Speaker: Elaheh Hosseini & , Chair: Chaoli Zhang
Title: Dusty sources in the vicinity of Sgr A* and constraining accretion flow
density profile near the Galactic Centre using S2 star
In the vicinity of Sgr A* (SMBH) we observed several dusty infrared sources
with NACO (in K_s and L’ band) and SINFONI mounted at the VLT/Chile. We are
able to identify D2, D3, D23, D3.1 . These sources show near-infrared excess
and Doppler shifted line emission. We investigate these sources in order to
clarify their nature and compare their relation to other observed NIR objects
close to Sgr A*. We need spatial and velocity information of these objects in
order to determine their orbits. We determine Keplerian orbits and apply a
photometric analysis in H, K_s, L’- band. The spectrum of our investigated
objects show a Doppler-shifted Br gamma, HeI and [FeIII] line emission. The
extracted near-infrared flux of our objects fit a SED model which reveals our
sources are dust enshrouded stars. In addition in order to constrain the
density of the ambient medium of Sgr A*, we study the orbit of S2 star and we
succeeded to put an upper limit on the density of this region.
Speaker: Madeleine Yttergren , Chair: Elaheh Hosseini
Title: Gas and stellar dynamics in Stephan’s Quintet
Compact galaxy groups are ideal laboratories for studying intense evolutionary activity. Stephan’s Quintet, a compact group cluster consisting of 5 galaxies, is the home to extensive inter-galactic star formation, active nuclei, previous interactions that can be traced via tidal tails as well as a current shock-inducing interaction. Through studying the gas and stellar dynamics of such a system we can shed light on galaxy evolution caused by extreme galaxy interactions, and thereby take us one step closer to understanding galaxy evolution over cosmic time.
In this talk I will discuss the importance of studying galaxy groups, show the results of our optical spectroscopy observations and briefly discuss the current stage of the analysis.