Cold CO Research Articles

IGRINS SPECTROSCOPY OF CLASS I SOURCES: IRAS 03445+3242 AND IRAS 04239+2436

ABSTRACT We have detected molecular and atomic line emission from the hot and warm disks of two Class I sources, IRAS 03445+3242 and IRAS 04239+2436, using the high-resolution Immersion GRating INfrared Spectrograph (IGRINS). CO overtone band transitions and near-IR lines of Na i and Ca i, all in emission, trace the hot inner disk, while CO rovibrational absorption spectra of the first overtone transition trace the warm gas within the inner few AU of the disk. The emission-line profiles for both sources show evidence for Keplerian disks. A thin Keplerian disk with power-law temperature and column density profiles with a projected rotational velocity of ∼60–75 km s−1 and a gas temperature of ∼3500 K at the innermost annulus can reproduce the CO overtone band emission. Na i and Ca i emission lines also arise from this disk, but they show complicated line features possibly affected by photospheric absorption lines. Multi-epoch observations show asymmetric variations of the line profiles on one-year (CO overtone bandhead and atomic lines for IRAS 03445+3242) or on one-day (atomic lines for IRAS 04239+2436) timescales, implying non-axisymmetric features in disks. The narrow CO rovibrational absorption spectra (v = 0 → 2) indicate that both warm (>150 K) and cold (∼20–30 K) CO gas are present along the line of sight to the inner disk. This study demonstrates the power of IGRINS as a tool for studies of the sub-AU-scale hot and AU-scale warm protoplanetary disks with its simultaneous coverage of the full H and K bands with high spectral resolution (R = 45,000) allowing many aspects of the sources to be investigated at once.

Erratum: Alignment-assisted field-free orientation of rotationally cold CO molecules [Phys. Rev. A90, 013419 (2014)

Erratum: Alignment-assisted field-free orientation of rotationally cold CO molecules [Phys. Rev. A<b>90</b>, 013419 (2014)

INVESTIGATION OF FOULING EFFECT ON OVERALL PERFORMANCE OF SHELL AND TUBE HEAT EXCHANGER IN A UREA FERTILIZER PRODUCTION COMPANY IN NIGERIA

Fouling is one of the major problems confronting heat exchangers in most industries. Shell and tube heat exchangers are perhaps the most common types of heat exchangers in industrial applications due to their flexibility and versatility. This study investigated the effect of fouling on the performance of the shell and tube heat exchanger unit of a CO 2 fertilizer production company in Nigeria. Two different heat exchanger units (cold gas pre-heater and CO 2 water cooler in scrubbing process) were considered for the analysis of this study. Data were obtained from operational log book, periodic maintenance data sheet and vendor’ design data sheet. The data were analyzed using various energy equations encoded in MATLAB to determine the overall heat transfer coefficients, heat duties, capacity ratios and effectiveness. The results obtained from the analysis showed that on average, the deviation of overall heat transfer coefficient, heat duty, and effectiveness from design values were 24.10%, 26.27%, and 17.17% respectively. Fouling factor was 31.58% more than the design value in a period of 47 days of operation. Fouling adversely affects the performance parameters of the heat exchangers. http://dx.doi.org/10.4314/njt.v35i1.20

Measuring and manipulating the temperature of cold molecules trapped on a chip

We demonstrate the measurement and manipulation of the temperature of cold CO molecules in a microchip environment. Through the use of time-resolved spatial imaging, we are able to observe the phase-space distribution of the molecules, and hence deduce the corresponding temperature. We do this both by observing the expansion of the molecular ensemble in time and through the use of numerical trajectory simulations. Furthermore, we demonstrate the adiabatic cooling of the trapped molecular sample and discuss this process.

The Dragonfly Galaxy

The Dragonfly Galaxy (MRC0152-209), at redshift z~2, is one of the most vigorously star-forming radio galaxies in the Universe. What triggered its activity? We present ALMA Cycle 2 observations of cold molecular CO(6-5) gas and dust, which reveal that this is likely a gas-rich triple merger. It consists of a close double nucleus (separation ~4 kpc) and a weak CO-emitter at ~10 kpc distance, all of which have counterparts in HST/NICMOS imagery. The hyper-luminous starburst and powerful radio-AGN were triggered at this precoalescent stage of the merger. The CO(6-5) traces dense molecular gas in the central region, and complements existing CO(1-0) data, which revealed more widespread tidal debris of cold gas. We also find ~10$^{10}$ M(sun) of molecular gas with enhanced excitation at the highest velocities. At least 20-50% of this high-excitation, high-velocity gas shows kinematics that suggests it is being displaced and redistributed within the merger, although with line-of-sight velocities of |v| < 500 km/s, this gas will probably not escape the system. The processes that drive the redistribution of cold gas are likely related to either the gravitational interaction between two kpc-scale discs, or starburst/AGN-driven outflows. We estimate that the rate at which the molecular gas is redistributed is at least ~1200 +- 500 M(sun)/yr, and could perhaps even approach the star formation rate of ~3000 +- 800 M(sun)/yr. The fact that the gas depletion and gas redistribution timescales are similar implies that dynamical processes can be important in the evolution of massive high-z galaxies.

