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Numrering	Referens	Omslagsbild	Hitta
1.	Aalto, Susanne, 1964 (författare) Molecules as tracers of galaxy evolution 2012 Ingår i: Proceedings of the International Astronomical Union. - 1743-9213 .- 1743-9221. ; 8:5287, s. 199-208 Konferensbidrag (refereegranskat)abstract Studying the molecular phase of the interstellar medium in galaxies is fundamental for the understandingof the onset and evolution of star formation and the growth of supermassive black holes. Wecan use molecules as observational tools exploiting them as tracers of chemical, physical and dynamicalconditions. In this short review, key molecules (e.g. HCN, HCO+, HNC, HC3N, CN, H3O+) in identifyingthe nature of buried activity and its evolution are discussed including some standard astrochemical scenarios.Furthermore, we can use IR excited molecular emission to probe the very inner regions of luminousinfrared galaxies (LIRGs) allowing us to get past the optically thick dust barrier of the compact obscurednuclei, e.g. in the dusty LIRG NGC4418. High resolution studies are often necessary to separate effectsof excitation and radiative transport from those of chemistry - one example is absorption and effects ofstimulated emission in the ULIRG Arp220. Finally, molecular gas in large scale galactic outflows is brieflydiscussed.
2.	Aalto, Susanne, 1964, et al. (författare) OH megamaser emission in the outflow of the luminous infrared galaxy Zw049.057 2022 Ingår i: Proceedings of the International Astronomical Union. - 1743-9213 .- 1743-9221. ; 18, s. 40-44 Konferensbidrag (refereegranskat)abstract High resolution (0.”26 × 0.”13 (70 × 35 pc)) L-band (18 cm) OH megamaser (OHM) e-Merlin observations of the LIRG Zw049.057 show that the emission is emerging from a low velocity outflowing structure - which is foreground to a fast, dense and collimated molecular outflow detected by ALMA. The extremely dusty compact obscured nucleus (CON) of Zw049.057 has no (or only little) OHM emission associated with it - possibly because of too high number densities that quench the OHM. In contrast we detect 6 cm H2CO emission primarily from the CON-region. We suggest that the OHM-region of Zw049.057 is not directly associated with star formation, but instead occurs in a wide-angle, slow outflow that surrounds the fast and dense outflow. The OHM is pumped by IR emission that likely stems from activities in the nucleus. We briefly discuss how OHM emission can be used as a probe of LIRG-CON galaxies.
3.	Aalto, Susanne, 1964 (författare) Physical conditions and chemistry of molecular gas in galactic centers 2014 Ingår i: Proceedings of the International Astronomical Union. - 1743-9213 .- 1743-9221. ; 9:S303, s. 15-28 Tidskriftsartikel (refereegranskat)abstract Studying the molecular phase of the interstellar medium in galaxy nuclei is fundamental for the understanding of the onset and evolution of star formation and the growth of supermassive black holes. We can use molecules as observational tools exploiting them as tracers of chemical, physical and dynamical conditions. The molecular physical conditions in galaxy centers show large variety among galaxies, but in general the average gas densities (traced by e.g.HCN) and temperatures (probed by e.g. H2CO, NH3) are greater than in their disks. Molecular gas and dust is being funneled to the centers of galaxies by spiral arms, bars, and interactions - and one example of this is the minor merger NGC1614. Gas surface densities are also greaterin galaxy nuclei and in extreme cases they become orders of magnitudes larger than what we find in the center of our own Milky Way. We can use IR excited molecular emission to probe the very inner regions of galaxies with deeply obscured nuclei where N(H2)>10^24 cm-2 -for example in the luminous infrared galaxy (LIRG) NGC4418. Abundances of key molecules such as HCN, HCO+, HNC, HC3N, CN, H3O+,are important tools in identifying the nature of buried activity and its evolution. Standard astrochemical scenarios (including X-ray Dominated regions (XDRs) and Photon Dominated Regions (PDRs)) are briefly discussed in this review and how we can use molecules to distinguish between them. High resolution studies are often necessaryto separate effects of excitation and radiative transfer from those of chemistry - one example is absorption and effects of stimulated emission in the ULIRG Arp220. The nuclear activity in luminous galaxies often drives outflows and winds and in some cases molecular gas is being entrained in the outflows. Sometimes the molecular gas is carrying the bulk of the momentum.We can study the structure and physical conditions of the molecular gas to constrain the mass outflow rates and the evolution and nature of the driving source and two examples are discussed here: NGC1377 and Mrk231
4.	Alves, F. O., et al. (författare) The magnetic field of IRAS 16293-2422 as traced by shock-induced H2O masers 2012 Ingår i: Proceedings of the International Astronomical Union. - 1743-9213 .- 1743-9221. ; 8:5287, s. 74-78 Konferensbidrag (refereegranskat)abstract H2O masers are important magnetic field tracers in very high density gas. We show one of the first magnetic field determinations at such high density in a low-mass protostar: IRAS 16293-2422. We used the Very Large Array (VLA) to carry out spectro-polarimetric observations of the 22 GHz Zeeman emission of H2O masers. A blend of at least three maser features can be inferred from our data. They are excited in zones of compressed gas produced by shocks between the outflows ejected by this source and the ambient gas. The post-shock particle density is in the range 1 - 3 × 109 cmt−3, and the line-of-sight component of the magnetic field is estimated as ~ 113 mG. The outflow dynamics is likely magnetically dominated.
5.	Amada, Kei, et al. (författare) Discovery of SiO masers in the Water Fountain source, IRAS 16552-3050 2022 Ingår i: Proceedings of the International Astronomical Union. - 1743-9213 .- 1743-9221. ; 18, s. 359-361 Konferensbidrag (refereegranskat)abstract We report new detections of SiO ν = 1 and ν = 2 J = 1 → 0 masers in the water fountain source IRAS 16552-3050, which was observed with the Nobeyama 45 m telescope from March 2021 to April 2023. Water fountains are evolved stars whose H2O maser spectra trace high-velocity outflows of >100 Km s-. This is the second known case of SiO masers in a water fountain, after their prototypical source, W 43A. The line-of-sight velocity of the SiO masers are blue-shifted by ∼25 km s-1 from the systemic velocity. This velocity offset imply that the SiO masers are associated with nozzle structure formed by a jet penetrating the circumstellar envelope, and that new gas blobs of the jet erupted recently. Thus, the SiO masers imply this star to be in a new evolutionary stage.
