News & Updates

Three hot terrestrial worlds orbiting the lowest-mass stars

(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.)

Adam Burgasser awarded graduate teaching award

(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!

A young and red L dwarf

(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.)

Sara Morrissey inducted into Phi Beta Kappa

(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!

Building a Galaxy at Space Day

(May 2024) UCSD Astronomy 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. 

Roman Gerasimov wins IAU Dissertation Prize

(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!

Three JWST studies of the globular cluster NGC 6397

(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.)

New atmosphere models for metal-poor brown dwarfs

(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.)

An Earth-sized world orbiting a cool star

(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).

Ultracool Dwarfs discovered with Gaia

(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.)

New Brown Dwarf Benchmarks

(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.)

Using Machine Learning to classify ultracool dwarfs

(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.)

A mini-Neptune in a triple star system

(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.)

Cruising to the solar eclipses

(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. We 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.

The multiple stellar populations of NGC 6752

(March 2024) Former Cool Star Lab graduate Roman Gerasimov contributed a new set of spectral and evolutionary models to accurately characterize the three distinct stellar populations of the NGC 6752 globular cluster imaged by HST. Roman's modeling framework spanning the entirety of the Main Sequence was able to show that these populations can be accurately modeled by varying sodium, carbon, oxygen, and aluminum abundances, and further show distinct luminosity functions that could be explained by dynamical scattering. (read the preprint by Scalco et al.)

Building the census of the Solar Neighborhood

(April 2024) Cool Star Lab members contributed to a detailed census of the local Solar Neighborhood. The volume-limited census of about 3600 individual objects, including components of multiple systems, extends from giant "planets" (≈ 5 Jupiter masses) to massive stars (≈8 solar masses). This comprehensive study reports the most accurate measurement of the stellar initial mass function to date, and finds that roughly 20% of all "stars" are substellar brown dwarfs. (read the ApJS article by Kirkpatrick et al.)

Ultracool Dwarfs Observed with APOGEE

(March 2024) Former Cool Star Lab graduate Dino Hsu has published a study of radial and rotational velocities of late-M and L dwarfs observed with the SDSS/APOGEE instrument. The high spectral resolution of APOGEE combined with a forward-modeling approach results in radial velocity precisions of 400 m/s. The study identified 3 new members of young moving groups, and 37 sources with significant radial velocity variations, including binaries with orbital periods measured in days. It also found an expected decline in radius (inferred from rotational velocity and variability period) with age. (read the preprint by Hsu et al.)

A Bevy of Brown Dwarf Companions

(March 2024) Cool Star Lab members contributed to a massive haul of benchmark ultracool dwarf companions to nearby stars identified by the Backyard Worlds Team. CUNY graduate student Austin Rothermich identified 89 new systems with G2-M9 primaries and M7-T9 companions with diverse spectral properties, and many of these systems appear to be triples and quadruples. These systems span exceptionally wide separations and low mass ratios, in the latter case with similar values as exoplanet systems.  (read the preprint by Rothermich et al. and watch his AAS 243 press conference)

Modeling Multiple Populations in NGC 6752

(March 2024) Former Cool Star Lab graduate Roman Gerasimov contributed a new set of spectral and evolutionary models to accurately characterize the three distinct stellar populations of the NGC 6752 globular cluster imaged by HST. Roman's modeling framework spanning the entirety of the Main Sequence was able to show that these populations can be accurately modeled by varying sodium, carbon, oxygen, and aluminum abundances, and further show distinct luminosity functions that could be explained by dynamical scattering. (read the preprint by Scalco et al.)

CERIC Workshops for Cal-Bridge

(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.

UCSD at CUWIP 2024

(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!

Tiffany Liou Awarded Chambliss Award

[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...]

Cool Star Lab at AAS 243

(Jan 2024) current and former Cool Star Lab members were out in full force at AAS 243 Winter meeting in New Orleans, LA, presenting research spanning a broad range of science, art, education and community issues. Presentations included: 

Adam Burgasser also co-led a booth on the Sound Planetarium project with Tara Knight and participated in a panel discussion on effective partnerships with HBCUs; Genevive Bjorn and Dino Hsu led a workshop on the CERIC method; and CLS alumna Jackie Faherty and her colleagues were featured in a press conference. Undergraduate members Malina Desai, Tiffany Liou, Brigette Vazquez-Segovia and Juan Diego Draxl Giannoni also presented, with Tiffany Liou winning a Chambliss! Wow!

Honoring the Hōkūleʻa

(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.

