Galactic astronomy research at Gemini encompasses many aspects of galactic evolution including the role of stellar clusters and the interstellar medium in the evolution of the Galactic environment. This research spans studies of the initial mass function, high mass clusters, stellar populations, infrared bubbles, molecular shocks, interstellar dust composition, and Galactic micro-quasar objects.
Extragalactic research at Gemini covers systems from the edge of the Galactic halo to high redshift. There is a strong contingent focusing on the nature of Active Galactic Nuclei (AGN). There is also extensive work on the evolution of galaxies and galaxy structures in environments ranging from the field, groups, and clusters over a wide range of look-back times. Several of the staff are also studying the nature of extragalactic globular cluster systems and are using globular clusters to trace the mass distributions of the host galaxies.
Keywords: stars: massive stars, supernovae
My main research interests are in time domain astronomy, and in particular core collapse supernovae and their massive star progenitors. I concentrate on optical and infrared photometry and spectroscopy of these objects, and use post-explosion observations to help constrain the age and mass of the supernova progenitor, and reconstruct the mass loss histories in the final years and decades before explosion. Supernovae that interact with the circumstellar material ejected by their progenitor are my personal favorite, as well as supernovae which form dust in the months to years after their explosion.
My research focuses on observing and characterizing exoplanet atmospheres. I do this using high-resolution observations from ground-based optical and NIR spectrographs, including GRACES, MAROON-X, and IGRINS. I'm mainly interested in characterizing the atmospheres of close-in, highly irradiated hot Jupiters and super-Earths, and trying to understand the extreme physical and chemical processes at work in their atmospheres. I'm also interested in using these present-day atmospheric characteristics and processes to shed light on the exoplanets' formation and evolutionary histories.
Emanuele Paolo (Ema) Farina (North)
Keywords: high redshift quasars and galaxies, epoch of reionization, circumgalactic medium, supermassive black holes, large and small scale clustering
I am an observational astronomer. I am using quasars as cosmic lighthouses to explore the formation of galaxies and black holes at the epoch of reionization and to investigate their evolution with Cosmic times. In recent times, I am pushing studies of the circum-galactic medium at the highest accessible redshifts to unveil the fingerprints of the baryon cycle onto the hazy gas halos of the first galaxies.
Joan Font-Serra (South)
Keywords: galaxies: dynamics
My interests in research are mainly in extragalactic astrophysics, and more specifically in studying the dynamics of disk galaxies, and how this is related to the morphology of the galaxies.
Tom Geballe (North)
My research involvements are all tied to infrared spectroscopy and cover a wide range of astrophysical research areas. In the area of stellar/sub-stellar astrophysics I am currently studying the evolutionary states of and chemical compositions of hot stars in the Galactic center. Via observations of isotopic abundances of oxygen I am investigating formation scenarios of R Corona Borealis stars and Hydrogen-deficient Carbon stars. I also am involved in following the currently rapidly evolving stars, Sakurai's Object (aka V4334 Sgr,) which likely underwent very late thermal pulse in 1996, and V838 Mon, which is believed to have undergone a stellar merger in 2002. I also am participating in spectroscopic studies of the very coolest (T, Y and beyond) brown dwarfs to understand their atmospheric structures and chemical compositions. In the domain of Galactic astronomy I am involved in studying the gaseous environment in the Central Molecular Zone of the Galaxy using as probes the molecular ion H3+ and the molecule CO. I also am leading an effort to understand, via deep IR spectroscopy of excited H2, the physics of shock waves in molecular gas and am following up on my team's recent discovery of the longest wavelength diffuse interstellar bands. In Solar System astrophysics the research team to which I belong is investigating the upper atmospheres and aurorae of the planetary gas giants (Jupiter - Neptune) and the surface compositions of dwarf planets and moons of the outer planets. Finally, I dabble a bit in extragalactic astrophysics, again using H3+ and CO to infer the natures of the cool gaseous environments ("dusty molecular toroids") surrounding AGN.
German Gimeno (South)
Keywords: galaxies: kinematics and dynamics
Observational Extragalactic Astronomy (mainly using longslit spectroscopy. MOS spectroscopy and direct imaging). I am a heavy GMOS user, also some NIR (Phoenix, Flamingos 2)
Disk galaxies morphology and kinematics.
Compact Groups of Galaxies, with emphasis on nearby goups.
