Anomalous gas in ESO 149-G003: a MeerKAT-16 view Józsa, Gyula I G; Thorat, Kshitij; Kamphuis, Peter ...
Monthly notices of the Royal Astronomical Society,
02/2021, Letnik:
501, Številka:
2
Journal Article
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ABSTRACT
ESO 149-G003 is a close-by, isolated dwarf irregular galaxy. Previous observations with the ATCA indicated the presence of anomalous neutral hydrogen ($\rm{H{\small I}}$) deviating from the ...kinematics of a regularly rotating disc. We conducted follow-up observations with the MeerKAT radio telescope during the 16-dish Early Science programme as well as with the MeerLICHT optical telescope. Our more sensitive radio observations confirm the presence of anomalous gas in ESO 149-G003, and further confirm the formerly tentative detection of an extraplanar $\rm{H{\small I}}$ component in the galaxy. Employing a simple tilted-ring model, in which the kinematics is determined with only four parameters but including morphological asymmetries, we reproduce the galaxy’s morphology, which shows a high degree of asymmetry. By comparing our model with the observed $\rm{H{\small I}}$, we find that in our model, we cannot account for a significant (but not dominant) fraction of the gas. From the differences between our model and the observed data cube, we estimate that at least 7–8 per cent of the $\rm{H{\small I}}$ in the galaxy exhibits anomalous kinematics, while we estimate a minimum mass fraction of less than 1 per cent for the morphologically confirmed extraplanar component. We investigate a number of global scaling relations and find that, besides being gas-dominated with a neutral gas-to-stellar mass ratio of 1.7, the galaxy does not show any obvious global peculiarities. Given its isolation, as confirmed by optical observations, we conclude that the galaxy is likely currently acquiring neutral gas. It is either re-accreting gas expelled from the galaxy or accreting pristine intergalactic material.
•Solvents were selected for extractive distillation of polar close-boiling mixtures.•Three mixtures (acid–acid), (ether–amine), and (alcohol–ketone) were studied.•Solvent functional groups were ...selected based on expected interactions.•Deviations from Raoult could be related to the intermolecular interactions.•With isothermal titration calorimetry, the intermolecular interactions were studied.
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Solvent selection is key in extractive distillation process development and solvent effects are often predicted based on the activity coefficients at infinite dilution. For close-boiling polar systems with strong or specific interacting species, standard simulation tools, e.g. using UNIFAC or COSMO-RS, often predict poor as the activity coefficients at infinite dilution not always reflect the selectivity in the process. For these systems, a heuristic solvent selection method in which molecular properties such as acidity, hydrogen bonding and polarity are applied is desired as first estimate in the solvent selection. To explore the key parameters for such a first selection, solvent effects on the relative volatility (α) were measured for three different industrially relevant polar mixtures, valeric acid – 2-methylbutyric acid, diethylmethylamine – diisopropylether, and 2-butanol – 2-butanone. For each of the cases the effect of potential solvents on α was measured in an ebulliometer. For the acids, the difference in pKa of 0.1 was too small to separate based on acidity with a moderately basic solvent. Stronger basic solvents resulted in thermal and chemical instability. Although the solvent methyl-2-methyl butyrate is not suitable as a solvent because of reactivity, this structurally similar solvent showed selectivity, indicating also in extractive distillation the like dissolves like phenomenon can be applied to induce selectivity. A larger difference in basicity of the mixture components (amine–ether mixture) and a difference in hydrogen bonding affinity between the mixture components (ketone–alcohol mixture) allowed for increasing α based on differences in acidity and hydrogen bonding, respectively.
Using data taken as part of the Bluedisk project, we study the connection between neutral hydrogen (H i) in the environment of spiral galaxies and that in the galaxies themselves. We measure the ...total H i mass present in the environment in a statistical way by studying the distribution of noise peaks in the H i data cubes obtained for 40 galaxies observed with Westerbork Synthesis Radio Telescope. We find that galaxies whose H i mass fraction is high relative to standard scaling relations have an excess H i mass in the surrounding environment as well. Gas in the environment consists of gas clumps which are individually below the detection limit of our H i data. These clumps may be hosted by small satellite galaxies and/or be the high-density peaks of a more diffuse gas distribution in the intergalactic medium. We interpret this result as an indication for a picture in which the
${\rm H}\,{\small {I}}$
-rich central galaxies accrete gas from an extended gas reservoir present in their environment.
We present Australia Telescope Compact Array radio data of the dwarf irregular galaxy ESO 324-G024 which is seen in projection against the giant, northern lobe of the radio galaxy Centaurus A (Cen A, ...NGC 5128). The distorted morphology and kinematics of ESO 324-G024, as observed in the 21 cm spectral line emission of neutral hydrogen, indicate disruptions by external forces. We investigate whether tidal interactions and/or ram pressure stripping are responsible for the formation of the H i tail stretching to the north-east of ESO 324-G024 with the latter being most probable. Furthermore, we closely analyse the sub-structure of Cen A's polarized radio lobes to ascertain whether ESO 324-G024 is located in front, within or behind the northern lobe. Our multiwavelength, multicomponent approach allows us to determine that ESO 324-G024 is most likely behind the northern radio lobe of Cen A. This result helps to constrain the orientation of the lobe, which is likely inclined to our line of sight by approximately 60° if NGC 5128 and ESO 324-G024 are at the same distance.
