PACS and SPIRE range spectroscopy of cool, evolved stars

Context: At the end of their lives AGB stars are prolific producers of dust and gas. The details of this mass-loss process are still not understood very well. Herschel PACS and SPIRE spectra offer a unique way of investigating properties of AGB stars in general and the mass-loss process in particular. Methods: The HIPE software with the latest calibration is used to process the available PACS and SPIRE spectra of 40 evolved stars. The spectra are convolved with the response curves of the PACS and SPIRE bolometers and compared to the fluxes measured in imaging data of these sources. Custom software is used to identify lines in the spectra, and to determine the central wavelengths and line intensities. Standard molecular line databases are used to associate the observed lines. Because of the limited spectral resolution of the spectrometers several known lines are typically potential counterparts to any observed line. To help identifications the relative contributions in line intensity of the potential counterpart lines are listed for three characteristic temperatures based on LTE calculations and assuming optically thin emission. Result: The following data products are released: the reduced spectra, the lines that are measured in the spectra with wavelength, intensity, potential identifications, and the continuum spectra, i.e. the full spectra with all identified lines removed. As simple examples of how this data can be used in future studies we have fitted the continuum spectra with three power laws and find that the few OH/IR stars seem to have significantly steeper slopes than the other oxygen- and carbon-rich objects in the sample. As another example we constructed rotational diagrams for CO and fitted a two-component model to derive rotational temperatures.Comment: A&A accepte

An ALMA view of CS and SiS around oxygen-rich AGB stars

We aim to determine the distributions of molecular SiS and CS in the circumstellar envelopes of oxygen-rich asymptotic giant branch stars and how these distributions differ between stars that lose mass at different rates. In this study we analyse ALMA observations of SiS and CS emission lines for three oxygen-rich galactic AGB stars: IK Tau, with a moderately high mass-loss rate of $5\times10^{-6}$M$_\odot$ yr$^{-1}$, and W Hya and R Dor with low mass loss rates of $\sim1\times10^{-7}$M$_\odot$ yr$^{-1}$. These molecules are usually more abundant in carbon stars but the high sensitivity of ALMA allows us to detect their faint emission in the low mass-loss rate AGB stars. The high spatial resolution of ALMA also allows us to precisely determine the spatial distribution of these molecules in the circumstellar envelopes. We run radiative transfer models to calculate the molecular abundances and abundance distributions for each star. We find a spread of peak SiS abundances with $\sim10^{-8}$ for R Dor, $\sim10^{-7}$ for W Hya, and $\sim3\times10^{-6}$ for IK Tau relative to H$_2$. We find lower peak CS abundances of $\sim7\times10^{-9}$ for R Dor, $\sim7\times10^{-8}$ for W Hya and $\sim4\times10^{-7}$ for IK Tau, with some stratifications in the abundance distributions. For IK Tau we also calculate abundances for the detected isotopologues: C$^{34}$S, $^{29}$SiS, $^{30}$SiS, Si$^{33}$S, Si$^{34}$S, $^{29}$Si$^{34}$S, and $^{30}$Si$^{34}$S. Overall the isotopic ratios we derive for IK Tau suggest a lower metallicity than solar.Comment: 16 page

The unusual 3D distribution of NaCl around the AGB star IK Tau

NaCl is a diatomic molecule with a large dipole moment, which allows for its detection even at relatively small abundances. It has been detected towards several evolved stars, among which is the AGB star IK Tau, around which it is distributed in several clumps that lie off-center from the star. We aim to study the three-dimensional distribution of NaCl around the AGB star IK Tau, and to obtain the abundance of NaCl relative to H$_2$ for each of the clumps. First, a new value for the maximum expansion velocity is determined. The observed ALMA channel maps are then deprojected to create a three-dimensional model of the distribution of NaCl. This model is then used as input for the radiative transfer modelling code magritte, which is used to obtain the NaCl abundances of each of the clumps by comparing the observations with the results of the magritte simulations. Additionally, the rotational temperature of the clumps is determined using population diagrams. We derive an updated value for the maximum expansion velocity of IK Tau $\upsilon_\mathrm{exp}$ = 28.4 km/s. A spiral-like shape can be discerned in our three-dimensional distribution model of the NaCl. This spiral lies more or less in the plane of the sky. The distribution is also flatter in the line-of-sight direction than in the plane of the sky. We find clump abundances between $9 \times 10^{-9}$ and $5 \times 10^{-8}$ relative to H$_2$, where the relative abundance is typically lower for clumps closer to the star. For the first time, we used deprojection to understand the three-dimensional environment of an AGB star and calculated the fractional abundance of NaCl in clumps surrounding the star.Comment: Accepted for publication in A&

New observations and models of circumstellar CO line emission of AGB stars in the Herschel SUCCESS programme

