacama Large Millimeter/submillimeter Array of HZ10 (CRISTAL-22). This dusty main sequence galaxy at z = 5.66 was observed as part of the [CII] Resolved Ism in STar-forming Alma Large program (CRISTAL). The high angular resolution of the ALMA Band 7 and new Band 9 data (∼0′′​​.4) reveals the complex structure of HZ10, which comprises two main components (HZ10-C and HZ10-W), along with a bridge-like dusty emission between them (i.e., “the bridge”). Using a modified blackbody function to model the dust spectral energy distribution (SED), we constrained the physical conditions of the interstellar medium (ISM) and its variations among the different components identified in HZ10. We find that HZ10-W (the more UV-obscured component) has an SED dust temperature of TSED ∼ 51.2 ± 13.1 K; this was found to be ∼5 K higher (which is statistically insignificant; i.e., less than 1σ) than that of the central component and previous global estimations for HZ10. Our new ALMA data allow us to reduce the uncertainties of global TSED measurements by a factor of ∼2.3, compared to previous studies. The HZ10 components have [CII]-to-far-infrared (FIR) luminosity ratios and FIR surface densities values that are consistent with local starburst galaxies. However, HZ10-W shows a lower [CII]/FIR ratio compared to the other two components (albeit still within the uncertainties), which may suggest a harder radiation field destroying polycyclic aromatic hydrocarbon associated with [CII] emission (e.g., active galactic nuclei or young stellar populations). While HZ10-C appears to follow the tight IRX-βUV relation seen in local UV-selected starburst galaxies and high-z star-forming galaxies, we find that both HZ10-W and the bridge depart from this relation and are well described by dust-screen models with holes in front of a hard UV radiation field. This suggests that the UV emission, which is likely coming from young stellar populations, is strongly attenuated in the “dustier” components of the HZ10 system.

Evidence for Spatially Distinct Galactic Dust Populations

We present an implementation of a Bayesian mixture model using Hamiltonian Monte Carlo techniques to search for the spatial separation of Galactic dust populations. Utilizing intensity measurements from the Planck High Frequency Instrument, we apply this model to high-latitude Galactic dust emission. Our analysis reveals a strong preference for a spatially varying two-population dust model over a one-population dust model, when the latter must capture the total variance in the sky. Each dust population is well characterized by a single-component spectral energy distribution (SED) and accommodates small variations. These populations could signify two distinct components or may originate from a one-component model with different temperatures resulting in different SED scalings. While no spatial information is built into the likelihood, our investigation unveils large-scale spatially coherent structures with high significance, pointing to a physical origin for the observed spatial variation. These results are robust to our choice of likelihood and input data. Furthermore, this spatially varying two-population model is the most favored from Bayesian evidence calculations. Incorporating IRAS 100 μm to constrain the Wein side of the blackbody function, we find the dust populations differ at the 2.5σ level in the spectral index (β d ) versus temperature (T d ) plane. The presence of multiple dust populations has implications for component separation techniques frequently employed in the recovery of the cosmic microwave background.

Concise Spectrotemporal Studies of Magnetar SGR J1935+2154 Bursts

SGR J1935+2154 has truly been the most prolific magnetar over the last decade: it has been entering into burst active episodes once every 1–2 yr since its discovery in 2014, it emitted the first Galactic fast radio burst associated with an X-ray burst in 2020, and it has emitted hundreds of energetic short bursts. Here, we present the time-resolved spectral analysis of 51 bright bursts from SGR J1935+2154. Unlike conventional time-resolved X-ray spectroscopic studies in the literature, we follow a two-step approach to probe true spectral evolution. For each burst, we first extract spectral information from overlapping time segments, fit them with three continuum models, and employ a machine-learning-based clustering algorithm to identify time segments that provide the largest spectral variations during each burst. We then extract spectra from those nonoverlapping (clustered) time segments and fit them again with the three models: the cutoff power-law model, the sum of two blackbody functions, and the model considering the emission of a modified blackbody undergoing resonant cyclotron scattering, which is applied systematically at this scale for the first time. Our novel technique allowed us to establish the genuine spectral evolution of magnetar bursts. We discuss the implications of our results and compare their collective behavior with the average burst properties of other magnetars.