6.	Amiri, N., et al. (författare) VLBA SiO maser observations of the OH/IR star OH 44.8-2.3: magnetic field and morphology 2012 Ingår i: Proceedings of the International Astronomical Union. - 1743-9213 .- 1743-9221. ; 8:5287, s. 54-58 Konferensbidrag (refereegranskat)abstract We report on Very Long Baseline Array SiO maser observations of the OH/IR star OH 44.8 - 2.3. The observations show that the maser features form a ring located at a distance of 5.4 AU around the central star. The masers show high fractional linear polarization up to 100%. The polarization vectors are consistent with a dipole field morphology. Additionally, we report a tentative detection of circular polarization of 7% for the brightest maser feature. This indicates a magnetic field of 1.5 ± 0.3 G. The SiO masers and the 1612 MHz OH masers suggest a mildly preferred outflow direction in the circumstellar environment of this star. The observed polarization is consistent with magnetic field structures along the preferred outflow direction. This could indicate the possible role of the magnetic fields in shaping the circumstellar environment of this object.
7.	Ao, Y., et al. (författare) The thermal state of molecular clouds in the Galactic center: evidence for non-photon-driven heating 2014 Ingår i: Proceedings of the International Astronomical Union. - 1743-9213 .- 1743-9221. ; 9:S303, s. 89-91 Tidskriftsartikel (refereegranskat)abstract We have used the Atacama Pathfinder Experiment (APEX) 12 m telescope at 218 GHz to observe molecular clouds simultaneously in the J_KA,Kc=3_03→2_02,3_22→2_21,and 3_21→2_20 transitions of para-H2CO to determine kinetic temperatures of the dense gas in the central molecular zone of the Galaxy. Gas kinetic temperatures for individual molecular clouds range from 55 to 125 K or even higher. The molecular clouds at high temperatures may be heated by turbulent dissipation and/or cosmic-rays
8.	Arnadottir, Anna, et al. (författare) Properties of the Milky Way stellar disks in the direction of the Draco dSph galaxy 2009 Ingår i: Proceedings of the International Astronomical Union. IAU Symposium No. 254. - 1743-9221 .- 1743-9213. ; 254 Konferensbidrag (refereegranskat)
9.	Azulay, R., et al. (författare) Radio Emission from Binary Stars in the AB Doradus Moving Group 2015 Ingår i: Proceedings of the International Astronomical Union. - 1743-9213 .- 1743-9221. ; 10, s. 117-118 Konferensbidrag (refereegranskat)abstract Precise determination of dynamical masses of pre-main-sequence stars is essential for calibrating stellar evolution models, that are widely used to derive theoretical masses of young low-mass objects. We have determined the individual masses of the pair AB Dor Ba/Bb using Australian Long Baseline Array observations and archive infrared data, as part of a larger program directed to monitor binary systems in the AB Doradus moving group. We have detected, for the first time, compact radio emission from both stars. This has allowed us to determine the orbital parameters of both the relative and absolute orbits and, consequently, their individual dynamical masses: 0.28±0.05 M⊙ and 0.25±0.05 M⊙. Comparisons of the dynamical masses with the prediction of pre-main-sequence (PMS) evolutionary models show that the models underpredict the dynamical masses of the binary components Ba and Bb by 10-30% and 10-40%, respectively.
10.	Bjerkeli, Per, 1977, et al. (författare) Resolving star and planet formation with ALMA 2020 Ingår i: Proceedings of the International Astronomical Union. - 1743-9213 .- 1743-9221. ; 14, s. 106-110 Konferensbidrag (refereegranskat)abstract Disks around young stars are the sites of planet formation. As such, the physical and chemical structure of disks have a direct impact on the formation of planetary bodies. Outflowing winds remove angular momentum and mass and affect the disk structure and therefore potentially planet formation. Until very recently, we have lacked the facilities to provide the necessary observational tools to peer into the wind launching and planet forming regions of the young disks. Within the framework of the Resolving star formation with ALMA program, young protostellar systems are targeted with ALMA to resolve the disk formation, outflow launching and planet formation. This contribution presents the first results of the program. The first resolved images of outflow launching from a disk were recently reported towards the Class I source TMC1A (Bjerkeli et al. 2016) where we also present early evidence of grain growth (Harsono et al. 2018).
11.	Black, John H, 1949 (författare) Conference Summary 2011 Ingår i: Proceedings of the International Astronomical Union. - 1743-9213 .- 1743-9221. - 9781107019805 ; 7:Symposium 280, s. 461-465 Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract By any measure, IAU Symposium 280 has been an outstanding success: more than 400 participants represented at least 30 countries with 74 presentations and more than 300 posters. Beyond these numbers, it is evident that the cross-disciplinary field of astrochemistry is flourishing with excellent prospects for growth in the future. We have enjoyed the excitement of new, unexpected results from the Herschel Space Observatory and eagerly await new opportunities and facilities that will arise in the coming months and years.
12.	Blommaert, Jadl, et al. (författare) On the nature and mass loss of Bulge OH/IR stars 2019 Ingår i: Proceedings of the International Astronomical Union. - 1743-9213 .- 1743-9221. ; 14:S343, s. 353-354 Konferensbidrag (refereegranskat)abstract We report on the successful search for CO (2-1) and (3-2) emission associated with OH/IR stars in the Galactic Bulge. We observed a sample of eight extremely red AGB stars with the APEX telescope and detected seven. The sources were selected at sufficient high Galactic latitude to avoid interference by interstellar CO, which hampered previous studies of inner galaxy stars. We also collected photometric data and Spitzer IRS spectroscopy to construct the SEDs, which were analysed through radiative transfer modelling. We derived variability periods of our stars from the VVV and WISE surveys. Through dynamical modelling we then retrieve the total mass loss rates (MLR) and the gas-to-dust ratios. The luminosities range between approximately 4,000 and 5,500 LâŠ™ and periods are below 700 days. The total MLR ranges between 10-5 and 10-4 MâŠ™ yr-1. The results are presented in Blommaert et al. 2018 and summarized below.
13.	Brand, J., et al. (författare) Patterns in water maser emission of evolved stars on the timescale of decades 2022 Ingår i: Proceedings of the International Astronomical Union. - 1743-9213 .- 1743-9221. ; 18, s. 319-323 Konferensbidrag (refereegranskat)abstract We present our past and current long-term monitoring program of water masers in the circumstellar envelopes of evolved stars, augmented by occasional interferometric observations. Using as example the Mira-variable U Her, we identify three types of variability: periodic (following the optical variation), long-term (years-decades) and short-term irregular (weeks-months). We show there are regions in the maser shell where excitation conditions are favourable, which remain stable for many years. Lifetimes of maser clouds in the wind-acceleration zone are of the order of up to a few years. Much longer lifetimes are found for the peculiar case of a maser cloud outside that zone (as in RT Vir), or in some cases where the motion of spectral features can be followed for the entire 2 decade monitoring period (as in red supergiant VX Sgr).