Oxygen in the Coldest Stars of 47 Tuc

(Oct 2023) Recent Cool Star Lab graduate Roman Gerasimov has led a study investigating the lower Main Sequence of the globular cluster 47 Tucanae. Using a suite of low-temperature atmosphere models he computed, and a novel analysis method, Roman was able to explain the spread of the lower Main Sequence of the 47 Tucanae population in HST color-magnitude diagrams as arising in variations in Oxygen abundances, and was able to infer the distribution of Oxygen from photometry alone. He also inferred the luminosity and mass functions of the lowest mass stars in this ancient system (read the preprint by Gerasimov et al.)

An unusual and cold brown dwarf

(Oct 2023) Cool Star Lab members contributed to the discovery of a new Y dwarf identified by the Backyard Worlds Team. The source, CWISE J105512.11+544328.3, was confirmed and classified with Keck/NIRES near-infrared spectroscopy, and has an estimated temperature of 500 K. It's extremely blue mid-infrared color suggests it may have an unusual, possibly metal-poor atmosphere. The publication was led by U. Florida undergraduate Grady Robbins (see the preprint by Robbins et al.)

Blended brown dwarf binaries from Backyard Worlds

(Oct 2023) Undergraduate researcher Alexia Bravo worked with collaborator Adam Schneider to analyze three peculiar brown dwarf spectra obtained as part of the Backyward Worlds project. She identified two spectral blend binaries and one potentially variable brown dwarf. The binaries may prove to be closely-separated systems for which mass measurements can be made, while the variable brown dwarf allows study of cloud formation and dynamics in low temperature atmospheres (see the preprint by Bravo et al. and the AAS Nova highlight)

Viewing the October 2023 partial eclipse of the Sun

(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...]

Cool Star Lab eclipse outreach on a cruise ship

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

A rare giant planet orbiting an M dwarf

(Oct 2023) Adam Burgasser contributed to the analysis of another giant planet orbiting a metal-rich early-M dwarf TOI-4201. The exoplanet, weighing in at 2.5 Jupiter masses and with an orbit period of just 3.6 days, occupies a sparse region in planet mass and separation among M dwarf systems (read the AJ article by Gan et al.). 

JWST Uncovers Distant Brown Dwarfs on the Outskirts of the Milky Way

(Sep 2023) Adam Burgasser and Roman Gerasimov 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.). 

Welcoming UCSD Alum Bill Forrest

Adam Burgasser welcomed IR astronomy colleague and Physics PhD alum Bill Forrest (1974) back to UCSD for his 50th reunion. Bill leads work on infrared detector technologies and studies dust, the ISM, and brown dwarfs. In addition to visiting the Physics and Astronomy & Astrophysics Departments, Bill got to check in on his favorite haunt, the Che Cafe (formerly the Coffee Hut), where his band Soledad Mountain Ramblers played, and he shared a recording of a concert his band played there in 1970 with Che Cafe staff. Bill organized the UCSD Mini Folk Fest in the early 1970s at the "Grassy Knoll", still located just east of the Main Gym [listen to Soledad Mountain Ramblers at the Coffee Hut, 1970

Lowest-mass host star to a giant exoplanet

(Sep 2023): 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.).  

A New Super-Earth planet orbiting an M dwarf

(Sep 2023): 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.). 

Honoring Prof. Laura Quaynor

(Sep 2023) The Cool Star Lab is remembering 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...).

UCSD Astronomy & Astrophysics Department kicks off!

(Sep 2023): UCSD has formally begun its 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)

Students present at UCSD Summer Research Conference

(Aug 2023): 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 presenters

(Aug 2023): 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...]

Introducing Dr. Aganze!

(Aug 2023): 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. 

A Wide Pair of L dwarfs Found by Citizen Scientists

(Aug 2023): 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.). 

2023 Summer Research Program Begins

(July 2023): 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. 

Burgasser Inducted into Athletics Hall of Fame

(July 2023): 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...)

Burgasser to Lead Eclipse Tour

(July 2023): 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 check out the AAS Eclipse page).

Cool Star Lab Partners with Native Like Water

(July 2023): 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. 

Prof. Theissen Joins Astronomy & Astrophysics

(July 2023): Dr. 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!

Planet host star has a dim companion

(Jun 2023): 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 preprint by Barkaoui et al.). 

Cool Star Lab Class of 2023

(June 2023): 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! 

CSL Undergraduates Earn Top Honors

(Jun 2023): Each year, the UCSD School of Physical Sciences awards Dean's Undergraduate Excellence Awards to those students who have demonstrated academic excellence and promise as researchers. This year, five CSL undergraduate students were named to this award: Malina Desia, Juan Diego Draxl Giannoni, Delilah Jacobsen, Natalie Lam, and Tiffany Liou. Congratulations to all the award recipients!

Spectra of a nearby massive star explosion

(Jun 2023): 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 (read the preprint by Jacobsen-Galan et al.)