We revisit the H I size-mass (D sub( HI)-M sub( HI)) relation of galaxies with a sample of more than 500 nearby galaxies covering over five orders of magnitude in HI mass and more than 10 B-band ...magnitudes. The relation is remarkably tight with a scatter s ~ 0.06 dex, or 14 per cent. The scatter does not change as a function of galaxy luminosity, HI richness or morphological type. The relation is linked to the fact that dwarf and spiral galaxies have a homogeneous radial profile of HI surface density in the outer regions when the radius is normalized by D sub( HI). The early-type disc galaxies typically have shallower HI radial profiles, indicating a different gas accretion history. We argue that the process of atomic-to-molecular gas conversion or star formation cannot explain the tightness of the D sub( HI)-M sub( HI) relation. This simple relation puts strong constraints on simulation models for galaxy formation.
The objective is to design a plant from raw material to product for the production of aniline by direct amination of benzene. The process design is started on a conceptual level and ended on a basic ...engineering level as well as a techno‐economical evaluation. The amination of benzene by hydroxylamine was used as basis. For the production of hydroxylamine four routes are proposed. The most promising route is the chemical reduction of nitric oxide with hydrogen. The process evaluation shows that 27 % of the atomic nitrogen is lost. The atomic carbon efficiency is close to unity. Furthermore, a significant amount of steam can be produced. From an economical perspective, there is still room for improvement because the return of investment is quite low and the payback period is quite high.
Aniline is a frequently used bulk chemical. Since today's synthetic routes suffer from low atomic efficiencies, a systematic approach was used to develop a process to produce aniline from benzene by direct amination. The proposed process can deliver a significant amount of high‐quality steam and is economically and technically feasible.
We present 21 cm observations and models of the H I kinematics and distribution of NGC 4244, a nearby edge-on Scd galaxy observed as part of the Westerbork HALOGAS (Hydrogen Accretion in LOcal ...GAlaxieS) survey. Our models give insight into the H I kinematics and distribution with an emphasis on the potential existence of extraplanar gas as well as a negative gradient in rotational velocity with height above the plane of the disk (a lag). Our models yield strong evidence against a significantly extended halo and instead favor a warp component along the line of sight as an explanation for most of the observed thickening of the disk. Based on these models, we detect a lag of -9{sup +3}{sub -2} km s{sup -1} kpc{sup -1} in the approaching half and -9 {+-} 2 km s{sup -1} kpc{sup -1} in the receding half. This lag decreases in magnitude to -5 {+-} 2 km s{sup -1} kpc{sup -1} and -4 {+-} 2 km s{sup -1} kpc{sup -1} near a radius of 10 kpc in the approaching and receding halves, respectively. Additionally, we detect several distinct morphological and kinematic features including a shell that is probably driven by star formation within the disk.
The H i Neighborhoods Around STARBIRDS Johnson, Megan C.; McQuinn, Kristen B. W.; Cannon, John ...
Proceedings of the International Astronomical Union,
08/2018, Letnik:
14, Številka:
S344
Journal Article
Recenzirano
Abstract
Starbursts are finite periods of intense star formation (SF) that can dramatically impact the evolutionary state of a galaxy. Recent results suggest that starbursts in dwarf galaxies last ...longer and are distributed over more of the galaxy than previously thought, with star formation efficiencies (SFEs) comparable to spiral galaxies, much higher than those typical of non-bursting dwarfs. This difference might be explainable if the starburst mode is externally triggered by gravitational interactions with other nearby systems. We present new, sensitive neutral hydrogen observations of 18 starburst dwarf galaxies, which are part of the STARburst IRregular Dwarf Survey (STARBIRDS) and each were mapped with the Green Bank Telescope (GBT) and/or Parkes Telescope in order to study the low surface brightness gas distributions, a common tracer for tidal interactions.
We present 21 cm observations and models of the H I kinematics and distribution of NGC 4244, a nearby edge-on Scd galaxy observed as part of the Westerbork HALOGAS (Hydrogen Accretion in LOcal ...GAlaxieS) survey. Our models give insight into the H I kinematics and distribution with an emphasis on the potential existence of extraplanar gas as well as a negative gradient in rotational velocity with height above the plane of the disk (a lag). Our models yield strong evidence against a significantly extended halo and instead favor a warp component along the line of sight as an explanation for most of the observed thickening of the disk. Based on these models, we detect a lag of --9+3 -- 2 km s--1 kpc--1 in the approaching half and --9 ? 2 km s--1 kpc--1 in the receding half. This lag decreases in magnitude to --5 ? 2 km s--1 kpc--1 and --4 ? 2 km s--1 kpc--1 near a radius of 10 kpc in the approaching and receding halves, respectively. Additionally, we detect several distinct morphological and kinematic features including a shell that is probably driven by star formation within the disk.
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