Application of absorption-line blackbody distribution functions for H2O-CO2 mixtures for the spectral integration of the radiative transfer equation with the SLW model

This study presents the generation and evaluation of absorption-line blackbody distribution functions for mixtures (ALBDF-M) of CO2 and H2O. These functions are employed in the spectral integration of the radiative transfer equation in the framework of the spectral line-based weighted-sum-of-gray-gases (SLW) model. The proposed approach avoids the need to model the mixture of gases when dealing with ALBDFs obtained for pure H2O and CO2 species, which is the methodology currently adopted in the SLW literature. The ALBDF-M can be used with any development of the SLW model to manage local variations of the thermodynamic state conditions. In the present study, both the rank (RC-) and the locally correlated (LC-) SLW methodologies are employed with the ALBDF-M for an uncouple solution of an axisymmetric field that is representative of the combustion of ethylene diluted with H2O. Comparisons with line-by-line (LBL) solutions show that using the ALBDF-M provides an improvement in the accuracy when compared to the standard methodology to combine the ALBDFs generated for CO2 and H2O individually.

Spectral and Jet Properties of the Quasi-thermal-dominated GRB 210121A, GRB 210610B, and GRB 221022B

Some quasi-thermal (QT)-dominated gamma-ray bursts (GRBs) could be well described by a multicolor blackbody (mBB) function or a combined model of a BB plus a nonthermal (NT) component. In this analysis, two QT radiation-dominated bursts with known emission properties (GRB 210610B, likely from a hybrid jet, and GRB 210121A, with a spectrum consistent with nondissipative photospheric emission from a pure hot fireball) are used to make a comparison between these two models. To diagnose the magnetization properties of the central engine, the “top-down” approach proposed by Gao and Zhang is adopted. It is found that diagnoses based on these two models provide similar conclusions qualitatively; however, the model with mBB (or mBB+NT) may give more reasonable physical explanations. This implies that impacts from the GRB jet structure and geometrical broadening on the observed spectrum should be considered. However, conservatively, these methods may be not sensitive enough to distinguish between a pure hot fireball and a mildly magnetized hybrid jet. Some other information is necessary to provide more evidence when determining the jet properties for similar GRBs. Based on these considerations, we suggest that the photospheric emission of GRB 221022B is from a hot jet, where dissipation is caused by an internal shock mechanism due to the increasing Lorentz factor with time, which makes its prompt emission display typical evolution from thermal to NT.

Bursts from High-magnetic-field Pulsars Swift J1818.0-1607 and PSR J1846.4-0258

The detection of magnetar-like bursts from highly magnetic (B > 1013 G) rotation-powered pulsars (RPPs) opened the magnetar population to yet another group of neutron stars. At the same time the question arose as to whether magnetar-like bursts from high-B RPPs have similar characteristics to bursts from known magnetar sources. We present here our analyses of the Fermi Gamma-ray Burst Monitor (GBM) data from two magnetar candidates, Swift J1818.0−1607 (a radio-loud magnetar) and PSR J1846.4−0258. Both sources entered active bursting episodes in 2020 triggering Fermi-GBM in 2020 and in early 2021. We searched for untriggered bursts from both sources and performed temporal and spectral analyses on all events. Here, we present the results of our comprehensive burst search and analyses. We identified 37 and 58 bursts that likely originated from Swift J1818.0−1607 and PSR J1846.4−0258, respectively. We find that the bursts from these sources are shorter on average than typical magnetar bursts. In addition, their spectra are best described with a single blackbody function with kT ∼ 10–11 keV; several relatively bright events, however, show higher energy emission that could be modeled with a cutoff power-law model. We find that the correlation between the blackbody emitting area and the spectral temperature for the burst ensemble of each pulsar deviates from the ideal Stefan–Boltzmann law, as it does for some burst-active magnetars. We interpret this characteristic as being due to the significant radiation anisotropy expected from optically thick plasmas in very strong magnetic fields.