14.	Brandenburg, Axel (författare) Magnetic field evolution in solar-type stars 2020 Ingår i: Proceedings of the International Astronomical Union. - : Cambridge University Press (CUP). - 1743-9213 .- 1743-9221. ; , s. 169-180 Tidskriftsartikel (refereegranskat)abstract We discuss selected aspects regarding the magnetic field evolution of solar-type stars. Most of the stars with activity cycles are in the range where the normalized chromospheric Calcium emission increases linearly with the inverse Rossby number. For Rossby numbers below about a quarter of the solar value, the activity saturates and no cycles have been found. For Rossby numbers above the solar value, again no activity cycles have been found, but now the activity goes up again for a major fraction of the stars. Rapidly rotating stars show nonaxisymmetric large-scale magnetic fields, but there is disagreement between models and observations regarding the actual value of the Rossby number where this happens. We also discuss the prospects of detecting the sign of magnetic helicity using various linear polarization techniques both at the stellar surface using the parity-odd contribution to linear polarization and above the surface using Faraday rotation.
15.	Brandenburg, Axel, et al. (författare) Turbulent diffusion and galactic magnetism 2009 Ingår i: Proceedings of the International Astronomical Union. - : Cambridge University Press. - 1743-9213 .- 1743-9221. ; 5, s. 432-433 Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract Using the test-field method for nearly irrotational turbulence driven by spherical expansion waves it is shown that the turbulent magnetic diffusivity increases with magnetic Reynolds numbers. Its value levels off at several times the rms velocity of the turbulence multiplied by the typical radius of the expansion waves. This result is discussed in the context of the galactic mean-field dynamo.
16.	Brunner, M., et al. (författare) The discovery of an asymmetric detached shell around the "fresh" carbon AGB star TX Psc 2019 Ingår i: Proceedings of the International Astronomical Union. - 1743-9213 .- 1743-9221. ; 14, s. 360-361 Konferensbidrag (refereegranskat)abstract We present ALMA observations of the circumstellar envelope around the AGB carbon star TX Psc in molecular CO(2-1) emission, and detect a previously unknown detached shell with filamentary structure and elliptical shape. Up to now, all observed detached shells are found around carbon AGB stars and are of remarkable spherical symmetry. The elliptical shell around TX Psc is the first clear exception to that rule, with TX Psc being classified as rather "fresh" carbon star, that most likely has only experienced very few thermal pulses yet. We investigate and discuss the 3D structure of the CSE and its most likely formation scenarios, as well as the link of this peculiar detached shell to the AGB evolutionary status of TX Psc.
17.	Byström, Joakim, et al. (författare) The Determination of Stellar Parameters of Giants in the Galactic Disks and Bulge 2007 Ingår i: Proceedings of the International Astronomical Union. - 1743-9213 .- 1743-9221. ; 241, s. 235-236, s. 235-236 Konferensbidrag (refereegranskat)
18.	Costagliola, Francesco, 1981, et al. (författare) Vibrationally Excited HC3N in NGC 4418 2010 Ingår i: Proceedings of the International Astronomical Union. - : Cambridge University Press (CUP). - 1743-9213 .- 1743-9221. - 9781107005334 ; 15, s. 421-422 Konferensbidrag (refereegranskat)abstract Luminous infrared galaxies (LIRGs) emit most of their radiation in the infrared region of the spectrum in the form of dust thermal continuum, with typical luminosities of LIR > 1010 L⊙. The central power source responsible for the total energy output is deeply buried in the dusty central regions of these objects and its origin still unclear. Recent studies by Spoon et al. (2007) and Aalto et al. (2007) suggest that some LIRGs might represent early obscured stages of active galaxies, either AGNs or starbursts, and thus play a fundamental role in galaxy formation and evolution.
19.	D’Ammando, F., et al. (författare) Gamma-ray emitting narrow-line Seyfert 1 galaxies. New discoveries and open questions 2014 Ingår i: Proceedings of the International Astronomical Union. - 1743-9213 .- 1743-9221. ; 9:S304, s. 140-143 Tidskriftsartikel (refereegranskat)abstract The discovery of γ-ray emission from 5 radio-loud narrow-line Seyfert 1 galaxies revealed the presence of a possible emerging third class of AGNs with relativistic jets, in addition to blazars and radio galaxies. The existence of relativistic jets also in this subclass of Seyfert galaxies opened an unexplored research space for our knowledge of the radio-loud AGNs. Here, we discuss the radio-to-γ-rays properties of the γ-ray emitting narrow-line Seyfert 1 galaxies, also in comparison with the blazar scenario.
20.	Desmurs, J. F., et al. (författare) Preliminary results on SiO v=3 J=1−0 maser emission from AGB stars 2012 Ingår i: Proceedings of the International Astronomical Union. - 1743-9213 .- 1743-9221. ; 8:5287, s. 252-253 Konferensbidrag (refereegranskat)abstract We present the results of SiO maser observations at 43 GHz toward two AGB stars using the VLBA. Our preliminary results on the relative positions of the different J=1–0 SiO masers (v=1,2 and 3) indicate that the current ideas on SiO maser pumping could be wrong at some fundamental level. A deep revision of the SiO pumping models could be necessary.
21.	Dravins, Dainis, et al. (författare) IAU Division IV: Stars 2007 Ingår i: Transactions of the International Astronomical Union, Reports on Astronomy. - 1743-9221 .- 1743-9213. ; 26A, s. 191-192 Bokkapitel (populärvet., debatt m.m.)
22.	Engels, D., et al. (författare) Variability of masers in circumstellar shells on timescales of decades 2007 Ingår i: Proceedings of the International Astronomical Union. - 1743-9213 .- 1743-9221. ; 3:S242, s. 318-319 Konferensbidrag (refereegranskat)abstract Based on a 15-20 year long monitoring program of H2O masers and new observations of OH masers discovered 35 years ago, we studied the variability of maser emission in AGB stars over timescales of decades. The H2O maser features in the semi-regular variable stars RX Boo and SV Peg, and of the Mira stars U Her and R Cas, showed strong fluctuations superposed in case of the Mira stars on regular variations due to the pulsation of the stars. The spatial distribution of the emission regions in RX Boo and U Her showed deviations from spherical symmetry, which remained unchanged over >10 years. We conclude that the spatial asymmetry is determined by the underlying asymmetry of the mass loss process. There is no evidence that mass loss rates or the wind geometry in these stars have varied over the last 20 years. In 2005 we re-detected at 1612 MHz the 114 OH/IR stars discovered before 1978, implying an OH maser lifetime of >2800 years (1). © 2008 International Astronomical Union.
