H2O Emission Lines Research Articles

Accretion and Outflow in Orion-KL Source I

We present Atacama Large Millimeter/submillimeter Array observations of SiO, SiS, H2O, NaCl, and SO line emission at ∼30–50 mas resolution. These images map the molecular outflow and disk of Orion Source I (SrcI) on ∼12–20 au scales. Our observations show that the flow of material around SrcI creates a turbulent boundary layer in the outflow from SrcI, which may dissipate angular momentum in the rotating molecular outflow into the surrounding medium. Additionally, the data suggest that the proper motion of SrcI may have a significant effect on the structure and evolution of SrcI and its molecular outflow. As the motion of SrcI funnels material between the disk and the outflow, some material may be entrained into the outflow and accrete onto the disk, creating shocks that excite the NaCl close to the disk surface.

JWST MIRI MRS Images of Disk Winds, Water, and CO in an Edge-on Protoplanetary Disk

We present JWST MIRI MRS observations of the edge-on protoplanetary disk around the young subsolar-mass star Tau 042021, acquired as part of the Cycle 1 GO program “Mapping Inclined Disk Astrochemical Signatures.” These data resolve the mid-IR spatial distributions of H2, revealing X-shaped emission extending to ∼200 au above the disk midplane with a semiopening angle of 35° ± 5°. We do not velocity-resolve the gas in the spectral images, but the measured semiopening angle of the H2 is consistent with a magnetohydrodynamic wind origin. A collimated, bipolar jet is seen in forbidden emission lines from [Ne ii], [Ne iii], [Ni ii], [Fe ii], [Ar ii], and [S iii]. Extended H2O and CO emission lines are also detected, reaching diameters of ∼90 and 190 au, respectively. Hot molecular emission is not expected at such radii, and we interpret its extended spatial distribution as scattering of inner disk molecular emission by dust grains in the outer disk surface. H i recombination lines, characteristic of inner disk accretion shocks, are similarly extended and are likely also scattered light from the innermost star–disk interface. Finally, we detect extended polycyclic aromatic hydrocarbon (PAH) emission at 11.3 μm cospatial with the scattered-light continuum, making this the first low-mass T Tauri star around which extended PAHs have been confirmed, to our knowledge. MIRI MRS line images of edge-on disks provide an unprecedented window into the outflow, accretion, and scattering processes within protoplanetary disks, allowing us to constrain the disk lifetimes and accretion and mass-loss mechanisms.

Diverse Molecular Gas Excitations in Quasar Host Galaxies at z ∼ 6

We present observations using the Northern Extended Millimetre Array (NOEMA) of CO and H2O emission lines and the underlying dust continuum in two quasars at z ∼ 6, i.e., P215−16 at z = 5.78 and J1429+5447 at z = 6.18. Notably, among all published CO spectral line energy distributions (SLEDs) of quasars at z ∼ 6, the two systems reveal the highest and the lowest CO levels of excitation, respectively. Our radiative transfer modeling of the CO SLED of P215−16 suggests that the molecular gas heated by active galactic nuclei could be a plausible origin for the high CO excitation. For J1429+5447, we obtain the first well-sampled CO SLED (from transitions from 2−1 to 10−9) of a radio-loud quasar at z ≳ 6. Analysis of the CO SLED suggests that a component from a single photodissociation region could explain the CO excitation in the radio-loud quasar J1429+5447. This work highlights the utility of the CO SLED in uncovering the properties of the interstellar medium in these young quasar–starburst systems at the highest redshift. The diversity of the CO SLEDs reveals the complexities in gas conditions and excitation mechanisms at their early evolutionary stage.

