IGRINS-2 System Verification

News

• February 2024: Call to join the Early Science Team (EST)
• April 2024: Early Science Team composition announced

Introduction

The IGRINS-2 System Verification observing run is planned for July 2024. The purpose of the run is to:

• perform end-to-end testing of the software, documentation, and operational procedures to prepare for instrument deployment (i.e. November IGRINS-2 Shared Risk Call for Fast Turnaround, Regular operations in 2025A and beyond); and
• provide an initial set of publicly available observations to showcase the instrument capabilities, the range of science cases, and inform the community in preparation for the call for proposals.

The International Gemini Observatory has allocated about 40 hours of engineering time for IGRINS-2 observations.

The Early Science Team (EST), which includes Gemini Observatory personnel and community representatives, will be responsible for developing the observations to take for the SV, reducing and analyzing the data, evaluating the observations, and presenting the results to support and promote the use of IGRINS-2 among the broader Gemini community. The EST is chosen in consultation with the Gemini Directorate, STAC, and the IGRINS-2 Instrument team.

Regular updates on the IGRINS-2 System Verification observation planning and results will be presented on this page. An expected timeline is provided below.

• 15 March 2024: Deadline for EST self-nomination.
• 5 April 2024: EST composition is announced.
• May-June: SV Observing plan (with priority) is finalized (the EST tests the Integration Time Calculator and the Phase I Tool software; the SV team tests the Observing Tool). The Target list is released to the community.
• July: Observations will be performed around 17-23 July. Description of the observations is released.
• August: Raw data released. Data quality evaluation released.
• September-October: Reduced data released. 
• November: IGRINS-2 will be offered in Shared Risk for Fast Turnaround proposals.

SV Team

Members of the Gemini community interested in joining the EST have applied using the self-nomination form at this link.

IGRINS-2 SV science cases

GN-2024B-SV-101: Disk signatures from secondaries in Be+sdO systems

PI: Felipe Navarete
Science Goals:  We plan to obtain high-SNR IGRINS-2 spectra of two known Be+sdO binary systems accessible from Gemini North. Such targets correspond to benchmark objects to understand the formation of rapidly rotating objects in binary systems. They are formed by a Be star with a circumstellar disk (the primary) and a stripped sdO or sdB star (the secondary). Recent models predict the formation of a disk around the secondary, formed by material accreted from the primary's disk. So far, clear evidence for such structures has been presented for only two objects: HD 55606 (Chojnowski et al., 2018) and V 658 Car (de Amorim, in prep.). At the moment, we have a list of 20 Be+sdO binary system candidates, from which 28 Cyg and 59 Cyg are visible for the IGRINS-2 SV run.
The accurate interpretation of the disk around the secondary star is essential for two critical analyses: 1) how the Be dumps material into the sdOB, and subsequently how much is absorbed by the sdOB, and 2) improving the constraints on the physical parameters of the secondary. Both results have the potential to refine our understanding of the evolution of such systems. A similar study is being carried out with regular observations of the V658 Car system at lower resolutions (R~3,000) using TripleSpec/SOAR, where we were able to successfully identify a disk-like structure around the subdwarf (de Amorim, in prep.), based on HeI features at 2.0581 micron. The proper identification of disk signatures around the primary and secondary stars will be identified through spectral monitoring of these objects at different orbital phases through radial velocity analysis.

GN-2024B-SV-102: High-velocity Supernova Ejecta Knots in Cas A

PI: Hyun-Jeong Kim, Heeyoung Oh
Science Goals: Cassiopeia A (Cas A) is the youngest core-collapse supernova remnant (SNR) known in the Galaxy. The remnant has a complex structure, manifesting the multidimensional nature of core collapse supernova explosions. One of the unique features is numerous compact ejecta knots outside the main shell of the O- and S-rich ejecta. It has been known that these fast-moving ejecta knots (FMKs) are composed of newly-synthesized heavy elements, indicating that they are dense knots expelled from the inner layers of supernova during the explosion. Previous optical and near-infrared (J and H band) spectroscopic observations detected ionic lines strong in shocked atomic gas, e.g., [S II] 1.03 um, [Fe II] 1.257/1.644 um lines. Recently, Cas A was observed by JWST using the NIRCam F162M, F356W, and F444W filters. The entire remnant was mapped, and it has been found that FMKs are bright in all three bands. In particular, the majority of FMKs are very bright in F444W. Their NIRCam colors strongly suggest that the F444W flux of FMKs is due to 4.6 um CO band emission, which needs to be confirmed by spectroscopic observations. The primary purpose of this proposal is to obtain IGRINS-2 spectra of several FMKs in order to confirm the presence of warm CO molecules in these shocked ejecta knots. The spectra will be also used to explore the velocity structures of [Fe II] 1.644 um and CO emission lines.