23.	Falstad, Niklas, 1987, et al. (författare) Herschel spectroscopic observations of Zw 049.057 and Arp 299a 2016 Ingår i: Proceedings of the International Astronomical Union. - : Cambridge University Press (CUP). - 1743-9213 .- 1743-9221. - 9781107135208 ; 315 Konferensbidrag (refereegranskat)abstract The presence of compact obscured nuclei in luminous infrared galaxies (LIRGs) is very well probed by the detection of highly excited absorption lines of OH and H2O in the far-infrared (far-IR), which require warm and optically thick dust to pump the high-lying rotational levels. We are using a spherically symmetric radiative transfer code to model the H2O lines, OH lines and continuum from these objects. We discuss the results and analysis of Herschel observations of the compact obscured nucleus in the extremely H2O luminous LIRG Zw 049.057. In this galaxy we have found very high H2O abundances in a Compton thick compact core. Abundant O-18 bearing species also suggest the presence of a relatively young starburst. We compare this to our observations and modeling of the luminous merger component Arp 299a, which is another source with prominent H2O and OH lines. Our preliminary results, however, suggest that its nuclear activity is in a different evolutionary state compared to Zw 049.057.
24.	Fan, Lulu, 1982, et al. (författare) Panchromatic modeling of the extremely luminous dust-obscured quasars at the cosmic noon 2019 Ingår i: Proceedings of the International Astronomical Union. - 1743-9213 .- 1743-9221. ; 15:S341, s. 268-270 Konferensbidrag (refereegranskat)abstract The massive galaxies and their central supermassive black holes (SMBHs) co-evolution scenario proposes that a gas-rich major merger can trigger the central starburst and feeding the SMBH accretion, and then star formation is eventually quenched by quasar feedback. In this evolutionary sequence, dust-obscured quasars may represent the critical transition phase between starburst and unobscured quasars. Modeling the panchromatic emission of these hidden monsters provides a unique way to explore their physical properties and therefore the co-evolution between SMBHs and their hosts. However, most of modelling methods are not suitable for the extremely luminous systems with obscured Active Galactic Nucleus (AGN) emission. Here we present two case studies of panchromatic modeling of the extremely luminous dust-obscured quasars at the cosmic noon.
25.	Feltzing, Sofia, et al. (författare) The age of the Galaxy's thick disk 2009 Ingår i: Proceedings of the International Astronomical Union, IAU Proceedings. - 1743-9221 .- 1743-9213. ; 258, s. 23-30 Konferensbidrag (refereegranskat)abstract We discuss the age of the stellar disks in the solar neighborhood. After reviewing the various methods for age dating, we discuss current estimates of the ages of both the thin- and the thick disks. We present preliminary results for kineymatically-selected stars that belong to the thin- as well as the thick disk. All of these dwarf and sub-giant stars have been studied spectroscopically and we have derived both elemental abundances as well as ages for them. A general conclusion is that in the solar neighborhood, on average, the thick disk is older than the thin disk. However, we caution that the exclusion of stars with effective temperatures around 6500 K might result in a biased view of the full age distribution for the stars in the thick disk.
26.	Geppert, W. D., et al. (författare) Dissociative recombination of CD3OD2 2005 Ingår i: Proceedings of the International Astronomical Union. - 1743-9213 .- 1743-9221. ; 1, s. 117-124 Tidskriftsartikel (refereegranskat)abstract The branching ratios of the different reaction pathways and the overall rate of the dissociative recombination of CD3OD2 + were measured at the CRYRING storage ring located at the Manne Siegbahn Laboratory in Stockholm, Sweden. A preliminary analysis of the data yielded that formation of methanol accounts for only 6±2% of the total reaction rate. Largely, dissociative recombination of CD3OD 2 + involves fragmentation of the C-O bond, the major process being the three-body break-up forming CD3, OD and D (branching ratio 0.59). A non-negligible formation of interstellar methanol by the previously proposed mechanism is therefore very unlikely.
27.	Goicoechea, Javier R., et al. (författare) The ALMA view of UV-irradiated cloud edges: unexpected structures and processes 2018 Ingår i: Proceedings of the International Astronomical Union. - 1743-9213 .- 1743-9221. ; S332, s. 210-217 Konferensbidrag (refereegranskat)abstract Far-UV photons (FUV, E < 13.6 eV) from hot massive stars regulate, or at least influence, the heating, ionization, and chemistry of most of the neutral interstellar medium (H i and H2 clouds). Investigating the interaction between FUV radiation and interstellar matter (molecules, atoms and grains) thus plays an important role in astrochemistry. The Orion Bar, an interface region between the Orion A molecular cloud and the H ii region around the Trapezium cluster, is a textbook example of a strongly illuminated dense PDR (photodissociation region). The Bar is illuminated by a FUV field of a few 104 times the mean interstellar radiation field. Because of its proximity and nearly edge-on orientation, it provides a very good template to investigate the chemical content, structure, and dynamics of a strongly irradiated molecular cloud edge. We have used ALMA to mosaic a small field of the Bar where the critical transition from atomic to molecular gas takes place. These observations provide an unprecedented sharp view of this transition layer (≲ 1″ resolution or ≲ 414 AU). The resulting images (so far in the rotational emission of CO, HCO+, H13CO+, SO+, SO, and reactive ions SH+ and HOC+) show the small-scale structure in gas density and temperature, and the steep abundance gradients. The images reveal a pattern of high-density substructures, photo-ablative gas flows and instabilities at the edge of the molecular cloud. These first ALMA images thus show a more complex morphology than the classical clump/interclump static model of a PDR. In order to quantify the chemical content in strongly FUV-irradiated gas, we have also used the IRAM-30 m telescope to carry out a complete line-survey of the illuminated edge of the Bar in the millimeter domain. Our observations reveal the presence of complex organic molecules (and precursors) that were not expected in such a harsh environment. In particular, we have reported the first detection of the unstable cis conformer of formic acid (HCOOH) in the ISM. The energy barrier to internal rotation (the conversion from trans to cis) is approximately 4827 cm−1 (≈7000 K). Hence, this detection is surprising. The low inferred trans-to-cis abundance ratio of 2.8±1.0 supports a photoswitching mechanism: a given conformer absorbs a FUV stellar photon that radiatively excites the molecule to electronic states above the interconversion barrier. Subsequent fluorescent decay leaves the molecule in a different conformer form. This mechanism, which we have specifically studied with ab initio quantum calculations, was not considered so far in astrochemistry although it can affect the structure of a variety of molecules in PDRs.