Z-GAL: A NOEMA spectroscopic redshift survey of brightHerschelgalaxies

Using the IRAM NOrthern Extended Millimetre Array (NOEMA), we conducted a Large Programme (z-GAL) to measure redshifts for 126 bright galaxies detected in theHerschelAstrophysical Large Area Survey (H-ATLAS), the HerMES Large Mode Survey (HeLMS), and theHerschelStripe 82 (HerS) Survey. We report reliable spectroscopic redshifts for a total of 124 of theHerschel-selected galaxies. The redshifts are estimated from scans of the 3 and 2-mm bands (and, for one source, the 1-mm band), covering up to 31 GHz in each band, and are based on the detection of at least two emission lines. Together with the Pilot Programme, where 11 sources had their spectroscopic redshifts measured, our survey has derived precise redshifts for 135 brightHerschel-selected galaxies, making it the largest sample of high-zgalaxies with robust redshifts to date. Most emission lines detected are from12CO (mainly fromJ = 2–1 to 5–4), with some sources seen in [CI] and H2O emission lines. The spectroscopic redshifts are in the range 0.8 < z < 6.55 with a median value ofz = 2.56 ± 0.10, centred on the peak epoch of galaxy formation. The linewidths of the sources are large, with a mean value for the full width at half maximum ΔVof 590 ± 25 km s−1and with 35% of the sources having widths of 700 km s−1 < ΔV < 1800 km s−1. Most of the sources are unresolved or barely resolved on scales of ∼2 to 3″ (or linear sizes of ∼15 − 25 kpc, unlensed). Some fields reveal double or multiple sources in line emission and the underlying dust continuum and, in some cases, sources at different redshifts. Taking these sources into account, there are, in total, 165 individual sources with robust spectroscopic redshifts, including lensed galaxies, binary systems, and over-densities. This paper presents an overview of thez-GAL survey and provides the observed properties of the emission lines, the derived spectroscopic redshifts, and a catalogue of the entire sample. The catalogue includes, for each source, the combined continuum and emission lines’ maps together with the spectra for each of the detected emission lines. The data presented here will serve as a foundation for the otherz-GAL papers in this series reporting on the dust emission, the molecular and atomic gas properties, and a detailed analysis of the nature of the sources. Comparisons are made with other spectroscopic surveys of high-zgalaxies and future prospects, including dedicated follow-up observations based on these redshift measurements, are outlined.

High-resolution emission spectroscopy retrievals of MASCARA-1b with CRIRES+: strong detections of CO, H2O, and Fe emission lines and a C/O consistent with solar

ABSTRACT The characterization of exoplanet atmospheres has proven to be successful using high-resolution spectroscopy. Phase curve observations of hot/ultra-hot Jupiters can reveal their compositions and thermal structures, thereby allowing the detection of molecules and atoms in the planetary atmosphere using the cross-correlation technique. We present pre-eclipse observations of the ultra-hot Jupiter, MASCARA-1b, observed with the recently upgraded CRIRES+ high-resolution infrared spectrograph at the VLT. We report a detection of Fe (≈ 8.3σ) in the K-band and confirm previous detections of CO (>15σ) and H2O (>10σ) in the day-side atmosphere of MASCARA-1b. Using a Bayesian inference framework, we retrieve the abundances of the detected species and constrain planetary orbital velocities, T–P profiles, and the carbon-to-oxygen ratio (C/O). A free retrieval results in an elevated CO abundance ($\log _{10}(\chi _{\rm {{}^{12}CO}}) = -2.85^{+0.57}_{-0.69}$), leading to a supersolar C/O ratio. More realistically, allowing for vertically-varying chemistry in the atmosphere by incorporating a chemical-equilibrium model results in a C/O of $0.68^{+0.12}_{-0.22}$ and a metallicity of $[\rm M/H] = 0.62^{+0.28}_{-0.55}$, both consistent with solar values. Finally, we also report a slight offset of the Fe feature in both Kp and vsys that could be a signature of atmospheric dynamics. Due to the 3D structure of exoplanet atmospheres and the exclusion of time/phase dependence in our 1D forward models, further follow-up observations and analysis are required to confirm or refute this result.

