TitleFabry-Perot studies of the Milky Way bar
NameRangwala, Naseem (author), Williams, Ted (chair), Pryor, Tad (internal member), Matilsky, Terry (internal member), Thomas, Scott (internal member), Zinn, Robert (outside member), Rutgers University, Graduate School - New Brunswick,
SubjectPhysics and Astronomy,
DescriptionGalactic bars and bulges play an important role in the formation and evolution processes in disk galaxies. There is now substantial evidence that our Galaxy is barred, and many unresolved questions about the structure, dynamics and star formation history of the inner Galaxy remain.
We use Fabry-Perot (FP) absorption line imaging spectroscopy to measure radial velocities using the CaII8542 line in 3360 stars towards three lines of sight in the Milky Way's bar: Baade's Window and offset positions at (l,b) ~ (pm 5.0, -3.5). This sample includes 2488 bar red clump giants, 339 bar M-giants, and 318 disk main sequence stars. We measure the first four
moments of the stellar velocity distribution of the red clump giants, and find it to be symmetric and flat-topped. We detect stellar streams at the near and far side of the bar with velocity difference ~ 30 km/s at l = +/- 5, indicating strong non-circular motions. We do
not detect two separate streams in Baade's Window. Our M-giants kinematics agree well with previous studies, but have dispersions systematically lower than those of the red clump giants by ~10 km/s.
We show that reliable absorption line strengths can also be measured using FP spectroscopy. The
CaII8542 line is a good indicator of metallicity and its calibration to [Fe/H] is determined for globular cluster red giants in previous investigations. We derive such a calibration for the bulge giants and use it to infer metallicities for our red clump sample. We present the stellar metallicity distributions along the major axis of the bar. We find the mean [Fe/H] in Baade's Window close to solar, and the distribution in this field agrees well with previous works. We find negative gradients in the mean metallicity and its dispersion along the bar. We detect a signature of a possible new tidal stream at l = +5.5, in both our velocity and metallicity distributions. We also measure the metallicity of a bulge globular cluster NGC 6522 in our Baade's Window field to be -0.9 dex, in good agreement with previous high-resolution spectroscopic measurements, demonstrating the reliability of our metallicity measurements.
We also present the design and testing of the FP system for the 10-meter class Southern African Large Telescope, and its characterization as measured in the laboratory. It provides spectroscopic imaging at any desired wavelength spanning a bandpass 430 -- 860 nm, at four different spectral resolving powers ranging from 300 to 9000. This FP system will provide a
powerful tool for imaging spectroscopy on one of the world's largest telescopes.
NoteIncludes bibliographical references
Noteby Naseem Rangwala
CollectionGraduate School - New Brunswick Electronic Theses and Dissertations
Organization NameRutgers, The State University of New Jersey
RightsThe author owns the copyright to this work