DOUBLE DCO+RINGS REVEAL CO ICE DESORPTION IN THE OUTER DISK AROUND IM LUP

In a protoplanetary disk, a combination of thermal and non-thermal desorption processes regulate where volatiles are liberated from icy grain mantles into the gas phase. Non-thermal desorption should result in volatile-enriched gas in disk-regions where complete freeze-out is otherwise expected. We present ALMA observations of the disk around the young star IM Lup in 1.4 mm continuum, C18O 2-1, H13CO+ 3-2 and DCO+ 3-2 emission at ~0".5 resolution. The images of these dust and gas tracers are clearly resolved. The DCO+ line exhibits a striking pair of concentric rings of emission that peak at radii of ~0".6 and 2" (~90 and 300 AU, respectively). Based on disk chemistry model comparison, the inner DCO+ ring is associated with the balance of CO freeze-out and thermal desorption due to a radial decrease in disk temperature. The outer DCO+ ring is explained by non-thermal desorption of CO ice in the low-column-density outer disk, repopulating the disk midplane with cold CO gas. The CO gas then reacts with abundant H2D+ to form the observed DCO+ outer ring. These observations demonstrate that spatially resolved DCO+ emission can be used to trace otherwise hidden cold gas reservoirs in the outmost disk regions, opening a new window onto their chemistry and kinematics.

Optimization of a CO2 storage project based on thermal, geomechanical and induced fracturing effects

Abstract A coupled flow, geomechanical and heat transfer model for a potential CO 2 storage zone and surrounding formations has been developed. The coupled dynamic, thermal fracture model shows that thermal effects of injection could increase the speed of fracture propagation in the storage layer depending on the injection rate. Our work shows that the injection capacity with cold CO 2 injection could be significantly lower than expected, and it may be impractical to avoid induced fracture development. An optimization algorithm is proposed for maximizing the storage based on injection temperature while limiting the maximum fracture length and minimizing the risk of leakage from thermal effects of CO 2 storage while improving the injection capacity.

Alignment-assisted field-free orientation of rotationally cold CO molecules

We follow the alignment-assisted orientation technique proposed by Zhang et al. [Phys. Rev. A 83, 043410 (2011)] to experimentally demonstrate a substantial enhancement of the field-free orientation by using a combination of single- and two-color laser pulses. When a two-color orienting pulse is preceded by a single-color aligning pulse by a suitable time, the resulting orientation is thrice as large as that obtained with the two-color pulse alone. We ensure that the orientation is the result of the hyperpolarizability interaction rather than ionization depletion by keeping the ionization due to the pump pulses small and demonstrate a useful level of orientation without the complications of a partially ionized target.

MESA and NuGrid simulations of classical novae: CO and ONe nova nucleosynthesis

Classical novae are the result of thermonuclear flashes of hydrogen accreted by CO or ONe white dwarfs, leading eventually to the dynamic ejection of the surface layers. These are observationally known to be enriched in heavy elements, such as C, O and Ne that must originate in layers below the H-flash convection zone. Building on our previous work, we now present stellar evolution simulations of ONe novae and provide a comprehensive comparison of our models with published ones. Some of our models include exponential convective boundary mixing to account for the observed enrichment of the nova ejecta even when accreted material has a solar abundance distribution. Our models produce maximum temperature evolution profiles and nucleosynthesis yields in good agreement with models that generate enriched ejecta by assuming that the accreted material was pre-mixed. We confirm for ONe novae the result we reported previously, i.e.\ we found that $^3$He could be produced {\it in situ} in solar-composition envelopes accreted with slow rates ($\dot{M} < 10^{-10}\,M_\odot/\mbox{yr}$) by cold ($T_{\rm WD} < 10^7$ K) CO WDs, and that convection was triggered by $^3$He burning before the nova outburst in that case. In addition, we now find that the interplay between the $^3$He production and destruction in the solar-composition envelope accreted with an intermediate rate, e.g.\ $\dot{M} = 10^{-10}\,M_\odot/\mbox{yr}$, by the $1.15\,M_\odot$ ONe WD with a relatively high initial central temperature, e.g.\ $T_{\rm WD} = 15\times 10^6$ K, leads to the formation of a thick radiative buffer zone that separates the bottom of the convective envelope from the WD surface. (Abridged)