The Way of Water: ALMA Resolves H2O Emission Lines in a Strongly Lensed Dusty Star-forming Galaxy at z ∼ 3.1

We report Atacama Large Millimeter/submillimeter Array (ALMA) high-resolution (≲0.3″) observations of water emission lines p-H2O(202 − 111), o-H2O(321 − 312), p-H2O(422 − 413), in the strongly lensed galaxy HATLASJ113526.2-01460 at redshift z ∼3.1. From the lensing-reconstructed maps of water emission and line profiles, we infer the general physical properties of the interstellar medium (ISM) in the molecular clouds where the lines arise. We find that the water vapor lines o-H2O(321 − 312), p-H2O(422 − 413) are mainly excited by far-infrared (FIR) pumping from dust radiation in a warm and dense environment, with dust temperatures ranging from 70 to ∼100 K, as suggested by the line ratios. The p-H2O(202 − 111) line, instead, is excited by a complex interplay between FIR pumping and collisional excitation in the dense core of the star-forming region. This scenario is also supported by the detection of the medium-level excitation of CO resulting in the line emission CO (J = 8–7). Thanks to the unprecedented high resolution offered by the combination of ALMA capabilities and gravitational lensing, we discern the different phases of the ISM and locate the hot molecular clouds into a physical scale of ∼500 pc. We discuss the possibility of J1135 hosting an active galactic nucleus in its accretion phase. Finally, we determine the relation between the water emission lines and the total IR luminosity of J1135, as well as the star formation rate as a function of water emission intensities, comparing the outcomes to local and high-z galactic samples from the literature.

Bright extragalactic ALMA redshift survey (BEARS) III: detailed study of emission lines from 71Herscheltargets

ABSTRACTWe analyse the molecular and atomic emission lines of 71 bright Herschel-selected galaxies between redshifts 1.4 and 4.6 detected by the Atacama Large Millimeter/submillimeter Array. These lines include a total of 156 CO, [C i], and H2O emission lines. For 46 galaxies, we detect two transitions of CO lines, and for these galaxies we find gas properties similar to those of other dusty star-forming galaxy (DSFG) samples. A comparison to photodissociation models suggests that most of Herschel-selected galaxies have similar interstellar medium conditions as local infrared-luminous galaxies and high-redshift DSFGs, although with denser gas and more intense far-ultraviolet radiation fields than normal star-forming galaxies. The line luminosities agree with the luminosity scaling relations across five orders of magnitude, although the star formation and gas surface density distributions (i.e. Schmidt–Kennicutt relation) suggest a different star formation phase in our galaxies (and other DSFGs) compared to local and low-redshift gas-rich, normal star-forming systems. The gas-to-dust ratios of these galaxies are similar to Milky Way values, with no apparent redshift evolution. Four of 46 sources appear to have CO line ratios in excess of the expected maximum (thermalized) profile, suggesting a rare phase in the evolution of DSFGs. Finally, we create a deep stacked spectrum over a wide rest-frame frequency (220–890 GHz) that reveals faint transitions from HCN and CH, in line with previous stacking experiments.

The Mid-infrared Molecular Inventory toward Orion IRc2

We present the first high spectral resolution mid-infrared survey in the Orion BN/KL region, covering 7.2–28.3 μm. With SOFIA/EXES, we target the enigmatic source Orion IRc2. While this is in the most prolifically studied massive star-forming region, longer wavelengths and molecular emission lines dominated previous spectral surveys. The mid-infrared observations in this work access different components and molecular species in unprecedented detail. We unambiguously identify two new kinematic components, both chemically rich with multiple molecular absorption lines. The “blue clump” has v LSR = −7.1 ± 0.7 km s−1, and the “red clump” has 1.4 ± 0.5 km s−1. While the blue and red clumps have similar temperatures and line widths, molecular species in the blue clump have higher column densities. They are both likely linked to pure rotational H2 emission also covered by this survey. This work provides evidence for the scenario that the blue and red clumps are distinct components unrelated to the classic components in the Orion BN/KL region. Comparison to spectroscopic surveys toward other infrared targets in the region show that the blue clump is clearly extended. We analyze, compare, and present in-depth findings on the physical conditions of C2H2, 13CCH2, CH4, CS, H2O, HCN, , HNC, NH3, and SO2 absorption lines and an H2 emission line associated with the blue and red clumps. We also provide limited analysis of H2O and SiO molecular emission lines toward Orion IRc2 and the atomic forbidden transitions [Fe ii], [S i], [S iii], and [Ne ii].

