Research

Current Research at Boston University

I am currently working with Professor Phil Muirhead on characterizing low-mass M dwarf stars using high resolution IR spectra. M dwarfs are the most abundant stars in the Galaxy, yet their fundamental parameters are still not well constrained. I am specifically interested in the well-known problem of inflated radii of M dwarfs (e.g., Torres & Ribas 2002). We have developed a novel way to test for inflated radii using single (non-binary) M dwarfs with known rotation periods (MEarth: Newton et al. 2016) in combination with projected rotational velocities (v sin i) to extract a distribution of radii modulated by the sin of the inclination. I am using the Immersion Grating Infrared Spectrograph (IGRINS) instrument on the Discovery Channel Telescope (DCT) to obtain v sin measurements of over 100 mid-to-late M dwarfs. Below are two M dwarf spectra centered around the CO bands taken using IGRINS at the DCT; one is a rapidly rotating star (period less than a day) and the other a slowly rotating star (period ~ 80 days). The rapidly rotating star beautifully demonstrates how rotational broadening changes the depth and shape of absorption lines.

COband_SlowFast

Previously at BU I worked with Andrew West, also on stellar characterization. I created an empirical template library for the full range of spectral types (O through L), luminosity classes (dwarf and giant) and metallicity bins (-2.0 to +0.5 dex) by co-adding individual stellar spectra from the Sloan Digital Sky Survey’s Baryon Oscillation Spectroscopic Survey (BOSS). This work was recently published in the Astrophysical Journal Supplements (ApJS paper). Accompanying the empirical template library we released PyHammer, which automatically (and/or visually) determines the spectral type and metallicity of any optical stellar spectrum (screenshot of the GUI, used for the optional visual classification, shown below). Click here to go to our github page.

PyHammer

Past Research

1.) While at Colby College I worked on massive highly redshifted galaxies, with Elizabeth McGrath.  We were attempting to morphologically classify the galaxies, to determine if there was a pattern in the abundance of disk dominated galaxies with redshift. I classified 140 galaxies from the CANDELS survey. We concluded that there seemed to be more disk dominated massive galaxies in the past than there are in the present day universe. Below are two examples of the highly redshifted galaxies I was looking at.

ds9_8485 ds9_5355

My thesis, entitled “Massive Quiescent Disk Galaxies in the CANDELS Survey” is available for download here: http://digitalcommons.colby.edu/honorstheses/707/

 

2.) I participated in an REU (Research Experience for Undergraduates) program at the University of Wisconsin in Madison. There I worked with Barbara Whitney, modeling variability young stellar objects. I used her radiative transfer code to model disks, warps in disks, hotspots, and spiral arms to try to match our models to observational data. 3col_180

Here is an example of an output image of an accretion disk with a warp in it. More information can be found on my REU website, or in the accompanying paper.