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

(May 2024) Cool Star Lab PI Adam Burgasser was awarded a UCSD Graduate and Professional Student Association Outstanding Faculty Teaching award! This annual award honors a faculty member at UCSD who is an exceptional educator at the graduate and/or professional level. Adam was nominated by Physics graduate student Thomas Wong. Congratulations Adam!

(May 2024) Cool Star Lab undergraduate researcher and TRELS scholar Sara Morrissey has been inducted into Phi Beta Kappa honor society. Phi Beta Kappa was founded in 1776, and is the oldest academic society in the US. Nominees represent no more than 10% of the student population, and requires a minimum GPA of 3.85, a broad academic curriculum, and completion of a foreign language. Congratulations Sara!

(May 2024) Former Cool Star Lab graduate Roman Gerasimov has been awarded the 2023 IAU Dissertation Prize, which recognizes outstanding scientific achievements among astronomy PhD students worldwide. Roman was awarded the Division G: Stars and Stellar Physics Prize, which noted “Dr. Gerasimov's thesis work highly impactful and relevant. The Committee was impressed by the combination of theoretical and observational aspects of the thesis, the extent of Dr. Gerasimov's acquired expertise ..and his commitment to work with undergraduate students.” Congratulations Roman!

(Apr 2024) Cool Star Lab PI Adam Burgasser led a cruise expedition on board the Holland America Koningsdam to view the total solar eclipse off the coast of Mexico. The crew were met with clear skies and over 4 minutes of totality! Adam also held several outreach talks on brown dwarfs, searches for life, and exciting results from JWST. See some of the media coverage at USA Today, Fox 5 San Diego, and ABC 10 San Diego.

(Jan 2024) Cool Star Lab undergraduate Tiffany Liou was awarded a Chambliss Astronomy Achievement Student Award at the AAS 243 Winter Meeting in New Orleans, LA. The Chambliss awards recognize exemplary research by undergraduate and graduate students who present at one of the poster sessions at the AAS meetings, and are honored with a Chambliss medal. Tiffany earned her Chambliss from her presentation "Rest-UV Properties of MUSE DR2 Galaxies". Congratulations Tiffany! [read more at AAS...]

(Oct 2023) Cool Star Lab members Bretton Simpson, Joman Wong, and Adam Burgasser led an outreach event on the Holland America cruise ship Volendam while it was in port, introducing 6th grade students from the Perkins school in Barrio Logan to the upcoming October 14th annular solar eclipse. The students got to "stare at the Sun" through eclipse glasses and their own homemade solar pinhole projection box [see the news coverage on CBS8]

Research Highlights

(May 2024) Cool Star Lab members contributed to the discovery of three new Earth-sized planets orbiting M dwarfs. The new planets, TOI-5720 b, TOI-6008 b, and TOI-6086 b all have orbit periods of about 1 day, and so close to their stars that they are too hot to be habitable. CSL member helped characterize the host stars using optical spectroscopy obtained with the Kast spectrograph on Lick Observatory (see the preprint by Barkaoui et al.)

(May 2024) The Backyard Worlds: Planet 9 collaboration reports the discovery of a new unusually red and young L dwarf. The source, VHS J1831-5513, lies right on the L dwarf/T dwarf transition and is the second reddest brown dwarf identified to date. Its near-infrared spectrum shows evidence of an unusually low surface gravity, and kinematic analysis suggests it is a member of the 22 Myr-old Beta Pictoris association. With an estimated mass of only 6.5±1.5 Jupiter masses, VHS J1831-5513 is a rare "free floating planet" (read the preprint by Bickle et al.)

(May 2024) Three new studies of the globular cluster NGC 6397 conducted with JWST have been released, including one led by former CLS graduate student Roman Gerasimov. Roman demonstrated the robust detection of brown dwarfs in this ancient stellar systems, and his new suite of SANDee evolutionary models successfully reproduced their location on the HR Diagram and demonstrated the determination of the brown dwarf cooling age of a globular cluster for the first time (read the preprints by Bedin et al., Gerasimov et al., and Scalco et al.)

