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The GEMMA Podcast

A podcast about Gemini Observatory and its role in the Era of Multi-Messenger Astronomy. Featuring news related to multi-messenger astronomy (MMA), time-domain astronomy (TDA), our visiting instrument program, and more through interviews with astronomers, engineers, and staff both here at Gemini (North and South) and abroad.

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CLICK HERE for a complete list of the Gemini research staff.

Scroll down for an overview of the research fields covered at Gemini.

Solar system and exoplanets
Solar system and exoplanet research at Gemini spans a wide range of topics from the chemical structure of bodies within the solar system to the possibility of life beyond it. Research activities aim to understand the formation of exoplanets and our own Solar System in the same context. The present day Trans-Neptunian population may be viewed as a highly evolved (and very local) circumstellar disk, with broad implications for the formation of planets in disks around other stars.
Gemini North Gemini South
Tom Geballe Fredrik Rantakyro
Thomas Seccull Joanna Thomas-Osip
Teo Mocnik
Siyi Xu

Stellar astrophysics

Stellar Astrophysics research at Gemini encompasses many aspects of stars, "failed" stars and ex-stars in our Galaxy. The objects under study range from brown dwarfs that are sub-stellar in mass and have more in common with the Solar System giant planets than the stars, to very massive stars and clusters of stars, and also white dwarfs, which are the final evolutionary stage of 90% of all stars. 
Gemini North Gemini South
André-Nicolas Chené Morten Andersen
Tom Geballe Erik Dennihy
Scot Kleinman Jeong-Eun Heo
Sandy Leggett Steve Margheim
Atsuko Nitta Fredrik Rantakyro
Andrew Stephens
Siyi Xu

Galactic astronomy
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. 
Gemini North Gemini South
Andy Adamson Morten Andersen
André-Nicolas Chené Rodrigo Carrasco
Tom Geballe Hwihyun Kim
Paul Hirst Steve Margheim
Andrew Stephens Bryan Miller
Ricardo Salinas

Extragalactic astronomy
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. 
Gemini North Gemini South
Kristin Chiboucas Morten Andersen
Jason Chu Rodrigo Carrasco
Tom Geballe German Gimeno
Paul Hirst Yijung Kang
Kathleen Labrie Hwihyun Kim
Marie Lemoine-Busserolle Bryan Miller
Julia Scharwaechter
Andrew Stephens
Hyewon Suh

Complete List

A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z



Andy Adamson  (North)

Keywords: ISM: dust, molecules, extinction
Principal research interests are the composition and physical properties of dust grains and small molecules in the interstellar medium, studied via infrared and visual spectroscopy and spectropolarimetry.

Morten Andersen  (South)

Keywords: Galaxy: open clusters, galaxies: star clusters
My research focusses on resolved young massive star clusters and their properties, in particular the Initial Mass Function and whether it differs in these extreme environments compared to nearby low mass embedded clusters. I use high spatial resolution observations from space and the ground in order to resolve the individual cluster members. I am also investigating the birth and disruption of massive star clusters.
I am further interested in dust, its growth in molecular clouds and its destruction in supernova shocks.






Rodrigo Carrasco  (South)

Keywords: galaxies: clusters
My research concentrate on the study of the galaxy population in cluster and groups of galaxies, focusing primarily in the kinematics and dynamics of the galaxies in these structures. In particular I’m interested in evolution of the cluster and their parent galaxy population and how the presence of sub-structures and cluster merges can affect the physics of the galaxies. Other research interest include: the study of field massive galaxies at high redshift and the effect of the minor and major mergers through cosmic time; Fossil and compact groups of galaxies and the connection between them.

André-Nicolas Chené  (North)

Keywords: stars: massive stars, Galaxy: open clusters
My main research interests are massive stars and star clusters. I study the fundamental parameters and the evolution of the massive (>=10 Msol) and very massive (>=100 Msol) stars. This work covers the observation of massive star binaries, Wolf-Rayet wind variability, the search for magnetic fields, the search for pulsations, and the discovery of new Galactic Wolf-Rayet stars.
Also, I am a member of the VISTA Variable in the Via Lactea (VVV; ESO public survey, operating on the 4m Visible and Infrared Survey Telescope for Astronomy (VISTA). I contribute to the study of Galactic open and globular star clusters, one of the prime science goal of the survey. The main objective of this effort is to produce a large sample of star clusters, which are practically invisible in the optical bands. The strength of this sample lies in the homogeneity of the data and analysis employed.
Finally, I am always inclined in using my skills in photometry and spectroscopy in both optical and infrared wavelengths to contribute to various projects on brown dwarfs, non-radial pulsating stars and high-redshift colliding galaxies.

