Abstract

Poster Presentation

 

1. Mapping Galaxy Clusters at z < 0.8 by Red Sequence Method in KS4 DR1: see poster

 

박보미 (Bomi Park)

 

Galaxy clusters, as the largest structures in the universe located at the top of the cosmological hierarchical model, are useful tool to understand the evolution of the universe. For various researches from galaxy clusters in statistically, the catalog with cluster information is basically plays an important role. A large number of catalogs for galaxy clusters in the northern sky have been published; however, there are few catalogs in the southern sky due to the lack of wide sky survey data. KMTNet Synoptic Survey of Southern Sky (KS4) project, which observes a wide area of the southern sky about 5500 deg2 with KMTNet telescopes for two years, is in progress under the SNU Astronomy Research Center. We detect galaxy clusters at redshift z < 0.8 using the cluster red sequence method from KS4 data release 1 (DR1). This new galaxy cluster catalog will improve the study of galaxy clusters in the southern sky.

 

 

2. Weak-lensing Analysis of Disturbed Galaxy Cluster Abell 2443: see poster

 

김효정 (Hyojeong Kim)

 

The galaxy cluster Abell 2443 at z = 0.11 presents compelling evidence of merging activity. This evidence includes a highly disturbed and elongated intracluster medium (NW-SE direction) consistent with the spatial distribution of cluster galaxies. A candidate radio relic detected near the cluster center, alongside an X-ray merger shock edge, suggests a complex merger scenario. Additionally, the neighboring galaxy cluster ZwCl 2224.2+1651 ( z ~ 0.1 ), located 2.7 Mpc to the southeast, indicates a potential physical connection and a link to cosmic filaments. To further investigate the merger history of Abell 2443 and its embedded dark matter distribution, we conducted a weak gravitational lensing analysis using deep, wide-field, high-quality imaging data from the Subaru Hyper Suprime-Cam (HSC). The extensive field of view provided by HSC covers areas beyond the cluster's virial radius, allowing the study of interactions with the surrounding environment. Our analysis reveals significant substructures in the mass distribution, elongated in the same NW-SE direction as the X-ray emission and galaxy distribution. By combining weak lensing analysis with multi-wavelength observations, this study provides a comprehensive view of the cluster's merging history and insights into the role of merging clusters in tracing large-scale cosmic structures.

 

 

Oral Presentation

 

======================== 21st Aug. 2024 (Wed) ========================

Session: Facility

 

 

1. Talk1   International Gemini Observatory: Present and Future

 

황나래 (Narae Hwang)

 

Introduction to the current and future prospect of International Gemini Observatory

 

2. Talk2  IGRINS I & II

 

(IGRINS-2 for Gemini Telescope: Development and early performance)

 

Youngsam Yu

 

IGRINS-2 is a high-resolution, near-infrared spectrograph developed by Korea Astronomy and Space Science Institute (KASI) for Gemini Observatory as a new facility instrument. It provides spectral resolving power of ~45,000 and a simultaneous wavelength coverage of 1.49-2.46 μm. IGRINS-2 is an improved version of IGRINS (Immersion GRating INfrared Spectrometer) with minor optical and mechanical design changes, new detector controllers, and operating software to be fully integrated into Gemini operating systems. Since the project began in early 2020, project key milestones including critical design review, fabrication, assembly and pre-delivery performance verification were completed, and IGRINS-2 was delivered to Gemini North in early September, 2023. After the successful post-delivery verification and telescope integration, the first light spectra were acquired in October 2023. We present design changes and upgrades made to IGRINS-2 from the original IGRINS, assembly and alignment procedures, and verification of the instrument requirements. We also report the preliminary results of the system performance tests. 

 

(IGRINS came back to Texas : planning for McDonald operation)

 

이재준 (Jae-Joon Lee)

 

IGRINS is a cross-dispersed near-IR spectrograph with a resolving power R=λ/Δλ = 45,000, developed by KASI together with UT Austin. After a successful visit to Gemini South from 2020 to May this year, IGRINS is now back to UT Austin lab for maintenance. And it will be offered at the 2.7m telescope at McDonald observatory, Texas, starting form late this year. We will highlight the scientific achievement of IGRINS so far and discuss the operation plan for the near future.

