About Me

Predoc, Astronomy PhD Candidate, and admirer of stars.

Hello! My name is Ben and I am a 4th year Astronomy PhD candidate at Boston University, and I am also currently a Smithsonian Astrophysical Observatory (SAO) predoctoral fellow where I work with Dr. Paul Green. I got my B.S. from Clarkson University in May of 2016 with a physics major and a mathematics minor. I earned my Masters in Astronomy from Boston University in May of 2018.

As an undergrad, I worked on the binary system R81 in the Large Magellanic Cloud with Dr. Joshua Thomas at Clarkson University. My research project focused on using spectra from the Cerro Tololo Inter-American Observatory and long baseline sampled photometric data from the All Sky Automated Survey to determine if there was mass transfer taking place in this close binary system.

My current research projects are part of the Time-Domain Spectroscopic Survey (TDSS), which is part of the Sloan Digital Sky Survey-IV (SDSS-IV), and focuses on the stellar samples of the TDSS survey.

One of my current research projects is working with dwarf Carbon stars from the TDSS. Carbon stars have atmospheres that are enhanced with carbon (with C/O > 1), giving them distinctive spectral features. Dwarf Carbon (dC) stars are main sequence stars that are unique since they could not have produced their own carbon! One theory is that these dwarf Carbon stars are the product of mass transfer from a higher mass companion. Using repeat epochs of SDSS spectra, I modeled the dC population and found them to be consistent with a 100% binary fraction. More information can be found in my Research section.

Another one of my research projects is working with the TDSS Variable Star sample. This sample was selected based on SDSS and PanSTARRS photometry for variability, for which the TDSS program got spectra for approximately 24,000 variable stars. I have also collected CRTS and ZTF light curves for all 24,000 variable stars with spectra. My research aims to analyze this sample to understand how the combination of spectra and light curves can aid in the classification of stellar variables. More information can be found in my Research section.

If you have any interest in my research or questions, feel free to contact me at one of the email addresses below! I am always looking to share my interests with people and to help spread astronomy to everyone!

Research

Dwarf Carbon Stars

One of my recent research projects is working with dwarf Carbon (dC) stars. Carbon stars have atmospheres that are saturated with carbon, giving them distinctive spectral features. It was thought that all Carbon stars are post-main sequence stars that had their atmospheres polluted by dredge ups, bringing carbon to the surface. This made the discovery of a dwarf Carbon star (dC) a surprise. One theory is that these dwarf Carbon stars are the product of mass transfer from a higher mass companion.

I used repeat epochs of spectroscopy from SDSS to measure the radial velocity shift (∆RV) between epochs of repeat spectra for a sample of 240 dC stars. By comparing the ∆RV distribution of dC stars to a well chosen sample of control stars, I used a combination of deconvolution and MCMC methods to show that the dCs have larger ∆RVs than the control sample (which corresponds to tighter orbits) and fit a binary separation distribution to show how close those orbits are.

The top left figure shows an example of what a dC spectrum looks like in the range or 5000Å to 6000Å. Two of the prominent C2 bands are visible and marked. The top panel of the figure shows both epochs overplotted while the bottom panel shows the same epochs, but the later MJD epoch has been shifted by the measured ∆RV value.

The top right figure shows both the dC (blue) and control (red) ∆RV histograms as well as a Gaussian mixture model that accounts for errors called Extreme Deconvolution (XD). From this figure, it is clear the the dC stars have many more systems that extend past the error dominated core due to their close orbits.

If you want to read more about this research project and the details of what went into it, feel free to read through my paper in ApJ. If you have any comments on how to improve this work, please send me an email to one of the addresses below.

 

TDSS Variable Stars

Another of my projects focuses on variable stars in the TDSS survey. This project consists of approximately 24,000 stars that were selected from SDSS and PanSTARRS photometry based on variability. Our TDSS program got spectra for all of these 24,000 variable stars. I have also collected CRTS and ZTF light curves for all 24,000 variable stars with spectra. My research aims to analyze this sample to understand how the combination of spectra and light curves can aid in the classification of stellar variables. This project is ongoing, and if you would like more information at this time feel free to contact!

 

Talks

List of Invited Talks
Talk Title Date Conference or Institute
The Time Domain Spectroscopic Survey: Overview June 25, 2019 SDSS Collaboration Meeting
List of Contributed Talks
Talk Title Date Conference or Institute
The Time Domain Spectroscopic Survey: Stellar Variables June 26, 2019 SDSS Collaboration Meeting
List of Posters
Poster Title Date Conference or Institute
Detection and Spectral Typing of Binaries from Optical Spectra with PyHammerSB2 January 4, 2020 AAS Meeting #235
Orbital Separations of Dwarf Carbon Stars January 5, 2019 AAS Meeting #233
Radial Velocity Variability in Dwarf Carbon Stars July 5, 2018 Cool Stars 20

Teaching

Teaching astronomy students about variable stars

I believe that teaching should be one of the core focuses of any academic. Beyond teaching students, we should all aim to share our research with the general public and support anyone who endeavors to learn more about astronomy. If you ask any random person on the street if they find space interesting and if they would like to learn more, you'd be hard pressed to find anyone who would say no to those questions.

Therefore, I think it is not only critical for all researchers to be versed and able to communicate their research to any person of any level who wishes to learn more, but that they strive to become better teachers and communicators. I fundamentally believe that any person has the capability to learn complex and deep topics, such as advanced astrophysics, if they put in effort and are given the chance with an instructor who cares deeply and is willing to adjust teaching styles on a student per student level.

Below, I include anonymous student teaching evaluations for myself from all courses that I have been a teaching assistant for.

Course Evaluations for Courses as Teaching Assistant
Course Number Semester University
PH131 Spring 2015 Clarkson University
PH131 Fall 2015 Clarkson University
PH132 Spring 2016 Clarkson University
AS202 Fall 2016 Boston University
AS202 Spring 2017 Boston University
AS101 Fall 2017 Boston University
AS203 Spring 2018 Boston University