Observations

May 18, 2019

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.

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 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.

Searching for new chemically peculiar stars in the southern hemisphere

2019-1-MLT-006

We aim at looking for new chemically peculiar stars (CPs) among southern late B-type stars. The region of the Main Sequence centered on early A and late B stars, also referred to as the “tepid stars”, represents an ideal laboratory to study a wide variety of physical processes that are at work in most stellar types. These processes include radiation driven diffusion, differential gravitational settling, and magnetic fields. While their observable manifestation is particularly prominent in tepid stars, some or all of them do play a significant role in the physics, formation, and evolution of most stars. Among the tepid stars, one identifies chemically peculiar objects, that have characteristic surface abundance patterns, strength and structure of the magnetic field, rotation, and multiplicity. For instance, the classical magnetic Bp-Si stars and the HgMn stars result from different formation and evolution scenarios. Their study allows to gain insight into the above-mentioned physical processes.

HRS HS-mode commissioning

2019-1-COM-002

Getting the HRS tuned up for exoplanet science

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

May 17, 2019

Variability Of CaII K and NaI D lines in the Direction Of Vela Supernova Remnant

2019-1-SCI-006

The interaction of supernova remnants (SNR) with the surrounding interstellar medium (ISM) plays an important role in the study of many areas in astronomy ranging from the dynamics of the ISM, chemical evolution of the Galaxy to star formation. The process of how supernova ejecta merges with surrounding, irregular cloudy ISM is the focus of our study. The nearest SNR to us is the Vela SNR that exploded 11000 years ago. The properties of the SNR medium are proposed to be studied by observing the stars in and behind the SNR through high resolution absorption line spectroscopy with HRS on SALT.

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.

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.