Kristin Chiboucas  (North)

Keywords: galaxies: formation, evolution, dwarf
Primary research interest is galaxy formation and evolution, investigated through a range of projects including the star formation and assembly histories of cluster galaxies as a function of redshift, the galaxy luminosity function as a function of environment, and the search for extreme dwarf galaxies including very low surface brightness and ultra compact dwarfs.

Jason Chu  (North)

Luminous and ultra-luminous infrared galaxies, or (U)LIRGs, are some of the most extreme objects in the universe with their elevated star formation rates (SFRs) and/or presence of a powerful active galactic nucleus (AGN), playing a central role in the evolution of galaxies throughout cosmic history. At low redshifts many of these objects are found in systems of gravitationally interacting or merging galaxies, where I am interested in modeling their infrared spectral energy distributions (SEDs) between 1-1000 μm. Using these models we can accurately probe far-infrared properties such as (luminosity weighted) dust temperatures and molecular hydrogen gas masses, and relate them to galaxy properties such as stellar masses and SFRs over time in the context of a galaxy’s life cycle. Though they are relatively rare in the local universe, (U)LIRGs become increasingly more common at high redshifts where they dominate the SFR density, and thus the stellar mass assembly of galaxies. However, the ISM properties of these early dusty galaxies, which reflects the combined effects of star formation and/or black hole accretion activity, are poorly understood. To address this problem, I am involved in multiple large NIR spectroscopic surveys on 8-10 m class telescopes of high-redshift star-forming galaxies.




Erik Dennihy  (South)

Keywords: instrumentation, stars: circumstellar disks, exoplanetary systems, white dwarfs
My scientific research focuses on post-main sequence exoplanetary systems, and how the properties of their now defunct host stars can be exploited to learn something new about exoplanets in general. My recent work has focused on observations of compact circumstellar accretion disks around white dwarf stars, which are believed to be composed of remnant, disrupted planetary material. These observations are carried out using a combination near-infrared photometry and optical spectroscopy, and often reveal variability over a wide range of timescales which can be used to probe the accretion disk structure and evolution. I also have a keen interest in astronomical instrumentation and in the past have led major upgrade projects to the Goodman Spectrograph on the SOAR 4.1m telescope and the Evryscope-North, a unique robotic all-sky gigapixel-scale telescope.







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.
Minor mergers
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



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.







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; 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 develope science projects with the instrument team and the users.

Scot Kleinman  (North)

Keywords: stars: white dwarfs, pulsations
My primary research interests are white dwarf stars and the use of large scale surveys. I use white dwarf stars as laboratories to explore the physics of matter in extreme conditions and the end products of most stars’ evolution. With colleagues, I have used the Sloan Digital Sky Survey (SDSS) to identify a large number of new white dwarf stars that is now an order of magnitude larger than existed prior to the SDSS. This new larger number of spectroscopically-confirmed white dwarf stars allows for more extensive investigations of class properties of interesting white dwarf subclasses than have been possible before. We are also building white dwarf luminosity functions and mass distributions to explore the history of star formation in the Galaxy. Additionally, I am  involved with the Whole Earth Telescope to discern white dwarf stars’ internal structures through their self-excited pulsations via the tools of asteroseismology.



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.

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.

Marie Lemoine-Busserolle  (North)

Keywords: galaxies: formation, evolution
My research interest focuses on galaxy formation and evolution through the study of physical properties of spatially resolved distant galaxies populations using mostly adaptive optics and integral-field spectroscopy in the optical and infrared on 8-m class telescopes. I also works on investigating the properties of high-redshift star-forming galaxies behind lensing clusters. My goal is to build a comprehensive view of the physical properties of populations of distant star-forming galaxies and to set constraints on the galaxy formation and evolution scenarios.



Steve Margheim  (South)

Keywords: stars: massive stars
My research interests include stellar evolution and galactic archaeology, primarily through the understanding of the most metal-poor stars in the universe through high-resolution spectroscopy; and understanding the fates of massive stars through the study of supernova and LBV.

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)

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.



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]

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.

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.