Stellar systems (theory/experimental):
Study of the dynamics of satellite galaxies and stellar streams via semianalytic modelling
GR approach to galactic dynamics
Zachary Hartman (North)
Keywords: Stars: Binaries
My research interests lie primarily in the study of binary stars. In particular, I have been studying wide binaries with separations of thousands of astronomical units. As these systems have separations at and even beyond that of protostellar cores, the formation of these systems is not well understood. To examine this, I have been searching for wide binaries that are actually higher order multiples, i.e. triples, quadruples, etc. Using high resolution imaging, mainly speckle imaging, I am able to examine stars in wide binaries for unresolved companions.
Paul Hirst (North)
Keywords: galaxies: black holes
My research interests are based around Active Galactic Nuclei, though I have extended this out to galactic micro-quasar objects, along with survey and follow-up techniques for finding and characterizing AGN at extremely high redshift. I utilize large databases and intensive computational techniques in my research, developing Data Science and Machine Learning techniques.
Jeong-Eun Heo (South)
My research focuses on symbiotic stars, which are interacting binary systems of a heavily mass losing giant and an accreting white dwarf. I have been investigating their nature and evolution by performing high-resolution spectroscopic observations and the theoretical modeling of radiative transfer. The specific topics that I have worked on include (1) profile analysis of Raman O VI features to probe an accretion flow around the white dwarf in symbiotic stars, (2) making an atlas of Raman O VI features in galactic symbiotics, (3) measurement of the mass loss rates using Raman He II features in symbiotic stars and planetary nebulae and (4) narrow-band imaging survey using Raman O VI filter to search extragalactic symbiotic objects.
Venu Kalari (South)
Keywords: stars: formation, massive stars, galaxies: star clusters
I am interested in understanding how stars form, and in particular how star formation in the past is different to star formation today- to help understand how the Universe we see today came to be, and what it may be like in the future. To do so, I employ either high angular resolution imaging, or spectroscopy at optical and near-infrared wavelengths observing and characterizing individual stars and star clusters in the Milky Way, and the nearby Magellanic Cloud Galaxies.
Yijung Kang (South)
Keywords: Cosmology: observations, Galaxies: elliptical and lenticular, cD, fundamental parameters, Supernovae: general
My primary research interest focuses on the stellar populations in early-type host galaxies of type Ia supernovae (SNe Ia). I have been investigating a possible look-back time evolution of the luminosity of SNe Ia by observing the absorption lines of their early-type host galaxies. In order to achieve this project, I have carried out the observations using the long-slit spectrographs and analyzed stellar population properties (e.g., age and metallicities) within SN Ia host galaxies. I am also interested in the evolution and stellar population of the early-type galaxies and MW globular clusters.
Hwihyun Kim (South)
Keywords: Galaxy: ultracompact HII regions, ISM: molecules, extinction, galaxies: resolved stars and star clusters, instrumentation: high-resolution infrared spectrograph.
My main research focuses on massive stars (ultracompact HII regions and OB-type stars) and star clusters in our Milky Way galaxy and nearby star-forming galaxies. I use space- and ground-based imaging and spectroscopic data to study how those massive systems regulate star formation and evolution activities in galaxies. Currently I am an active member of the HST Legacy Extragalactic UV Survey (LEGUS; legus.stsci.edu) coordinating the Star Cluster Interest Group. Part of my research work is also involved with instrumentation, specifically high-resolution nearinfrared spectrometer IGRINS (Immersion GRating near-INfrared Spectrometer). I worked and continue working as an IGRINS instrument support scientist to analyze the performance and develop science projects with the instrument team and the users.
Kathleen Labrie (North)
Keywords: gravitational lensing: weak
I am currently part of a collaboration studying quasars, in particular the broad emission line region. The primary approach is through the observation of multi-imaged lensed quasars and the analysis of the differential micro-lensing observed between spectra of the lensed images. In a multi-imaged quasar, differential microlensing is characterized by a variation in the magnification levels of different spectral components in a single lens image, compared to the non-microlensed quasar spectrum. In the absence of microlensing, we expect emission line and continuum flux ratios to be equivalent to each other and to agree with the macro-model flux ratios, and we therefore expect flat, featureless spectral ratios. In the presence of differential microlensing, the emission lines from the broad emission line region and/or the continuum will cause features on the spectral ratios. The flux ratios and the shape of the features in the spectral ratios can be used to put constraints on the size and the kinematics of the sources of emission. I bring my expertise in data reduction of Gemini data to this collaboration.
I am also active in the field of scientific software and algorithms for data reduction and analysis.
