Yasuo Doi - Academia.edu (original) (raw)
Papers by Yasuo Doi
The Astrophysical Journal, 2022
We present 850 μm polarimetric observations toward the Serpens Main molecular cloud obtained usin... more We present 850 μm polarimetric observations toward the Serpens Main molecular cloud obtained using the POL-2 polarimeter on the James Clerk Maxwell Telescope as part of the B-fields In STar-forming Region Observations survey. These observations probe the magnetic field morphology of the Serpens Main molecular cloud on about 6000 au scales, which consists of cores and six filaments with different physical properties such as density and star formation activity. Using the histogram of relative orientation (HRO) technique, we find that magnetic fields are parallel to filaments in less-dense filamentary structures where N H 2 < 0.93 × 10 22 cm−2 (magnetic fields perpendicular to density gradients), while they are perpendicular to filaments (magnetic fields parallel to density gradients) in dense filamentary structures with star formation activity. Moreover, applying the HRO technique to denser core regions, we find that magnetic field orientations change to become perpendicular to den...
The Astrophysical Journal, 2021
Astronomy & Astrophysics, 2021
Context. Molecular filaments and hubs have received special attention recently thanks to new stud... more Context. Molecular filaments and hubs have received special attention recently thanks to new studies showing their key role in star formation. While the (column) density and velocity structures of both filaments and hubs have been carefully studied, their magnetic field (B-field) properties have yet to be characterized. Consequently, the role of B-fields in the formation and evolution of hub-filament systems is not well constrained. Aims. We aim to understand the role of the B-field and its interplay with turbulence and gravity in the dynamical evolution of the NGC 6334 filament network that harbours cluster-forming hubs and high-mass star formation. Methods. We present new observations of the dust polarized emission at 850 μm toward the 2 pc × 10 pc map of NGC 6334 at a spatial resolution of 0.09 pc obtained with the James Clerk Maxwell Telescope (JCMT) as part of the B-field In STar-forming Region Observations (BISTRO) survey. We study the distribution and dispersion of the polari...
Monthly Notices of the Royal Astronomical Society, 2019
We present the first release of the data and compact-source catalogue for the JCMT Large Program ... more We present the first release of the data and compact-source catalogue for the JCMT Large Program SCUBA-2 Continuum Observations of Pre-protostellar Evolution (SCOPE). SCOPE
Publications of the Astronomical Society of Australia, 2018
Measurements in the infrared wavelength domain allow direct assessment of the physical state and ... more Measurements in the infrared wavelength domain allow direct assessment of the physical state and energy balance of cool matter in space, enabling the detailed study of the processes that govern the formation and evolution of stars and planetary systems in galaxies over cosmic time. Previous infrared missions revealed a great deal about the obscured Universe, but were hampered by limited sensitivity.SPICA takes the next step in infrared observational capability by combining a large 2.5-meter diameter telescope, cooled to below 8 K, with instruments employing ultra-sensitive detectors. A combination of passive cooling and mechanical coolers will be used to cool both the telescope and the instruments. With mechanical coolers the mission lifetime is not limited by the supply of cryogen. With the combination of low telescope background and instruments with state-of-the-art detectors SPICA provides a huge advance on the capabilities of previous missions.SPICA instruments offer spectral re...
The Astrophysical Journal, 2018
We present 850 μm imaging polarimetry data of the ρ Oph-A core taken with the Submillimeter Commo... more We present 850 μm imaging polarimetry data of the ρ Oph-A core taken with the Submillimeter Common-User Bolometer Array-2 (SCUBA-2) and its polarimeter (POL-2) as part of our ongoing survey project, B-fields In STar forming RegiOns (BISTRO). The polarization vectors are used to identify the orientation of the magnetic field projected on the plane of the sky at a resolution of 0.01 pc. We identify 10 subregions with distinct polarization fractions and angles in the 0.2 pc ρ Oph-A core; some of them can be part of a coherent magnetic field structure in the ρ Oph region. The results are consistent with previous observations of the brightest regions of ρ Oph-A, where the degrees of polarization are at a level of a few percent, but our data reveal for the first time the magnetic field structures in the fainter regions surrounding the core where the degree of polarization is much higher (>5%). A comparison with previous near-infrared polarimetric data shows that there are several magnetic field components that are consistent at near-infrared and submillimeter wavelengths. Using the Davis-Chandrasekhar-Fermi method, we also derive magnetic field strengths in several subcore regions, which range from approximately 0.2 to 5 mG. We also find a correlation between the magnetic field orientations projected on the sky and the core centroid velocity components.