28.	Harrison, C. M., et al. (författare) Do AGN really suppress star formation? 2019 Ingår i: Proceedings of the International Astronomical Union. - 1743-9213 .- 1743-9221. ; 15, s. 199-203 Tidskriftsartikel (refereegranskat)abstract Active galactic nuclei (AGN) are believed to regulate star formation inside their host galaxies through "AGN feedback". We summarise our on-going study of luminous AGN (z ∼0.2-3; LAGN,bol 1043 erg s-1), which is designed to search for observational signatures of feedback by combining observed star-formation rate (SFR) measurements from statistical samples with cosmological model predictions. Using the EAGLE hydrodynamical cosmological simulations, in combination with our Herschel + ALMA surveys, we show that - even in the presence of AGN feedback - we do not necessarily expect to see any relationships between average galaxy-wide SFRs and instantaneous AGN luminosities. We caution that the correlation with stellar mass for both SFR and AGN luminosity can contribute to apparent observed positive trends between these two quantities. On the other hand, the EAGLE simulations, which reproduce our observations, predict that a signature of AGN feedback can be seen in the wide specific SFR distributions of all massive galaxies (not just AGN hosts). Overall, whilst we can not rule out that AGN have an immediate small-scale impact on in-situ star-formation, all of our results are consistent with a feedback model where galaxy-wide in-situ star formation is not rapidly suppressed by AGN, but where the feedback likely acts over a longer timescale than a single AGN episode.
29.	Harrison, C. M., et al. (författare) Establishing the impact of powerful AGN on their host galaxies 2020 Ingår i: Proceedings of the International Astronomical Union. - 1743-9213 .- 1743-9221. ; 15, s. 203-211 Konferensbidrag (refereegranskat)abstract Establishing the role of active galactic nuclei (AGN) during the formation of galaxies remains one of the greatest challenges of galaxy formation theory. Towards addressing this, we summarise our recent work investigating: (1) the physical drivers of ionised outflows and (2) observational signatures of the impact by jets/outflows on star formation and molecular gas content in AGN host galaxies. We confirm a connection between radio emission and extreme ionised gas kinematics in AGN hosts. Emission-line selected AGN are significantly more likely to exhibit ionised outflows (as traced by the [O iii] emission line) if the projected linear extent of the radio emission is confined within the spectroscopic aperture. Follow-up high resolution radio observations and integral field spectroscopy of 10 luminous Type 2 AGN reveal moderate power, young (or frustrated) jets interacting with the interstellar medium. We find that these sources live in highly star forming and gas rich galaxies. Additionally, by combining ALMA-derived dust maps with integral field spectroscopy for eight host galaxies of z ≈ 2 X-ray AGN, we show that Hα emission is an unreliable tracer of star formation. For the five targets with ionised outflows we find no dramatic in-situ shut down of the star formation. Across both of these studies we find that if these AGN do have a negative impact upon their host galaxies, it must be happening on small (unresolved) spatial scales and/or an observable galaxy-wide impact has yet to occur.
30.	Heesen, Volker, et al. (författare) Stellar feedback in dwarf irregular galaxies with radio continuum observations 2019 Ingår i: Proceedings of the International Astronomical Union. - 1743-9213 .- 1743-9221. ; 14:S344, s. 255-258 Konferensbidrag (refereegranskat)abstract Low-mass dwarf irregular galaxies are subject to outflows, in which cosmic rays may play a very important role; they can be traced via their electron component, the cosmic ray electrons (CRe), in the radio continuum as non-thermal synchrotron emission. With the advent of sensitive low-frequency observations, such as with the Low-Frequency Array (LOFAR), we can trace CRe far away from star formation sites. Together with GHz-observations, such as with the Very Large Array (VLA), we can study spatially resolved radio continuum spectra at matched angular resolution and sensitivity. Here, we present results from our 6-GHz VLA survey of 40 nearby dwarf galaxies and our LOFAR study of the nearby starburst dwarf irregular galaxy IC 10. We explore the relation of RC emission with star formation tracers and study in IC 10 the nature of a low-frequency radio halo, which we find to be the result of a galactic wind.
31.	Hobbs, David, et al. (författare) Determining PPN gamma with Gaia's astrometric core solution 2010 Ingår i: Relativity in Fundamental Astronomy: Dynamics, Reference Frames, and Data Analysis (IAU Symposium). - 1743-9221 .- 1743-9213. ; 261, s. 315-319 Konferensbidrag (refereegranskat)abstract The ESA space astrometry mission Gala, due for launch in early 2012, will in addition to its huge output of fundamental astrometric and astrophysical data also provide stringent tests of general relativity. In this paper we present an updated analysis of Gaia's capacity to measure the PPN parameter gamma as part of its core astrometric solution. The analysis is based on small-scale astrometric solutions taking into account the simultaneous determination of stellar astrometric parameters and the satellite attitude. In particular, the statistical correlation between PPN gamma and the stellar parallaxes is considered. Extrapolating the results to a full-scale solution using some 100 million stars, we find that PPN gamma could be obtained to about 10(-6), which is significantly better than today's best estimate from the Cassini mission of 2 x 10(-5).
32.	Holl, Berry, et al. (författare) Spatial correlations in the Gaia astrometric solution 2010 Ingår i: Relativity in Fundamental Astronomy: Dynamics, Reference Frames, and Data Analysis (IAU Symposium). - 1743-9213 .- 1743-9221. ; 261, s. 320-324 Konferensbidrag (refereegranskat)abstract Accurate characterization of the astrometric errors in the forthcoming Gaia catalogue is essential for making optimal use of the data. Using small-scale numerical simulations of the astrometric solution, we investigate the expected spatial correlation between the astrometric errors of stars as function of their angular separation. Extrapolating to the full-scale solution for the final Gala catalogue, we find that the expected correlations are generally very small, but could reach some fraction of a percent for angular separations smaller than about one degree. The spatial correlation length is related to the size of the field of view of Gala., while the maximum correlation coefficient is related to the mean number of stars present in the field at any time. Our scalable simulation tool (AGISLab) makes it possible to characterize the astrometric errors and correlations, e.g., as functions of position and magnitude.
