Research and Teaching

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RESEARCH

PhD:

Topic: 'Investigating Gaseous Disks around Herbig Be Stars'

Supervisors: Dr. Aaron Sigut & Dr. John Landstreet.

Herbig Be stars are massive, pre-main sequence stars that inherit a circumstellar disk of dust and gas from the star formation phase. The region close to the star is gaseous as dust is thought to have evaporated due to high temperatures; and this region is currently poorly understood. Using the non-LTE circumstellar disk codes BEDISK and BERAY, as well as observed spectra (3700 to 10,500 \AA ) from the ESPaDOnS instrument on CFHT, we are attempting to constrain the physical properties of this inner, gaseous region. By comparing synthetic line profiles of hydrogen and ionized metals with the observed line profiles, we hope to understand the geometry, density structure, and kinematics of the gaseous disk.

Thesis: "The Inner Gaseous Disks of Herbig Be Stars"

Papers:

Photoionization Models of the Inner Gaseous Disk of the Herbig Be Star BD+65 1637", 2016, ApJ, 817, 29P.

Photoionization Models for the Inner Gaseous Disks of Herbig Be Stars: Evidence against Magnetospheric Accretion?, 2017, ApJ, 836, 214P.

If interested, you can watch my PhD Public Lecture on Youtube!

Masters:

Topic: 'Modeling the Hα-UBV Signature of Disk Growth and Dissipation in Classical Be Stars'

Supervisors: Dr. Aaron Sigut & Dr. John Landstreet.

Be stars show short and long term variations in their spectra due to the presence of the circumstellar disk and it is the long term variations that are attributed to formation and dissipation of the circumstellar disk. Be stars show a correlation between Hα emission, which is produced in the disk, and UBV colours. These correlations are likely determined by the viewing angle of the observer, and these correlations can be useful to constraint the scale height of the circumstellar disks and the extent of gravitational darkening of the central star. In this report, we investigate these correlations by using BEDISK and BERAY codes to reproduce the emission and colours at different viewing angles for a simple model. These models are shown to be consistent with the observed correlations showing both positive and negative correlations between Hα emission and UBV colours. To further investigate the effect of the disk scale height on these correlations, the emission and colours were produced for a disk with an enhanced scale height. For higher inclinations, the enhanced scale height models show a large change in brightness compared to the basic model, suggesting that the scale height of the disk is important at such inclinations. Be stars, being rapid rotators, are darker at the equator and this can affect UBV colours. Gravitationally darkened models show a reduced change in colours at higher rotation rates which are close to the critical velocity. 

Paper:

"The Correlation between Hα Emission and Visual Magnitude during Long-term Variations in Classical Be Stars", 2013, ApJ, 765, 41S.

 

TEACHING

I have had a pleasure to work in many different settings such as tutorials, physics laboratories, and observatory in roles of instructor and coordinator.

Here's the list of classes I have worked as Teaching Assistant for:

  • Exploring the Stars Astronomy Outreach Program - Instructor and Coordinator
  • Center for Planetary Science & Exploration Outreach Program - Instructor and Coordinator
  • Ast1011- General Astronomy (Distance Studies)
  • Ast1021- General Astronomy
  • Ast2012- Search for Life in Universe
  • ASTA02- Introduction to Astronomy- Beyond the Sun and the Planets
  • ASTA01- Introduction to Astronomy- The Sun and the Planets
  • First Year Physics Laboratory