 

3. Talk3  RUBIN (Rubin/LSST Current Status)

 

신윤경 (Yun-Kyeong Sheen)        

 

We present current status of Rubin/LSST project and some updates from Rubin Community Workshop 2024 in July.

 

 

4. Talk4  GMT (GMT Project: Progress and Status)

 

Byeong-Gon Park

 

A brief introduction to the current progress and prospects of the GMT project will be presented in this contribution.

 

 

Session: AGN/SMBH/QSO/High-z

 

 

1. Talk1     GMOS-IFU Survey of AGN-driven Outflows: Spatial Constraints on AGN Feedback

 

김창석 (Changseok Kim)

 

While active galactic nucleus (AGN) feedback has been an essential component in galaxy evolution models to regulate star formation, its role and mechanism are yet to be well constrained by observations. To address this, we have investigated spatially resolved properties of 45 AGN host galaxies at z < 0.3 using Gemini Multi-Object Spectrograph Integral Field Unit (GMOS-IFU). In this talk, we present key results from our GMOS-IFU survey, constraining spatial properties of the AGN feedback via gas outflows. Our sample shows a clear blueshifted region and AGN photoionization at the center, indicating AGN-driven outflows. We will describe how we determined the outflow sizes based on kinematics. Particularly, we will verify the kinematic outflow size – [OIII] luminosity relation by adding type 1 AGNs to the sample and discuss the limited impact of the outflows on global star formation. Lastly, we will introduce our new IFU studies of post-starburst AGNs (PSAs), simultaneously exhibiting recently quenched stellar population and AGN signature, and present primary science goals, the PSA sample selection, and preliminary results of the projects.

 

2. Talk2    Discovery and Gemini Follow-up of a Mid-infrared Only Flare in the Seyfert Galaxy NGC 3786

 

손수연 (Suyeon Son)

 

We serendipitously discover an obscured mid-infrared flare in the nucleus of Seyfert 1.8 NGC 3786. We present immediate spectroscopic follow-up results obtained through the Gemini Fast Turnaround Program. With high S/N optical and near-infrared spectra from GMOS-N and GNIRS, we witness the changing-look phenomenon from type 1.8 to type 1 during the flare. We discuss the possible physical connection of the MIR-only flare with the tidal disruption event or the accretion mode transition.        

 

3. Talk3       z~5 Quasar Search via Deep Learning and Bayesian Information Criterion from The Hyper Suprime-Cam SSP Survey PDR3 Data

 

최윤이 (Yunyi Choi)

 

Using the Deep/UltraDeep(D/UD) data from the Hyper Supreme-Cam Subaru Strategic Survey Program data (HSC-SSP PDR3), we employed an artificial neural network to select quasar candidates near z ∼ 5. Recent JWST observations uncover exceedingly faint AGNs with M1450 = −(18 − 20), which surprisingly supports that AGNs contribute half of the cosmic re-ionization budget at z ∼ 5. Still, the luminosity range of M1450 = −(22− 24.5) remains critical for determining the quasar contribution to cosmic re-ionization. In a previous study by Shin et al. (2022), a flag called ’pixelflags crcenter’ was used to exclude objects with cosmic rays detected within 3 pixels of the center of that object when selecting quasar candidates. This significantly reduced the effective survey area (nearly by a factor of two) and the number of quasars discovered. To maximize the selection of quasar candidates, we have excluded this flag in our catalog query conditions. We applied artificial neural networks and Bayesian Information Criterion methods to select quasar candidates, achieving a lower contamination rate (reduced from 20.7% to 3.4%) and a higher recovery rate compared to traditional color selection methods. We have proposed observing our candidates with Gemini/GMOS long-slit starting from the 23B semester. It is noteworthy that QSO 1003_0133, the sole observed target thus far, exhibits a discernible Lyman alpha emission line, which serves as compelling evidence that it is a quasar.      

