iSHELL: a 1–5 micron R = 80,000 Immersion Grating Spectrograph for the NASA Infrared Telescope Facility

Rayner, John; Tokunaga, A. T.; Jaffe, D. T.; Bond, Timothy N.; Bonnet, Morgan; Ching, Gregory K.; Cushing, Michael C.; Kokubun, Daniel; Lockhart, Charles; Vacca, W.; Warmbier, Eric

doi:10.1088/1538-3873/ac3cb4

Cited by 28 publications

(21 citation statements)

References 44 publications

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Section: Observations and Data Reductionmentioning

confidence: 99%

“…We observed W3 IRS 5 with the iSHELL spectrograph (Rayner et al 2022) at the NASA InfraRed Telescope Facility (IRTF) 3.2 m telescope as part of program 2018B095 on UT 09:00 2018 October 5. The instrument was used in its spectral mode M1 (see Table 1 in Rayner et al 2022) with a slit width of 0 375. This provides a resolving power of R = λ/Δλ = 88,100 ± 2000 (Rayner et al 2022) over a wavelength range of 4.52-5.25 μm, excluding small gaps between the echelle orders.…”

Section: Observations and Data Reductionmentioning

confidence: 99%

“…The instrument was used in its spectral mode M1 (see Table 1 in Rayner et al 2022) with a slit width of 0 375. This provides a resolving power of R = λ/Δλ = 88,100 ± 2000 (Rayner et al 2022) over a wavelength range of 4.52-5.25 μm, excluding small gaps between the echelle orders. The total on-source integration time was 30 minutes, and the airmass was in the range of 1.535-1.443.…”

Section: Observations and Data Reductionmentioning

confidence: 99%

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High-resolution M-band Spectroscopy of CO toward the Massive Young Stellar Binary W3 IRS 5

Boogert

Barr

et al. 2022

ApJ

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We present in this paper the results of high spectral resolution (R = 88,100) spectroscopy at 4.7 μm with iSHELL/IRTF of hot molecular gas close to the massive binary protostar W3 IRS 5. The binary was spatially resolved, and the spectra of the two sources (MIR1 and MIR2) were obtained simultaneously for the first time. Hundreds of 12CO ν = 0–1, ν = 1–2 lines, and ν = 0–1 transitions of the isotopes of 12CO were detected in absorption and are blueshifted compared to the cloud velocity v LSR = −38 km s−1. We decompose and identify kinematic components from the velocity profiles and apply rotation diagram and curve-of-growth analyses to determine their physical properties. The temperatures and column densities of the identified components range from 30 to 700 K and 1021 to 1022 cm−2, respectively. Our curve-of-growth analyses consider two scenarios. One assumes a foreground slab with a partial covering factor, which well reproduces the absorption of most of the components. The other assumes a circumstellar disk with an outward-decreasing temperature in the vertical direction and reproduces the absorption of all of the hot components. We attribute the physical origins of the identified components to the foreground envelope (<100 K), post-J-shock regions (200–300 K), and clumpy structures on the circumstellar disks (∼600 K). We propose that the components with a J-shock origin are akin to water maser spots in the same region and complement the physical information of water masers along the direction of their movements.

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Section: Observations and Data Reductionmentioning

confidence: 99%

Section: Observations and Data Reductionmentioning

confidence: 99%

Section: Observations and Data Reductionmentioning

confidence: 99%

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High-resolution M-band Spectroscopy of CO toward the Massive Young Stellar Binary W3 IRS 5

Boogert

Barr

et al. 2022

ApJ

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“…I obtained high-resolution IR spectra of 39 candidate members of 32 Ori using iSHELL at the IRTF (Rayner et al 2022). The selected observing mode for iSHELL (Table 1) produced spectra in orders 238-211, which span wavelengths from 2.17 to 2.46 μm.…”

Section: Radial Velocitiesmentioning

confidence: 99%

A Census of the 32 Ori Association with Gaia*

Luhman

2022

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I have used high-precision photometry and astrometry from the third data release of Gaia (DR3) to identify candidate members of the 32 Ori association. Spectral types and radial velocities have been measured for subsets of the candidates using new and archival spectra. For the candidates that have radial velocity measurements, I have used UVW velocities to further constrain their membership, arriving at a final catalog of 169 candidates. I estimate that the completeness of the survey is ∼90% for spectral types of ≲M7 (≳0.06 M ⊙). The histogram of spectral types for the 32 Ori candidates exhibits a maximum at M5 (∼0.15 M ⊙), resembling the distributions measured for other young clusters and associations in the solar neighborhood. The available UVW velocities indicate that the association is expanding, but they do not produce a well-defined kinematic age. Based on their sequences of low-mass stars in color–magnitude diagrams, the 32 Ori association and Upper Centaurus-Lupus/Lower Centaurus-Crux (UCL/LCC) are coeval to within ±1.2 Myr, and they are younger than the β Pic moving group by ∼3 Myr, which agrees with results from previous analysis based on the second data release of Gaia. Finally, I have used mid-IR photometry from the Wide-field Infrared Survey Explorer to check for excess emission from circumstellar disks among the 32 Ori candidates. Disks are detected for 18 candidates, half of which are reported for the first time in this work. The fraction of candidates at ≤M6 that have full, transitional, or evolved disks is 10 / 149 = 0.07 − 0.02 + 0.03 , which is consistent with the value for UCL/LCC.

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“…However, with a slit, diffraction produces beams with non-flat amplitude/phase distributions at the grating surface. 11 2. In the MIR, imaging performance tends to be close to the diffraction limit; therefore, it is inappropriate to use geometrical-optics-based concepts (e.g.…”

Section: Introductionmentioning

confidence: 99%

Simulations of the Spectral Resolving Power of a Compact Space-Borne Immersion-Echelle Spectrometer Using Mid-Infrared Wave Tracing

Itoh,

Ishihara,

Wada

et al. 2022

Preprint

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We performed wave-optics-based numerical simulations at mid-infrared wavelengths to investigate how the presence or absence of entrance slits and optical aberrations affect the spectral resolving power R of a compact, high-spectral-resolving-power spectrometer containing an immersion-echelle grating. We tested three cases of telescope aberration (aberration-free, astigmatism and spherical aberration), assuming the aberration budget of the Space Infrared Telescope for Cosmology and Astrophysics (SPICA), which has a 20-µm-wavelength diffraction limit. In cases with a slit, we found that the value of R at around 10-20 µm is approximately independent of the assumed aberrations, which is significantly different from the prediction of geometrical optics. Our results also indicate that diffraction from the slit improves R by enlarging the effective illuminated area on the grating window and that this improvement decreases at short wavelengths. For the slit-less cases, we found that the impact of aberrations on R can be roughly estimated using the Strehl ratio.

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iSHELL: a 1–5 micron R = 80,000 Immersion Grating Spectrograph for the NASA Infrared Telescope Facility

Cited by 28 publications

References 44 publications

High-resolution M-band Spectroscopy of CO toward the Massive Young Stellar Binary W3 IRS 5

High-resolution M-band Spectroscopy of CO toward the Massive Young Stellar Binary W3 IRS 5

A Census of the 32 Ori Association with Gaia*

Simulations of the Spectral Resolving Power of a Compact Space-Borne Immersion-Echelle Spectrometer Using Mid-Infrared Wave Tracing

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