The dusty heart of Circinus

Context. Active galactic nuclei play a key role in the evolution of galaxies, but their inner workings and physical connection to the host are poorly understood due to a lack of angular resolution. Infrared interferometry makes it possible to resolve the circumnuclear dust in the nearby Seyfert 2 galaxy, the Circinus Galaxy. Previous observations have revealed complex structures and polar dust emission but interpretation was limited to simple models. The new Multi AperTure mid-Infrared Spectro-Scopic Experiment (MATISSE) makes it possible to image these structures for the first time. Aims. We aim to precisely map the morphology and temperature of the dust surrounding the supermassive black hole through interferometric imaging. Methods. We observed the Circinus Galaxy with MATISSE at the Very Large Telescope Interferometer (VLTI), producing 150 correlated flux spectra and 100 closure phase spectra. The novel inclusion of closure phases makes interferometric imaging possible for the first time. We reconstructed images in the N-band at ∼10 mas resolution. We fit blackbody functions with dust extinction to several aperture-extracted fluxes from the images to produce a temperature distribution of central dusty structures. Results. We find significant substructure in the circumnuclear dust: central unresolved flux of ∼0.5 Jy, a thin disk 1.9 pc in diameter oriented along ∼45°, and a ∼4 × 1.5 pc polar emission extending orthogonal to the disk. The polar emission exhibits patchiness, which we attribute to clumpy dust. Flux enhancements to the east and west of the disk are seen for the first time. We distinguish the temperature profiles of the disk and of the polar emission: the disk shows a steep temperature gradient indicative of denser material; the polar profile is flatter, indicating clumpiness and/or lower dust density. The unresolved flux is fitted with a high temperature, ∼370 K. The polar dust remains warm (∼200 K) out to 1.5 pc from the disk. We attribute approximately 60% of the 12 μm flux to the polar dust, 10% to the disk, and 6% is unresolved; the remaining flux was resolved out. The recovered morphology and temperature distribution resembles modeling of accretion disks with radiation-driven winds at large scales, but we placed new constraints on the subparsec dust. Conclusions. The spatially resolved subparsec features imaged here place new constraints on the physical modeling of circumnuclear dust in active galaxies; we show strong evidence that the polar emission consists of dust clumps or filaments. The dynamics of the structures and their role in the Unified Model remain to be explored.

Transient Joule- and (ac) Josephson-like photon emission in one- and two- nucleon tunneling processes between superfluid nuclei: Blackbody and coherent spectral functions

Effective charged neutrons involved in one- and two- nucleon tunneling processes in heavy ion collisions between superfluid nuclei are expected to emit photons. Although the centroid, width and integrated energy area characterizing the associated gamma-strength functions are rather similar, the corresponding line shapes reflect the thermal equilibrated-like character of the quasiparticle transfer (1n-channel, blackbody spectral functional dependence), and the quantal coherent character of the Cooper pair transfer (2n-channel, Gaussian functional dependence) respectively. The predicted angular distributions, polarizations and analyzing power provide further insight into the profoundly different physics to be found at the basis of what can be considered a transient Joule-like and a (ac) Josephson-like nuclear processes

A Comprehensive Study of Bright Fermi-GBM Short Gamma-ray Bursts: I. Multi-Pulse Lightcurves and Multi-Component Spectra

Sorted by the photon fluences of short Gamma-ray Bursts (SGRBs) detected by the Fermi-Gamma Ray Burst Monitor (GBM), nine brightest bursts are selected to perform a comprehensive analysis. All GRB lightcurves are fitted well by 1 to 3 pulses that are modelled by fast-rising exponential decay profile (FRED), within which the resultant rising time is strongly positive-correlated with the full time width at half maxima (FWHM). A photon spectral model involving a cutoff power-law function and a standard blackbody function (CPL + BB) could reproduce the spectral energy distributions of these SGRBs well in the bursting phase. The CPL’s peak energy is found strongly positive-correlated with the BB’s temperature, which indicates they might be from the same physical origin. Possible physical origins are discussed to account for these correlations.

