ZTF Faces: Summer students and their mentors
Salvatore Cordova (Boston University)
My name is Salvatore Cordova, and I am currently a senior majoring in Physics and Philosophy
at Boston University. I was born in Chile, but lived most of my life in Peru. I've always been
deeply curious about how the world works; a passion that has manifested itself in my pursuit
of astronomy, condensed matter physics, teaching, and ethics. When I’m not talking about
physics or philosophy, I can usually be found playing Chess or petting the nearest dog!
Quanzhi Ye (University of Maryland, College Park)
I am an astronomer at the University of Maryland and a long-term visitor at Boston University.
I am primarily interested in the small bodies of the Solar System – asteroids, comets, and meteoroids.
These objects are pristine remnants from the early times of Solar System and can help us understand
planetary formation, migration, and evolution.
I was captivated by the stars when I was a child. I still enjoy going out for (non-work-related)
stargazing every once in a while. Besides stars, I also have a passion for music. I have played
violin, viola and cello in various orchestras and string ensembles as I move from China to Canada
and then the US. Most recently, I played viola and cello in Caltech’s wonderful Chamber Music program.
Detection of the desintegrated long-period comet C/2019 Y4 (ATLAS)
In early 2020, a comet named C/2019 Y4 (ATLAS) garnered significant interest due to its potential for naked-eye visibility; an exciting prospect for professional and amateur astronomers around the world. However, as it approached perihelion, the comet began to disintegrate, fragmenting into four main components (fragments A, B, C, and D). Before this project, the last detection of the comet was in May of 2020, 10 days before perihelion. Most signs pointed towards the comet having undergone complete disintegration.
We searched for remnants of C/2019 Y4 in data from the Lowell Discovery Telescope (LDT) and the Zwicky Transient Facility (ZTF). By generating ephemerides for the trajectory for each fragment and combining multiple pictures while accounting for the fragments’ velocities, we were able to compare their predicted locations with our data. To our surprise, we were able to detect fragment B in data from five months after the comet’s last detection, demonstrating that part of the comet had survived its perihelion approach. We were also able to use the ZTF data to constrain the size of fragment A.
The successful detection of C/2019 Y4 months after its presumed complete disintegration provides insight into the life-cycle of near-Sun comets. It also raises questions regarding the possibility to re-detect comets that are assumed to be irretrievably lost.
How do you pick a project to work on?
I’ve always been passionate about astronomy, and when I began to search for
research opportunities within the field, Dr. Ye’s C/2019 Y4 project stood out to me. The
prospect of searching for a comet that many had thought to have completely disintegrated
seemed like an exciting and rewarding challenge, and I’m glad to report that my expectations
have been exceeded.
How do you formulate a project for a student?
I pick projects based on the interest of the student and what I think is beneficial for the
student. I asked Salvatore what he wanted to take out from this internship when we first met,
and he said he wanted direct research experience in astronomy, so I assigned him to this
small but self-contained project.
What is the number one quality you look at when you select a mentor to work with?
I think a good mentor must be enthusiastic about their research and about the
prospect of mentoring. Lacking either of these qualities can make it difficult for a student to
engage with their research, as it can lead to difficulties asking questions or appreciating the
purpose behind their work. On the other hand, a combination of these two traits can be an
incredibly motivating and exciting thing for students. I’m fortunate that my mentor, Dr. Ye, has
been incredibly supportive to me, and his passion for the field of astronomy is absolutely
evident.
What is the number one quality you look at when you select a student to work with?
Dedication. This is clear from Salvatore’s resume – I learned that he had been TA’ing several
courses and was apparently very dedicated to his job, so I decided to work with him.
Was there a specific moment during the summer research work that was particularly exciting?
How about challenging?
There have been many exciting highlights and challenging moments throughout this
project, but I’ll try to be brief and share two exciting moments and one challenging one. The
first one was when I received Dr. Ye’s email that I had been selected to work with him. I
remember calling my mom and sharing my excitement at getting my first ever research
opportunity! The next exciting moment was when we found a remnant of C/2019 Y4 within our
data; something we were not expecting to achieve as the comet had been thought to have fully
disintegrated. This was very exciting, as Dr. Ye had assured me that, while a null result is still of
value, a successful detection would be even more interesting
The interesting thing about facing challenging moments is that they are often the most
instructive. I spent a couple of weeks trying to get some Python packages to play nice with
each other, a challenge that felt frustrating at the moment, but in retrospect taught me a lot
about coding and data analysis. I think facing challenges is an inherent part of learning and of
doing research, so I encourage everyone to actively seek them out.
Was there a specific moment during the summer research work that was particularly exciting?
How about challenging?
We found that the comet of our interest, quite unexpectedly, had survived what we thought
was a disruptive disintegration. That was quite an eureka moment! As for challenging – we had long discussions on how to interpret some of the negative data.
But those turned out to be scientifically rewarding discussions!
What do you think is the most valuable thing you learned this summer?
It’s difficult to choose a specific thing as being the most valuable, since I think there'll
be a ton of different lessons that I’ve learned that will be immensely valuable to me in the
future. Overall, I think having been given the opportunity to see how research actually works
will prove to be the most valuable lesson to me, as it has convinced me to pursue a future in
academia. I think people often view the process of doing research as looking like a bunch of
people in lab coats magically conjuring amazing scientific results effortlessly, but the reality is
a lot more subtle. There were many moments where I got stuck: be it an issue with running a
complicated program or getting writer’s block during our paper-writing process. I learned that
sometimes it is best to take a short break, think about something else, and then return to the
problem with a fresh perspective.
What do you think is the most valuable thing you learned this summer?
Mentors learn and grow with the students too. As Salvatore becomes an expert on this project,
there are often times that he raises an excellent point that prompts me to think deeply. And
those are scientifically rewarding times for both of us!
In science, answering one question also results in asking oneself a set of new ones. What are
these for you at the end of this project?
Now that we’ve confirmed that at least one part of C/2019 Y4 (specifically, fragment
B) survived its perihelion approach, this raises questions regarding the potentiality for the
re-detection of comets that are currently thought to have completely disintegrated. We hope
that this result will encourage others to look at older comets, especially as telescopes continue
to improve.
In science, answering one question also results in asking oneself a set of new ones. What are
these for you at the end of this project?
During one of our last meetings, we casually chatted about the possibility that some
presumably disrupted comets might have survived, just like the comet that we studied. We
quickly realized that this was an excellent point and needs to be looked into further!
The universe never fails to surprise us, but did you manage to surprise yourself this summer?
If yes, how?
Of course! I’m the first person in my family to go to college, and certainly the first to
pursue a career in science. Although I’ve been very fortunate to have very encouraging parents
and mentors, there’s always that little bit of doubt that creeps in. When Dr. Ye told me that he
wanted to work with me, I was incredibly excited! But I also wondered to myself: “Am I good
enough for this?” It’s interesting to think back on that moment now, knowing that we’ve been
able to achieve some exciting results. If I had listened to those doubts, I wouldn’t be here
writing about my awesome experience.
If you’re reading this and feel like you can relate to this struggle, I encourage you to recognize
that it can certainly be a difficult feeling to get rid of, but you shouldn’t let it get in the way of
pursuing research opportunities. Take the leap, apply, give it a shot. Don’t let yourself get in
the way. If you’re truly passionate about what you’re pursuing, then I assure you that you can
achieve genuinely meaningful work.