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Both science public outreach and citizen science projects have gained immense momentum in the western world in recent years. This work aims to outline some ongoing and possible future projects in the developing world on this front. Cooperation and collaboration with IAU-OAD is envisaged.
The discovery of the ubiquity of filaments in the interstellar medium in the last two decades has begged the question: “What role do filaments play in star formation?” Here we describe how our automated filament finding algorithms can combine with both magnetic field measurements and high-resolution observations of dense cores in these filaments, to provide a statistically large sample to investigate the effect of filaments on star formation. We find that filaments are likely actively accreting mass from the interstellar medium, explaining why some 60% of stars, and all massive stars, form “on-filament”.
In the cores of galaxy clusters there is a population of lows-mass stellar systems such as dwarf Early-type galaxies, ultra-compact dwarf galaxies (UCDs) and ultra diffuse dwarf galaxies. We present here the photometric and morphological characterization of this population of objects using deep CFHT images of a sample of clusters belonging to the WINGS survey (0.04 < z < 0.06). We study only galaxies that are spectroscopically confirmed members of the cluster. The population of dwarfs ranges from ∽ 30% for the more rich clusters to ∽ 5-6% for the less rich ones.
The scenario of star cluster formation can be better understood based on the detailed study of the dynamical conditions of the associated gas, clustering properties and effects of ionizing sources, among others. Some of these characteristics are explored in our ongoing work based on observations with the SOAR and T80-S telescopes. With these data we have obtained a complete multi-band photometric catalogue of selected clusters that we characterize using color-color diagrams and flux ratios. In particular, this work is focused on SOAR/Spartan (near-infrared) observations of the Canis Major star-forming region.
Dense cores represent a critical stage in the star-formation process, but are not physically well-defined entities. We present a new technique to define core boundaries in observations of molecular clouds based on the physical properties of the cloud medium. Applying this technique to regions in the Pipe nebula, we find that our core boundaries differ from previous analyses, with potentially crucial implications for the statistical properties of the core sample.
The primary objectives of the ExoplANETS-A project are to: establish new knowledge on exoplanet atmospheres; establish new insight on influence of the host star on the planet atmosphere; disseminate knowledge, using online, web-based platforms. The project, funded under the EU’s Horizon-2020 programme, started in January 2018 and has a duration ∼3 years. We present an overview of the project, the activities concerning the host stars and some early results on the host stars.
The sculpting of the Egg Nebula continues to defy a coherent explanation. Bipolar outflows from the center of the nebula have created bipolar optical lobes that are illuminated by searchlight beams; multiple bipolar outflows orthogonal to the lobes create the appearance of a dark lane; and quasi-circular arcs are imprinted on an approximately spherically-symmetric wind from the progenitorAGB-star. Here, we use archival data from ALMA to study at high angular resolution dust and molecular gas at the center of the nebula. We find that: (i) dust is concentrated in multiple blobs that outline the base of the northern optical lobe; (ii) dense molecular gas forms the wall of a channel swept up and compressed by the outflows that created the bipolar optical lobes; (iii) the expansion and illumination center of the nebula lies at or close to center of the outflow channel. We present a simple working model for the Egg Nebula, and highlight the difficulties that any model face for explaining all the features seen in this nebula.
The study of dwarf spheroidal galaxies (dSph) is of great importance to understand galaxy evolution at the low-mass end. In the Local Group the majority of them are found to be satellites of the Milky Way or M31. The closest ones have been studied in great detail, however it is hard to constrain if their present-day observed properties are mainly caused by internal or environmental mechanisms. In order to minimize these effects and gain an insight into their intrinsic properties, we are studying two of the three isolated dSph galaxies in the Local Group, i.e. Cetus and Tucana, located far beyond the virial radius of the Milky Way and M31. We present here results from our recently published analysis of Cetus (Taibi2018) and preliminary results for Tucana (Taibi et al. in prep.).
In this contribution we introduce the motivation and goals of IAU Focus Meeting 8, “New Insights in Extragalactic Magnetic Fields”. We provide a background for the nine contributions included in these proceedings, as well as the online contributions. A recap of the meeting is provided in the form of audience feedback that was collected during the wrap-up session at the conclusion of FM8.