Characterization of dense Planck clumps observed with Herschel and SCUBA-2

Context. Although the basic processes of star formation (SF) are known, more research is needed on SF across multiple scales and environments. The Planck all-sky survey provided a large catalog of Galactic cold clouds and clumps that have been the target of several follow-up surveys. Aims. We aim to characterize a diverse selection of dense, potentially star-forming cores, clumps, and clouds within the Milky Way in terms of their dust emission and SF activity. Methods. We studied 53 fields that have been observed in the JCMT SCUBA-2 continuum survey SCOPE and have been mapped with Herschel. We estimated dust properties by fitting Herschel observations with modified blackbody functions, studied the relationship between dust temperature and dust opacity spectral index β, and estimated column densities. We extracted clumps from the SCUBA-2 850 μm maps with the FellWalker algorithm and examined their masses and sizes. Clumps are associated with young stellar objects found in several catalogs. We estimated the gravitational stability of the clumps with virial analysis. The clumps are categorized as unbound starless, prestellar, or protostellar. Results. We find 529 dense clumps, typically with high column densities from (0.3–4.8) × 1022 cm−2, with a mean of (1.5 ± 0.04) ×1022 cm−2, low temperatures (T ∼ 10–20 K), and estimated submillimeter β = 1.7 ± 0.1. We detect a slight increase in opacity spectral index toward millimeter wavelengths. Masses of the sources range from 0.04 M⊙ to 4259 M⊙. Mass, linear size, and temperature are correlated with distance. Furthermore, the estimated gravitational stability is dependent on distance, and more distant clumps appear more virially bound. Finally, we present a catalog of properties of the clumps. Conclusions. Our sources present a large array of SF regions, from high-latitude, nearby diffuse clouds to large SF complexes near the Galactic center. Analysis of these regions will continue with the addition of molecular line data, which will allow us to study the densest regions of the clumps in more detail.

GRB 130310A: very high peak energy and thermal emission

The special GRB 130310A was observed by Fermi Gamma-Ray Burst Monitor and Large Area Telescope, with T 90∼ 2.4 s. With a combination of a Band function and a blackbody (BB) function, the time-resolved spectral analysis of GRB 130310A confirmed that there is a sub-dominate thermal component in the early period (e.g., slice T 0 + [4.03 – 4.14] s) spectrum with BB temperature (kT) being ∼7∼5 keV, which can be interpreted as photosphere emission. The precursor of GRB 130310A can be fitted well with a BB component with kT ∼ 45 keV, which is higher than that of the main burst. It suggests that the radiation of GRB 130310A is in transition from thermal to non-thermal. Such a transition is an indication of the change in jet composition from a fireball to a Poynting-flux-dominated jet. A very high peak energy is obtained in the first time bin, with the peak energy Ep of the Band component for Band+BB and Band model being ∼8.5∼5.2 MeV and ∼11.1∼7.4 MeV, respectively. Afterwards, the Ep drops to ∼ 1 MeV. The Ep evolution patterns with respect to the pulses in the GRB 130310A light curves show a hard-to-soft evolution. The interpretation of the high peak energy Ep within the photosphere and internal shock model is difficult. It also suggests that at least for some bursts, the Band component must invoke a non-thermal origin in the optically thin region of a GRB outflow. Assuming the redshift is z ∼ 0.1 ∼ 8, the radius of the jet base r 0 ∼ 109 cm to allow (1 + σ 15) > 1 in line with the calculation results of the magnetization parameter at ∼1015 cm (σ 15). However, the value of (1 + σ 15) is ≃ 1 in the zone z around 3 for r 0 ∼ 109 cm, suggesting the non-excluded possibility that the origin is from ICMART with a low value. The photosphere-internal shock seems capable of interpreting the high peak energy, which requires electron Lorentz factor γe ∼ 60 and εe ∼ 0.06.