Dissecting the central regions of OH 231.8+4.2 with ALMA: A salty rotating disk at the base of a young bipolar outflow

We present a set of Atacama Large Millimeter/submillimeter Array (ALMA) continuum and molecular line emission maps at ~1 mm wavelengths of OH 231.8+4.2. This is a well studied bipolar nebula around an asymptotic giant branch (AGB) star that is key in investigations of the origin of the remarkable changes in nebular morphology and kinematics during the short transition from the AGB to the planetary nebula (PN) phase. The excellent angular resolution of our maps (~20 mas ≈ 30 au) allows us to scrutinize the central nebular regions of OH 231.8+4.2, which hold the clues to unravel how this iconic object assembled its complex nebular architecture. We report, for the first time for this object and others of its kind (i.e.,pre-PN with massive bipolar outflows), the discovery of a rotating circumbinary disk selectively traced by NaCl, KCl, and H2O emission lines. This represents the first detection of KCl in an oxygen-rich (O-rich) AGB circumstellar envelope (CSE). The rotating disk, of a radius of ~30 au, lies at the base of a young bipolar wind traced by SiO and SiS emission (referred to as the SS-outflow), which also presents signs of rotation at its base. The NaCl equatorial structure is characterised by a mean rotation velocity of Vrot ~ 4 km s−1 and extremely low expansion speeds, Vexp ~ 3 km s−1. The SS-outflow has predominantly expansive kinematics, characterized by a constant radial velocity gradient of ~65km s−1 arcsec−1 at its base. Beyond r ~ 350 au, the gas in the SS-outflow continues its radial flow at a constant terminal speed of Vexp ~ 16 km s−1. Our continuum maps reveal a spatially resolved dusty disk-like structure perpendicular to the SS-outflow, with the NaCl, KCl, and H2O emission arising from the surface layers of the disk. Within the disk, we also identify an unresolved point continuum source, which likely represents the central Mira-type star QX Pup enshrouded by a ~3 R* component of hot, (~1400 K) freshly formed dust. The point source is slightly off-center (by ~6.6mas) from the disk centroid, enabling us to place the first constraints on the orbital separation and period of the central binary system, namely: a ~ 20 au and Porb ~ 55 yr, respectively. The formation of the dense rotating equatorial structure at the core of OH 231.8+4.2 is most likely the result of wind Roche lobe overflow (WRLOF) mass transfer from QX Pup to the main-sequence companion; this scenario is greatly favored by the extremely low AGB wind velocity, the relatively high mass of the companion, and the comparable sizes of the dust condensation radius and the Roche lobe radius deduced from our data. The Vexp∝ r kinematic pattern observed within the r ≲ 350 au inner regions of the SS-outflow suggest that we are witnessing the active acceleration of the companion-perturbed wind from QX Pup as it flows through low-density polar regions.

A First Look at CRIRES+: Performance Assessment and Exoplanet Spectroscopy

High-resolution spectroscopy has proven to be a powerful avenue for atmospheric remote sensing of exoplanets. Recently, ESO commissioned the CRIRES+ high-resolution infrared spectrograph at the Very Large Telescope. CRIRES+ is a cross-dispersed spectrograph with high throughput and wide wavelength coverage across the near-infrared (0.95–5.3 μm), designed to be particularly suited for atmospheric characterization of exoplanets. In this work, we report early insights into the performance of CRIRES+ for exoplanet spectroscopy and conduct a detailed assessment of the data reduction procedure. Because of the novelty of the instrument, we perform two independent data reduction strategies using the official CR2RES pipeline and our new custom-built ExoRES pipeline. Using science verification observations we find that the spectral resolving power of CRIRES+ can reach R ≳ 100,000 for optimal observing conditions. Similarly, we find the signal-to-noise ratio (S/N) to be consistent with expected and empirical estimates for the observations considered. As a case study, we perform the first application of CRIRES+ to the atmospheric characterization of an exoplanet—the ultrahot Jupiter MASCARA-1 b. We detect CO and H2O in the atmosphere of MASCARA-1 b at a S/N of 12.9 and 5.3, respectively, and a temperature inversion revealed through the CO and H2O emission lines, the first for an exoplanet. We find a combined S/N of 13.8 for CO and H2O together, with a preference for lower H2O abundance compared to CO. Our findings demonstrate the scientific potential of CRIRES+ and highlight the excellent opportunity for high-resolution atmospheric spectroscopy of diverse exoplanets.