Accreting carbon–oxygen white dwarfs at explosive C ignition

The conditions at which an accreting carbon-oxygen white dwarf (CO WD) ignites C explosively have been considered to be possibly responsible for the maximum luminosity of Type Ia supernovae (SNe Ia). However, the exact conditions for this explosion have been in controversy. Employing the latest powerful stellar evolution code, Modules for Experiments in Stellar Astrophysics, and the descriptions of the single-degenerate (SD) model for progenitors of SNe Ia, we studied the evolution of several Pop I CO WDs from the onset of mass accretion to the explosive C ignition, where the temperature increases sharply but the density keeps in constant at the maximum temperature point (T-max) of the accreting CO WD. The accreted material is CO-rich and we include two sets of calculations, i.e. one is for a simple accretion like in Lesaffre et al. (2006) while the other artificially adds an energy generation rate (1 x 10(5) erg g(-1) s(-1)) in the outermost 0.005 M-circle dot material during accretion to mimic the energy delivered inwards from H- and He-burning. Both simulations show that most CO WDs ignite C explosively (at the T-max) in the centre, with very similar properties such as WD masses (similar to 1.387 M-circle dot), central densities (similar to 2.63 x 10(9) g cm(-3)), central temperatures(similar to 10(9) K) and binding energies (similar to 5.23 x 10(50) erg). This means that most SNe Ia are ignited initially in the centre of CO WDs based on the SD model. However, the central density and WD mass have been influenced by the initial C/O ratio at the centre of CO WDs. A few initially very cold massive CO WDs ignite C at off-centre points but still in the deep interior of WDs. In these explosions, the offset distance to the centre, the WD mass and central density at the explosion clearly increase with the cooling age, while the inclusion of an extra energy source resists this increasing in part. The off-centre explosions can only occasionally happen in relatively old galaxies and could partly contribute to the diversity of SNe Ia.

Geological CO2 storage: Incorporation of pore-pressure/stress coupling and thermal effects to determine maximum sustainable pressure limit

Abstract Ensuring geomechanical integrity is a critical factor in the successful operation of geological CO 2 storage. Injecting pressurized cold CO 2 into a reservoir will trigger two geomechanically coupled phenomena, hydro- and thermomechanical coupling, which should be taken into account when determining the maximum sustainable pressure limit. In this regard, we briefly introduce poroelastic and thermally induced stresses as cold fluid is injected into a geologic formation. We then propose new equations that incorporate pore-pressure/stress coupling and thermal stress effects to calculate for various stress regimes—including normal-, reverse-, and strike-slip faulting—the maximum pressure limit before reactivation of preexisting fractures. The suggested equations are tested for a case study in the literature in which the maximum pressure limit was estimated based on complex numerical simulations. Lastly, sensitivity analysis based on these suggested equations sheds light on how sensitive the maximum pressure limit is to several input parameters, including saturated rock density, Biot's coefficient, Poisson's ratio, initial total horizontal-to- vertical stress ratio, temperature drop, and Young's modulus.

ALMA CONTINUUM OBSERVATIONS OF A 30 Myr OLD GASEOUS DEBRIS DISK AROUND HD 21997

Circumstellar disks around stars older than 10 Myr are expected to be gas-poor. There are, however, two examples of old (30-40 Myr) debris-like disks containing a detectable amount of cold CO gas. Here we present ALMA and Herschel Space Observatory observations of one of these disks, around HD 21997, and study the distribution and origin of the dust and its connection to the gas. Our ALMA continuum images at 886um clearly resolve a broad ring of emission within a diameter of ~4.5 arcsec, adding HD 21997 to the dozen debris disks resolved at (sub)millimeter wavelengths. Modeling the morphology of the ALMA image with a radiative transfer code suggests inner and outer radii of ~55 and ~150 AU, and a dust mass of 0.09 M_Earth. Our data and modeling hints at an extended cold outskirt of the ring. Comparison with the morphology of the CO gas in the disk reveals an inner dust-free hole where gas nevertheless can be detected. Based on dust grain lifetimes, we propose that the dust content of this gaseous disk is of secondary origin produced by planetesimals. Since the gas component is probably primordial, HD 21997 is one of the first known examples of a hybrid circumstellar disk, a so-far little studied late phase of circumstellar disk evolution.