Publications of the Astronomical Society of Australia, 2017
IR spectroscopy in the range 12–230 μm with the SPace IR telescope for Cosmology and Astrophysics... more IR spectroscopy in the range 12–230 μm with the SPace IR telescope for Cosmology and Astrophysics (SPICA) will reveal the physical processes governing the formation and evolution of galaxies and black holes through cosmic time, bridging the gap between the James Webb Space Telescope and the upcoming Extremely Large Telescopes at shorter wavelengths and the Atacama Large Millimeter Array at longer wavelengths. The SPICA, with its 2.5-m telescope actively cooled to below 8 K, will obtain the first spectroscopic determination, in the mid-IR rest-frame, of both the star-formation rate and black hole accretion rate histories of galaxies, reaching lookback times of 12 Gyr, for large statistically significant samples. Densities, temperatures, radiation fields, and gas-phase metallicities will be measured in dust-obscured galaxies and active galactic nuclei, sampling a large range in mass and luminosity, from faint local dwarf galaxies to luminous quasars in the distant Universe. Active gal...
![Research paper thumbnail of Diffuse far-infrared [C ii ] line emission from high Galactic latitude](https://attachments.academia-assets.com/109989331/thumbnails/1.jpg)
](Astronomy and Astrophysics, 2002
The Far-Infrared Line Mapper (FILM) onboard the Infrared Telescope in Space (IRTS) made a survey ... more The Far-Infrared Line Mapper (FILM) onboard the Infrared Telescope in Space (IRTS) made a survey for the far-infrared [C ii] 158 µm line emission with high sensitivity and moderate spatial resolution. We have found that diffuse [C ii] line emission extends to high Galactic latitude regions. The [C ii] line intensity at |b| ∼ 60 • ranges from 2 × 10 −7 to 1.5 × 10 −6 erg cm −2 s −1 sr −1. Comparisons of the distribution of the [C ii] line emission with those of the H i column density and far-infrared radiation show some correlations, but the [C ii] line emission differs from the far-IR and HI emission at high Galactic latitudes. These differences suggest that the [C ii] line primarily comes from ionized gas in the high-latitude regions. The intensities of the [C ii] line emission on the southern side (b < 0 •) of the Galactic plane are systematically larger than those on the northern side (b > 0 •). We infer from this difference that there is a displacement of the Sun with respect to the center of interstellar medium from which the [C ii] line comes. When an exponential distribution is assumed for the [C ii] emitting gas, it is expected that the Sun is located at the distance of about 17% of the scale height above the center of the gas. This is consistent with the previously reported displacement of the Sun from the Galactic plane.
Astronomy & Astrophysics, 2022
Context. Despite recent observational and theoretical advances in mapping the magnetic fields ass... more Context. Despite recent observational and theoretical advances in mapping the magnetic fields associated with molecular clouds, their three-dimensional (3D) morphology remains unresolved. Multi-wavelength and multi-scale observations will allow us to paint a comprehensive picture of the magnetic fields of these star-forming regions. Aims. We reconstructed the 3D magnetic field morphology associated with the Perseus molecular cloud and compared it with predictions of cloud-formation models. These cloud-formation models predict a bending of magnetic fields associated with filamentary molecular clouds. We compared the orientation and direction of this field bending with our 3D magnetic-field view of the Perseus cloud. Methods. We used previous line-of-sight and plane-of-sky magnetic field observations as well as Galactic magnetic field models to reconstruct the complete 3D magnetic field vectors and morphology associated with the Perseus cloud. Results. We approximated the 3D magnetic ...
Proceedings of the International Astronomical Union, 2017
We estimate the column density of the Galactic foreground interstellar medium (GFISM) in the dire... more We estimate the column density of the Galactic foreground interstellar medium (GFISM) in the direction of extragalactic sources. All-sky AKARI FIS infrared sky survey data might be used to trace the GFISM with a resolution of 2 arcminutes. The AKARI based GFISM hydrogen column density estimates are compared with similar quantities based on HI 21cm measurements of various resolution and of Planck results. High spatial resolution observations of the GFISM may be important recalculating the physical parameters of gamma-ray burst (GRB) host galaxies using the updated foreground parameters.
