Theory Group Concepción

Departamento de Astronomía, Universidad de Concepción, Chile

Tools and Downloads

New web-tool: Online Calculator RESoRt (Radio Emission Star Formation Rate)

The online calculator RESoRt (Radio Emission Star formation Rate) is a tool for determining the star formation rate (SFR) from the non-thermal galactic radio flux or vice versa.

In short, the physical background for a connection between the SFR and the radio flux is the following:
Non-thermal long-wavelength photons are emitted by highly energetic charged particles that travel in spiral motion around the interstellar magnetic field lines. These cosmic rays are connected to star formation as they are produced in supernova shock fronts. The link between synchrotron emission and the SFR is, however, not direct because the cosmic ray spectrum is affected by various processes, such as inverse Compton scattering, bremsstrahlung, ionization of the interstellar medium, interaction with the interstellar radiation field, and galactic outflows. Especially in galaxies with high gas densities, cosmic rays lose a large fraction of their energy via ionization. As a result, the radio flux does not contain any information about the SFR below a critical radio frequency.More details and the calculator itself can be found here:

Geryon 2 explanation slides

The slides from the Geryon 2 presentation can be found HERE

New Web-tool for the Applegate Mechansim

Our group has developed a unique web-tool to calculate the magnetic activity in Binary Stars via the Applegate Mechanism. This work is part of a joint project with the Hamburg Observatory, Germany.

This module allows to calculate whether eclipsing time variations of a given magnitude can be produced via magnetic activity, specifically by what is referred to as the Applegate mechanism. This formalism considers changes in the stellar quadrupole moment, arising as a result of angular momentum redistribution due to magnetic activity. The change in the quadrupole moment couples to the binary orbit via gravity, thus inducing the period change. The calculation below assesses the required energy for the change in the quadrupole moment, which is compared to the energy that is produced by the star. The latter is crucial to assess the feasibility of the Applegate mechanism within a specific system.

Have a look for yourself: Applegate

An extensive catalogue of early-type galaxies in the nearby Universe

We present a catalogue of 1715 early-type galaxies from the literature, spanning the luminosity range from faint dwarf spheroidal galaxies to giant elliptical galaxies. The aim of this catalogue is to be one of the most comprehensive and publicly available collections of data on early-type galaxies. The emphasis in this catalogue lies on dwarf elliptical galaxies, for which some samples with detailed data have been published recently. For almost all of the early-type galaxies included in it, this catalogue contains data on their locations, distances, redshifts, half-light radii, the masses of their stellar populations and apparent magnitudes in various passbands. Data on metallicity and various colours are available for a majority of the galaxies presented here, including many of the rather faint early-type galaxies in the Local Group. The data on magnitudes, colours, metallicities and masses of the stellar populations is supplemented with entries that are based on fits to data from simple stellar population models and existing data from observations. Also, some simple transformations have been applied to the data on magnitudes, colours and metallicities in this catalog, in order to increase the homogeneity of this data. Estimates on the Sersic profiles, internal velocity dispersions, maximum rotational velocities, dynamical masses and ages are listed for several hundreds of the galaxies in this catalogue. Finally, each quantity listed in this catalogue is accompanied with information on its source, so that users of this catalogue can easily exclude data that they do not consider as reliable enough for their purposes.
( Dabringhausen & Fellhauer, 2016, MNRAS, 460, 4492)

The catalogue files can be downloaded here.

KROME - a chemical network package

Our group is involved in the devellopment of the KROME package.
For more information please visit the KROME homepage

© Theory Group Concepcion 2019