Initial Results from the GeMS/GSAOI Galactic Globular Cluster Survey (G4CS)" and "A Study of Nearby Isolated Elliptical Galaxies

Wednesday, 24 August 2016 9 a.m. — 10 a.m. MST

AURA Lecture Hall

NOIRLab South Colloquia
STEPHANIE MONTY; NICKLAS HAMMAR (University of Victoria and Gemini South Research Intern)

Initial Results from The GeMS/GSAOI Galactic Globular Cluster Survey (G4CS)

Exploiting the exquisite resolution capabilities of the Gemini Multi-Conjugate Adaptive Optics Systems (GeMS), coupled with the Gemini South Adaptive Optics Imager (GSAOI), a study has been made of the two galactic globular clusters, NGC 3201 and NGC 2298. Using GSAOI J, H, and KS data collected in 2013-B and 2014-A coupled with HST UV data (F275W, F336W and F438W WFC3 filters) from Piotto et al. 2015 and optical data (F606W and F814W ACS filters) from Sarajedini et al. 2007, we have generated color magnitude diagrams (CMDs) spanning the UV to the near IR for both clusters. These CMDs have revealed, for the first time, the lower main sequence "knee", a feature characteristic of near-IR CMDs. Utilizing the main sequence "knee" allows for precise distance and reddening independent age determination. Other features recovered in both clusters include a binary sequence and hints of possible multiple stellar populations. Several CMDs will be presented, along with a discussion of the techniques used to reduce and analyze this difficult data set and initial science results, including preliminary isochrone fitting.


A Study of Nearby Isolated Elliptical Galaxies

Observations of 13 elliptical galaxies were obtained from two sources - two of the 1m Las Cumbres Observatory Global Telescope Network telescopes, and the 1.6m Korean Microlensing Telescope Network telescope, all at CTIO. The observations were reduced and coadded using the THELI software package. SExtractor was used to create masks for the images, and the IRAF task ellipse was then used to model each galaxy. From there, several avenues of analysis were explored, including creating surface brightness profiles and fitting them with Sersic profiles, producing radial plots of number density of background galaxies, and calculating a quantitative measure of tidal disruption, in a ''tidal parameter''. The galaxy models were also subtracted from the images in order to visually identify any tidal features present.