Water in star-forming regions: physics and chemistry from clouds to disks as probed by Herschel spectroscopy

Water in star-forming regions: physics and chemistry from clouds to disks as probed by <i>Herschel</i> spectroscopy

Close-up view of a luminous star-forming galaxy at z = 2.95

Exploiting the sensitivity of the IRAM NOrthern Extended Millimeter Array (NOEMA) and its ability to process large instantaneous bandwidths, we have studied the morphology and other properties of the molecular gas and dust in the star forming galaxy, H-ATLAS J131611.5+281219 (HerBS-89a), at z = 2.95. High angular resolution (0.″3) images reveal a partial 1.″0 diameter Einstein ring in the dust continuum emission and the molecular emission lines of 12CO(9−8) and H2O(202 − 111). Together with lower angular resolution (0.″6) images, we report the detection of a series of molecular lines including the three fundamental transitions of the molecular ion OH+, namely (11 − 01), (12 − 01), and (10 − 01), seen in absorption; the molecular ion CH+(1 − 0) seen in absorption, and tentatively in emission; two transitions of amidogen (NH2), namely (202 − 111) and (220 − 211) seen in emission; and HCN(11 − 10) and/or NH(12 − 01) seen in absorption. The NOEMA data are complemented with Very Large Array data tracing the 12CO(1 − 0) emission line, which provides a measurement of the total mass of molecular gas and an anchor for a CO excitation analysis. In addition, we present Hubble Space Telescope imaging that reveals the foreground lensing galaxy in the near-infrared (1.15 μm). Together with photometric data from the Gran Telescopio Canarias, we derive a photometric redshift of zphot = 0.9−0.5+0.3 for the foreground lensing galaxy. Modeling the lensing of HerBS-89a, we reconstruct the dust continuum (magnified by a factor μ ≃ 5.0) and molecular emission lines (magnified by μ ∼ 4 − 5) in the source plane, which probe scales of ∼0.″1 (or 800 pc). The 12CO(9 − 8) and H2O(202 − 111) emission lines have comparable spatial and kinematic distributions; the source-plane reconstructions do not clearly distinguish between a one-component and a two-component scenario, but the latter, which reveals two compact rotating components with sizes of ≈1 kpc that are likely merging, more naturally accounts for the broad line widths observed in HerBS-89a. In the core of HerBS-89a, very dense gas with nH2 ∼ 107 − 9 cm−3 is revealed by the NH2 emission lines and the possible HCN(11 − 10) absorption line. HerBS-89a is a powerful star forming galaxy with a molecular gas mass of Mmol = (2.1 ± 0.4) × 1011 M⊙, an infrared luminosity of LIR = (4.6 ± 0.4) × 1012 L⊙, and a dust mass of Mdust = (2.6 ± 0.2) × 109 M⊙, yielding a dust-to-gas ratio δGDR ≈ 80. We derive a star formation rate SFR = 614 ± 59 M⊙ yr−1 and a depletion timescale τdepl = (3.4 ± 1.0) × 108 years. The OH+ and CH+ absorption lines, which trace low (∼100 cm−3) density molecular gas, all have their main velocity component red-shifted by ΔV ∼ 100 km s−1 relative to the global CO reservoir. We argue that these absorption lines trace a rare example of gas inflow toward the center of a galaxy, indicating that HerBS-89a is accreting gas from its surroundings.