Janice Lee (NOIRLab HQ, Tucson)
Keywords: Extragalactic astronomy: star formation and the interstellar medium, stellar populations, star clusters, dwarf galaxies, galaxy evolution
My research aims to constrain the physics that drive, regulate, and extinguish massive star formation across different galactic environments. I've been particularly interested in using the extreme environments of low mass dwarf galaxies, galaxy outskirts, and starbursts as observational laboratories. The majority of my work is based on large, multi-wavelength imaging surveys of nearby galaxies that I've had the good fortune of leading/co-leading over the past 15 years: Spitzer Local Volume Legacy Survey (LVL); HST Legacy ExtraGalactic Ultraviolet Survey (LEGUS); and most recently, PHANGS-HST/JWST
Sandy Leggett (North)
Keywords: stars: brown dwarfs, white dwarfs
My primary research area is brown dwarfs, objects with a mass below that required for stable hydrogen burning. I work with collaborators to identify candidate brown dwarfs in optical, near-infrared and mid-infrared sky surveys. We obtain optical through mid-infrared photometry and spectroscopy of these candidates, and brown dwarfs identified by other means, to compare to current model atmospheres. The goal is to determine the fundamental parameters of these faint, usually isolated, objects. If temperature and gravity can be determined then evolutionary models allow us to constrain both mass and age. As cooler and cooler brown dwarfs are found this work becomes more challenging observationally and theoretically.
A secondary research interest is cool white dwarfs. I have been involved with searches of sky surveys for low-temperature white dwarfs. The coolest white dwarfs, with effective temperature around 4000K, must be older than 8 Gyr, and so are useful for constraining the age of the Galaxy.
Brian C. Lemaux (North)
Keywords: galaxies: clusters, groups, proto-clusters, formation, evolution, high-redshift, reionization
My primary area of interest is large optical/near infrared spectroscopic galaxy surveys with a focus on the effect of environment on galaxy evolution. My main expertise is in designing surveys and methodologies to detect clusters of galaxies, their less massive counterparts (galaxy groups), and their progenitors (proto-clusters and proto-groups) in the distant universe. Once found, I study galaxies in, out, and around these environments to place constraints on both environmentally-induced star formation and nuclear activity in galaxies, as well as induced quenching of these processes. I have also been involved in a large number of surveys related to field (i.e., non-cluster, non-group) galaxy evolution from a variety of different perspectives including those with ALMA, Herschel, JVLA, and Chandra. Additionally, I use galaxy clusters for another purpose, to act as lenses to study even more distant galaxies at the epoch of reionization in order to place constraints on the internal processes of those galaxies and the evolution of the neutral fraction of the intergalactic medium at those redshifts.
Clara Martínez-Vázquez (North)
Keywords: Stars: variables: RR Lyrae, Cepheids, δ Scuti. Galaxies: evolution, stellar content, star clusters, Local Group.
My main scientific interests are in stellar population, galaxy formation and evolution, and time domain astronomy. My research focuses on galactic-archeology through the study and characterization of pulsating variable stars (such as RR Lyrae, Cepheids, delta Scuti stars) found in dwarf galaxies and stellar clusters in different environments within the Local Group. In particular, I use these stars as distance indicators and as tracers of stellar populations of different ages and metallicities of the systems they belong to, providing information about the properties of the underlying population and a way to study their galactic structure, star-formation history and evolution.
Bryan Miller (South)
Keywords: galaxies: dwarf, elliptical, kinematics and dynamics, nuclei, star clusters
My current research focuses on the evolution of galaxies, especially dwarf galaxies, and star clusters in the nearby universe. The big questions that I'm trying to answer are: 1) How do star clusters form and evolve; 2) What are the connections between star clusters, nuclei, and galaxies; 3) What is the distribution and nature of dark matter; and 4) Can we test alternatives to dark matter? I am using Gemini to study the nature of star clusters and nuclei of dwarf elliptical galaxies and to measure the velocities of the star clusters in order to determine dynamical masses. Another project uses use wide-field imaging to characterize the baryonic structures (especially stellar shells, star clusters, and dwarf galaxies) in nearby galaxy groups and clusters. We will follow this up with integral-field and multi-object spectroscopy with the aim of determining dark matter distributions at very large projected radii. I'm also involved a project to use GeMS/GSAOI to study the stellar populations in Galactic globular clusters. My other interests include the star formation histories of dwarf galaxies, HII region abundances, star cluster formation in merging galaxies, and integral-field spectroscopy.