 

4. Talk4   Lyman Alpha Blobs at High Redshift Universe Discovered by ODIN Survey

 

문병하 (Byeongha Moon)

 

Lyα blob (LAB) is spatially extended Lyα emitting object embedding multiple galaxies at high redshift universe. The rarity and association with over-dense regions imply they are proto-group candidates. Therefore, LABs are cosmic laboratories to understand galaxy evolution and association with their underlying environment. However, their nature and statistical properties are still puzzling due to their small number statistics, strong field-to-field variation, and small survey area. In particular, different survey depths and definitions of the LAB sample make systematic studies challenging (e.g., number density, redshift evolution, luminosity function, clustering). One-hundred-deg^2 DECam Imaging in Narrowbands (ODIN) survey provides a chance to overcome this constraint with the largest survey volume to date at three cosmic slices (z ~ 2.4, 3.1, and 4.5). ODIN has discovered the largest samples of LABs (>400), and confirmed Lyα spectra from some blobs with large telescopes (e.g., Gemini/GMOS). Thanks to the largest and systematic ODIN-LAB samples to date, the first statistical study for LABs finally became possible. Here, we will present an overview of ODIN-LABs and preliminary statistical studies.

     

5. Talk5    Nature of Dust-Obscured Galaxies at Cosmic Noon

 

정웅섭 (Woong-Seob JEONG)

 

High-redshift luminous galaxy population with intense star formation rate is one of key components in our understanding of massive galaxy formation. In addition, there is increasing evidence that the star formation and black hole growth proceed more rapidly in more massive haloes, a phenomenon commonly referred to as downsizing. Given that they are likely progenitors of massive galaxies or clusters, it is essential to understand the evolutionary sequence of most-luminous population from galaxy/BH mergers to QSOs and/or red-and-dead ellipticals. We have investigated the peculiar physical properties from our unique DOG sample at Cosmic Noon. Here, we report the progress on our GEMINI observations and discuss the future GMT observations on our sample.

 

6. Talk6    Gemini Gravitational-wave Source Follow-up Observation Program

 

Myungshin Im

 

We will outline our Gemini program to follow-up Gravitational-wave sources. We will present our optical counterpart search strategy and our plan about how to use Gemini for the multi-messenger astronomy studies.

 

 

======================== 22nd Aug. 2024 (Thu) ========================

Session: Gemini  Webinar

 

 

1. Talk1      Science Operations at Gemini Observatory

 

Andy Adamson    

 

2. Talk2     Gemini Instruments (Current & Future)

 

Emily Deibert & Zachary Hartman        

 

3. Talk3   How to apply for Gemini

 

Zachary Hartman   

 

4. Talk4     DRAGONS - Gemini's Data Reduction Platform

 

Kathleen Labrie

 

5. Talk5   GPP Explore  

 

Andrew Stephens

 

 

Session: Galaxies/Galaxy clusters

 

 

1. Talk1    From Galaxy Clusters to Superclusters: GMOS Spectroscopic Surveys of the Planck Cluster Candidates 

 

박형욱 (Hyeonguk Bahk)

 

Spectroscopic surveys of galaxy clusters are essential for understanding their dynamical states and the evolution of structures in a cosmological context. Spectroscopy uniquely allows us to separate cluster members from background galaxies, thereby facilitating detailed studies of cluster properties via their individual member galaxies. We therefore have launched a pilot survey using GMOS multi-object spectroscopy to spectroscopically confirm cluster candidates identified in the Planck Sunyaev-Zeldovich Source Catalog and to measure their redshifts and masses. During the target selection phase of this survey, we serendipitously discovered a supercluster candidate characterized by a significant galaxy overdensity in the optical images. We estimate its redshift to be about 0.4, a range currently underrepresented in supercluster catalogs. Upcoming GMOS multi-object spectroscopic observations will aim to determine its mass, morphology, and dynamics by measuring the redshifts of its member galaxies. This will provide a valuable sample for studying supercluster evolution over cosmic time.