Publications of The Korean Astronomical Society, 2017
We have observed ∼60 Weak-line T Tauri stars (WTTSs) toward the Chamaeleon star forming region us... more We have observed ∼60 Weak-line T Tauri stars (WTTSs) toward the Chamaeleon star forming region using the AKARI Far-Infrared Surveyor (FIS) All-Sky maps. We could not detect any significant emission from each source even at the most sensitive WIDES band. Then, we have performed stacking analysis of these WTTSs using the WIDES band images to improve the sensitivity. However, we could not detect any significant emission in the resultant image with a noise level of 0.05 MJy sr −1 , or 3 mJy for a point source. The three-sigma upper limit of 9 mJy leads to the disk dust mass of 0.01 M ⊕. This result suggests that the disks around Chamaeleon WTTSs are already evolved to debris disks.
SPICA joint European/Japanese Workshop, 2009
SPICA will provide the best sensitivity and image quality than ever at 5-210 μm. This will revolu... more SPICA will provide the best sensitivity and image quality than ever at 5-210 μm. This will revolutionize our understanding of exoplanets, protoplanetary disks, debris disks, and Solar system small bodies. This paper summarizes such key sciences with SPICA discussed so far among the Japanese SPICA Science Working Group, stressing on the planetary formation, and exoplanet detection and characterization.
We present a far-infrared all-sky atlas from a sensitive all-sky survey using the Japanese AKARI ... more We present a far-infrared all-sky atlas from a sensitive all-sky survey using the Japanese AKARI satellite. The survey covers > 99 photometric bands centred at 65 μm, 90 μm, 140 μm, and 160 μm with spatial resolutions ranging from 1 to 1.5 arcmin. These data provide crucial information for the investigation and characterisation of the properties of dusty material in the Interstellar Medium (ISM), since significant portion of its energy is emitted between ∼50 and 200 μm. The large-scale distribution of interstellar clouds, their thermal dust temperatures and column densities, can be investigated with the improved spatial resolution compared to earlier all-sky survey observations. In addition to the point source distribution, the large-scale distribution of ISM cirrus emission, and its filamentary structure, are well traced. We have made the first public release of the full-sky data to provide a legacy data set for use by the astronomical community.
We present a new catalog of 118 Ultraluminous Infrared Galaxies (ULIRGs) and one Hyperluminous In... more We present a new catalog of 118 Ultraluminous Infrared Galaxies (ULIRGs) and one Hyperluminous Infrared Galaxy (HLIRG) by crossmatching AKARI all-sky survey with the Sloan Digital Sky Survey Data Release 10 (SDSS DR10) and the Final Data Release of the Two-Degree Field Galaxy Redshift Survey (2dFGRS). 40 of the ULIRGs and one HLIRG are new identifications. We find that ULIRGs are interacting pair galaxies or ongoing/post mergers. This is consistent with the widely accepted view: ULIRGs are major mergers of disk galaxies. We confirm the previously known positive trend between the AGN fraction and IR luminosity. We show that ULIRGs have a large off-set from the 'main sequence' up to z~1; their off-set from the z~2 'main sequence' is relatively smaller. We find a consistent result with the previous studies showing that compared to local star forming SDSS galaxies of similar mass, local ULIRGs have lower oxygen abundances. We for the first time demonstrate that ULIRGs fo...
![Research paper thumbnail of Far-Infrared [C II] Line Survey Observations of the Galactic Plane](https://attachments.academia-assets.com/84351579/thumbnails/1.jpg)
](We present results of our survey observations of the [C II] 158 micron line emission from the Gal... more We present results of our survey observations of the [C II] 158 micron line emission from the Galactic plane using the Balloon-borne Infrared Carbon Explorer (BICE). Our survey covers a wide area (350 deg < l < 25 deg, |b| < 3 deg) with a spatial resolution of 15'. We employed a new observing method called the ``fast spectral scanning'' to make large-scale observations efficiently. Strong [C II] line emission was detected from almost all areas we observed. In the general Galactic plane, the spatial distribution of the [C II] line emission correlates very well with that of far-infrared continuum emission, but diffuse components are more prominent in the [C II] line emission; the I_[CII]/I_FIR ratio is ~0.6 % for diffuse components but is ~0.2 % for compact sources such as active star-forming regions. In the Galactic center region, on the other hand, the distribution of the [C II] line emission is quite different from that of the far-infrared continuum emission, a...