Treatment of Vulvar Intraepithelial Neoplasia With CO2 Laser Vaporization and Excision Surgery

To evaluate the recurrence rate after a single treatment of vulvar intraepithelial neoplasia (VIN) with CO(2) laser vaporization. Fifty women with usual-type or differentiated VIN (grades 2 and 3) treated with CO(2) laser vaporization or surgery excision (cold knife or CO(2) laser) were retrospectively evaluated. Of the 50 patients, 41 (82.0%) had usual-type VIN and 9 (18.0%) had differentiated VIN. Moreover, 24 (48.0%) were treated with surgery excision and 26 (52.0%) underwent CO(2) laser vaporization. Laser-treated patients were significantly younger (p < .01) with more multifocal (p < .05) and multicentric lesions (p < .01) than in the surgery group. Recurrence-free survival (RFS) rates at 1 year were 91.0% for the surgery and 65.2% for the laser vaporization groups (p < .01). At 5 years, RFS rates were unchanged for the surgery group and dropped to 51.3% (p < .01) for the laser group. On the univariate analysis, current smoker (p = .03), multicentric VIN (p = .02), and laser vaporization treatment (p < .01) had a statistically significant impact on RFS. One patient progressed to invasive cancer (2%). The recurrence rate after CO(2) laser vaporization requires regular, close, and extended monitoring.

CARBON MONOXIDE IN THE COLD DEBRIS OF SUPERNOVA 1987A

We report spectroscopic and imaging observations of rotational transitions of cold CO and SiO in the ejecta of SN1987A, the first such emission detected in a supernova remnant. In addition to line luminosities for the CO J=1-0, 2-1, 6-5, and 7-6 transitions, we present upper limits for all other transitions up to J=13-12, collectively measured from the Atacama Large Millimeter Array (ALMA), the Atacama Pathfinder EXperiment (APEX), and the Herschel Spectral and Photometric Imaging REceiver (SPIRE). Simple models show the lines are emitted from at least 0.01 solar masses of CO at a temperature > 14 K, confined within at most 35% of a spherical volume expanding at ~ 2000 km/s. Moreover, we locate the emission within 1'' of the central debris. These observations, along with a partial observation of SiO, confirm the presence of cold molecular gas within supernova remnants and provide insight into the physical conditions and chemical processes in the ejecta. Furthermore, we demonstrate the powerful new window into supernova ejecta offered by submillimeter observations.

Emissions performance of a hybrid hydrogen–gasoline engine-powered passenger car under the New European Driving Cycle

This paper investigated the emissions performance of a passenger car powered by the hybrid hydrogen–gasoline engine under the New European Driving Cycle. The hydrogen was produced from an onboard water electrolysis hydrogen generator fixed in the trunk. The test results demonstrated that, when the engine was started with pure hydrogen for the first 7s and fueled with the pure gasoline after 11s from the onset of the cold start, CO and HC emissions were reduced by 62.1% and 64.1%, respectively. The vehicle emissions performance could be improved from the Euro-II emissions standard of the original vehicle to the Euro-IV emissions standard of the hybrid hydrogen–gasoline engine-powered vehicle.

Observational constraints for the circumstellar disk of the B[e] star CPD−52 9243

Fil: Cidale, Lydia Sonia. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico la Plata. Instituto de Astrofisica de la Plata; Argentina. Universidad Nacional de la Plata. Facultad de Ciencias Astronomicas y Geofisicas; Argentina

MAGNETIC FIELD IN THE ISOLATED MASSIVE DENSE CLUMP IRAS 20126+4104

We measured polarized dust emission at 350um towards the high-mass star forming massive dense clump IRAS 20126+4104 using the SHARC II Polarimeter, SHARP, at the Caltech Submillimeter Observatory. Most of the observed magnetic field vectors agree well with magnetic field vectors obtained from a numerical simulation for the case when the global magnetic field lines are inclined with respect to the rotation axis of the dense clump. The results of the numerical simulation show that rotation plays an important role on the evolution of the massive dense clump and its magnetic field. The direction of the cold CO 1-0 bipolar outflow is parallel to the observed magnetic field within the dense clump as well as the global magnetic field, as inferred from optical polarimetry data, indicating that the magnetic field also plays a critical role in an early stage of massive star formation. The large-scale Keplerian disk of the massive (proto)star rotates in almost opposite sense to the clump's envelope. The observed magnetic field morphology and the counter-rotating feature of the massive dense clump system provide hints to constrain the role of magnetic fields in the process of high mass star formation.