Detection of H2O and OH+ in z &gt; 3 hot dust-obscured galaxies

Aims. In this paper we present the detection of H2O and OH+ emission in z &gt; 3 hot dust-obscured galaxies (Hot DOGs). Methods. Using ALMA Band-6 observations of two Hot DOGs, we detected H2O(202 − 111) in W0149+2350, and H2O(312 − 303) and the multiplet OH+(11 − 01) in W0410−0913. These detections were serendipitous, falling within the side-bands of Band-6 observations aimed to study CO(9−8) in these Hot DOGs. Results. We find that both sources have luminous H2O emission with line luminosities of LH2O(202 − 111) &gt; 2.2 × 108 L⊙ and LH2O(312 − 303) = 8.7 × 108 L⊙ for W0149+2350 and W0410−0913, respectively. The H2O line profiles are similar to those seen for the neighbouring CO(9–8) line, with line widths of full width at half maximum (FWHM) ∼800−1000 km s−1. However, the H2O emission seems to be more compact than the CO(9−8). OH+(11 − 01) is detected in emission for W0410−0913, with a FWHM = 1000 km s−1 and a line luminosity of LOH+(11 − 01) = 6.92 × 108 L⊙. The ratio of the observed H2O line luminosity over the IR luminosity, for both Hot DOGs, is consistent with previously observed star-forming galaxies and active galactic nuclei (AGN). The H2O/CO line ratio of both Hot DOGs and the OH+/H2O line ratio of W0410−0913 are comparable to those of luminous AGN found in the literature. Conclusions. The bright H2O(202 − 111), and H2O(312 − 303) emission lines are likely due to the combined high star formation levels and luminous AGN in these sources. The presence of OH+ in emission, and the agreement of the observed line ratios of the Hot DOGs with luminous AGN in the literature, would suggest that the AGN emission is dominating the radiative output of these galaxies. However, follow-up multi-transition observations are needed to better constrain the properties of these systems.

ALMA (finally!) discloses a rotating disk+bipolar wind system at the centre of the wind-prominent pPN OH 231.8+4.2

AbstractWe present interferometric continuum and molecular line emission maps obtained with the Atacama Large Millimeter/submillimeter Array (ALMA) of OH231.8+4.2, a well studied bipolar nebula around an asymptotic giant branch (AGB) star that is key to understand the remarkable changes in nebular morphology and kinematics during the short transition from the AGB to the Planetary Nebula (PN) phase. The excellent angular resolution of our maps (∼20 mas ∼30 AU) allows us to scrutinize the central nebular regions of OH231.8+4.2, which hold the clues to understanding how this iconic object assembled its complex nebular architecture. We report, for the first time in this object and others of its kind (i.e. pre-PNe with massive bipolar outflows), the discovery of a rotating circumbinary disk of radius ∼30 AU traced by NaCl, KCl, and H2O emission lines. The disk lies at the base of a young bipolar wind with signs of rotation as well. A compact spatially resolved dust disk is found perpendicular to the bipolar outflow. We also identify a point-like continuum source, which likely represents the central Mira star enshrouded by a ∼3 R* shell or disk of hot (∼1400 K) freshly formed dust. The point source is slightly off-centre from the disk centroid, enabling us for the first time to place constraints to the orbital separation of the central binary system.

Monitoring of the evolution of H2O vapor in the stratosphere of Jupiter over an 18-yr period with the Odin space telescope

Context. The comet Shoemaker-Levy 9 impacted Jupiter in July 1994, leaving its stratosphere with several new species, with water vapor (H2O) among them. Aims. With the aid of a photochemical model, H2O can be used as a dynamical tracer in the Jovian stratosphere. In this paper, we aim to constrain the vertical eddy diffusion (Kzz) at levels where H2O is present. Methods. We monitored the H2O disk-averaged emission at 556.936 GHz with the space telescope between 2002 and 2019, covering nearly two decades. We analyzed the data with a combination of 1D photochemical and radiative transfer models to constrain the vertical eddy diffusion in the stratosphere of Jupiter. Results. Odin observations show us that the emission of H2O has an almost linear decrease of about 40% between 2002 and 2019. We can only reproduce our time series if we increase the magnitude of Kzz in the pressure range where H2O diffuses downward from 2002 to 2019, that is, from ~0.2 mbar to ~5 mbar. However, this modified Kzz is incompatible with hydrocarbon observations. We find that even if an allowance is made for the initially large abundances of H2O and CO at the impact latitudes, the photochemical conversion of H2O to CO2 is not sufficient to explain the progressive decline of the H2O line emission, which is suggestive of additional loss mechanisms. Conclusions. The Kzz we derived from the Odin observations of H2O can only be viewed as an upper limit in the ~0.2 mbar to ~5 mbar pressure range. The incompatibility between the interpretations made from H2O and hydrocarbon observations probably results from 1D modeling limitations. Meridional variability of H2O, most probably at auroral latitudes, would need to be assessed and compared with that of hydrocarbons to quantify the role of auroral chemistry in the temporal evolution of the H2O abundance since the SL9 impacts. Modeling the temporal evolution of SL9 species with a 2D model would naturally be the next step in this area of study.