CONTEXT: Asymptotic giant branch (AGB) stars are in one of the latest evolutionary stages of low to intermediate-mass stars. Their vigorous mass loss has a significant effect on the stellar evolution, and is a significant source of heavy elements and dust grains for the interstellar medium. The mass-loss rate can be well traced by carbon monoxide (CO) line emission. AIMS: We present new Herschel HIFI and IRAM 30m telescope CO line data for a sample of 53 galactic AGB stars. The lines cover a fairly large range of excitation energy from the $J=1\to0$ line to the $J=9\to8$ line, and even the $J=14\to13$ line in a few cases. We perform radiative transfer modelling for 38 of these sources to estimate their mass-loss rates. METHODS: We used a radiative transfer code based on the Monte Carlo method to model the CO line emission. We assume spherically symmetric circumstellar envelopes that are formed by a constant mass-loss rate through a smoothly accelerating wind. RESULTS: We find models that are consistent across a broad range of CO lines for most of the stars in our sample, i.e., a large number of the circumstellar envelopes can be described with a constant mass-loss rate. We also find that an accelerating wind is required to fit, in particular, the higher-J lines and that a velocity law will have a significant effect on the model line intensities. The results cover a wide range of mass-loss rates ($\sim 10^{-8}$ to $2\times 10^{-5}~\mathrm{M}_\odot~\mathrm{ yr}^{-1}$) and gas expansion velocities (2 to $21.5$ km s$^{-1}$), and include M-, S-, and C-type AGB stars. Our results generally agree with those of earlier studies, although we tend to find slightly lower mass-loss rates by about 40%, on average. We also present "bonus" lines detected during our CO observations.Comment: 36 page

An ALMA view of SO and SO2_2 around oxygen-rich AGB stars

We present and analyse SO and SO$_2$, recently observed with high angular resolution and sensitivity in a spectral line survey with ALMA, for two oxygen-rich AGB stars: the low mass-loss rate R Dor and high mass-loss rate IK Tau. We analyse 8 lines of SO detected towards both stars, 78 lines of SO$_2$detected towards R Dor and 52 lines of SO$_2$ detected towards IK Tau. We detect several lines of $^{34}$SO, $^{33}$SO and $^{34}$SO$_2$ towards both stars, and tentatively S$^{18}$O towards R Dor, and hence derive isotopic ratios for these species. The spatially resolved observations show us that the two sulphur oxides are co-located towards R Dor and trace out the same wind structures in the circumstellar envelope (CSE). Much of the emission is well reproduced with a Gaussian abundance distribution spatially centred on the star. Emission from the higher energy levels of SO and SO$_2$ towards R Dor provide evidence in support of a rotating inner region of gas identified in earlier work. The new observations allow us to refine the abundance distribution of SO in IK Tau derived from prior observations with single antennas, and confirm the distribution is shell-like with the peak in the fractional abundance not centred on the star. The confirmation of different types of SO abundance distributions will help fine-tune chemical models and allows for an additional method to discriminate between low and high mass-loss rates for oxygen-rich AGB stars.Comment: Accepted for publication in MNRA

Rotational spectra of vibrationally excited AlO and TiO in oxygen rich stars

Rotational transitions in vibrationally excited AlO and TiO -- two possible precursors of dust -- were observed in the 300 GHz range (1 mm wavelength) towards the oxygen rich AGB stars R Dor and IK Tau with ALMA, and vibrationally excited AlO was observed towards the red supergiant VY CMa with the SMA. The $J=11 \to 10$ transition of TiO in the $v=1~{\rm{and}}~2$ levels, and the $N = 9 \to 8$ transition in the $v=2$ level of AlO were identified towards R Dor; the $J=11 \to 10$ line of TiO was identified in the $v=1$ level towards IK Tau; and two transitions in the $v=1~{\rm{and}}~2$ levels of AlO were identified towards VY CMa. The newly-derived high vibrational temperature of TiO and AlO in R Dor of $1800 \pm 200$ K, and prior measurements of the angular extent confirm that the majority of the emission is from a region within $\lesssim2R_{\star}$ of the central star. A full radiative transfer analysis of AlO in R Dor yielded a fractional abundance of $\sim$3% of the solar abundance of Al. From a similar analysis of TiO a fractional abundance of $\sim78$% of the solar abundance of Ti was found. The observations provide indirect evidence that TiO is present in a rotating disk close to the star. Further observations in the ground and excited vibrational levels are needed to determine whether AlO, TiO, and TiO$_2$ are seeds of the Al$_2$O$_3$ dust in R Dor, and perhaps in the gravitationally bound dust shells in other AGB stars with low mass loss rates.Comment: Accepted for publication in Ap