Prevention of Vessel Desiccation and Maintenance of Normal Morphology During Endovascular Harvesting Using Humidified Warmed Gas

Endoscopic vessel harvesting (EVH) traditionally uses carbon dioxide (CO(2)) gas for insufflation. The CO(2) based on government regulations is bone dry and room temperature. All previous EVH studies use this type of unconditioned gas. It is hypothesized that by changing the quality of CO(2) gas differences may occur that are attributable to dry gas versus wet gas exposure. A comparison of the effect(s) of traditional dry CO(2) gas compared to humidified exposure was done using a porcine model and evaluated in a double-blind randomized controlled fashion. Vessels exposed to traditional dry cold gas had morphologic and structural changes noted on histologic evaluation. This included desiccation changes of the tunica adventitia desiccation and tunica media collagen and elastin. Vessels exposed to dry gas showed 10% to 12% contraction and constriction with tortuous changes to the intima and endothelial lining that were progressive with increasing volumes of gas exposure. No desiccation or morphologic changes were seen with humidified warmed gas produced using the VesselGuardian. Traditional dry cold CO(2) caused vascular tissue damage extending from the adventitia to intima, changing the vessel in morphologic and structural configuration. With the VesselGuardian humidified warmed, gas maintained vessel morphology and integrity by preventing desiccation. Changing the quality of CO(2) from dry and cold to wet and warm may offer clinical utility for a better quality conduit for coronary artery bypass graft procedures.

Contribution of CO&lt;SUB align="right"&gt;2 emitted to the atmosphere by diffuse degassing from volcanoes: The Furnas Volcano case study

Furnas Volcano is a dormant central volcano located in the eastern part of Sao Miguel Island (Azores archipelago, Portugal). The last volcanic eruption in this volcanic system took place in 1630 causing about 200 victims. Present-day activity comprises fumarolic fields, thermal and cold CO 2 -rich springs and soil diffuse degassing areas. CO 2 diffusely released from the volcano soils was estimated at ~ 0.4 Mt y –1 . Only about 14% of this emission has a biogenic origin, the highest amount of the CO 2 emitted being mantle derived. Hydrothermal CO 2 released from Furnas Volcano is in the same order of magnitude as emissions from other volcanic geothermal areas of the world. This work highlights the need to account for the natural CO 2 emitted from quiescent volcanoes to refine the global carbon budget modelling.

Evaluation of pediatric subglottic cysts

Introduction Subglottic cysts (SGCs) are increasingly recognized as a cause of upper airway obstruction in previously intubated infants. Endoscopic marsupialization with cold steel instruments or CO 2 laser has been reported to be the standardised treatment method for SGCs. SGC case series of 9 patients who were treated with endoscopic marsupialization with cold steel instruments or CO 2 laser and mechanical decompression with balloon dilatation are presented. Patients and methods Retrospective study of 9 cases of subglottic cysts treated between 2003 and 2010 was done. Diagnoses were made by performing flexible nasopharyngolaryngoscopy and surgical treatment was done through endoscopic marsupialization with cold steel instruments or CO 2 laser. Results The age range of SGC patients were between 3 months and 36 months (average 12, 11 months). Two of the patients were female (2/9), 7 of them were male (7/9). SGC diagnoses were made by flexible nasopharyngolaryngoscopy. History of intubation was noted in 3 of the patients (3/9). Duration of intubation was 28 days, 6 days, and 8 days respectively. Cysts were multiple in all cases, and located posteriorly and laterally at the subglottic area and upper trachea. The patients presented with were stridor, fail to thrive, and recurrent croup attacks. Treatment methods preferred for these patients were endoscopic marsupialization with cold steel instruments or CO 2 laser and mechanical decompression with balloon dilatation. The follow-up period after treatment ranged between 8 months and 3 years. Recurrence of the SGCs did not happen and re-evaluation under general anesthesia was reserved for the symptomatic patients. Conclusion Diagnostic laryngoscopy and bronchoscopy are important in diagnosing SGC. History of premature birth and intubation are not ‘sine qua non’ of SGC as SGC may be congenital as well. Symptoms of SGCs may mimic the characteristic features of chronic obstructive lung disease, so evaluation of the airway should be considered in such infants if they have stridor or hoarseness not responding to routine treatment. Laryngoscopy and bronchoscopy are routinely indicated for airway evaluation in at-risk infants.