Low Water Outgassing from (24) Themis and (65) Cybele: 3.1 μm Near-IR Spectral Implications

Abstract Asteroids (24) Themis and (65) Cybele have an absorption feature at 3.1 μm reported to be directly linked to surface water ice. We searched for water vapor escaping from these asteroids with the Herschel Space Observatory Heterodyne Instrument for the Far Infrared. While no H2O line emission was detected, we obtain sensitive 3σ water production rate upper limits of Q(H2O) &lt; 4.1 × 1026 molecules s−1 for Themis and Q(H2O) &lt; 7.6 × 1026 molecules s−1 for Cybele. Using a thermophysical model, we merge data from the Subaru/Cooled Mid-Infrared Camera and Spectrometer and the Herschel/Spectral and Photometric Imaging Receiver with the contents of a multi-observatory database to derive new radiometric properties for these two asteroids. For Themis, we find a thermal inertia J m−2 s−1/2 K−1, a diameter km, and a geometric V-band albedo p V = 0.07 ± 0.01. For Cybele, we obtain a thermal inertia J m−2 s−1/2 K−1, a diameter 282 ± 9 km, and an albedo p V = 0.042 ± 0.005. Using all inputs, we estimate that water ice intimately mixed with the asteroids’ dark surface material would cover &lt;0.0017% (for Themis) and &lt;0.0033% (for Cybele) of their surfaces, while an areal mixture with very clean ice (Bond albedo 0.8 for Themis and 0.7 for Cybele) would cover &lt;2.2% (for Themis) and &lt;1.5% (for Cybele) of their surfaces. While surface (and subsurface) water ice may exist in small localized amounts on both asteroids, it is not the reason for the observed 3.1 μm absorption feature.

An Unusually Powerful Water-Maser Flare in the Galactic Source W49N

The most powerful flare ever registered in the Galactic water-maser source W49N has been detected in long-term monitoring data in the 616–523 transition with line frequency f = 22.235 GHz carried out on the 22-m Simeiz, 32-m Torun, 100-m Effelsberg, and 32-m Medicina radio telescopes, beginning in September 2017 and continuing in 2018. Some stages of the flare were monitored daily. Detailed variations of the source spectral flux density with time have been obtained. At the flare maximum, the flux exceeded P ≈ 8 × 104 Jy, and this was record highest flux registered over the entire history of observations of this source. Important conclusions related to details of the mechanism for the H2O line emission have been drawn. An exponential increase in the flare flux density was detected during both the rise and decline of the flare. The data obtained indicate that the maser is unsaturated, and remained in this state up to the maximum observed flux densities. Additional support for the idea that the maser is unsaturated is the shape of the dependence of the line width on the flux. The characteristics of the variations of the spectral flux density are probably associated with a sharp increase in the density of the medium and the photon flux that led to an increase in the temperature from an initial level of 10–40 K to hundreds of Kelvins. Interferometric maps of the object during the increase in the spectral flux density of the flare have been obtained. A possible mechanism for the primary energy release in W49N is considered.

Imaging the molecular interstellar medium in a gravitationally lensed star-forming galaxy at z = 5.7

Aims. We present and study spatially resolved imaging obtained with the Atacama Large Millimeter/submillimeter Array (ALMA) of multiple 12CO(J = 6 − 5, 8−7, and 9−8) and two H2O(202−111 and 211−202) emission lines and cold dust continuum toward the gravitationally lensed dusty star-forming galaxy SPT 0346-52 at z = 5.656. Methods. Using a visibility-domain source-plane reconstruction we probe the structure and dynamics of the different components of the interstellar medium (ISM) in this galaxy down to scales of 1 kpc in the source plane. Results. Measurements of the intrinsic sizes of the different CO emission lines indicate that the higher J transitions trace more compact regions in the galaxy. Similarly, we find smaller dust continuum intrinsic sizes with decreasing wavelength, based on observations at rest frame 130, 300, and 450 μm. The source shows significant velocity structure, and clear asymmetry where an elongated structure is observed in the source plane with significant variations in their reconstructed sizes. This could be attributed to a compact merger or turbulent disk rotation. The differences in velocity structure through the different line tracers, however, hint at the former scenario in agreement with previous [CII] line imaging results. Measurements of the CO line ratios and magnifications yield significant variations as a function of velocity, suggesting that modeling of the ISM using integrated values could be misinterpreted. Modeling of the ISM in SPT 0346-52 based on delensed fluxes indicates a highly dense and warm medium, qualitatively similar to that observed in high-redshift quasar hosts.

