• 천문학회보
• /
• 제39권2호
• /
• pp.93.2-93.2
• /
• 2014

Planetary nebulae (PN) are the last stages of evolution of intermediate mass (1-8 Msolar) stars. Their shapes are thought to result from interactions between the present-day, fast (emerging white dwarf) and previously ejected, slow (red giant) stellar winds. The observation of young, bright PN, NGC7027 and BD+30 3639, was made on July 7, 2014 using the 2.7m Harlan J. Smith telescope at the McDonald Observatory. IGRINS with high spatial (0.27") and high spectral ($7.5km\;s^{-1}$) resolution will provide more nebular lines and excitation/abundances to constrain the morphology and kinematics of the Nebula and the PDRs. Combined with other archival data (X-ray, 2MASS, WISE, Spitzer, Herschel) for PN, high-resolution IR spectroscopy will yield insight into poorly understood aspects of PN morphologies and the late stages of binary star evolution.

• 천문학회보
• /
• 제41권2호
• /
• pp.55.4-55.4
• /
• 2016

We observed 10 Class I sources as part of the IGRINS (Immersion GRating INfrared Spectroscoph) Legacy Program, "IGRINS Survey of Protoplanetary Disks (PI: Jeong-Eun Lee)". Unlike other Class I sources, IRAS 16316-1540 shows broad absorption features in the near-infrared spectra (H and K bands). The broadened absorption features have been detected toward FU Orionis-type objects. Boxy or double-peaked absorption profiles can be produced by a Keplerian disk that has the hot mid-plane heated by a burst mass accretion. We could fit the broad absorption features of IRAS 16316-1540 with a K5 V template stellar spectrum convolved with a disk rotation profile of 45 km s-1. Therefore, rotationally broadened absorption features detected in this Class I source suggest that the episodic accretion process occurs from the early stage of star formation.

• 천문학회보
• /
• 제44권1호
• /
• pp.66.3-66.3
• /
• 2019

We present near-infrared spectroscopic results for three nearby class I sources, IRAS 03445+3242, IRAS 04239+2436 and ESO $H{\alpha}$ 279a. We detected many molecular and atomic line emissions, e.g., $H_2$, [Fe II], Hydrogen Bracket series recombination, Ca I, Na I & CO overtone band, from these sources using the high-resolution Immersion GRating INfrared Spectrometer (IGRINS; R~45,000). Previous studies showed that all the three sources posses actively accreting Keplerian disks. We performed spectral analysis to understand the origin of Hydrogen Bracket series recombination lines. We also estimated the accretion properties and mass loss rates of circumstellar disks for all the three sources.

• 천문학회보
• /
• 제44권1호
• /
• pp.67.3-67.3
• /
• 2019

Massive stars play an important role in terms of their feedback, but their formation process is poorly understood. Direct observational evidence for the formation of massive stars through accretion disks is rare. Hence the detection of disks in massive young stellar objects (MYSOs), if any, could be important to constrain the formation process of massive stars. The inner gaseous disk can be observed by the high-resolution near-infrared spectroscopy. We observed a MYSO, Min 2-62, using IGRINS and detected a double peak feature, which could be an evidence of a rotating disk, in the Bracket and Pfund series lines. We report the preliminary observational results of Min 2-62 with IGRINS.

• 천문학회보
• /
• 제44권1호
• /
• pp.68.1-68.1
• /
• 2019

Using IPHAS $H{\alpha}$ data, we found bright $H{\alpha}$ regions inside the elongated $^{13}CO$ cavity around a Herbig star, MWC 1080. To investigate the ionized hydrogen regions and the molecular cavity, we perform near-IR high-resolution spectroscopic of hydrogen Brackett lines and molecular hydrogen lines by Immersion GRating INfrared Spectrograph (IGRINS) observations. We detected broad Brackett line series and sharp molecular lines with various velocity components. We present three ionized hydrogen regions (near MWC 1080A, MWC 1080E, and CO boundary) with different line widths, central radial velocities, and line ratios. We also show two spatially-separate $Br{\gamma}$ ${\lambda}2.1662{\mu}m$ peaks near MWC 1080A. To reveal a 3D structure of the cavity around MWC 1080, we try to use the detected sharp molecular lines.

• 천문학회보
• /
• 제45권1호
• /
• pp.51.2-51.2
• /
• 2020

Luminous blue variables (LBVs) are massive evolved stars that show unpredictable photometric and spectral variation. It is generally assumed that they undergo one or more of large eruptions. We have obtained high dispersion NIR spectra of several LBVs with Immersion GRating INfrared Spectrometer (IGRINS). One notable feature in their IGRINS spectra is the existence of broad lines (~ a few hundred km/s) with unusual boxy profile. They are fluorescent lines of Fe II by Lyman α photons in the stellar wind. However, modeling of these lines with radiative transfer code CMFGEN predicts much weaker line strength. We propose that incorporating broadening of Lyman α line by scattering processes in dense wind can enhance the Fe II fluorescent lines. We further discuss how these Fe II fluorescent lines can be used to characterize massive LBV wind.