 

2. Talk2    Very Wide-field Weak Lensing: Unveiling Dark Matter in Galaxy Clusters and Their Large-Scale Surroundings

 

조혜전 (Hyejeon Cho)

 

Galaxy clusters, forming the nodes in the cosmic web, grow by accumulating mass over time. Significant growth occurs when galaxy clusters merge, providing an ideal laboratory to study the nature of dark matter and the evolution of the cosmic web. Merging clusters that exhibit radio relics are particularly valuable for investigating the merger stages, the geometric configuration of merging constituents, and the particle acceleration mechanisms that generate the relics. Weak lensing (WL) allows us to identify and characterize the substructures of merging constituents, especially those of dark matter. However, accurate WL measurements hinge on increasing the number density of resolved source galaxies and adequately controlling systematic uncertainties. In this talk, I will present WL studies of radio relic clusters using Subaru Hyper Suprime-Cam (HSC) imaging data collected via the Gemini-Subaru time exchange program. Our WL analysis pipeline excels in modeling and correcting dominant sources of systematics in wide-field, high-quality HSC images. Combining WL data with spectroscopic, radio, and X-ray observations enhances our ability to discern substructures within individual radio relic clusters and reconstruct their merging histories. Additionally, the HSC's very wide field of view enables our studies to extend beyond individual clusters to include large-scale structures. I will highlight the first robust WL detections of low-density contrast structures around nearby clusters. Through this comprehensive approach, we aim to advance our understanding of the intrinsic link between galaxy clusters and the cosmic web.

 

3. Talk3     Emission-line Analysis for Starburst Galaxies at Intermediate Redshifts Using Gemini GMOS/IFU

 

이정환 (Jeong Hwan Lee)

 

Integral field spectroscopy (IFS) provides valuable insights into galaxy structures by providing spatially resolved properties such as kinematics, dynamics, and stellar/gas properties. Utilizing the strengths of IFS, we present recent research on starburst galaxies at intermediate redshifts (z>0.1) through their emission lines. Firstly, we investigate the star formation activity of five jellyfish galaxies in massive galaxy clusters at z~0.3. These jellyfish galaxies exhibit asymmetric tails and clumpy structures composed of young stellar populations and ionized gas. They are thought to be snapshots of the starburst phase induced by environmental effects such as ram-pressure stripping in galaxy groups or clusters. Using the Gemini GMOS/IFU spectrograph, we examine how the star formation rates of these jellyfish galaxies are connected to the properties of their host clusters. By combining our sample with jellyfish galaxies in lower-mass host clusters, we find that star formation activity in jellyfish galaxies tends to be more enhanced in more massive and dynamically unstable hosts. Additionally, we report preliminary results on compact starburst galaxies at z=0.1-0.3, known as ‘green pea galaxies’, also observed with the GMOS/IFU. This study aims to understand the mechanisms of Lyman alpha photon escape. Through these findings, we demonstrate the potential of Gemini GMOS/IFU for emission-line analysis of intermediate-redshift galaxies.

 

4. Talk4    Ongoing Morphological Transformation from Elliptical to Spiral Galaxies Induced by Gas Accretion from Neighboring Galaxies

 

임상혁 (Sang Hyeok Im)

 

According to galaxy evolution models, galaxies are expected to evolve from spirals (star-forming) to ellipticals (quenched). However, some numerical simulations showed that elliptical galaxies can also change their morphology to spirals due to gas accretion from neighboring galaxies. Indeed, Park et al. (2008) found such cases from the SDSS data, which shows signs of gas accretion from spiral galaxies to their elliptical (or S0) neighbors. To detect the evidence for the gas inflow and to analyze the radial stellar population profile of each galaxy, we have conducted the GMOS long-slit observations of those galaxy pairs along the gas accretion and the direction of connecting the nuclei of the two galaxies. These data will allow us, for the first time, to identify the ongoing morphological transformation from elliptical to spiral and improve our understanding of galaxy evolution.         