The Astrophysical Journal, 2022
We present 850 μm polarimetric observations toward the Serpens Main molecular cloud obtained usin... more We present 850 μm polarimetric observations toward the Serpens Main molecular cloud obtained using the POL-2 polarimeter on the James Clerk Maxwell Telescope as part of the B-fields In STar-forming Region Observations survey. These observations probe the magnetic field morphology of the Serpens Main molecular cloud on about 6000 au scales, which consists of cores and six filaments with different physical properties such as density and star formation activity. Using the histogram of relative orientation (HRO) technique, we find that magnetic fields are parallel to filaments in less-dense filamentary structures where N H 2 < 0.93 × 10 22 cm−2 (magnetic fields perpendicular to density gradients), while they are perpendicular to filaments (magnetic fields parallel to density gradients) in dense filamentary structures with star formation activity. Moreover, applying the HRO technique to denser core regions, we find that magnetic field orientations change to become perpendicular to den...
The Astrophysical Journal, 2021
Astronomy & Astrophysics, 2021
Context. Molecular filaments and hubs have received special attention recently thanks to new stud... more Context. Molecular filaments and hubs have received special attention recently thanks to new studies showing their key role in star formation. While the (column) density and velocity structures of both filaments and hubs have been carefully studied, their magnetic field (B-field) properties have yet to be characterized. Consequently, the role of B-fields in the formation and evolution of hub-filament systems is not well constrained. Aims. We aim to understand the role of the B-field and its interplay with turbulence and gravity in the dynamical evolution of the NGC 6334 filament network that harbours cluster-forming hubs and high-mass star formation. Methods. We present new observations of the dust polarized emission at 850 μm toward the 2 pc × 10 pc map of NGC 6334 at a spatial resolution of 0.09 pc obtained with the James Clerk Maxwell Telescope (JCMT) as part of the B-field In STar-forming Region Observations (BISTRO) survey. We study the distribution and dispersion of the polari...
Monthly Notices of the Royal Astronomical Society, 2019
We present the first release of the data and compact-source catalogue for the JCMT Large Program ... more We present the first release of the data and compact-source catalogue for the JCMT Large Program SCUBA-2 Continuum Observations of Pre-protostellar Evolution (SCOPE). SCOPE
Publications of the Astronomical Society of Australia, 2018
Measurements in the infrared wavelength domain allow direct assessment of the physical state and ... more Measurements in the infrared wavelength domain allow direct assessment of the physical state and energy balance of cool matter in space, enabling the detailed study of the processes that govern the formation and evolution of stars and planetary systems in galaxies over cosmic time. Previous infrared missions revealed a great deal about the obscured Universe, but were hampered by limited sensitivity.SPICA takes the next step in infrared observational capability by combining a large 2.5-meter diameter telescope, cooled to below 8 K, with instruments employing ultra-sensitive detectors. A combination of passive cooling and mechanical coolers will be used to cool both the telescope and the instruments. With mechanical coolers the mission lifetime is not limited by the supply of cryogen. With the combination of low telescope background and instruments with state-of-the-art detectors SPICA provides a huge advance on the capabilities of previous missions.SPICA instruments offer spectral re...
The Astrophysical Journal, 2018
We present 850 μm imaging polarimetry data of the ρ Oph-A core taken with the Submillimeter Commo... more We present 850 μm imaging polarimetry data of the ρ Oph-A core taken with the Submillimeter Common-User Bolometer Array-2 (SCUBA-2) and its polarimeter (POL-2) as part of our ongoing survey project, B-fields In STar forming RegiOns (BISTRO). The polarization vectors are used to identify the orientation of the magnetic field projected on the plane of the sky at a resolution of 0.01 pc. We identify 10 subregions with distinct polarization fractions and angles in the 0.2 pc ρ Oph-A core; some of them can be part of a coherent magnetic field structure in the ρ Oph region. The results are consistent with previous observations of the brightest regions of ρ Oph-A, where the degrees of polarization are at a level of a few percent, but our data reveal for the first time the magnetic field structures in the fainter regions surrounding the core where the degree of polarization is much higher (>5%). A comparison with previous near-infrared polarimetric data shows that there are several magnetic field components that are consistent at near-infrared and submillimeter wavelengths. Using the Davis-Chandrasekhar-Fermi method, we also derive magnetic field strengths in several subcore regions, which range from approximately 0.2 to 5 mG. We also find a correlation between the magnetic field orientations projected on the sky and the core centroid velocity components.
