Observations

Feb 22, 2017

Dark energy tests with quasar monitoring IX

2016-2-SCI-024

The Cosmos is an amazing place full of surprises. Current astronomical observations indicate that the Universe consists in only 5% of the well-known matter, but in 95% of invisible and not understood substances: dark matter and dark energy. Astronomers are convinced of the existence of dark matter, as there is strong observational evidence that it prevents clusters of galaxies from dispersing and forms dark halos around individual galaxies. However, most of the unknown stuff has the form of even more mysterious dark energy, which acts in the opposite way to gravitational attraction: it causes the acceleration of the universal expansion. This conclusion is so peculiar that we need to be sure that our measurements of the expansion are correct, and for that we need various independent measurement methods. The approach that we use to trace dark energy employs quasars – very luminous centres of active galaxies, which are observed from even very large distances – and we need to monitor their behaviour for many consecutive years. Our monitoring is one of the possible ways to answer various questions about dark energy. We predict that quasars can be used to probe the properties of dark energy in a complementary way to the currently employed supernovae type Ia.

Monitoring the line emission in Southern Galactic Be/X-ray binaries

2016-2-SCI-047

Lines arising from the disc of material around Be/X-ray binaries are highly variable on multiple timescales. The variability seen is intimately linked to the mass transfer and resulting X-ray emission seen in such systems, though the details of this link are still not well understood. We are monitoring these lines with SALT/RSS to see how they change during periods of differing X-ray activity and at different points around their orbits.

Spectroscopic observations of bright RR Lyrae variables lacking radial-velocity measurements

2016-1-MLT-003

Spectroscopic observations of bright RR Lyrae variables lacking radial-velocity measurements

Completing RINGS: the RSS Imaging spectroscopy Nearby Galaxy Survey (Phase II)

2016-2-SCI-010

We will measure the orbital speeds of hydrogen gas cloudsin nearby galaxies like our own Milky Way, and we will use them to derive the total mass distribution of each system. By comparing this mass to those of the gas and the stars in each system, we can map its dark matter content. Our main scientific goal is to compare this dark matter content to theoretical models developed from computer simulations of the evolution of the Universe: are our observationsconsistent with predictions from the standard cosmological model input into the simulations, or is our understanding of cosmology and/or galaxy formation incomplete?

Spectroscopy of Low Surface Brightness Galaxies in the GAMA regions

2016-2-SCI-036

We are measuring the emission lines of small, faint galaxies known as low surface brightness galaxies, in order to estimate their distance and how fast they are forming stars.

Systematic radial velocity monitoring of likely intermediate period post-AGB binaries

2016-2-SCI-034

We are looking for double stars in planetary nebulae.

Feb 21, 2017

Completing RINGS: the RSS Imaging spectroscopy Nearby Galaxy Survey (Phase II)

2016-2-SCI-010

We will measure the orbital speeds of hydrogen gas cloudsin nearby galaxies like our own Milky Way, and we will use them to derive the total mass distribution of each system. By comparing this mass to those of the gas and the stars in each system, we can map its dark matter content. Our main scientific goal is to compare this dark matter content to theoretical models developed from computer simulations of the evolution of the Universe: are our observationsconsistent with predictions from the standard cosmological model input into the simulations, or is our understanding of cosmology and/or galaxy formation incomplete?

Evolved binaries in the Magellanic Clouds – ideal tracers of binary interaction physics

2016-2-SCI-003

Stellar Evolution is an important building block in the framework of the Universe. For single stars, like our Sun, the late-stages of evolution involves a rapid transition from the Asymptotic Giant Branch (AGB) phase through the transient post-AGB phase towards the Planetary Nebula Phase (PNe), before the stellar remnant cools down as a White Dwarf (WD). However, more than half of the stars are born as binaries. The evolution of a star can be significantly affected if the star is in a binary system and the outcome is not yet fully understood. Here, we propose to observe and study evolved binary objects that will help understand binary interaction processes which are essential to constrain stellar evolution.

SALT Observations of Planck Clusters

2016-2-SCI-023

Confirmation and redshift determination of possible galaxy clusters.

Spectroscopic Observations of the Hill Sphere Transit in star Beta Pictoris

2016-2-MLT-005

South Africa is a growing community of astronomers working on one of many subsets of astronomy like searching for exoplanets. South Africa has premier observing facilities and is an advantaged astronomical observing site due to its incredible dark skies, geographical location, and range of facilities. It provides a unique window on the southern skies covering the gap between observatories in Australia and South America to provide 24 hour coverage of astronomical objects. In addition, access to the Southern African Large Telescope High Resolution Spectrograph (SALT-HRS) in Sutherland provide access explore the Universe and solar systems similar to us. For this project, the ability to coverage this observing window as well as access to the spectroscopic capabilities with SALT will allow a detailed study of any disk that will be detected in the Beta Pictoris system. Exoplanets and the discovery of worlds around other stars are exciting. Discovering a ring system, such as Saturn, around another star is not only an opportunity to discover how our solar system formed, but a chance to help explain how our Universe works. Furthermore, with the opportunity of observing a bright object, schools and amateur astronomers can be engaged to provide additional monitoring of the objects. This will increase the impact of the overall project and provide ways to engage the public in this exciting project and inspire the next generation of scientist.