(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.)

(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)

(March 2023) 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.)

(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!

[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...]

(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: 

• Christian Aganze: "Prospects for Detecting Gaps in Globular Cluster Stellar Streams in External Galaxies with the Nancy Grace Roman Space Telescope"

• Adam Burgasser: "JWST/NIRSpec Spectroscopy of Three Cold Brown Dwarfs at Kiloparsec Distances: Metallicity Signatures in Low-Temperature Atmospheres"

• Roman Gerasimov: "NGC 6752: New Light on Multiple Populations in Globular Clusters"

• Dino Hsu "The Brown Dwarf Kinematics Project (BDKP). VI. Ultracool Dwarf Radial and Rotational Velocities from SDSS/APOGEE High-Resolution Spectroscopy" (talk)

• Preethi Karpoor: "Unveiling the Super-Earth Occurrence Rate in M Dwarfs via Magnitude-Limited Samples"

• Tara Knight: "Sound Planetarium: 100 Brightest Stars" (talk)

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!

(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) 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.)

(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.)

(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)

(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] 

(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.). 

(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.). 

(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.).  

(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.). 

(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)

(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! 

(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...]

(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. 

(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.). 

(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. 

(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...)

(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).

(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!

(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.). 

(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.)

(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

(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.

(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...)

(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 

(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.)

(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.)

(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...)

(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...)

(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).

(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...)

(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...) 

(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).

(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)

(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.

(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!

(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).

(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)

(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)

(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).

(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!

(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)

(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...)

(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...)

(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...)