GN-2024B-SV-103: High resolution spectroscopy of Exoplanet atmospheres

PI: Megan Weiner Mansfield, Emily Deibert
Science Goals: A primary goal of exoplanet observations has been to precisely measure their atmospheric compositions in order to better understand planet formation. In particular, measurement of the carbon-to-oxygen (C/O) ratio can reveal details about a planet’s formation location and history (e.g., Oberg et al. 2011). Recently, near-infrared, high-resolution spectroscopy of exoplanet atmospheres has emerged as a powerful technique to measure their C/O ratios (e.g., Line et al. 2021; Brogi et al. 2023). We propose to observe emission from the dayside atmosphere of a hot Jupiter with IGRINS-2. We will observe the planet just before or just after secondary eclipse to measure atmospheric abundances of key carbon- and oxygen-bearing species such as water, CO, and methane. Additionally, observing near secondary eclipse will allow us to constrain the thermal structure of the dayside atmosphere.
The most compelling target to observe during the SV run is MASCARA-1b. MASCARA-1b has been previously observed at high resolution in the infrared with Gemini-S/IGRINS and shows a clear detection of the atmospheric signal (PI private communication). Our proposed second observation would strengthen the detection of the signal and allow for tighter constraints on atmospheric abundances, while also allowing the opportunity to verify the capabilities of IGRINS-2 against the previous IGRINS result. Additionally, MASCARA-1b has been observed in optical wavelengths with Gemini-S/GHOST and Gemini-N/MAROON-X (PI private communication). Optical observations can measure the abundances of refractory species which, when combined with near-infrared information on carbon and oxygen abundances, can shed additional light on planet formation processes (e.g., Lothringer et al. 2021).

GN-2024B-SV-104: High resolution NIR observations of HAeBe stars

PI: Bill Vacca
Science Goals: We wish to obtain high S/N (~100) H and K band spectra of a small sample of bright HAeBe stars in order to measure the strengths of the atomic and molecular emission lines arising from the ionized regions in these systems. We are particularly interested in the 2.3 micron CO 2-0 and 3-1 bandhead emission, models of which can yield the physical properties of the accretion disks. We will also make use of the high resolution afforded by IGRINS-2 to search for weak absorption lines arising from the underlying stellar source. This will allow us to classify the sources directly, rather than relying on arguments dependent on estimates of the bolometric flux or the SED. Some of these systems have been observed previously at moderate resolution (R~2000), and one (MWC 297) has been previously observed with iSHELL/IRTF at R=80,000 but at low S/N. The proposed IGRINS-2 observations will be compared with the existing spectra in order to demonstrate the capabilities of this new instrument.

GN-2024B-SV-105: Characterizing the members of Halo Wide Binary systems with IGRINS-2

PI: Zach Hartman, Dongwook Lim
Science Goals: The release of the Gaia data over the past decade has revolutionized many fields of stellar astronomy. In particular, it has allowed for the identification of many more wide visual binary systems, which can be used by astronomers to study a number of different scientific questions. We propose to observe several wide binary systems that were found in previous surveys through their similar astrometric properties. Our goal is two-fold: Compare the chemical compositions of the wide binary pair and search for signs of possible third components in these systems. By characterizing the components in these systems, we can further our understanding of the formation and evolution of these binary systems. We will combine the IGRINS-2 data with Gaia RVs to search for possible signs of third companions. In particular, we will examine metal-poor Galactic halo star wide binaries, which have yet to be fully examined.

GN-2024B-SV-106: Breaking the metals! Spectrally resolving the metal enrichment of galaxies at Cosmic dawn

PI: Ema Farina, Bill Vacca, Zach Hartman, Hyewon Suh
Science Goals: The discovery of the ultra-luminous quasars at z>5 opened a new window for our understanding of early metal enrichment of galaxies. Indeed, thanks to their brightness, metal absorption at z>5 can be identified with reasonable exposures with 8-m class telescopes. We target the two brightest QSOs known at z>5 J0306+1853 (K=15.1 Vega mag) and J0100+2802 (K=15.2 Vega mag) which show interesting absorption features along their sightlines. IGRINS-2 observations will resolve these metal absorption lines down to a few tens of km/s, a precision that was previously accessible only at much lower redshifts.