Cool Star Lab Presents at AAS 242

(Jun 2023): Adam Burgasser and Roman Gerasimov presented research at the 242nd AAS Meeting in Albuquerque, NM. Adam presented work on metallicity indices for T subdwarfs, and co-led a watercolor painting workshop with AAS President Kelsey Johnson. Roman presented his thesis dissertation on low-mass stellar populations in globular clusters

Introducing Dr. Gerasimov

(May 2023): Congratulations to Dr. Roman Gerasimov who successfully defended his PhD thesis, entitled "Evolution, Atmospheres and Chemistry of Ancient Stellar Populations"! Roman will be startinga postdoctoral position at the University of Notre Dame in September.

Adam Burgasser earns Division EDI Award

(May 2023): Adam Burgasser was a recipient of the 2023 UCSD School of Physical Science EDI Excellence Award, for his work on developing antiracism seminars and pedagogy in Physics and Astronomy. (read more...)

ARMS-BSP Symposium feature Prof. Charles Brown II

(May 2023): Cool Star Lab members of the Advocating for and Representing Minority Students (ARMS) group co-hosted the second ARMS-BSP symposium with the UCSD Black Studies Project, featuring experimental quantum physicist and #BlackInPhysics co-founder Prof. Charles Brown II 

The host star of the habitable zone Super-Earth TOI-715b

(May 2023): Adam Burgasser and Christian Aganze helped characterize a new low-mass exoplanet host star TOI-715, an old M4 dwarf that hosts a super-Earth planet in its habitable zone. Adam analyzed optical spectra obtained with Magellen/LDSS-3C, while Christian used GALAH data to statistically constrain the star's age (read the prepint by Dransfield et al.)

Stream gaps to study dark matter

(May 2023): Christian Aganze led a study simulating gaps in stellar streams created by dark matter halos. Such gaps, recently detected in tidal streams in the Milky Way, provide a means of testing dark matter models. Christian demonstrated that stream gaps created by million solar-mass dark matter halos could be detected in galaxies up to 2-3 Mpc away by the Nancy Grace Roman Space Telescope (read the preprint by Aganze et al.)

First ARMS-BSP Symposium

(May 2023): Cool Star Lab members Delilah Jacobsen and Natalie Lam were among several student leaders from the Advocating for and Representing Minority Students (ARMS) group to co-host with the UCSD Black Studies Project the first ARMS-BSP symposium, featuring astronomer and artist Prof. Nia Imara (read more...)

Christian Aganze named a Stanford Science Fellow

(April 2023): Graduating PhD student Christian Aganze is one of ten Stanford Science Fellows starting a 5-year postdoctoral position this Fall. This highly competitive program for postdoctoral researchers aims to support scholars while advancing foundational science and fostering effective interdisciplinary approaches to fundamental questions through research. Congratulations Christian! (read more...)

The first Y dwarf binary

(Mar 2023): Cool Star Lab researchers contributed to the discovery of the first Y dwarf binary, WISE J0336-0143AB, identified with JWST/NIRCam. The close pair is separated by less than 1 AU, and the secondary has a mass near or below the deuterium fusion limit, often consider the boundary between brown dwarf and planetary masses. The article has been accepted for publication in ApJ Letters (read the paper by Calissendorff et al. at ApJ Letters).

Theissen recognized as a top UCSD postdoc

(Mar 2023): Cool Star Lab postdoctoral scholar Christopher Theissen was recently featured in a UC San Diego Today article highlighting the campus's fantastic postdocs! (read more...)

UCSD's New Astronomy Graduate Program

(Mar 2023): UCSD's new Astronomy Graduate Program is wrapping up its first academic year! Learn about the motivation for the program and the experiences of the inaugural class in an article featured in UC San Diego Today (read more...

The exoplanet host star TOI-2096

(Mar 2023): Cool Star Lab researchers helped characterize the low-mass stellar host of the double-planet system TOI-2096. TESS and ground-based monitoring show that this system contains both a super-Earth and a mini-Neptune orbiting a star less than a quarter the mass of the Sun. The CSL team obtained optical spectroscopy with Kast on the Lick Shane Telescope that determined the host star's spectral type, temperature, and metallicity. (read the paper by Pozuelos et al. at Astronomy & Astrophysics).

Finding benchmark ultracool dwarfs

(Mar 2023): Cool Star Lab undergraduates Tianxing Zhou, Delilah Jacobsen, and Brigette Vazquez-Segovia have reported a new sample of benchmark ultracool dwarfs, based on co-moving systems identified by Gaia. These include 100 systems within 100 pc of the Sun that currently lack spectroscopic characterization (read the paper by Zhou et al. at AAS Research Notes)

Meeting with INSITE artists

(Feb 2023): Adam Burgasser hosted an international group of artists to discuss art-science collaborations, as part of the INSITE Lab program. Adam discussed some of the science-art partnerships the Cool Star Lab has participated in over the years, and Emma Softich conducted a live demonstration of N-body dynamics using rulers and masking tape.