 

5. Talk5    Measuring the Bar Pattern Speed for Galaxies with Nuclear Rings from Gemini/long-slit observations

 

Yun Hee Lee

 

Barred structures in the central regions of spiral galaxies are common in the local universe, accounting for 60% of disk galaxies. N-body and cosmological simulations show that bar structures grow longer and stronger while slowing down as they lose angular momentum through interactions with the dark matter halo. However, observations do not find evidence for the growth of bar structures in terms of their length, strength, and pattern speed, which induces tension between the distribution of dark matter in simulations and observations. To look for evidence of interactions with the dark matter halo, we observe two barred galaxies with nuclear rings, NGC 6951 and NGC 7716, using the Gemini/GMOS long-slit. Nuclear rings are related to the inner Lindblad resonance, which occurs with the slow rotation of bar structures. We directly measure the pattern speed of bars by adopting the Tremaine-Weinberg method from five long-slit observations for each target. Additionally, we measure the velocity curve, resonance radii, bar length, strength, and nuclear ring radius using both Gemini spectroscopy and PSI photometry. We discuss the properties of bars and nuclear rings in NGC 6951 and NGC 7716 in the context of bar and ring formation and evolution. Lastly, we address the challenges and importance of measuring bar pattern speed.        

 

 

Session: Star/Star cluster

 

 

1. Talk1   Gemini Integrated Spectroscopic Survey of Young Stellar Clusters in External Galaxies for Probing the Variety of the Stellar Initial Mass Function  

 

Beomdu Lim

 

Our previous survey of young open clusters in the Galaxy found the signature of the variation of the intial mass function (IMF) with respect to the properties of clusters and the Galactocentric distances. However, there are several limitations and observational biases even though the individual members in stellar clusters are spatially resolved and studied in detail. We have thus initiated a integrated spectroscopic survey of young stellar clusters in remote galaxies to validate the variety of the stellar initial mass function (IMF). While stellar clusters in external galaxies are not spatially resolved, their integrated spectra open another window to probe their underlying IMFs. In this talk, we present the current status of this survey and future prospects.

 

2. Talk2   Near-IR stellar spectroscopy using Gemini/IGRINS

 

임동욱 (Dongwook Lim)

 

As extensive photometric surveys of Milky Way stars progress, including Gaia and VVV, the importance of high-resolution spectroscopy for individual stars is also increasing. While detailed chemical abundances of stars were primarily measured in the optical region, near-IR spectroscopy offers a novel perspective on Milky Way stellar astronomy. Near-IR spectroscopy has two major advantages: the ability to see regions of severe interstellar extinction and the capability to measure the abundance of specific elements with greater precision. In particular, the Immersion Grating Infrared Spectrometer (IGRINS), which provides high spectral resolution (R ~ 45,000) across the H- and K-band spectral regions, is one of the ideal instruments for examining the detailed chemical properties of stars. IGRINS was mounted on the Gemini South telescope until 2024, and IGRINS-2 will operate on the Gemini North telescope soon. Under the K-GMP Science Program, we have conducted several stellar studies using IGRINS spectroscopic data. In this talk, I will present the importance of near-IR spectroscopy and the effectiveness of IGRINS through two science cases: one on bulge globular clusters and the other on wide binary systems.        

 

3. Talk3   Unusual Helium-deficient Dwarf Novae with a Short Orbital Period Identified by Gemini/GMOS

 

이영대 (Youngdae Lee)

 

Dwarf novae are binary systems consisting of a white dwarf and a low-mass companion possibly evolving to a Type Ia Supernova. Hydrogen mass transfer produces outbursts in their accretion disk semi-regularly triggered by thermal instability for long-period (>75 minutes) sources, while helium transfer does for short-period ones, since the hydrogen mass transfer leads to the revelation of the helium shell of the low-mass companion as the orbital period decreases. We have recently discovered, for the first time, two unusual helium-deficient dwarf novae with short orbital periods (<75 minutes) using Gemini/GMOS in the KMTNet Supernova Program. In this talk, we will present the properties of these two helium-deficient dwarf novae and discuss their implications in our understanding of the evolution of low-mass binary systems.        