Publications of the Astronomical Society of Australia, 2017
IR spectroscopy in the range 12–230 μm with the SPace IR telescope for Cosmology and Astrophysics... more IR spectroscopy in the range 12–230 μm with the SPace IR telescope for Cosmology and Astrophysics (SPICA) will reveal the physical processes governing the formation and evolution of galaxies and black holes through cosmic time, bridging the gap between the James Webb Space Telescope and the upcoming Extremely Large Telescopes at shorter wavelengths and the Atacama Large Millimeter Array at longer wavelengths. The SPICA, with its 2.5-m telescope actively cooled to below 8 K, will obtain the first spectroscopic determination, in the mid-IR rest-frame, of both the star-formation rate and black hole accretion rate histories of galaxies, reaching lookback times of 12 Gyr, for large statistically significant samples. Densities, temperatures, radiation fields, and gas-phase metallicities will be measured in dust-obscured galaxies and active galactic nuclei, sampling a large range in mass and luminosity, from faint local dwarf galaxies to luminous quasars in the distant Universe. Active gal...
Astronomy and Astrophysics, 2002
The Far-Infrared Line Mapper (FILM) onboard the Infrared Telescope in Space (IRTS) made a survey ... more The Far-Infrared Line Mapper (FILM) onboard the Infrared Telescope in Space (IRTS) made a survey for the far-infrared [C ii] 158 µm line emission with high sensitivity and moderate spatial resolution. We have found that diffuse [C ii] line emission extends to high Galactic latitude regions. The [C ii] line intensity at |b| ∼ 60 • ranges from 2 × 10 −7 to 1.5 × 10 −6 erg cm −2 s −1 sr −1. Comparisons of the distribution of the [C ii] line emission with those of the H i column density and far-infrared radiation show some correlations, but the [C ii] line emission differs from the far-IR and HI emission at high Galactic latitudes. These differences suggest that the [C ii] line primarily comes from ionized gas in the high-latitude regions. The intensities of the [C ii] line emission on the southern side (b < 0 •) of the Galactic plane are systematically larger than those on the northern side (b > 0 •). We infer from this difference that there is a displacement of the Sun with respect to the center of interstellar medium from which the [C ii] line comes. When an exponential distribution is assumed for the [C ii] emitting gas, it is expected that the Sun is located at the distance of about 17% of the scale height above the center of the gas. This is consistent with the previously reported displacement of the Sun from the Galactic plane.
Astronomy & Astrophysics, 2022
Context. Despite recent observational and theoretical advances in mapping the magnetic fields ass... more Context. Despite recent observational and theoretical advances in mapping the magnetic fields associated with molecular clouds, their three-dimensional (3D) morphology remains unresolved. Multi-wavelength and multi-scale observations will allow us to paint a comprehensive picture of the magnetic fields of these star-forming regions. Aims. We reconstructed the 3D magnetic field morphology associated with the Perseus molecular cloud and compared it with predictions of cloud-formation models. These cloud-formation models predict a bending of magnetic fields associated with filamentary molecular clouds. We compared the orientation and direction of this field bending with our 3D magnetic-field view of the Perseus cloud. Methods. We used previous line-of-sight and plane-of-sky magnetic field observations as well as Galactic magnetic field models to reconstruct the complete 3D magnetic field vectors and morphology associated with the Perseus cloud. Results. We approximated the 3D magnetic ...
Proceedings of the International Astronomical Union, 2017
We estimate the column density of the Galactic foreground interstellar medium (GFISM) in the dire... more We estimate the column density of the Galactic foreground interstellar medium (GFISM) in the direction of extragalactic sources. All-sky AKARI FIS infrared sky survey data might be used to trace the GFISM with a resolution of 2 arcminutes. The AKARI based GFISM hydrogen column density estimates are compared with similar quantities based on HI 21cm measurements of various resolution and of Planck results. High spatial resolution observations of the GFISM may be important recalculating the physical parameters of gamma-ray burst (GRB) host galaxies using the updated foreground parameters.