Christian Aganze recieves honorable mention for Bouchet Society

(Jan 2023): Christian Aganze was selected as an honorable mention for the Bouchet Graduate Honor Society, co-founded in 2005 by Yale and Howard Universities and named for Edward Alexander Bouchet, the first African American doctoral recipient in the United States. Congratulations Christian!

Pop III Study highlighted in Nature Astronomy

(Jan 2023): The study of Population III star detectability led by former CSL undergraduate Mikaela Larkin was recently singled out as a Research Highlight by Nature Astronomy (read the highlight and the article).

First brown dwarf discovery in JWST

(Jan 2023) Adam Burgasser contributed to the discovery of the first brown dwarf to be found with JWST, a late T dwarf 570-720 pc from the Sun (read the paper by Nonino et al. at ApJ Letters)

Using Machine Learning to find binaries

(Jan 2023): The Cool Star Lab Machine Learning group published a Research Note demonstrating spectral binary identification with a random forest classifier. The paper was led by undergraduate researcher Malina Desai (read the paper by Desai et al. at RNAAS)

Cool Star Lab undergraduate investigates the first stars

(Jan 2023) Meet Mikaela Larkin, an undergraduate researcher with the Cool Star Lab group who worked on the first generation of stars, in this addition of "Alumni spotlight" (read more...)

Discovery of a young planetary mass object

(Jan 2023): The Cool Star Lab contributed to the discovery of an extremely red L/T dwarf by the Backyard Worlds program, which is likely a planetary mass object in the 22 Myr-old Beta Pic moving group. The CSL team obtained the spectrum of this unique young source with the NIRES spectrograph at Keck Observatory (read the paper by Schneider et al. in ApJ Letters).

Shortest-period ultracool dwarf binary 

(Jan 2023) Dino Hsu, a PhD graduate of the Cool Star Lab and now postdoctoral scholar at Northwestern University, reported the discovery of the shortest-period ultracool dwarf binary, LP 413-53AB, based on multiple epochs of Keck/NIRSPEC measurements. This remarkable binary has an orbit of only 17 hours, and its components appear to straddle the hydrogen fusion mass limit. The discovery was reported at a press conference at the AAS 241 meeting in Seattle, WA (read the press release and the paper by Hsu et al. at ApJ Letters).

Cool Star Lab at AAS 241

(Jan 2023): Cool Star Lab members were out in full force at the American Astronomical Society (AAS) 241st meeting in Seattle, WA. Adam Burgasser, in his role as one of three AAS Vice-Presidents, helped organize the national meeting, which drew over 3,000 astronomers from around the world. He also presented two posters, one on T subdwarfs identified by the Backyard World: Planet 9 project and one on the CERIC method for reading primary literature. Former graduate student Dino Hsu presented his discovery of the shortest-period ultracool dwarf binary (he also have a press conference on this). Thesis talks were given by Christian Aganze and Roman Gerasimov. And Cool Star Lab undergraduates Tiffany Liou, Brigette Vazquez-Sagovia, and Angelica Whisnant all presented research at the meeting. What a turnout!

The M dwarf companion to µ Virgenes

(Dec 2022) Summer research student and Lamat Institute scholar Julissa Villalobos Valencia led a spectroscopic study of the M5 dwarf companion to the bright star µ Virgenes, which is visible to the naked eye (read the paper by Villalobos Valencia et al. at AAS Research Notes)

Discovering super planets

(Nov 2022) Adam Burgasser and Christian Aganze talk about the discovery of two super-Earths orbiting the nearby M star LP 890-9, in this edition of "The Science of" (read more...)


(Oct 2022): Adam Burgasser represented UC San Diego and the American Astronomical Society (AAS) at the 2022 SACNAS meeting in San Juan, Puerto Rico. In addition to staffing booths for both organizations, Adam participated in a session on Puerto Rican astronomy organized by the AAS Committee on the Status of Minorities in Astronomy (learn more...)

Welcome to our new graduate students!

(Sep 2022): Cool Star Lab welcomes two new graduate students to our group in Fall 2022: Preethi Karpoor & Emma Softich. Preethi and Emma are part of the inaugural class of the new Astronomy PhD program at UCSD (learn more...)

Cool Star Lab at the Southeast Science & Art Expo

(Aug 2022): Cool Star Lab team members participated in the 2022 Southeast Science and Art Expo at the Malcolm X Library, where they led demonstrations in physics phenomena and made a to-scale model of the Solar System along the Library parking lot (learn more...)