 

4. Talk4   Probing CO and dust formation in a type II SN 2023ixf using NIR spectroscopy

 

박성현 (Seong Hyun Park)

 

The large amount of dust found in the early universe cannot be fully accounted for by the dust produced in the AGB stars but is suggested to be a product of core-collapse supernovae. The dust emission is frequently detected in core-collapse supernovae and supernova remnants, while the timescale of dust formation and the temporal evolution remain an unclosed question. In addition, CO molecular lines can be used as a useful tracer of dust production since CO cooling lowers the ejecta temperature allowing dust formation. We present NIR spectra of a type II SN 2023ixf ranging from 17 to 278 days after the explosion including five spectra taken with GNIRS. NIR spectra taken within two weeks from the explosion show narrow emission lines attributed to CSM interaction. We analyze the CO first overtone emission and the dust continuum appearing at later epochs (t~250 d) in the 2.0-2.5 um range. The CO temperature, velocity, and masses are approximately T~1500 K, v~2000 km/s, M~(2-4)e-4 Msun, respectively. The dust temperature and masses are Td~900-1000 K, Md~(1-2)e-5 Msun. Using a LTE-based model of CO emission, we find the temperature of CO molecules in SN 2023ixf to be lower than that of another type II SN 1987A. 

 

5. Talk5  Gemini  (2024 Korea Gemini Office Report

 

양성철 (SOUNG-CHUL YANG)

           

 

======================== 23rd Aug. 2024 (Fri) ========================

Session: Synergy

 

 

1. Talk1    Observations with ground-based and space telescopes : collaborative efforts

 

이호규 (Ho-Gyu Lee)

  

Ground-based 8-10 meter class telescopes such as Gemini have been among the most competitive facilities for making important discoveries about the universe. Since the start of the K-GMT science program, opportunities for Korean astronomers to use these telescopes have dramatically increased. However, access to space telescopes through PI programs remains limited. In this talk, I will introduce some efforts to foster collaborative studies.

 

2. Talk2    Synergies between ALMA and IFU/IFS data: local galaxies

 

이범현 (Bumhyun Lee)

 

Recently, many extragalactic studies have been utilizing extensive multiwavelength data to obtain a deeper understanding of the physical properties of galaxies, the baryon cycle, and galaxy evolution. In particular, for galaxies in the local Universe, we can study stars, metallicities, star formation rates, multi-phase (ionized/molecular) gas components, and stellar/gas kinematics in great detail by using high-resolution IFU/IFS and ALMA data. Furthermore, these datasets are also useful for diagnosing the effects of internal and external processes (e.g., AGN and ram pressure stripping) on the physical properties of galaxies. In this talk, I will introduce recent results of several ALMA - IFU/IFS synergetic projects, and I will discuss potential ALMA - GEMINI synergies for nearby/local galaxies.         

 

3. Talk3    Synergies with All-sky Spectral Survey  

 

Minjin Kim

 

We will briefly introduce the upcoming all-sky optical to infrared spectral surveys and review their scientific impact on understanding the evolution of galaxies and supermassive black holes. We will present the necessity of the pre-spectroscopic and follow-up observations with Gemini telescopes.

 

 

Session: Solar system/Exoplanet/Star

 

 

1. Talk1    Chemodynamical Analysis of Dynamically Associated Metal-Poor (DAMP) Star with GEMINI-S/GHOST

 

 

Miji Jeong

       

We present results on the chemodynamical analysis of LAMOST J122216.86-063345.26 (J1222), a promising member dynamically associated with Gaia-Enceladus-Sausage (GSE). GSE is the debris of a massive merger event that contributed to the formation of the Milky Way. This star was selected from LAMOST, using Gaia DR2 astrometric information. High-resolution spectrum was obtained using the newest optical spectrograph, Gemini High-resolution Optical Spectrograph (GHOST), at the Gemini-South telescope, allowing us to determine stellar atmospheric parameters (Teff, log g, and [Fe/H]) and the chemical abundances of 42 elements from lithium to thorium. Our analysis reveals that J1222 exhibits r-process enhancement, a notable characteristic among halo stars. We compared J1222 with other halo stars in the Milky Way within a similar metallicity range, and we conducted a kinematic analysis using Gaia DR3 data to study the dynamical properties of J1222 to confirm its association with the GSE. We will discuss the preliminary results.

