UC San Diego Cool Star Lab

Welcome to the homepage of the UC San Diego Cool Star Lab! Feel free to use the links below to learn about our research, teaching, and community activities, and meet our present and past members.

In the News

The Cool Star Lab is honoring Prof. Laura Quaynor, a research collaborator on graduate reading skill development. Dr. Quaynor was department chair of Advanced Studies in Education at Johns Hopkins University and one of the lead authors of the CERIC method. Dr. Quaynor will be remembered as a kind and effective mentor, and a valued colleague. We share our grief and condolences with her family (read more...).

Adam Burgasser has been selected to the UCSD Athletics Hall of Fame. Adam was a NCAA Div III National Champion diver at UCSD, and received NCAA's Diver of the Year, Top VIII and  Silver Anniversary awards. This year's inductees will be celebrated in an event on November 11 (read more...)

Adam Burgasser will be leading an eclipse viewing from a cruise ship next year! The April 2024 "Eclipse America" will pass across Mexico and the US, and Adam will be helping sea voyagers on Holland America get the best view (read more.. and also the AAS Eclipse page).

Christopher Theissen has accepted a position as Assistant Professor in the new Department of Astronomy & Astrophysics. He is the first hire to be made in the Department, and will be leading work on mining large astronomical datasets. Welcome Prof. Theissen!

UCSD has announced the formation of a new Department of Astronomy and Astrophysics! Two A&A major programs and a minor will start in Fall 2024 (read more... and visit the Department webpage)

CSL undergraduate researchers earned top honors as recipients of the UCSD School of Physical Sciences Dean's Undergraduate Excellence Awards: Malina Desai, Juan Diego Draxl Giannoni, Deliliah Jacobsen, Natalie Lam, and Tiffany Liou were among 27 recipients selected from other 4,000 physical science majors. Congratulations to our outstanding undergraduates!

Research Highlights

Adam Burgasser analyzed the optical spectrum of the host star to the newly-discovered giant exoplanet TOI-4860b. The Magellan/MagE spectrum revealed this source to be an inactive, slightly metal-rich M4.5 dwarf, making it the lowest-mass star known to host a giant planet (read the MNRAS article by Triaud et al.). 

Adam Burgasser led an article analyzing JWST/NIRSpec data of three distant T dwarfs identified in the UNCOVER survey of the Abell 2744 lensing field. The NIRSpec prism data allowed full analysis of the 1-5 µm spectra, revealing all three to be T dwarfs at kiloparsec distances, two with evidence of subsolar metallicities. The coldest of the three, previously identified photometrically as GLASS-BD-1, shows evidence of phosphine in its infrared spectra, a potential new indicator of subsolar metallicity in cool brown dwarf spectra (read the preprint by Burgasser et al.). 

The Cool Star Lab obtained Keck/NIRES and Keck/NIRSPEC data for a newly-resolved L dwarf binary pair identified by citizen scientists in the Backyard Worlds: Planet 9 program. CWISE J0617+1945AB is an L2 + L4 pair at 28 pc separated by 1.3 arcseconds. Its wide separation makes it an important benchmark for comparative L dwarf studies (read the Research Note by Humphries et al.). 

Cool Star Lab team members helped to characterize the low-mass stellar host to a new Super Earth planet. The star, TOI-1680, was found to be an inactive M4.5, right at the fully convective stellar mass boundary. The planet, TOI-1680b, has a radius about 50% larger than Earth, and is also warmer with a 400 K equilibrium temperature. The relatively bright primary and favorable radius ratio makes this an important new target for atmospheric characterization with JWST (read the A&A article by Ghachoui et al.). 

Adam Burgasser and Carl Melis obtained Lick/Kast optical spectra for one of two new low-mass planet host stars identified in TESS + SPECULOOS. The star, TOI-2084, has a previously unrecognized co-moving, low-mass stellar companion 1400 AU away, giving the 6.7 Earth-mass planet a second "dim red bulb" to illuminate it (read the A&A article by Barkaoui et al.). 

Cool Star Lab members contributed observations obtained with Lick/Kast to help characterize a nearby Type II supernova, SN 2023ixf, detected in Messier 101. The observations covered the first 2 weeks of the explosion, and caught early ionization of circumstellar material around the star, followed by the breakthrough of material from the exploded massive star. The CSL team also contributed time to make spectropolarimetry measurements of the explosion at is it broke through previously released circumstellar gas (read the articles by Jacobsen-Galan et al. and Vasylyev et al.)

In the Community

Cool Star Lab summer research students participated in the UCSD Summer Undergradute Research Conference, taking over an unprecedented two full sessions and more! Research talks can be viewed on YouTube: Galaxies & Stars session, Astronomy & Astrophysics session, and Teaching & Learning session. Congratulations to all of the researchers for all their accomplishments this summer! 

ENLACE participants Jean Louis Marroquín Tapia and Rodrigo Cuesta Cortés, both from Instituto de Polytechnico Nacional in Mexico City, wrapped up their summer research experience with a presentation on the infrared spectra of cataclysmic variables, novae, and supernovae mined from the IRTF Legacy Archive. Jean & Rodrigo were part of team testing a new reduction tool aimed at reducing over 20 years of IRTF/SpeX data [see the talk...]

Cool Star Lab members organized a pair of outreach events with the Native Like Water program, demonstrating physics concepts at UCSD and holding a star party at the La Jolla Indian Reservation Campground. Native Like Water curates experiences through an Indigenous lens, focusing on conservation and cultural practice. 

Congratulations to Dr. Christian Aganze who successfully defended his PhD dissertation "Galactic Archeology with Ultracool Dwarfs and Stellar Streams". Christian will be starting a prize postdoctoral position at Stanford University in September. 

Cool Star Lab's summer research season has begun with 20 undergraduate students participating in various programs, including UCSD STARS, Cal-Bridge/CAMPARE, UC LEADS, UCSD Summer Undergraduate Research Award, UCSD TRELS, and VERSA. They'll be exploring various projects in astronomy and education research over the next 8-10 weeks. 

Congratulations to our graduates! The CSL had a record number of undergraduates earn there Bachelor's degrees in Physics this year, with many now continuing on to graduate study and jobs in industry. This graduating class is particularly impressive for having taken on a challenging major during the COVID pandemic and remote learning. We are so proud of all you have accomplished!