Connor Pickett
Academic and research departments
Astrophysics Research Group, Faculty of Engineering and Physical Sciences.About
My research project
M31 Dwarf GalaxiesMy research focuses on dark matter in Andromeda's satellite galaxies, particularly ultra diffuse dwarf galaxies. I measure the mass, velocity, and luminosity of these objects to further understand their dark matter composition. In doing so, I am able to compare these results with our current understanding of these dwarfs, helping to better understand the creation and current status of the M31 system.
I primarily use Justin Read's GravSphere software, allowing for the measurement of dwarfs' dark matter profiles. The resulting data contributes to the ongoing process of a finding a solution to the infamous "cusp-core" problem in galactic astronomy. I also work closely with students in the EDGE Simulation collaboration, in which dark matter plays a key role in simulating dwarf galaxies and globular clusters in the Universe.
Supervisors
My research focuses on dark matter in Andromeda's satellite galaxies, particularly ultra diffuse dwarf galaxies. I measure the mass, velocity, and luminosity of these objects to further understand their dark matter composition. In doing so, I am able to compare these results with our current understanding of these dwarfs, helping to better understand the creation and current status of the M31 system.
I primarily use Justin Read's GravSphere software, allowing for the measurement of dwarfs' dark matter profiles. The resulting data contributes to the ongoing process of a finding a solution to the infamous "cusp-core" problem in galactic astronomy. I also work closely with students in the EDGE Simulation collaboration, in which dark matter plays a key role in simulating dwarf galaxies and globular clusters in the Universe.
Publications
The Na D absorption doublet in the spectrum of η Carinae is complex, with multiple absorption features associated with the Great Eruption (1840s), the Lesser Eruption (1890s), and the interstellar clouds. The velocity profile is further complicated by the P Cygni profile originating in the system's stellar winds and blending with the He i λ5876 profile. The Na D profile contains a multitude of absorption components, including those at velocities of −145 km s−1, −168 km s−1, and +87 km s−1, which we concentrate on in this analysis. Ground-based spectra recorded from 2008 to 2021 show significant variability of the −145 km s−1 absorption throughout long-term observations. In the high-ionization phases of η Carinae prior to the 2020 periastron passage, this feature disappeared completely but briefly reappeared across the 2020 periastron, along with a second absorption at −168 km s−1. Over the past few decades, η Carinae has been gradually brightening, which is shown to be caused by a dissipating occulter. The decreasing absorption of the −145 km s−1 component, coupled with similar trends seen in absorptions of ultraviolet resonant lines, indicate that this central occulter was possibly a large clump associated with the Little Homunculus or another clump between the Little Homunculus and the star. We also report on a foreground absorption component at +87 km s−1. Comparison of Na D absorption in the spectra of nearby systems demonstrates that this redshifted component likely originates in an extended foreground structure consistent with a previous ultraviolet spectral survey in the Carina Nebula.
The binary η Carinae is the closest example of a very massive star, which may have formed through a merger during its Great Eruption in the mid-19th century. We aimed to confirm and improve the kinematics using a spectroscopic data set taken with the Cerro Tololo Inter-American Observatory 1.5-m telescope over the time period of 2008–2020, covering three periastron passages of the highly eccentric orbit. We measure line variability of H α and H β, where the radial velocity and orbital kinematics of the primary star were measured from the H β emission line using a bisector method. At phases away from periastron, we observed the He ii 4686 emission moving opposite the primary star, consistent with a possible Wolf–Rayet companion, although with a seemingly narrow emission line. This could represent the first detection of emission from the companion.