 

2. Talk2   Jupiter's North Polar Hotspot: The 44-Year Mystery May Now Be Solved?

 

Sang Joon Kim

 

Jupiter's mid-infrared north polar hot spot, ~20 K warmer than the surrounding polar stratosphere, has been observed for over four decades. Its unusual appearance and longevity have not been fully understood, although several mechanisms have been proposed to explain its existence. We utilized the Gemini Near-Infrared Spectrograph at Gemini/North telescope to spectrally map Jupiter in the 3-micron emission lines of CH4 (methane) and C2H6 (ethane) across Jupiter's northernmost latitudes where its mysterious north polar hotspot is located. These lines are emitted high above the stratosphere and are excellent monitors of auroral energy being deposited downward into the stratosphere. By comparing the emission from CH4 with that from C2H6, we propose that the transient heating and bright line emissions from these molecular species are caused by increased precipitation of high-speed auroral particles, which are produced in Jupiter's turbulent magnetosphere and ionosphere near its poles. The heating extends down into the stratosphere where the hotspot is located. At that depth, heating up and cooling off is much more gradual than at higher altitudes. Additionally, the free flow of warm gas in the hot spot to the surrounding polar regions is resisted by recently detected polar stratospheric jets associated with polar fronts. Other heating mechanisms proposed in the literature, such as Joule heating, polar haze heated by sunlight, etc., seem only the secondary mechanisms that follow atmospheric ionization caused by the energetic particle bombardment.    

 

3. Talk3   Understanding the Origin and Fate of Hot Jupiters through Observing Puffy Ones

 

최연호 (Yeon-Ho Choi)

 

A "hot Jupiter" is a type of exoplanet that is similar in characteristics to Jupiter but orbits very close to its parent star, resulting in extremely high surface temperatures. Puffy hot Jupiters, with their inflated atmospheres due to intense stellar radiation, offer opportunities to study atmospheric composition and dynamics under extreme conditions. High-resolution spectrographs installed at Gemini, such as IGRINS and GHOST, allow for the analysis of their atmospheric structures, chemical compositions, and thermal properties. By analyzing these puffy hot Jupiters, we can understand their formation mechanisms, such as disk migration, and their potential evolutionary paths, such as atmospheric evaporation. This comprehensive understanding of puffy hot Jupiters helps to clarify the broader processes that govern the origin and fate of hot Jupiters in general. In this talk, I will present observational results on the atmospheric chemical composition of WASP-69b and WASP-33b using IGRINS/IGRINS-2, as well as an approved observation plan for investigating the atmospheric escape of WASP-62b using GHOST.

        

4. Talk4   Spectroscopy of RR Telescopii Using GHOST  

 

이희원 (Hee-Won Lee)

 

High resolution spectroscopy of the D-type symbiotic star RR Telescopii has been performed using GHOST in order to secure Raman-scattered He II features blueward of hydrogen Balmer lines. The scattering cross section of He II near Lyman epsilon is comparable to that for O VI 1032 and hence a useful spectroscopic probe for investigation of very thick neutral regions associated with the heavy mass loss of the Mira component of RR Tel. We briefly discuss the capability of the new spectrograph GHOST to delve into the distribution and kinematics of neutral components that may provide crucial information regarding the mass loss and mass transfer processes in the binary systems of white dwarfs.

 

5. Talk5   Chemical Peculiarities of Ice Grains in Dense Molecular Clouds of the Central Molecular Zone

 

 

강예원 (Yewon Kang)

 

The presence of CO₂ ice absorption at 15.4 µm, indicative of ice mixed with CH₃OH, can serve as an empirical method for identifying dense clouds or dense envelopes of young stellar objects (YSOs) throughout the Milky Way and nearby galaxies. However, previous studies have found this feature to be significantly stronger toward a few red point-like objects in the Central Molecular Zone (CMZ). In this study, we investigate the chemical properties of these objects by obtaining L-band spectra using GNIRS at Gemini North, and estimate the column densities of H₂O and CH₃OH ices, and foreground extinction towards 15 objects. We confirm substantial amounts of both foreground dust and H₂O toward most of these objects, but find that the column densities of CH₃OH ices are within the range observed in dense clouds or YSOs in nearby star-forming regions. Our findings suggest that the strong CO₂ ice absorption at 15.4 µm largely results from a relatively low mixing ratio of CH₃OH in the CO₂-CH₃OH ice matrix. This further implies that the extreme gas conditions in the CMZ favor the production of CO₂ through a higher oxidation rate of CO, rather than the production of CH₃OH through its hydrogenation.