Modelling mid-infrared molecular emission lines from T Tauri stars

We introduce a new modelling framework including the Fast Line Tracer (FLITS) to simulate infrared line emission spectra from protoplanetary discs. This paper focusses on the mid-IR spectral region between 9.7 and 40 μm for T Tauri stars. The generated spectra contain several tens of thousands of molecular emission lines of H2O, OH, CO, CO2, HCN, C2H2, H2, and a few other molecules, as well as the forbidden atomic emission lines of S I, S II, S III, Si II, Fe II, Ne II, Ne III, Ar II, and Ar III. In contrast to previously published works, we do not treat the abundances of the molecules nor the temperature in the disc as free parameters, but use the complex results of detailed 2D PRODIMO disc models concerning gas and dust temperature structure, and molecular concentrations. FLITS computes the line emission spectra by ray tracing in an efficient, fast, and reliable way. The results are broadly consistent with R = 600 Spitzer/IRS observational data of T Tauri stars concerning line strengths, colour, and line ratios. In order to achieve that agreement, however, we need to assume either a high gas/dust mass ratio of order 1000, or the presence of illuminated disc walls at distances of a few au, for example, due to disc–planet interactions. These walls are irradiated and heated by the star which causes the molecules to emit strongly in the mid-IR. The molecules in the walls cannot be photodissociated easily by UV because of the large densities in the walls favouring their re-formation. Most observable molecular emission lines are found to be optically thick. An abundance analysis is hence not straightforward, and the results of simple slab models concerning molecular column densities can be misleading. We find that the difference between gas and dust temperatures in the disc surface is important for the line formation. The mid-IR emission features of different molecules probe the gas temperature at different depths in the disc, along the following sequence: OH (highest)–CO–H2O and CO2–HCN–C2H2 (deepest), just where these molecules start to become abundant. We briefly discuss the effects of C/O ratio and choice of chemical rate network on these results. Our analysis offers new ways to infer the chemical and temperature structure of T Tauri discs from future James Webb Space Telescope (JWST)/MIRI observations, and to possibly detect secondary illuminated disc walls based on their specific mid-IR molecular signature.

The Volatile Composition of Comet C/2017 E4 (Lovejoy) before its Disruption, as Revealed by High-resolution Infrared Spectroscopy with iSHELL at the NASA/IRTF

Abstract In 2017 April, we acquired comprehensive high-resolution spectra of newly discovered comet C/2017 E4 (Lovejoy) as it approached perihelion, and before its disintegration. We detected many cometary emission lines in the range (2.8–5.3) μm, in four customized instrument settings (L1-c, L3, Lp1-c, and M1) of iSHELL—the new near-IR high-resolution immersion echelle spectrograph at NASA/IRTF (Maunakea, Hawaii). We identified 12 molecular species: nine primary volatiles (H2O, HCN, NH3, CO, C2H2, C2H6, CH4, CH3OH, H2CO) and three product species (CN, NH2, OH). We detected 85 H2O emission lines from 12 water vibrational bands across L1-c and M1 settings. The many detected water emission lines enabled retrieval of accurate measures for ortho- and para-H2O independently, thereby reducing systematic uncertainty in the derived ortho–para ratio and nuclear spin temperature. Excitation analyses and emission profile analyses were performed for all species, and molecular abundance ratios relative to water are compared with values found for other Oort Cloud comets in our infrared database. Abundance ratios are consistent for most species, with the exception of underabundant methanol and overabundant ammonia in E4.