Panchromatic properties of the extreme Fe ii emitter PHL 1092

ABSTRACT We present near-infrared spectroscopy of the NLS1 galaxy PHL 1092 (z = 0.394), the strongest Fe ii emitter ever reported, combined with optical and UV data. We modelled the continuum and the broad emission lines using a power-law plus a blackbody function and Lorentzian functions, respectively. The strength of the Fe ii emission was estimated using the latest Fe ii templates in the literature. We re-estimate the ratio between the Fe ii complex centred at 4570 Å and the broad component of H β, R4570, obtaining a value of 2.58, nearly half of that previously reported (R4570 = 6.2), but still placing PHL 1092 among extreme Fe ii emitters. The full width at half-maximum (FWHM) values found for low-ionization lines are very similar (FWHM ∼ 1200 km s−1), but significantly narrower than those of the hydrogen lines (FWHMH β ∼ 1900 km s−1). Our results suggest that the Fe ii emission in PHL 1092 follows the same trend as in normal Fe ii emitters, with Fe ii being formed in the outer portion of the BLR and co-spatial with Ca ii, and O i, while H β is formed closer to the central source. The flux ratio between the UV lines suggests high densities, log(nH) ∼ 13.0 cm−3, and a low ionization parameter, log(U) ∼ −3.5. The flux excess found in the Fe ii bump at 9200 Å after the subtraction of the NIR Fe ii template and its comparison with optical Fe ii emission suggests that the above physical conditions optimize the efficiency of the Ly α-fluorescence process, which was found to be the main excitation mechanism in the Fe ii production. We discuss the role of PHL 1092 in the eigenvector 1 context.

Burst Properties of the Most Recurring Transient Magnetar SGR J1935+2154

Abstract We present timing and time-integrated spectral analysis of 127 bursts from SGR J1935+2154. These bursts were observed with the Gamma-ray Burst Monitor on the Fermi Gamma-ray Space Telescope and the Burst Alert Telescope on the Neil Gehrels Swift Observatory during the source’s four active episodes from 2014 to 2016. This activation frequency makes SGR J1935+2154 the most burst prolific transient magnetar. We find the average duration of all the detected bursts to be much shorter than the typical, anticipated value. We fit the burst time-integrated spectra with two blackbody functions, a Comptonized model and three other simpler models. Bursts from SGR J1935+2154 exhibit similar spectral properties to other magnetars, with the exception of the power-law index from the Comptonized model, which correlates with burst fluence. We find that the durations and both blackbody temperatures of the bursts have significantly evolved across the four active episodes. We also find that the burst time history exhibits two trends, which are strongly correlated with the decay of the persistent emission in each outburst.

ALMA Imaging of the CO (7–6) Line Emission in the Submillimeter Galaxy LESS 073 at z = 4.755*

Abstract In this paper we present our imaging observations on the CO (7−6) line and its underlying continuum emission of the young submillimeter galaxy LESS 073 at redshift 4.755, using the Atacama Large Millimeter/submillimeter Array. At the achieved resolution of ∼ (8 × 6 kpc2), the CO (7−6) emission is largely unresolved (with a deconvolved size of ), and the continuum emission is totally unresolved. The CO (7−6) line emission has an integrated flux of 0.86 ± 0.08 Jy km s−1, and a line width of 343 ± 40 km s−1. The continuum emission has a flux density of 0.51 mJy. By fitting the observed far-infrared spectral energy distribution (SED) of LESS 073 with a single-temperature modified blackbody function, we obtained a dust temperature K, 60–100 μm flux density ratio , and total infrared luminosity . The SED-fit-based is consistent with those estimated from various line ratios as advocated by our earlier work, indicating that the proposed line-ratio-based method can be used to practically derive for high-z sources. The total molecular gas mass of LESS 073 is , and the inferred gas depletion time is about 43 Myr.

The Carnegie Supernova Project II

Supernova LSQ13abf was discovered soon after explosion by the La Silla-QUEST Survey and then followed by the Carnegie Supernova Project II at its optical and near-IR wavelengths. Our analysis indicates that LSQ13abf was discovered within two days of explosion and its first ≈10 days of evolution reveal a B-band light curve with an abrupt drop in luminosity. Contemporaneously, the V-band light curve exhibits a rise towards a first peak and the r- and i-band light curves show no early peak. The early light-curve evolution of LSQ13abf is reminiscent of the post-explosion cooling phase observed in the Type Ib SN 2008D, and the similarity between the two objects extends over weeks. Spectroscopically, LSQ13abf also resembles SN 2008D, with P Cygni He I features that strengthen over several weeks. Spectral energy distributions are constructed from the broad-bandphotometry, a UVOIR light curve is constructed by fitting black-body (BB) functions, and the underlying BB-temperature and BB-radius profiles are estimated. Explosion parameters are estimated by simultaneously fitting an Arnett model to the UVOIR light curve and the velocity evolution derived from spectral features, and an in addition to a post-shock breakout cooling model to the first two epochs of the bolometric evolution. This combined model suggests an explosion energy of 1.27 ± 0.23 × 1051 ergs, in addition to a relatively high ejecta mass of 5.94 ± 1.10 M⊙, a 56Ni mass of 0.16 ± 0.02 M⊙, and a progenitor-star radius of 28.0 ± 7.5 R⊙. The ejecta mass suggests the origins of LSQ13abf lie with a > 25 M⊙ zero-age-main-sequence mass progenitor and its estimated radius is three times larger compared to the result obtained from the same analysis applied to observations of SN 2008D, and nine times larger compared to SN 1999ex. Alternatively, a comparison of hydrodynamical simulations of ≳20−25 M⊙ zero-age-main-sequence progenitors that evolve to pre-supernova envelope masses of ≲10 M⊙ and extended (∼100 R⊙) envelopes also broadly match the observations of LSQ13abf.

