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
(July 2024) Comic Con 2024 has come to San Diego! Cool Star Lab PI Adam Burgasser participated in a panel discussion on the TV series For All Mankind: Historic Fiction, Real Science with several experts in space science, engineering, biology, and sociology. The panel was hosted by the Fleet Center's Andrea Decker. Read how several UCSD folks contributed to Comic Con, and watch the For All Mankind panel discussion on YouTube.
(July 2024) The discovery of a hot Earth-sized planet orbiting the M-type star SPECULOOS-3, reported by Gillon et al. (2024), has been featured on the cover of Nature Astronomy! Read the paper by Gillon et al. (2024) and the press release by UCSD Physical Sciences.
(June 2024) Research led by Adam Burgasser and Roman Gerasimov were both featured in press conferences at the AAS 244 meeting in Madison, Wisconsin. Adam reported the discovery of a remarkably fast-moving, metal-poor L dwarf uncovered by citizen scientists that may be on its way to escaping the Milky Way. Roman reported the first discovery of brown dwarfs in JWST observations of the globular cluster NGC 6397. Learn more by watching the AAS 244 press conferences by Adam and Roman; you can also see some of the press images for the speedy L subdwarf in the UCSD Physical Science press release.
(May 2024) Research led by Cool Star alum Roman Gerasimov was featured on the cover of the May 2024 edition of Astronomische Nachrichten! The cover shows the remarkable color-magnitude diagram of stars and white dwarfs in the globular cluster NGC 6752, based on HST data, and appears in Scalco et al. (2024). Roman computed the stellar models that accurately encompass the low mass stars in the upper right portion of the figure.
(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) 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!
Research Highlights
(August 2024) The Cool Star Lab has contributed to the discovery of two new Super-Earths orbiting nearby M dwarfs. The two host stars, TOI-5713 and TOI-6002 were first identified with TESS and followed up by the SPECULOOS team. Shane/Kast optical spectra captured by the Cool Stars team were able to determine both stars are M4 dwarfs, with TOI-5713 being unusually active. The two planets, both about 70% larger than Earth, are notably in the "radius valley" when comparing planet radius to orbital period, and are promising targets for JWST atmosphere reconnaissance (read the preprint by Ghachoui et al.)
(July 2024) Adam Burgasser led a study on a remarkably fast-moving, metal-poor L dwarf uncovered by citizen scientists associated with the Backyard Worlds: Planet 9 program. The source, CWISE J1249+3621, has speed of 456± 27 km/s in the Milky Way rest frame, placing it near the local Galactic escape velocity. The research team considered several possible origins for the source, including ejection from the center of the Milky Way or globular clusters after interaction with black holes, escape from an exploding Type Ia supernova, and infall from a Milky Way satellite. The result was highlighted in a press conference at AAS 244 (read the preprint by Burgasser et al.)
(July 2024) Members of the TRAPPIST-1 Community Initiative, including Adam Burgasser, have published a Nature Astronomy Perspective presenting a roadmap for study of the multi-planet systems around mid- and late-M dwarf stars like TRAPPIST-1 with JWST. Multi-planet systems are particularly useful for correcting for flare and spot modulations from the star, which can overwhelm any atmosphere detection. The specific plan advocated is to first conduct MIRI emission observations to first assess the presence of an atmosphere among inner planets, which can be inferred from phase variation. When there are inner planets lacking atmospheres, these can be used to calibrate for stellar variations in the atmospheric exploration of other planets in the system. In cases where the inner planets have atmospheres, monitoring of the full stellar rotation curve is required. This plan realizes the unique benefits of observing multiple simultaneous transits and the coordination of joint space- and ground-based programs to maximize the science return for these unique systems. (read the Nature Astronomy perspective by the Trappist-1 Community Initiative)
(July 2024) The SPECULOOS team, including Adam Burgasser and Cool Star Lab alumna Aishwarya Iyer, have conducted a comprehensive reanalysis of the host star of the TRAPPIST-1 system, combining spectral data from the UV to the infrared, including data from JWST. The analysis provides the best constraints on the temperature, luminosity, and metallicity of this source, and investigated spectral model fits for a heterogenous atmosphere. One of the key conclusions is that even the most advanced spectral models are unable to accurately replicate the spectrum of this important star, motivating the need to improve spectral modeling of low-mass planet host stars. (read the ApJ Letter by Davoudi et al.)
(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 article in AJ by Bickle et al.)
In the Community
(August 2024) Members of the Cool Star Lab participated in the UCSD Astronomy & Astrophysics booth at the 4th Southeast Art & Science Expo at Malcolm X library in San Diego. This community event engages people of all ages in science, art, technology and exploration. Our booth featured demonstrations on optics, representations of the electromagnetic spectrum, tactile "images" of cosmic sources, and an opportunity to see the sunspots on our currently highly active Sun.
(July 2024) The first STARTastro scholars have begun their summer program at UCSD! STARTastro, funded by the Heising Simons Foundation, is led by Adam Burgasser and Karin Sandstrom at UCSD, and Kate Rubin at SDSU, and aims to support community college transfer students bridge into their UC astronomy/physics/etc. majors. The STARTastro scholars hail from 6 CCs in San Diego, Orange, and LA counties, and will embark on an 8-week program of academic and professional development and research.
(June 2024) UCSD hosted the 22nd Cambridge Workshop on Cool Stars, Stellar Systems and the Sun this month. This major biennial international conference has been running for over 40 years, and has featured some of the biggest discoveries in the field, including the first exoplanet and the first brown dwarf. This year, over 300 scientists from around the globe presented the latest discoveries, theories, and technologies for studying stars and planets. Chris Theissen led the meeting, Quinn Konopacky and Adam Burgasser were part of the SOC, and Emma Softich and Preethi Karpoor were part of the LOC and presented their work. You can view all of the posters and watch select talks from the conference [TBD].
(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 Galaxy Garden, creating various cosmic sources with crafts and imagination and seeding them across the Milky Way. The original Galaxy Garden was created by space artist Jon Lomborg. You can see a quick view of the construction process on YouTube.
(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.
(March 2024) Cool Star Lab alumnus Bretton Simpson was featured in a UCSD Physical Science Student Spotlight! Learn about Bretton's path to astrophysics and the work he is now doing in the Optical-Infrared Lab led by Prof. Shelley Wright (read the Spotlight...)