UV radiation plays a critical role in the chemistry of circumstellar envelopes (CSEs) around evolved stars on the asymptotic giant branch (AGB). However, the effects of all potential sources of UV radiation have not been included in models. We present preliminary results of adding an internal source of UV to the CSE chemistry and predict large enhancements of atomic and ionic species arising from photo-destruction of parent species. Observations of atomic carbon towards the UV-bright AGB star o Cet are consistent with the modelling. In addition, we calculate the precise depth dependence of the CO photodissociation rate in an expanding CSE. We incorporate this within a chemical network active in the outflows of AGB stars, which includes 933 species and 15182 reactions. Our results show that the CO envelope size is about 30% smaller at half abundance than the most commonly used radius reported by Mamon et al. (1988).
Reproducing the planes of co-orbiting satellites observed in the MW and M31 so far has represented a challenge for cosmological simulations. We have developed a new method to search for kinematically-coherent groups of satellites and applied it to 2 different cosmological hydro-simulations of disc galaxies. In each simulation we have found such a group, that represents roughly half of the total satellite population and is distributed on a fairly thin plane that persists in time. These results are compatible with the MW and M31 observed planes.
The unprecedented sensitivity, angular resolution and broad bandwidth coverage of Square Kilometre Array (SKA) radio polarimetric observations will allow us to address many long-standing mysteries in cosmic magnetism science. I will highlight the unique capabilities of the SKA to map the warm hot intergalactic medium, reveal detailed 3-dimensional structures of magnetic fields in local galaxies and trace the redshift evolution of galactic magnetic fields.
We follow up on a previous finding that Miras containing the third dredge-up (3DUP) indicator technetium (Tc) in their atmosphere form a different sequence of K – [22] colour as a function of pulsation period than Miras without Tc. A near-to-mid-infrared colour such as K – [22] is a good probe for the dust mass-loss rate (MLR) of these AGB stars. Contrary to what one might naïvely expect, Tc-poor Miras show redderK – [22] colours (i.e. higher dust MLRs) than Tc-rich Miras at a given period. In the follow-up work, the previous sample is extended and the analysis is expanded towards other colours and ISO dust spectra to check if the previous finding is due to a specific dust feature in the 22 μm band. We also investigate if the same two sequences can be revealed in the gas MLR. Different hypotheses to explain the observation of two sequences in the P vs. K – [22] diagram are discussed and tested, but so far none of them convincingly explains the observations.
The chemical enrichment of the Universe is considerably affected by the contribution of cool evolved stars. We studied the O-rich star R Peg and the C-rich star V Oph, using respectively the VLTI/GRAVITY and VLTI/MIDI instruments. We interpret the data using grids of 1-D and 3-D dynamic model atmospheres.
Analyzing 41 targets data of the Kepler K2 Campaign 2 mission suspected to be Long Period Variables (LPVs), we developed a method for the prediction of periods longer than the observation period of 77.48d using the 3500 data points provided by K2. The ‘Self-Flat-Field’ method (K2SFF or SFF) of the ‘ Kepler K2 High Level Science Product’ (K2HLSP) corrected the instrumental effects best.
The Planck catalogue of Galactic cold clumps, PGCC, contains sources of ongoing and future star formation. The data show clear variations also in their dust properties.
We use Planck polarization measurements to investigate the polarization fraction in PGCC clumps and the relative orientation of filamentary structures and magnetic fields (Alina et al. 2017). The decrease of polarization fraction as a function of column density can be related to the field geometry but also suggest some loss of grain alignment.
PGCCs have been studied with ground-based observations (Liu et al. 2018). The first SCUBA-2/POL-2 polarization studies have targeted the infrared dark cloud G35.39-0.33. The magnetic field is found to be mostly perpendicular to the main filament. The plane-of-the-sky field strength is $\sim 50\mu \,{\rm{G}}$, a noticeable support against gravity. The polarization fraction decreases with increasing column density. This matches predictions of RAT grain alignment models but the relative contribution of the field morphology is hard to quantify (Juvela et al. 2018).
We continue to use MHD simulations to study the same phenomena, with synthetic observations of clumps and filaments.