The dust mass function from z ∼0 to z ∼2.5

ABSTRACT We derive for the first time the dust mass function (DMF) in a wide redshift range, from z ∼ 0.2 up to z ∼ 2.5. In order to trace the dust emission, we start from a far-IR (160-μm) Herschel selected catalogue in the COSMOS field. We estimate the dust masses by fitting the far-IR data (λrest$\,\, \buildrel\gt \over \sim \,\,$50 μm) with a modified black body function and we present a detailed analysis to take into account the incompleteness in dust masses from a far-IR perspective. By parametrizing the observed DMF with a Schechter function in the redshift range 0.1 < z ≤ 0.25, where we are able to sample faint dust masses, we measure a steep slope (α ∼1.48), as found by the majority of works in the Local Universe. We detect a strong dust mass evolution, with $M_{\rm d}^{\star }$ at z ∼ 2.5 almost 1 dex larger than in the local Universe, combined with a decrease in their number density. Integrating our DMFs, we estimate the dust mass density (DMD), finding a broad peak at z ∼ 1, with a decrease by a factor of ∼ 3 towards z ∼ 0 and z ∼ 2.5. In general, the trend found for the DMD mostly agrees with the derivation of Driver et al., another DMD determination based also on far-IR detections, and with other measures based on indirect tracers.

30-micron sources in galaxies with different metallicities

Aims. We present an analysis and comparison of the 30 μm dust features seen in the Spitzer Space Telescope spectra of 207 carbon-rich asymptotic giant branch (AGB) stars, post-AGB objects, and planetary nebulae (PNe) located in the Milky Way, the Magellanic Clouds (MCs), or the Sagittarius dwarf spheroidal galaxy (Sgr dSph), which are characterised by different average metallicities. We investigated whether the formation of the 30 μm feature carrier may be a function of the metallicity. Through this study we expect to better understand the late stages of stellar evolution of carbon-rich stars in these galaxies. Methods. Our analysis uses the “Manchester method” as a basis for estimating the temperature of dust for the carbon-rich AGB stars and the PNe in our sample. For post-AGB objects we changed the wavelength ranges used for temperature estimation, because of the presence of the 21 μm feature on the short wavelength edge of the 30 μm feature. We used a black-body function with a single temperature deduced from the Manchester method or its modification to approximate the continuum under the 30 μm feature. Results. We find that the strength of the 30 μm feature increases until dust temperature drops below 400 K. Below this temperature, the large loss of mass and probably the self-absorption effect reduces the strength of the feature. During the post-AGB phase, when the intense mass-loss has terminated, the optical depth of the circumstellar envelope is smaller, and the 30 μm feature becomes visible again, showing variety of values for post-AGB objects and PNe, and being comparable with the strengths of AGB stars. In addition, the AGB stars and post-AGB objects show similar values of central wavelengths – usually between 28.5 and 29.5 μm. However, in case of PNe the shift of the central wavelength towards longer wavelengths is visible. The normalised median profiles for AGB stars look uniformly for various ranges of dust temperature, and different galaxies. We analysed the profiles of post-AGB objects and PNe only within one dust temperature range (below 200 K), and they were also similar in different galaxies. In the spectra of 17 PNe and five post-AGB objects we found the broad 16–24 μm feature. Two objects among the PNe group are the new detections: SMP LMC 51, and SMP LMC 79, whereas in the case of post-AGBs the new detections are: IRAS 05370-7019, IRAS 05537-7015, and IRAS 21546+4721. In addition, in the spectra of nine PNe we found the new detections of 16–18 μm feature. We also find that the Galactic post-AGB object IRAS 11339-6004 has a 21 μm emission. Finally, we have produced online catalogues of photometric data and Spitzer IRS spectra for all objects that show the 30 μm feature. These resources are available online for use by the community. Conclusions. The most important conclusion of our work is the fact that the formation of the 30 μm feature is affected by metallicity. Specifically that, as opposed to more metal-poor samples of AGB stars in the MCs, the feature is seen at lower mass-loss rates, higher temperatures, and has seen to be more prominent in Galactic carbon stars. The averaged feature (profile) in the AGB, post-AGB objects, and PNe seems unaffected by metallicity at least between a fifth and solar metallicity, but in the case of PNe it is shifted to significantly longer wavelengths.

