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Register a new userHow to organize an online conference -- Lessons learned from Cool Stars 20.5 (virtually cool)
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Added by
Hans Moritz G\\\"unther
Publication date
2021
fields
Physics
and research's language is
English
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The virtual meeting was a success. Several people told us that this was the best virtual meeting they had seen so far, which, a year into the pandemic and without a commercial provider in the back, is a great success. The biggest point of criticism was the timing: We had programming from UTC 17:00-22:00 (evening and night in central Europe, afternoon on the US East Coast, during the day in South America and on the US West coast, but in the middle of the night for Asia and Australia). There is no good solution, but at least some variation in session time might go a long way to make it easier for all to attend at least some sessions. Feedback also indicates that the schedule was too compressed. Poster sessions and social contacts with the tool Gathertown worked out really well for all that used it. Our way of combining several services (Zoom for plenary and break-out rooms, Zenodo for uploading and viewing posters and proceedings, Google forms for registration and abstract submission, gathertown) allowed for a very low-cost meeting with little overhead (total cost: 600 $ for gathertown, zoom was provided through an institutional subscription, just 4 people on the LOC).
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The 15th European Conference on Computer Systems (EuroSys20) was organized as a virtual (online) conference on April 27-30, 2020. The main EuroSys20 track took place April 28-30, 2020, preceded by five workshops (EdgeSys20, EuroDW20, EuroSec20, PaPoC20, SPMA20) on April 27, 2020. The decision to hold a virtual (online) conference was taken in early April 2020, after consultations with the EuroSys community and internal discussions about potential options, eventually allowing about three weeks for the organization. This paper describes the choices we made to organize EuroSys20 as a virtual (online) conference, the challenges we addressed, and the lessons learned.
We performed a wide-area (2000 deg$^{2}$) g and I band experiment as part of a two month extension to the Intermediate Palomar Transient Factory. We discovered 36 extragalactic transients including iPTF17lf, a highly reddened local SN Ia, iPTF17bkj, a new member of the rare class of transitional Ibn/IIn supernovae, and iPTF17be, a candidate luminous blue variable outburst. We do not detect any luminous red novae and place an upper limit on their rate. We show that adding a slow-cadence I band component to upcoming surveys such as the Zwicky Transient Facility will improve the photometric selection of cool and dusty transients.
Stellar flares, winds and coronal mass ejections form the space weather. They are signatures of the magnetic activity of cool stars and, since activity varies with age, mass and rotation, the space weather that extra-solar planets experience can be very different from the one encountered by the solar system planets. How do stellar activity and magnetism influence the space weather of exoplanets orbiting main-sequence stars? How do the environments surrounding exoplanets differ from those around the planets in our own solar system? How can the detailed knowledge acquired by the solar system community be applied in exoplanetary systems? How does space weather affect habitability? These were questions that were addressed in the splinter session Cool stars and Space Weather, that took place on 9 Jun 2014, during the Cool Stars 18 meeting. In this paper, we present a summary of the contributions made to this session.
The current and planned high-resolution, high-multiplexity stellar spectroscopic surveys, as well as the swelling amount of under-utilized data present in public archives have led to an increasing number of efforts to automate the crucial but slow process to retrieve stellar parameters and chemical abundances from spectra. We present MyGIsFOS, a code designed to derive atmospheric parameters and detailed stellar abundances from medium - high resolution spectra of cool (FGK) stars. We describe the general structure and workings of the code, present analyses of a number of well studied stars representative of the parameter space MyGIsFOS is designed to cover, and examples of the exploitation of MyGIsFOS very fast analysis to assess uncertainties through Montecarlo tests. MyGIsFOS aims to reproduce a ``traditional manual analysis by fitting spectral features for different elements against a precomputed grid of synthetic spectra. Fe I and Fe II lines can be employed to determine temperature, gravity, microturbulence, and metallicity by iteratively minimizing the dependence of Fe I abundance from line lower energy and equivalent width, and imposing Fe I - Fe II ionization equilibrium. Once parameters are retrieved, detailed chemical abundances are measured from lines of other elements. MyGIsFOS replicates closely the results obtained in similar analyses on a set of well known stars. It is also quite fast, performing a full parameter determination and detailed abundance analysis in about two minutes per star on a mainstream desktop computer. Currently, its preferred field of application are high-resolution and/or large spectral coverage data (e.g UVES, X-Shooter, HARPS, Sophie).
Massive galaxy clusters with cool-cores typically host diffuse radio sources called mini-haloes, whereas, those with non-cool-cores host radio haloes. We attempt to understand the unusual nature of the cool-core galaxy cluster CL1821+643 that hosts a Mpc-scale radio halo using new radio observations and morphological analysis of its intra-cluster medium. We present the Giant Metrewave Radio Telescope (GMRT) 610 MHz image of the radio halo. The spectral index, $alpha$ defined as $Spropto u^{-alpha}$, of the radio halo is $1.0pm0.1$ over the frequency range of 323 - 610 - 1665 MHz. Archival {it Chandra} X-ray data were used to make surface brightness and temperature maps. The morphological parameters Gini, $M_{20}$ and concentration ($C$) were calculated on X-ray surface brightness maps by including and excluding the central quasar (H1821+643) in the cluster. We find that the cluster CL1821+643, excluding the quasar, is a non-relaxed cluster as seen in the morphological parameter planes. It occupies the same region as other merging radio halo clusters in the temperature- morphology parameter plane. We conclude that this cluster has experienced a non-core-disruptive merger.
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