Publications of The Korean Astronomical Society, 2017
We have observed ∼60 Weak-line T Tauri stars (WTTSs) toward the Chamaeleon star forming region us... more We have observed ∼60 Weak-line T Tauri stars (WTTSs) toward the Chamaeleon star forming region using the AKARI Far-Infrared Surveyor (FIS) All-Sky maps. We could not detect any significant emission from each source even at the most sensitive WIDES band. Then, we have performed stacking analysis of these WTTSs using the WIDES band images to improve the sensitivity. However, we could not detect any significant emission in the resultant image with a noise level of 0.05 MJy sr −1 , or 3 mJy for a point source. The three-sigma upper limit of 9 mJy leads to the disk dust mass of 0.01 M ⊕. This result suggests that the disks around Chamaeleon WTTSs are already evolved to debris disks.
SPICA joint European/Japanese Workshop, 2009
SPICA will provide the best sensitivity and image quality than ever at 5-210 μm. This will revolu... more SPICA will provide the best sensitivity and image quality than ever at 5-210 μm. This will revolutionize our understanding of exoplanets, protoplanetary disks, debris disks, and Solar system small bodies. This paper summarizes such key sciences with SPICA discussed so far among the Japanese SPICA Science Working Group, stressing on the planetary formation, and exoplanet detection and characterization.
We present a far-infrared all-sky atlas from a sensitive all-sky survey using the Japanese AKARI ... more We present a far-infrared all-sky atlas from a sensitive all-sky survey using the Japanese AKARI satellite. The survey covers > 99 photometric bands centred at 65 μm, 90 μm, 140 μm, and 160 μm with spatial resolutions ranging from 1 to 1.5 arcmin. These data provide crucial information for the investigation and characterisation of the properties of dusty material in the Interstellar Medium (ISM), since significant portion of its energy is emitted between ∼50 and 200 μm. The large-scale distribution of interstellar clouds, their thermal dust temperatures and column densities, can be investigated with the improved spatial resolution compared to earlier all-sky survey observations. In addition to the point source distribution, the large-scale distribution of ISM cirrus emission, and its filamentary structure, are well traced. We have made the first public release of the full-sky data to provide a legacy data set for use by the astronomical community.
We present a new catalog of 118 Ultraluminous Infrared Galaxies (ULIRGs) and one Hyperluminous In... more We present a new catalog of 118 Ultraluminous Infrared Galaxies (ULIRGs) and one Hyperluminous Infrared Galaxy (HLIRG) by crossmatching AKARI all-sky survey with the Sloan Digital Sky Survey Data Release 10 (SDSS DR10) and the Final Data Release of the Two-Degree Field Galaxy Redshift Survey (2dFGRS). 40 of the ULIRGs and one HLIRG are new identifications. We find that ULIRGs are interacting pair galaxies or ongoing/post mergers. This is consistent with the widely accepted view: ULIRGs are major mergers of disk galaxies. We confirm the previously known positive trend between the AGN fraction and IR luminosity. We show that ULIRGs have a large off-set from the 'main sequence' up to z~1; their off-set from the z~2 'main sequence' is relatively smaller. We find a consistent result with the previous studies showing that compared to local star forming SDSS galaxies of similar mass, local ULIRGs have lower oxygen abundances. We for the first time demonstrate that ULIRGs fo...
We present results of our survey observations of the [C II] 158 micron line emission from the Gal... more We present results of our survey observations of the [C II] 158 micron line emission from the Galactic plane using the Balloon-borne Infrared Carbon Explorer (BICE). Our survey covers a wide area (350 deg < l < 25 deg, |b| < 3 deg) with a spatial resolution of 15'. We employed a new observing method called the ``fast spectral scanning'' to make large-scale observations efficiently. Strong [C II] line emission was detected from almost all areas we observed. In the general Galactic plane, the spatial distribution of the [C II] line emission correlates very well with that of far-infrared continuum emission, but diffuse components are more prominent in the [C II] line emission; the I_[CII]/I_FIR ratio is ~0.6 % for diffuse components but is ~0.2 % for compact sources such as active star-forming regions. In the Galactic center region, on the other hand, the distribution of the [C II] line emission is quite different from that of the far-infrared continuum emission, a...