Observations

Jul 16, 2019

2018-2 OU-SALT: Establishing a homogeneous database for activity of close-in planet hosts

2018-2-MLT-003

We are observing stars with planets orbiting very close to them. These planets complete an orbit around their star in about a day. This means the planets are heated and pulled by the star’s gravity and magnetic field. We are looking at the signatures of that in emission from calcium in the outer layers of the star’s atmosphere.

Surface Chemistry of Peculiar Hot Subdwarfs

2019-1-MLT-003

Stars approaching the end of their lives expand and, in many cases, exchange material with close companions. This has a radical effect on their evolution and surface composition, producing a zoo of rare but highly exotic stars. By exploring the propertiesof thes pathological cases, we are endeavouring to understand the ways in which stars exhange matter and evolve towardstheir final fate as white dwarfs or supernovae. The stars in this programme are perfect examples — many of them have completelylost their surface hydrogen, for reasons still to be explained. These observations will tell us about the abundances of otherelements — previously we have discovered huge overabundances of exotic species such as lead and zirconium, and will explore how some of these stars may vary over time.

Asymmetry is Destiny: Wolf-Rayet Binary Stars as GRB Progenitors

2018-2-MLT-005

This program aims to use the recently-commissioned high-precision spectropolarimetry mode of RSS to probe the prodigious mass-loss from certain massive evolved stars known as Wolf-Rayet stars which are in binary systems. These objects are possible progenitors of Gamma-Ray Bursts, which are the most energetic explosions yet known, and can be seen across the entire known universe.

TESSting the interior structures of supernova progenitors

2019-1-SCI-036

Just as we know the interior structure of the Earth from the analysis of earthquakes, astronomers use stellar oscillations – “starquakes” to sound the inner life of the stars. Very precise measurements, such as from the upcoming NASA mission TESS, are required for this effort. The present project uses stellar spectral from SALT to characterize some targets for TESS, stars which are highly interesting because they are tomorrow’s supernovae.

SALT Spectroscopy of Gaia Hypervelocity Stars

2019-1-SCI-020

Following fast-moving stars found by Gaia. @_sublunar_ @kenjshen

SALT HRS radial velocity monitoring of post-AGB binary stars

2018-2-MLT-007

We are searching for binary stars in some of the most beautiful stellar remnants in the Galaxy.

Spectroscopic observations of central stars of mid-infrared nebulae discovered w ith Spitzer and WISE

2019-1-MLT-002

Spectroscopic observations of central stars of mid-infrared nebulae discovered w ith Spitzer and WISE

Observing the Transient Universe

2018-2-LSP-001

This large SALT program is aimed at studying “things that go bang in the night”, namely transient objects in the Universe which either are newly discovered objects, or known objects who suddenly change their appeatance. Such things include binary stars with accreting compact companions, many of them X-ray or gamma ray sources, eruptive stars which suddenly brighten, black holes systems, including active galaxies powered by them, and all manner of explosions including the most energetic of all, gamma ray bursts.

Jul 15, 2019

HRS monitoring of yellow symbiotic systems

2019-1-MLT-008

We propose to obtain high resolution (R~40000) high S/N (≳50) spectra for two dozens of so called yellow symbiotic systems using HRS spectrograph in MR mode. The aim of the proposal is to use HRS spectra for the radial velocity monitoring and to measure abundances of chemical elements. Radial velocities will be derived through cross-correlation technique. Abundances will be measured using the spectral synthesis employing the method of standard LTE analysis. We will also look for possible abundance anomalies due to, e.g., former mass transfer pollution. We expect to obtain new information about orbital parameters of these systems. Using it together with new Gaia DR2 distances we are going to revise and put new constraints on the physical parameters (temperature, luminosity, abundances) of these giants. It seems be very likely that these objects may turn out to have significantly larger diameters, and so be located at longer distances, be significantly colder and more luminous – the bright giants rather than a normal giants

Surface Chemistry of Peculiar Hot Subdwarfs

2019-1-MLT-003

Stars approaching the end of their lives expand and, in many cases, exchange material with close companions. This has a radical effect on their evolution and surface composition, producing a zoo of rare but highly exotic stars. By exploring the propertiesof thes pathological cases, we are endeavouring to understand the ways in which stars exhange matter and evolve towardstheir final fate as white dwarfs or supernovae. The stars in this programme are perfect examples — many of them have completelylost their surface hydrogen, for reasons still to be explained. These observations will tell us about the abundances of otherelements — previously we have discovered huge overabundances of exotic species such as lead and zirconium, and will explore how some of these stars may vary over time.