Teo Mocnik (North)
Keywords: exoplanets, variable stars, planetary nebulae
My main research subject is exoplanets and their host stars. I'm a member of the TESS-Keck Survey, which aims to measure precise masses of 100 strategically selected planets discovered by the Transiting Exoplanet Survey Satellite. This sample will allow us to address some of the biggest outstanding questions in the exoplanet community. Specifically, my specialty is the data reduction and analysis of high-precision lightcurves, target selection infrastructure and target vetting.
Atsuko Nitta (North)
Keywords: stars: white dwarfs, oscillations
I am interested in learning the physics under extreme conditions by studying the interior of white dwarf stars. White dwarf stars also provide the end point of stellar evolution and therefore their structure provide us with boundary conditions to the stellar evolution. The white dwarf stars as an ensemble can also be used to trace us star formation history of the group they belong to. Last but not the least, we have used white dwarf stars to as independent chronometer to put age limit on our galactic disk and hence the age of the universe. The observational method I primarily use to study above are via technique of asteroseismology, spectroscopy and use of large survey data such as the Sloan Digital Sky Survey.
Fredrik Rantakyro (South)
Keywords: star: Be, planets: detection
Be Stars: These stellar objects are critical rotators and important in understanding stellar evolution. I have been using a variety of instruments to observe them at different scales i.e. MIDI and AMBER at scales of a few milliarcseconds to understand the spatial structure close to the interface between the disk and the star.
Phoenix for high resolution spectroscopy of in particular -lines for a better understanding of the dynamics
GPI, when commissioned the NRM mode of GPI then using this will allow sample the spatial scales of sub arc seconds with 60mas resolution.
Planetary systems: I’m a member of both the GPIES and the GPI LLP program on stellar disks.
GPI is the ideal instrument to study young sub stellar objects to better understand the different possibilities in planetary formation.
Stellar disks are the birthplace of planets and thus a better understanding of the disk evolution and disk properties are critical in understanding their evolution. On the horizon is using ALMA to obtain complementary high spatial resolution spectroscopy and imaging of the extended disks.
Mark Rawlings (North)
Keywords: Keywords: ISM: dust, molecules, extinction, Stars: formation, evolution
My primary areas of scientific interest include the properties of the dust and molecules that make up the interstellar medium, with a particular focus on the Diffuse Interstellar Bands. I am also interested in the properties and structure of star-forming regions, and the environments around evolved stars. In addition, I am currently a member of a number of large scientific consortia, including multiple JCMT Large Programs and the Event Horizon Telescope.
Ricardo Salinas (South)
Keywords: Galaxy: globular clusters, galaxies: kinematics and dynamics, star clusters
I have an interest in all things globular cluster, Galactic or extragalactic. In Galactic clusters I study the presence of multiple stellar populations and their variable star content. In the extragalactic realm, I study the globular cluster systems of isolated ellipticals, and also globular cluster system dynamics as a proxy to the dark matter content of galaxies.
You can reach me at rsalinas [at] gemini.edu
Julia Scharwaechter (North)
Keywords: galaxies: nuclei, active, ISM, kinematics and dynamics; galaxies: quasars: supermassive black holes
My main research area is the (co-)evolution of galaxies and their supermassive black holes. I am interested in studying the role of AGN feedback and the nature of black hole mass-host galaxy scaling relations. My observational projects mostly aim at spatially resolved studies of galaxy nuclei in the nearby Universe. I use 3D spectroscopy in the optical, near-infrared, and at millimeter wavelengths to probe the stellar and gas component in galaxies, with a special focus on gas-kinematic black hole mass measurements and gas excitation/kinematics around AGN. I am also interested in galaxy dynamics and galaxy merger simulations using N-body/SPH codes.
Thomas Seccull (North)
My primary research interest is the surface composition of minor planets in the outer Solar System (Trans-Neptunian Objects and centaurs), how the composition of each of these objects relates to its formation environment and evolutionary history, and what the material makeup of these minor planets can tell us as a population about how our planetary system has formed and changed over time. To study the surfaces of TNOs and centaurs I spectroscopically observe the sunlight they reflect in an attempt to detect and characterise any solid state absorption bands that are created by the ices, hydrocarbons, and silicates on their surfaces. To calibrate observations of planetary targets it is necessary to remove the spectroscopic signature of the Sun, so I am also interested identifying fainter (V>9) Solar Analog stars and Solar twins. Identifying fainter Sun-like stars becomes more important in planetary spectroscopy as fainter TNOs are observed with ever larger telescopes.