(May 2024) Cool Star Lab undergraduate researcher and UC LEADS Scholar Efrain Alvardo led the release of a new set of atmosphere models for metal-poor brown dwarfs. The Spectral ANalogs of Dwarfs (SAND) models were developed with form CSL graduate student Roman Gerasimov, and fills an important gap in current brown dwarf modeling suites (read the Research Note by Alvarado et al.)

(May 2024) Cool Star Lab members Adam Burgasser, Christian Aganze, and Christopher Theissen contributed to the discovery of a new Earth-sized planet orbiting a late-type M dwarf. The planet, named SPECULOOS-3, is on a mere 17-hour orbit around its cool host star, making it too hot to be a habitable world. However, it is one of the best targets to measure dayside emission, which may reveal the geological properties of this terrestrial exoplanet (read the Nature Astronomy paper by Gillon et al. and the UCSD press release).

(May 2024) Adam Burgasser contributed to a study of new nearby ultracool dwarfs identified by Gaia. Near-infrared spectroscopy reveal the majority to be late-M dwarfs and early L dwarfs, with several resolved an unresolved binaries in the sample. This work continues to improve the census of our nearest neighbors (read the A&A paper by Ravinet et al.)

(April 2024) Cool Star Lab members contributed to the discovery of 13 new M dwarf + T dwarf wide binaries identified in CATWISE2020 and Backyard Worlds data. These important benchmark systems enable better understanding of the influence of age and metallicity on the evolution and atmospheres of low-temperature brown dwarfs. The sample includes at least one potentially young T dwarf that could have a mass as low as 2 Jupiter masses (read the preprint by Marocco et al.)

(April 2024) Cool Star Lab undergraduate researcher Tianxing "Sky" Zhou has a led a study investigating machine learning methods for spectral classification of ultracool dwarf spectra. Sky was able to demonstrate 95%+ reliability for k-nearest neighbors and random forest methods over a broad range of spectra types (read the Research Note by Zhou et al.)

(April 2024) Adam Burgasser contributed to analysis of the host star of the newly-discovered mini-Neptune exoplanet TOI-4336A b. The star is part of a hierarchical M dwarf triple system with nearly identical masses, mirroring the alien host star system in the Three Body Problem. The planet, which is about twice the size of Earth and receives 50% more light than Earth, is a promising target for transmission spectroscopy of a habitable zone world (read the preprint by Timmermans et al.)

In the Community

(May 2024) Cool Star Lab members shared the wonders of the Universe with the public as part of the Space Day event at the San Diego Air & Space Museum. In addition to physics and astronomy demonstrations, participants got the chance to collectively build a Garden Galaxy, creating various cosmic sources with crafts and imagination. 

(Apr 2024) Cool Star Lab PI Adam Burgasser led a cruise expedition on board the Holland America Koningsdam to view the total solar eclipse off the coast of Mexico. The crew were met with clear skies and over 4 minutes of totality! Adam also held several outreach talks on brown dwarfs, searches for life, and exciting results from JWST. See some of the media coverage at USA Today, Fox 5 San Diego, and ABC 10 San Diego.

(Jan 2024) Cool Star Lab members participated in the Southern California Workshop for Cal-Bridge Scholars, hosted at UCSD. In addition to running lab tours for visiting Scholars, Genevive Bjorn & Adam Burgasser led a 3-hour workshop on the CERIC method for reading the primary literature.

(Jan 2024) Members of the UCSD Astronomy & Astrophysics and Physics community participated in the 2024 CUWIP conference, hosted regionally by the University of San Diego. Faculty and students participated in discussion panels, workshops, and graduate program information sessions. UCSD is gearing up to host the 2025 CU*IP conference in January 2025!

(Nov 2023) Adam Burgasser joined UCSD community members to share lunch with members of the crew of the Hōkūleʻa, an event hosted by the Birch Aquarium and the Polynesian Voyaging Society. This famous Polynesian traditional voyaging vessel, or wa'a, was ending its first leg of the Moananuiākea voyage before going back to Hawai'i.

(Oct 2023) UCSD Astronomy & Astrophysics students, faculty, and researchers came out to celebrate and educate the partial eclipse of the Sun on October 14th at the Fleet Museum at Balboa Park. We brought various telescopes for viewing and projecting the eclipse for several hundred community members, some of whom got to hold the crescent Sun in their hands! [see the news coverage...]