GN-2024B-SV-107: Structure and kinematics of gaseous disks around massive stars in transition phases

PI: Maria Laura Arias
Science Goals: The post-main sequence evolution of massive stars give place to several phases with strong, often eruptive mass-loss events, including the enigmatic B[e] supergiants and yellow hypergiants. Stars in these groups are surrounded by disks, which are cool and dense, and give rise to a complex chemistry, producing molecules and dust. Near infrared emission in CO bands has proven to be a major indicator for disk dynamics, as it originates typically from the inner edge of the molecular disk or ring. To better understand  the mass-loss history in those objects, which is an essential ingredient for accurate predictions (e.g. of final stages) from stellar evolution calculations, a detailed study of their circumstellar material is crucial. Thus, we propose to use the IGRINS spectrograph to obtain high-resolution near-IR spectra for a sample of B[e] supergiants and YHGs, with confirmed CO emission through low resolution spectroscopy, to model in detail the structure and kinematics of their circumstellar disks. We are interested also in other lines that trace the hot inner disk (Na I 2.206/09 μm, Ca I around 1.9 μm as well as many lines of Fe II and [Fe II] in the region around 1.6 -1.9 μm), and the wind (He I lines at 1.70, 2.058 and 2.112/3 μm)

GN-2024B-SV-108: Surface Magnetic fields and Line profile variability in rapidly oscillating, magnetic chemically peculiar stars

PI: Bill Vacca
Science Goals: We propose to observe two very bright magnetically Chemically Peculiar (MCP) stars. High resolution near-infrared spectra will allow us to determine the strength of the surface magnetic fields using the strengths, widths, and profiles of magnetically sensitive absorption lines (primarily those of Fe) in the H band. Both of the proposed target stars are also known to exhibit variations in the profiles of optical lines, due to pulsations, with periods of about 12 min. By observing them repeatedly in the NIR with very short exposures (on the order of only 10 sec) over two periods each, we will be able to characterize the gas dynamics in the atmospheric layers of these stars that give rise to the NIR absorption lines.

GN-2024B-SV-109: Exploring the oldest stars in the near-infrared

PI: Federico Sestito
Science Goals: The most metal-poor stars are extremely useful probes in Galactic Archaeology as they serve as invaluable tools for studying the early Universe. Their chemistry provide unique ways to gather information about the very First Stars and how they chemically enriched the interstellar medium of the earliest galaxies. Three bright Galactic metal-poor stars are selected. Their chemical properties are very well known in the optical wavelength range. One of them (HD 122563) has also been observed with IGRINS at McDonald telescope. The scope of this proposal is to explore the infrared spectra of these targets to 1) measure the chemical abundances of some atomic/molecular species not accessible in the optical, which are also linked to the earliest stages of nucleosynthesis, 2) estimate any offset between optical and infrared abundances and hence test the quality of laboratory atomic data in the infrared, 3) provide metal-poor standard stars to the Galactic archaeology community, which will be needed to calibrate future chemical abundance measurement in the infrared.

GN-2024B-SV-110: Coronal line emission in NGC 6302

PI: Bill Vacca
Science Goals: We propose to observe the extreme bipolar planetary nebula (PN) NGC 6302. This source contains several solar masses of nebular material irradiated by a luminous, extremely hot central star (T>200,000 K), descended from an intermediate-mass (~5-6 M⊙) object. The central star is surrounded by a dense molecular disk, and drives focused, axisymmetric outflows of ionized and molecular material at velocities of up to hundreds of km/s. The optical and mid-infrared spectrum of NGC 6302 exhibits emission from diverse species including H2, [Fe II], and “coronal lines” such as [Mg VIII] and [Si IX] from ions that require photons with energies > 200 eV to form. We aim to study the abundances and kinematics of gas near its dense, dusty molecular torus, including coronal lines such as [Al IX] 2.04 μm, [Ca VIII] 2.32 μm, and [Si VI] – [Si IX] lines, taking advantage of the high velocity resolution (~6.7 km/s) of IGRINS-2 in order to examine systematic differences between distinct components projected along the line of sight as well as between neutral and ionized regions. In addition to understanding this enigmatic source for its own sake, the spectrum of NGC 6302 can serve as an atlas of spectral features for Gemini/IGRINS-2 observations from a range of interstellar/circumstellar structures including circumstellar disks around YSO's, ejected material around evolved stars, and even AGN.

GN-2024B-SV-111: Probing the gas content in Young Planetary Systems

PI: Cicero Lu
Science Goals: We plan to observe high S/N (SNR~100-300) IGRINS-2 H and K spectra of  young planetary systems to search for the CO overtone emission (~2.3 microns) and H2 emission. The selected planetary systems span in both their evolutionary stages (from gas-rich protoplanetary disks to gas-poor hybrid disk and debris disk) and stellar types, consequently exhibiting a continuous change in their UV emission features, from strong to weak. More specifically, while 51 Oph has previous epochs of NIR hi-res spectra, we aim to obtain another epoch of data to examine the time variable nature of the CO overtone emission. On the other hand, CO and H2 overtone emission has not been previously searched for in 49 Ceti and AU Mic but HST and JWST data suggest otherwise. Mounting evidence from the JWST NIRSpec low-res spectra has shown CO fundamental emission, pointing to the possibility of CO overtone emission in 49 Ceti and H2 emission or absorption in AU Mic.