33.	Humphreys, E., et al. (författare) (Sub)mm Observations of Evolved Stars 2022 Ingår i: Proceedings of the International Astronomical Union. - 1743-9213 .- 1743-9221. ; 18, s. 309-313 Konferensbidrag (refereegranskat)abstract Evolved stars on the asymptotic giant branch and red supergiants have multiple processes that can be studied in the (sub)mm, including stellar surfaces, circumstellar thermal gas and dust, and masers. Telescopes such as APEX and ALMA have opened the possibility to perform studies that are revealing new information on these, as well as on the role of binaries in shaping stellar winds and the evolution to planetary nebulae. Here, we discuss some recent results for (sub)mm observations towards evolved stars focusing particularly on masers. This includes SiO and water masers, as well as ALMA high angular resolution observations of HCN masers towards a carbon-rich star.
34.	Imai, H., et al. (författare) Water and silicon-monoxide masers monitored towards the water fountain sources 2021 Ingår i: Proceedings of the International Astronomical Union. - 1743-9213 .- 1743-9221. ; 17, s. 91-93 Konferensbidrag (refereegranskat)abstract We have investigated the evolution of 12 water fountain sources in real time in the accompanying H2O 2o and SiO masers through our FLASHING (Finest Legacy Acquisitions of SiO-/ H2O 2o-maser Ignitions by Nobeyama Generation) project. It has been confirmed that these masers are excellent probes of new jet blob ejections, acceleration of the material supplied from the parental circumstellar envelope and entrained by the stellar jets yielding its deceleration. Possible periodic variations of the maser emission, reflecting properties of the central dying stars or binary systems, will be further investigated.
35.	Imai, Hiroshi, et al. (författare) Water Fountain Sources Monitored in FLASHING 2022 Ingår i: Proceedings of the International Astronomical Union. - 1743-9213 .- 1743-9221. ; 18, s. 333-337 Konferensbidrag (refereegranskat)abstract We have investigated the spectral evolutions of H2O and SiO masers associated with 12 water fountain sources in our FLASHING (Finest Legacy Acquisitions of SiO-/H2O-maser Ignitions by Nobeyama Generation) project. Our monitoring observations have been conducted using the Nobeyama 45 m telescope every 2 weeks-2 months since 2018 December except during summer seasons. We have found new extremely high velocity H2O maser components, breaking the records of jet speeds in this type of sources. Systematic line-of-sight velocity drifts of the H2O maser spectral peaks have also been found, indicating acceleration of the entrained material hosting the masers around the jet. Moreover, by comparing with previous spectral data, we can find decadal growths/decays of H2O maser emission. Possible periodic variations of the maser spectra are further being inspected in order to explore the periodicity of the central stellar system (a pulsating star or a binary). Thus we expect to see the real-time evolution/devolutions of the water fountains over decades.
36.	Justtanont, Kay, 1965, et al. (författare) ALMA spectrum of the extreme OH/IR star OH 26.5+0.6 2019 Ingår i: Proceedings of the International Astronomical Union. - 1743-9213 .- 1743-9221. ; 14, s. 436-437 Konferensbidrag (refereegranskat)abstract We present ALMA band 7 data of the extreme OH/IR star, OH 26.5+0.6. In addition to lines of CO and its isotopologues, the circumstellar envelope also exhibits a number of emission lines due to metal-containing molecules, e.g., NaCl and KCl. A lack of C18O is expected, but a non-detection of C17O is puzzling given the strengths of H217O in Herschel spectra of the star. However, a line associated with Si17O is detected. We also report a tentative detection of a gas-phase emission line of MgS. The ALMA spectrum of this object reveals intriguing features which may be used to investigate chemical processes and dust formation during a high mass-loss phase.
37.	Kalenskii, S.V., et al. (författare) Class I methanol masers in low-mass star formation regions 2012 Ingår i: Proceedings of the International Astronomical Union. - 1743-9213 .- 1743-9221. ; 8:5287, s. 161-165 Konferensbidrag (refereegranskat)abstract Four Class I maser sources were detected at 44, 84, and 95 GHz toward chemically rich outflows in the regions of low-mass star formation NGC 1333I4A, NGC 1333I2A, HH25, and L1157. One more maser was found at 36 GHz toward a similar outflow, NGC 2023. Flux densities of the newly detected masers are no more than 18 Jy, being much lower than those of strong masers in regions of high-mass star formation. The brightness temperatures of the strongest peaks in NGC 1333I4A, HH25, and L1157 at 44 GHz are higher than 2000 K, whereas that of the peak in NGC 1333I2A is only 176 K. However, a rotational diagram analysis showed that the latter source is also a maser. The main properties of the newly detected masers are similar to those of Class I methanol masers in regions of massive star formation. The former masers are likely to be an extension of the latter maser population toward low luminosities of both the masers and the corresponding YSOs.
38.	Kalenskii, S. V., et al. (författare) Class I methanol masers in low-mass star formation regions 2017 Ingår i: Proceedings of the International Astronomical Union. - 1743-9213 .- 1743-9221. ; 13:S336, s. 33-36 Tidskriftsartikel (refereegranskat)abstract We present a review of the properties of Class I methanol masers detected in low-mass star forming regions (LMSFRs). These masers, henceforth called LMMIs, are associated with postshock gas in the lobes of chemically active outflows in LMSFRs NGC1333, NGC2023, HH25, and L1157. LMMIs share the main properties with powerful masers in regions of massive star formation and are a low-luminosity edge of the total Class I maser population. However, the exploration of just these objects may push forward the exploration of Class I masers, since many LMSFRs are located only 200-300 pc from the Sun, making it possible to study associated objects in detail. EVLA observations with a 0.2″ spatial resolution show that the maser images consist of unresolved or barely resolved spots with brightness temperatures up to 5 × 105 K. The results are marginally consistent with the turbulent model of maser emission.
39.	Kang, Ji-hyun, et al. (författare) Linear polarisation of Class i methanol masers in massive star formation regions 2017 Ingår i: Proceedings of the International Astronomical Union. - 1743-9213 .- 1743-9221. ; 13:S336, s. 243-246 Tidskriftsartikel (refereegranskat)abstract We present the results of the linear polarisation observations of methanol masers at 44 and 95 GHz towards 39 massive star forming regions (Kang et al. 2016). These two lines are observed simultaneously with the 21-m Korean VLBI Network (KVN) telescope in single dish mode. About 60% of the observed showed fractional polarisation of a few percents at least at one of the two transition lines. We note that the linear polarisation of the 44 GHz methanol maser is first detected in this study including single dish and interferometer observations. We find the polarisation properties of these two lines are similar as expected, since they trace similar regions. As a follow-up study, we have carried out the VLBI polarisation observations toward some 44 GHz maser targets using the KVN telescope. We present preliminary VLBI polarisation results of G10.34-0.14, which show consistent polarisation properties in multiple epoch observations.