Отдаленные исходы реваскуляризации миокарда и мозга при помощи чрескожных коронарных вмешательств и каротидной эндартерэктомии в гибридном и поэтапном режимах

Aim To evaluate in-hospital and long-term outcomes of myocardial and cerebral revascularization with combined or staged PCI and carotid endarterectomy.Methods.263 myocardial and cerebral revascularizations with PCI and CEA in patients with combined cerebral and coronary artery lesions in the period from 2011 to 2017 were performed. Patients were divided into two groups depending on the surgical strategy. Patient (n = 133) who underwent a staged intervention (CEA and PCI) were included in Group 1, whereas patients (n = 130) who underwent a hybrid intervention (CEE+PCI CA) were included in Group 2. The mean follow-up was 3.5 years.Results.100% of patients in Group 2 underwent coronary and internal carotid revascularization according to the results of in-hospital and long-term follow-up. 81.35% of patient in Group 1 underwent PCI and CEA, whereas 3.01% of patients underwent only PCI and 6.77% of patients – CEA. 1.5% of patients in Group 1 did not receive any surgical treatment. The most common causes of incomplete revascularization were the subsequent change of the initially defined treatment for myocardial (6.02%) or cerebral revascularization (0.75%). The rest refused the second stage, or it was associated with extremely high risk and the strategy was switched to the conservative therapy.Conclusion.100% of patients received hybrid myocardial and cerebral revascularization during one hospitalization. It allowed reducing mortality from MI and stroke during the waiting period for the next stage of the treatment in Group 1 (almost 5%). Hybrid interventions can be used in patients with high risk for open-heart surgery, severe comorbidities (obesity, diabetes, renal dysfunction), significant coronary and cerebral artery lesions with high risk of MI and stroke. However, hybrid approach was associated with high rate (almost 7%) of non-fatal MI in the long-term follow-up.Цель.Оценка госпитальных и отдаленных исходов реваскуляризации головного мозга и миокарда при помощи чрескожного коронарного вмешательства (ЧКВ) и каротидной эндартерэктомии (КЭЭ) в поэтапном и гибридном режимах.Материалы и методы.С 2011 по 2017 г. выполнено 263 реваскуляризации миокарда и головного мозга с использованием ЧКВ и КЭЭ у пациентов с мультифокальным атеросклерозом с сочетанным поражением церебральных и коронарных артерий. В зависимости от выбранных стратегий лечения пациенты были разделены на две группы: 1-я группа (n = 133) – поэтапные вмешательства (КЭЭ и ЧКВ); 2-я группа (n = 130) – гибридные вмешательства (КЭЭ + ЧКВ). Средний период наблюдения составил 3,5 года.Результаты.В группе гибридных операций реваскуляризация двух сосудистых бассейнов (коронарных и внутренних сонных артерий) выполнена в 100% случаев. В группе поэтапной тактики полный объем запланированной реваскуляризации получили лишь 81,35% пациентов, тогда как в 3,01% случаев выполнено только ЧКВ, в 6,77% случаев – только КЭЭ, а в 1,5% – не выполнен ни один этап реваскуляризации. Самыми распространенными причинами неполной реваскуляризации явились изменение тактики реваскуляризации миокарда (6,02%) или головного мозга (0,75%), в оставшихся случаях пациенты не являлись на второй этап лечения по субъективным причинам или его выполнение было сопряжено с крайне высоким риском, в связи с чем тактика была пересмотрена в пользу консервативной терапии.Заключение.Гибридные вмешательства продемонстрировали 100% доступность реваскуляризации миокарда и головного мозга в течение одной госпитализации, что значительно сокращало летальность пациентов от инфаркта миокарда и острого нарушения мозгового кровообращения в период ожидания следующего этапа лечения при поэтапной стратегии (почти на 5%). Гибридные вмешательства могут применяться у пациентов с высоким риском «открытых» операций на сердце, тяжелой сопутствующей патологией (ожирением, сахарным диабетом, нарушением функции почек), значимым поражением коронарных и церебральный артерий с высоким риском инфаркта миокарда и острого нарушения мозгового кровообращения. Недостатком гибридной стратегии явилась более высокая частота (почти на 7%) нефатального инфаркта миокарда в отдаленном периоде наблюдения

Morphology and optical properties of aluminum oxide formed into oxalic electrolyte with addition surface active agents

The article discusses the results of investigations of porous films of alumina, formed into oxalic electrolyte with addition surface active agents, in particular, ordering structure, roughness of a surface, the optical transparency of the electrolyte concentration and surface active agents. Also discusses the features of the formation of porous films of temperature and IR radiation

SYNTHESIS OF NONSTOCHIOMETRIC NANO-NBC AND ITS ELECTROCHEMICAL PERFORMANCE

This work was supported by the Russian Science Foundation (RNF grant No. 19-73-20012)