GN-2024B-SV-112: A spectroscopic study on red supergiants in M31

PI: Jae-Joon Lee
Science Goals: Red supergiants (RSGs) are massive stars (M > 8.0 Msun) in the post-main sequence phase. Stellar evolution models indicate that the surface properties and evolution of RSGs are very sensitive to the assumed physical processes like convection, semi convection and rotation. Therefore, RSGs are often considered as “magnifying glass” for stellar evolution theory. Unlike the RSGs in the Milky Way and other nearby galaxies including LMC and SMC, RSGs in M31 exhibit a bifurcation in the temperature distribution. One sequence consists of early K-type supergiants and the other consists of M-type supergiants. There exists no stellar evolution models that can explain this bifurcation.
We propose a spectroscopic study on RGSs in M31 using IGRINS2. The purposes of this study are 1) to confirm the bifurcation in the temperature distribution and 2) to systematically compare the chemical compositions at the surface for the two sequences (K type and M type), which might provide an important clue on the origin of the temperature bifurcation.

GN-2024B-SV-113: Specphots with hot and cool stars

PI: Venu Kalari
Science Goals: Spectrophotometric standards are a classic tool to measure spectral response, providing also cross-calibration between different instruments and allowing absolute comparison of object fluxes. While the near-infrared spectrophotometric flux standard is not as well established as the optical counterpart, vetting of near-infrared flux is essential for any new instrumentation, and multiple science cases (for e.g. emission line fluxes). Here we propose high SNR observations of well characterized specphot standards of hot dwarfs (with broad absorption lines) and solar analog calibrators. The ultimate aim of this would be to examine the final absolute flux calibration of spectra achieved compared to the literature.

GN-2024B-SV-114: Near-IR kinematics and physics of the collimated outflows from intermediate-mass young star

PI: Heeyoung Oh
Science Goals: Mass accretion and outflows are essential processes in the formation of stars and planets, as they remove the angular momentum of the infalling material (Hartigan et al. 1995). It is believed that the formation mechanism and evolution pattern are different depending on the mass of the star (e.g, low-, intermediate, and massive star). In Particular, massive star formation is not understood well (Zinnecker & Yorke 2007) but they are thought to form in multiple systems and in filamentary structures in molecular clouds. LkHα 233 is a Herbig Ae/Be star of intermediate mass, with around 4 solar masses. Usually, low-mass stars have good collimation and outflow, but this object is a rare case of such a phenomenon among medium-mass stars. It is also known as one of the special examples of driving parsec scale outflow with a distribution spanning over 3 parsecs. Optical spectroscopic observations have shown jets over 100 km/s near the central star Lkhα 233 with various emission lines (e.g., Corcoran and Ray 1998), while there is a lack of study in the infrared region. IFU observations conducted using OSIRIS/Keck detected 1.64 um [FeII] emission at a speed close to 200 km/s (Perrin et al. 2007). In the case of the 2.12 um H2, it was detected very weakly, possibly because it was at the edge of the filter's coverage, or because it was actually weak. With IGRINS-2, multiple lines can be observed simultaneously with wider spatial and wavelength coverage, and more detailed velocity structures can be revealed with high spectral resolution. Since past observations (e.g., Oh et al. 2018) have proven that IGRINS is a very powerful tool for studying the kinematics and physics of outflow, we will also test this possibility with IGRINS-2.

GN-2024B-SV-115: IGRINS-2 Monitoring observation of a recurrent Nova T CrB

PI: Jae-Joon Lee
Science Goals: T Coronae Borealis (T CrB) is a recurring nova, whose last event was seen in 1946. T CrB has started its Pre‐eruption Dip in early 2023 and the eruption is predicted to happen around 2024.4±0.3. We propose to conduct monitoring observation of T CrB during the SV run of IGRINS2. During the eruption, IGRIN2 would be able to detect the hydrogen and helium emission lines (possibly multiple components), CO band-head emission at 2.29 μm and other coronal lines. And it will help us to understand kinematics, and energetics of warm atomic and molecular gas present in the inner few tenths of AU. During the quiescent phase, the IGRINS2 spectra will mostly show the spectra of a red giant star, whose pre-eruption behavior is not well known. T CrB is quite bright in NIR (~5th mag in K) and a single quad of ABBA nodding with an exposure of 25s will provide SNR larger than 100 which is enough for our purpose. We request a maximum of 5 visits to the target, minimum of two visits; one at the beginning of the SV run and another at the end of the run.

Acknowledgment to include in papers using IGRINS-2 SV data

Please include the following acknowledgment in any paper that makes use of IGRINS-2 SV data, in addition to the general Gemini acknowledgment (see Section 8.2 here).

``This work used the Immersion Grating Infrared Spectrograph 2 (IGRINS-2) developed and built by a collaboration between Korea Astronomy and Space Science Institute (KASI) and the International Gemini Observatory.''