40.	Karlsson, Roland, 1948-, et al. (författare) Hydroxyl, water, ammonia, carbon monoxide and neutral carbon towards the Sgr A complex 2014 Ingår i: Proceedings of the International Astronomical Union. - 1743-9213 .- 1743-9221. ; 9:303, s. 97-99 Tidskriftsartikel (refereegranskat)abstract We observed Hydroxyl, water, ammonia, carbon monoxide and neutral carbon towards the +50 km s−1 cloud (M−0.02−0.07), the circumnuclear disk (CND) and the +20 km s−1 (M−0.13−0.08) cloud in the Sgr A complex with the VLA, Odin and SEST. Strong OH absorption, H2O emission and absorption lines were seen at all three positions. Strong C18O emissions were seen towards the +50 and +20 km s−1 clouds. The CND is rich in H2O and OH, and these abundances are considerably higher than in the surrounding clouds, indicating that shocks, star formation and clump collisions prevail in those objects. A comparison with the literature reveals that it is likely that PDR chemistry including grain surface reactions, and perhaps also the influences of shocks has led to the observed abundances of the observed molecular species studied here. In the redward high-velocity line wings of both the +50 and +20 km s−1 clouds and the CND, the very high H2O abundances are suggested to be caused by the combined action of shock desorption from icy grain mantles and high-temperature, gas-phase shock chemistry. Only three of the molecules are briefly discussed here. For OH and H2O three of the nine observed positions are shown, while a map of the C18O emission is provided. An extensive paper was recently published with Open Access (Karlsson et al. 2013, A&A 554, A141).
41.	Khouri, Theo, 1985, et al. (författare) Imaging the dust and the gas around Mira using ALMA and SPHERE/ZIMPOL 2018 Ingår i: Proceedings of the International Astronomical Union. - 1743-9213 .- 1743-9221. ; 14:S343, s. 31-35 Konferensbidrag (refereegranskat)abstract The mass-loss mechanism of asymptotic giant branch stars has long been thought to rely on two processes: Stellar pulsations and dust formation. The details of the mass-loss mechanism have remained elusive, however, because of the overall complexity of the dust formation process in the very dynamical pulsation-enhanced atmosphere. Recently, our understanding of AGB stars and the associated mass loss has evolved significantly, thanks both to new instruments which allow sensitive and high-angular-resolution observations and the development of models for the convective AGB envelopes and the dust formation process. ALMA and SPHERE/ZIMPOL on the VLT have been very important instruments in driving this advance in the last few years by providing high-angular resolution images in the sub-mm and visible wavelengths, respectively. I will present observations obtained using these instruments at the same epoch (2.5 weeks apart) of the AGB star Mira that resolve even the stellar disk. The ALMA data reveals the distribution and dynamics of the gas around the star, while the polarised light imaged using SPHERE shows the distribution of the dust grains expected to drive the outflows. Moreover, the observations show a central source surrounded by asymmetric distributions of gas and dust, with complementary structures seen in the two components. We model the observed CO v = 1, J = 3-2 line to determine the density, temperature and velocity of gas close to the star. This model is then used to estimate the abundance of AlO. Our results show that only a very small fraction of aluminium (‰20.1%) is locked in AlO molecules. We also calculate models to fit the observed polarised light based on the gas densities we find. The low level of visible-light polarisation detected using ZIMPOL implies that, at the time of the observations, aluminium atoms are either not efficiently depleted into dust or the aluminium-oxide grains are relatively small (‰20.02μm).
42.	Knudsen, Kirsten Kraiberg, 1976 (författare) Observations of molecules in high redshift galaxies 2011 Ingår i: Proceedings of the International Astronomical Union. - 1743-9213 .- 1743-9221. - 9781107019805 ; 7:280, s. 325-338 Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract I present an overview of the molecular gas observations in high redshift galaxies. This field has seen tremendous progress in the past few years, with an increased number of detections of other molecules than CO. The molecular line observations are done towards different classes of massive starbursts, including submillimeter galaxies, quasars, and massive gas-rich disks. I will highlight results of detections of HCN, HCO+, and other small molecules, as well as the Spitzer detections of PAHs. Additionally, I will discuss about the excitation of CO and other species in the high-z galaxies and put this in the context of new telescopes such as ALMA.
43.	Lankhaar, Boy, 1991 (författare) A comprehensive model of maser polarization 2022 Ingår i: Proceedings of the International Astronomical Union. - 1743-9213 .- 1743-9221. ; 18, s. 430-434 Konferensbidrag (refereegranskat)abstract Maser polarization observations have been successfully used to characterize magnetic fields towards a variety of astrophysical objects. Circular polarization yields the magnetic field strength of the maser source, and linear polarization yields information on the magnetic field morphology. Linear polarization can be produced when the maser saturates or through its anisotropic pumping. We present a comprehensive model of the polarization of masers. In contrast to regular excitation modeling, we relax the assumption of isotropically populated level populations, and model both the total population and level alignments. Through this approach, we obtain quantitative estimates on the anisotropic pumping of a variety of maser sources. In this way, the maser polarization may be related to the gas density, temperature, geometry and the magnetic field. Using the results of our modeling, we discuss, and give predictions, of the polarization of SiO, methanol, and water (mega)masers.
44.	Lankhaar, Boy, 1991, et al. (författare) Quantum-Chemical calculations revealing the effects of magnetic fields on methanol masers 2017 Ingår i: Proceedings of the International Astronomical Union. - 1743-9213 .- 1743-9221. ; 13:S336, s. 23-26 Tidskriftsartikel (refereegranskat)abstract Maser observations of both linearly and circularly polarized emission have provided unique information on the magnetic field in the densest parts of star forming regions, where non-maser magnetic field tracers are scarce. While linear polarization observations provide morphological constraints, magnetic field strengths are determined by measuring the Zeeman splitting in circularly polarized emission. Methanol is of special interest as it is one of the most abundant maser species and its different transitions probe unique areas around the protostar. However, its precise Zeeman-parameters are unknown. Experimental efforts to determine these Zeeman-parameters have failed. Here we present quantum-chemical calculations of the Zeeman-parameters of methanol, along with calculations of the hyperfine structure that are necessary to interpret the Zeeman effect in methanol. We use this model in re-analyzing methanol maser polarization observations. We discuss different mechanisms for hyperfine-state preference in the pumping of torsion-rotation transitions involved in the maser-action.