Lyman Continuum Observations of Solar Flares Using SDO/EVE

Abstract The Extreme ultraviolet Variability Experiment (EVE) was designed to observe the Sun-as-a-star in the extreme ultraviolet—a wavelength range that has remained spectrally unresolved for many years. It has provided a wealth of data on solar flares, perhaps most uniquely, on the Lyman spectrum of hydrogen at high cadence and moderate spectral resolution. In this paper, we concentrate on the analysis of Lyman continuum (LyC) observations and their temporal evolution in a sample of six major solar flares. By fitting both the pre-flare and flare excess spectra with a blackbody function, we show that the color temperature derived from the slope of LyC reveals temperatures in excess of 104 K in the six events studied—an increase of a few thousand Kelvin above quiet-Sun values (typically ∼8000–9500 K). This was found to be as high as 17000 K for the 2017 September 6 X9.3 flare. Using these temperature values, and assuming a flaring area of 1018 cm2, estimates of the departure coefficient of hydrogen, b 1, were calculated. It was found that b 1 decreased from 102–103 in the quiet-Sun, to around unity during the flares. This implies that LyC is optically thick and formed in local thermodynamic equilibrium during flares. It also emanates from a relatively thin (≲100 km) shell formed at deeper, denser layers than in the quiescent solar atmosphere. We show that in terms of temporal coverage and resolution, EVE provides a more comprehensive picture of the response of the chromosphere to the flare energy input with respect to those of the Skylab/Harvard College Observatory spatially resolved observations of the 1970s.

Properties of Konus-Wind SGR bursts

We present preliminary results of systematic temporal and spectral analysis of the Konus-Wind observational data on short and intermediate SGR bursts. We conclude that the burst energy spectra are equally well described, in the 20 − 200 keV range, by both power-law with an exponential cutoff, and double black-body functions. We also discuss energetics and durations of the bursts, distributions of the spectral parameters and correlations between them.

Precessing Jet and Large Dust Grains in the V380 Ori NE Star-forming Region

The V380 Ori NE bipolar outflow was imaged in the SiO and CO lines, and dense cores in L1641 were observed in the 2.0–0.89 mm continuum. The highly collimated SiO jet shows point-symmetric oscillation patterns in both position and velocity, which suggests that the jet axis is precessing and the driving source may belong to a non-coplanar binary system. By considering the position and velocity variabilities together, accurate jet parameters were derived. The protostellar system is viewed nearly edge-on, and the jet has a flow speed of ∼35 km s−1 and a precession period of ∼1600 years. The CO outflow length gives a dynamical timescale of ∼6300 years, and the protostar must be extremely young. The inferred binary separation of 6–70 au implies that this protobinary system may have been formed through the disk instability process. The continuum spectra of L1641 dense cores indicate that the emission comes from dust, and the fits with modified blackbody functions give emissivity power indices of β = 0.3–2.2. The emissivity index shows a positive correlation with the molecular line width, but no strong correlation with bolometric luminosity or temperature. V380 Ori NE has a particularly low value of β = 0.3, which tentatively suggests the presence of millimeter-sized dust grains. Because the dust growth takes millions of years, much longer than the protostellar age, this core may have produced large grains in the starless core stage. HH 34 MMS and HH 147 MMS also have low emissivity indices.