Gaetano Sivo (South)
Keywords: instrumentation: high angular resolution
My main research is related to high angular resolution for astronomy. I have been working in the era of Adaptive Optics (AO) since 2009. I am now an AO assistant scientist at Gemini. My expertise in AO is control algorithm, disturbance correction and modeling perturbation (atmospheric turbulence, vibrations, windshake…). I am working on optimal control for classical and wide-field AO. The optimal control such as a Linear Quadratic Gaussian (LQG) enables to estimate and predict the perturbation phase with a Kalman filter based on models describing the evolution of the perturbation (spatial and temporal priors needed). The same description is used to describe vibrations affecting the system. Using an autoregressive model of order 2 we can identify a set a parameters that will describe the evolution of the perturbation. I am highly interested in using this smart controller to mitigate perturbation like vibrations affecting the AO system.
I am currently working on implementing an LQG control for the tip/tilt (TT) loop for GeMS. In simulation using on-sky GeMS data we have shown that we can improve the performance obtained by 5 to 10 mas rms of TT error. I am also a member of the CANARY team. CANARY is a wide-field AO demonstrator built to test new methods/concepts/design of AO and AO related research.
My research is very instrument related, instrumentation for astronomy.
Monika Soraisam (North)
Keywords: Stars: novae, supernovae, massive stars, variable stars, methods: statistical
My research sits at the juncture of time-domain astronomy and data science. I work with data from time-domain surveys to study populations of stellar variables and transients in nearby galaxies and develop statistical models for finding peculiar astrophysical events in their alert streams in real time. I am also involved in the development of ANTARES, which is a community alert-broker for the current and next-generation optical time-domain surveys, in particular Vera Rubin Observatory Legacy Survey of Space and Time. At Gemini, I work in the Science User Support group on the Data Reduction for Astronomy from Gemini Observatory North and South (DRAGONS) project.
URL: Personal website
Andrew Stephens (North)
Keywords: Galaxy: globular clusters, galaxies: formation, evolution
Andrew obtained his BS in 1996 from the Pennsylvania State University, and his PhD in 2001 from the Ohio State University. He was awarded the Princeton - Catolica Prize Fellowship in 2001, of which 1 year was spent at Princeton University, and 2 years at the Pontificia Universidad Catolica in Santiago Chile. In 2004 he began work at Gemini. His research interests include galaxy formation and evolution through the study of resolved stellar populations using space-based telescopes and ground-based telescopes with adaptive optics, and stellar chemical abundances and dynamics via optical and infrared spectroscopy.
Hyewon Suh (North)
Keywords: Supermassive black holes and Active galaxies, Active Galactic Nuclei, Galaxy evolution and formation
My research mainly focuses on the multi-wavelength studies of Active Galactic Nuclei and their host galaxies to understand the growth of black holes in the context of galaxy evolution. While the deep, large-area extragalactic surveys have greatly enriched our knowledge of the early universe, there are several missing pieces in the understanding of the formation and the growth of supermassive black holes. I am interested in the most energetic and obscured phase of accreting black holes to explore the formation of the first accreting black holes, and to provide the crucial observational constraints on a hidden phase in the early universe.
Joanna Thomas-Osip (South)
Keywords: minor planets, asteroids, Kuiper belt: general
I am observational astronomer and planetary scientist with an eclectic taste for problem solving. My experience and interests include light scattering and remote sensing properties of dust particles (from atmospheric aerosols to interstellar grains), planetary occultation predictions, observations, and atmospheric modeling, characterization of small bodies in the solar system (from Near Earth Asteroids to Kuiper Belt Objects), and observatory environmental monitoring and characterization (especially image quality, turbulence, and precipitable water vapor).
Siyi Xu (North)
Keywords: circumstellar disks, minor planets, white dwarfs, chemical compositions
I am mostly interested in extrasolar planetary systems and how it connects with our own solar system. Specifically, I study planetary systems around evolved stars, particularly around white dwarfs. Sometimes, these systems can provide us with unique information that is not possible to study for planets around main sequence stars. I was trained in high-resolution optical and ultraviolet spectroscopy to measure the chemical compositions of extrasolar planetary debris. I also do infrared photometry to study circumstellar disks. Recently, I became interested in high-cadence photometry to study disintegrating asteroids around white dwarfs.