Astronomy
My research as a graduate student focused on young, low-mass stars, ranging from how they change on timescales of minutes to years, to how their disk masses are distributed in star-forming regions.
Low-mass stars (whose masses are less than about 2 solar masses), are overwhelmingly the most common kind of star in the universe. As such (and because these stars live for many billions of years), we believe they are the ideal places to look for life. But these potentially life-harboring planets form from a primordial disk of gas and dusk (think Saturn's rings), which display a wide range of characteristics. y work sought to better understand these disks, how they interact with their host star, and how that interaction impacted the disks' potential to form planets.
I was primarily an observational astronomer: I collected and analyzed data from telescopes around the world to better understand what is physically happening in the targets of interest. These data came in a variety of forms: millimeter-wavelength, interferometric observations from the Atacama Large Millimeter Array (ALMA) in Chile; images taken at ultraviolet, visible, and infrared wavelengths from a collection of smaller telescopes scattered across the globe; and ultraviolet to infrared spectra from the ever famous Hubble Space Telescope (HST) orbiting the Earth.
I couldn't have carried out this work without the help and guidance of my many great colleagues, both past and present: Catherine Espaillat (my advisor), Enrique Macias, Connor Robinson, Sierra Grant, Anneliese Rilinger, Thanawuth Thanathibodee, and Caeley Pittman, and Nuria Calvet. Check out their great works for more interesting science.
Accretion and Variability in Young Stars
Low-mass stars, the most plentiful in the universe, accrete most of their mass within a few million years. That accretion process is very complex, but also very energetic, having an enormous impact on the disk itself. Because of this, it is vital to understand the star-disk accretion process to fully understand how planets form within these disks.
My thesis, UNDERSTANDING ACCRETION VARIABILITY IN YOUNG, LOW-MASS STARS THROUGH MULTI-EPOCH, MULTI-WAVELENGTH OBSERVATIONS, focused a sample of extensive observations of 4 young stars. These multi-wavelength, time-dependent observations showed that accretion is highly variable in young stars, higher than previously estimated. I also showed that the relationship between accretion and various observational tracers differ between targets and in time, further complicating the study of accretion in young stars.
If you're brave, you can read my dissertation here, but should otherwise check out some of my papers on the topic:
These images show how the magnetic field in GM Aurigae funnels matter from the disk onto the star, creating hotspots that rotate into and out-of view.
From Espaillat et al. (2021).
This plot shows the simulated accretion rate of a young stars over time. Large spikes indicate FUor-like bursts.
Adapted from Vorobyov & Basu (2006).
FU Orionis Objects
FU Orionis stars (aka FUors) are the youngest low-mass stars, specifically those that have recently (or are currently) undergoing huge bursts of accretion. These repetitive bursts can be so strong that they can account for 10-20% of the star's final mass. Furthermore, the energy released from this process is thought to have a huge impact on the future evolution of the circumstellar disk, and therefore any planets that may form within.
My work specifically has found that FUors can exhibit variability at millimeter wavelengths, which complicates our understanding of how massive their disks are. And it's important to understand these disks masses, so that we can determine how these huge accretion events might be triggered.
Read more about my work on FUors here.
Protoplanetary Gas and Dust Masses
Low-mass stars are plentiful throughout our galaxy, most of which have a surrounding protoplanetary disk composed of gas and dust. These disks are hotbeds for planet formation, but potential relies heavily on the disk's mass, size, and composition -- among other things.
A huge ALMA study revealed that the L1641 star-forming region in Orion may have more massive disks than other comparably-aged regions. We also discovered some objects with interesting and unexpected morphologies.
Read more about my work on disk masses here.
Each of these blobs shows the dust contained in each star's surrounding disk. In reality, these disks are probably much more chaotic and non-symmetric than what is shown here.
From Grant et al. (2021)