45.	Leal-Ferreira, M.L., et al. (författare) Water Maser Emission Around Low/Intermediate Mass Evolved Stars 2012 Ingår i: Proceedings of the International Astronomical Union. - 1743-9213 .- 1743-9221. ; 8:S287, s. 79 - 80 Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract We present results of Very Long Baseline Array (VLBA) polarimetric 22 GHz H2O maser observations of a number of low/intermediate mass evolved stars. We observed 3 Miras (Ap Lyn, IK Tau and IRC+60370), 1 semi-regular variable (RT Vir) and 1 pPN (OH231.8+4.2). Circular polarization is detected in the H2O maser region of OH231.8+4.2 and we infer a magnetic field of \|B\|\|\| = ~45 mG. This implies an extrapolated magnetic field of ~2.5 G on the surface of the central star. The preliminary results on RT Vir and IRC+60370 also indicate the first detection of weak H2O maser linear polarization.
46.	Lee, Bumhyun, et al. (författare) The Impact of the Group Environment on the Molecular Gas and Star Formation Activity 2021 Ingår i: Proceedings of the International Astronomical Union. - 1743-9213 .- 1743-9221. ; 17, s. 136-139 Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract At least half of the local galaxies reside in galaxy groups, which indicates that the group is the common environment where galaxies evolve. Therefore, it is important to probe how significantly galaxies are affected by group environmental processes, in order to obtain a better understanding of galaxy evolution. We carried out a new CO imaging survey for 31 galaxies in the IC 1459 and NGC 4636 groups, using the Atacama Compact Array, to study the effect of the group environment on the molecular gas properties and the star formation activity. With our resolved CO data, combined with high-resolution H i images, we find asymmetric CO and H i distributions in the group galaxies. Compared to isolated galaxies, group members have relatively low molecular gas fraction and low star formation rate. These results suggest that the group environment can change the properties of cold gas components and star formation in group galaxies.
47.	Lindegren, Lennart (författare) Gaia: Astrometric performance and current status of the project 2010 Ingår i: Relativity in Fundamental Astronomy: Dynamics, Reference Frames, and Data Analysis (IAU Symposium). - 1743-9213 .- 1743-9221. ; 261, s. 296-305 Konferensbidrag (refereegranskat)abstract The scientific objectives of the Cain mission cover areas of galactic structure and evolution, stellar astrophysics, exoplanets, solar system physics, and fundamental physics. Astrometrically, its main contribution will be the determination of millions of absolute stellar parallaxes and the establishment of a very accurate, dense and faint non-rotating optical reference frame. With a planned launch in spring 2012, the project is in its advanced implementation phase. In parallel, preparations for the scientific data processing are well under way within the Cain Data Processing and Analysis Consortium. Final mission results are expected around 2021, but early releases of preliminary data, are expected. This review summarizes the main science goals and overall organisation of the project, the measurement principle and core astrometric solution, and provide an updated overview of the expected astrometric performance.
48.	Lindroos, Lukas, 1986, et al. (författare) Stacking of interferometric data 2012 Ingår i: Proceedings of the International Astronomical Union. - 1743-9213 .- 1743-9221. - 9781107033849 ; 8:S295, s. 94-94 Konferensbidrag (refereegranskat)abstract Radio and mm observations play an important role in determining the star formation properties of high redshift galaxies. However, most galaxies at high redshift are too faint to be detected individually at these wavelengths. A way to study this population of galaxies is to use stacking. By averaging the emission of a large number of galaxies detected in optical or near infrared surveys, we can achieve statistical detection. We investigate methods for stacking data from interferometric surveys. Interferometry poses unique challenges in stacking due to the nature of imaging of this data. We have compared directly stacking the uv data with stacking of the imaged data, the latter being the typically used approach. Using simulated data, we find that uv-stacking may provide around 50% less noise and that image based stacking systematically loses around 10% of the flux.
49.	Matsuura, M., et al. (författare) ALMA observations of Molecules in Supernova 1987A 2017 Ingår i: Proceedings of the International Astronomical Union. - : Cambridge University Press. - 1743-9213 .- 1743-9221. ; :S331, s. 294-299 Tidskriftsartikel (refereegranskat)abstract Supernova (SN) 1987A has provided a unique opportunity to study how SN ejecta evolve in 30 years time scale. We report our ALMA spectral observations of SN 1987A, taken in 2014, 2015 and 2016, with detections of CO, 28SiO, HCO+ and SO, with weaker lines of 29SiO. We find a dip in the SiO line profiles, suggesting that the ejecta morphology is likely elongated. The difference of the CO and SiO line profiles is consistent with hydrodynamic simulations, which show that Rayleigh-Taylor instabilities causes mixing of gas, with heavier elements much more disturbed, making more elongated structure. Using 28SiO and its isotopologues, Si isotope ratios were estimated for the first time in SN 1987A. The estimated ratios appear to be consistent with theoretical predictions of inefficient formation of neutron rich atoms at lower metallicity, such as observed in the Large Magellanic Cloud (about half a solar metallicity). The deduced large HCO+ mass and small SiS mass, which are inconsistent to the predictions of chemical model, might be explained by some mixing of elements immediately after the explosion. The mixing might have made some hydrogen from the envelope to sink into carbon and oxygen-rich zone during early days after the explosion, enabling the formation of a substantial mass of HCO+. Oxygen atoms may penetrate into silicon and sulphur zone, suppressing formation of SiS. Our ALMA observations open up a new window to investigate chemistry, dynamics and explosive-nucleosynthesis in supernovae.
50.	Mitra, Dhrubaditya, et al. (författare) Oscillatory migratory large-scale fields in mean-field and direct simulations 2009 Ingår i: Proceedings of the International Astronomical Union. - 1743-9213 .- 1743-9221. ; 5, s. 197-201 Tidskriftsartikel (refereegranskat)abstract We summarise recent results form direct numerical simulations of both non-rotating helically forced and rotating convection driven MHD equations in spherical wedge-shape domains. In the former, using perfect-conductor boundary conditions along the latitudinal boundaries we observe oscillations, polarity reversals and equatorward migration of the large-scale magnetic fields. In the latter we obtain angular velocity with cylindrical contours and large-scale magnetic field which shows oscillations, polarity reversals but poleward migration. The occurrence of these behviours in direct numerical simulations is clearly of interest. However the present models as they stand are not directly applicable to the solar dynamo problem. Nevertheless, they provide general insights into the operation of turbulent dynamos.

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