• 천문학회보
• /
• 제36권2호
• /
• pp.156-156
• /
• 2011

VPH (Volume Phase Hologram) grating is one of the transmission gratings and is known as its remarkable efficiency (>90%). It has two different densities of gelatins causing interference patterns. The VPH grating is favored in many astronomical instruments these days and also IGRINS, which is up coming near infrared high-resolution spectroscope expected to see the first light next year, uses the VPH grating as its cross-disperser. The infrared astronomical instruments operate at cryogenic temperature (~100K) in order to cut down thermal noise and the optical components of IGIRNS will be operated at 130K. The VPH grating is sandwiched in between fused silica or glass and glued together using optical adhesive. IGRINS is expected to go through 50 times of thermal cycling in 10 years including the performance test and this research is to check whether the physical characteristic such as the adhesion or dichromatic gelatin does not break and change from the several cryogenic thermal cycling. The two identical test gratings provided from Kaiser Optical System, Inc. are used in this test. One VPH grating is cooled down to 100K for 2 hours with maximum dT/dt = 5 and warmed up to the room temperature and another grating is kept stored in the room temperature and used as a control sample. In order to check the change, we inspected the grating with eyes and checked its efficiency and transmission at the room temperature every 10 cycling. From the 40 times of cryogenic temperature cool down cycling, the VPH grating showed no signs of change within the error compared to the control sample. We concluded the VPH grating is durable through several cryogenic thermal cycling.

• 천문학회보
• /
• 제36권2호
• /
• pp.155.1-155.1
• /
• 2011

The Korea Astronomy and Space Science Institute (KASI) and the Department of Astronomy at the University of Texas at Austin (UT) are developing a near infrared wide-band high resolution spectrograph, IGRINS (Immersion Grating Infrared Spectrograph). The white-pupil design of the instrument optics uses 7 cryogenic mirrors including 3 aspherical off-axis collimators and 4 flat fold mirrors. Two of the 3 collimators are H- and K-band pupil transfer mirrors and they are designed as compensators for the system alignment in each channel. Therefore, their mount design will be one of the most sensitive parts in the IGRINS optomechanical system. The other flat fold mirrors are designed within the limited area. Each of those includes the features of 3 axial hard points and 2 radial hard points with one spring plunger in order for the proper deflection of the mirror. The design work will include the computer-aided 3D modeling and finite element analysis (FEA) to optimize the structural stability and the thermal behavior of the mount models. The mount body will also include a tip-tilt and translation adjustment mechanism to be used as the alignment compensators.

• 한국우주과학회:학술대회논문집(한국우주과학회보)
• /
• 한국우주과학회 2009년도 한국우주과학회보 제18권2호
• /
• pp.32.4-32.4
• /
• 2009

한국천문연구원은 미국 텍사스대학교와 공동으로 근적외선 광대역 고분산 분광기 IGRINS (Immersion Grating Infrared Spectrograph)를 개발하고 있다. IGRINS는 R=40,000의 높은 분광분해능으로 H-밴드 ($1.49\sim1.80{\mu}m$)와 K-밴드 ($1.96\sim2.46{\mu}m$) 전체 분광스펙트럼을 한 번에 관측할 수 있다. IGRINS를 구성하는 핵심 부품은 실리콘 담금격자 (Silicon Immersion Grating)와 VPH (Volume Phased Holographic) 격자, 그리고 HAWAII2RG 적외선 센서이다. 실리콘 담금격자를 사용함으로써 적외선 분광기의 크기를 일반적인 격자를 사용한 것보다 2-3배정도 줄일 수 있게 되었다. IGRINS는 개발 후 미국 맥도날드 천문대에 3년간 장착하여 관측연구에 활용될 예정이다. 이후 IGRINS는 4미터급 이상의 망원경에 장착될 예정이다. 한국천문연구원은 IGRINS 국제공동 개발을 위하여 2009년 8월 텍사스 대학과 양해각서(MOU)를 교환하였으며 현재 개념 설계를 끝내고 기본 설계를 진행하고 있다. 기본설계검토 회의 (Preliminary Design Review)은 12월에 실시할 예정이다. 또한 과학연구 활용 극대화를 위하여 사용자 그룹을 조직하였으며, 여름학교를 열어 적외선 분광 연구에 대한 교육을 실시하였다. 이 발표에서는 IGRINS의 개발 현황을 보고하고, IGRINS의 설계와 활용 분야에 대하여 소개한다.

• 천문학회보
• /
• 제39권1호
• /
• pp.54.2-54.2
• /
• 2014

IGRINS (Immersion GRating Infrared Spectrograph) is a high spectral resolution near-infrared spectrograph that has been developed in a collaboration between the Korea Astronomy & Space Science Institute and the University of Texas at Austin. By using a silicon immersion echelle grating, the size of the fore optics is reduced by a factor of three times and we can make a more compact instrument. One exposure covers the whole of the H- and K-band spectrum with R=40,000. While the operation of and data reduction for this instrument is relatively simple compared to other grating spectrographs, we still need to operate three infrared arrays, cryostat sensors, calibration lamp units, and the telescope during astronomical observations. The IGRINS Instrument Control Software consists of a Housekeeping Package (HKP), Slit Camera Package (SCP), Data Taking Package (DTP), and Quick Look Package (QLP). The SCP will do auto guiding using a center finding algorithm. The DTP will take the echellogram images of the H and K bands, and the QLP will confirm fast processing of data. We will have a commissioning observations in 2014 March. In this poster, we present the performance of the software during the test observations.