scholarly journals C+ distribution around S 1 in ρ Ophiuchi

2018 ◽  
Vol 616 ◽  
pp. A31 ◽  
Author(s):  
B. Mookerjea ◽  
G. Sandell ◽  
W. Vacca ◽  
E. Chambers ◽  
R. Güsten
Keyword(s):  
Northwestern Part ◽  
Hyperfine Component ◽  
Data Set ◽  
Strong Emission ◽  
James Clerk Maxwell ◽  
Hot Gas ◽  
Systemic Velocity ◽  
C Distribution ◽  
Co Emission ◽  
Cloud Core

We analyze a [C II] 158 μm map obtained with the L2 GREAT receiver on SOFIA of the reflection nebula illuminated by the early B star S 1 in the ρ Oph A cloud core. This data set has been complemented with maps of CO(3–2), 13CO(3–2), and C18O(3–2), observed as a part of the James Clerk Maxwell Telescope (JCMT) Gould Belt Survey, with archival HCO+(4–3) JCMT data, as well as with [O I] 63 and 145 μm imaging with Herschel/PACS. The [C II] emission is completely dominated by the strong emission from the photon dominated region (PDR) in the nebula surrounding S 1 expanding into the dense Oph A molecular cloud west and south of S 1. The [C II] emission is significantly blueshifted relative to the CO spectra and also relative to the systemic velocity, particularly in the northwestern part of the nebula. The [C II] lines are broader toward the center of the S 1 nebula and narrower toward the PDR shell. The [C II] lines are strongly self-absorbed over an extended region in the S 1 PDR. Based on the strength of the [13C II] F = 2–1 hyperfine component, [C II] is significantly optically thick over most of the nebula. CO and 13CO(3–2) spectra are strongly self-absorbed, while C18O(3–2) is single peaked and centered in the middle of the self-absorption. We have used a simple two-layer LTE model to characterize the background and foreground cloud contributing to the [C II] emission. From this analysis we estimated the extinction due to the foreground cloud to be ~9.9 mag, which is slightly less than the reddening estimated toward S 1. Since some of the hot gas in the PDR is not traced by low-J CO emission, this result appears quite plausible. Using a plane parallel PDR model with the observed [O I](145)/[C II] brightness ratio and an estimated FUV intensity of 3100–5000 G0 suggests that the density of the [C II] emitting gas is ~3–4  × 103 cm−3.

Hot gas in the nucleus of IC 342 - Detection of J = 3-2 CO emission

1987 ◽  
Vol 322 ◽  
pp. L67 ◽  
Author(s):  
Paul T. P. Ho ◽  
Jean L. Turner ◽  
Robert N. Martin
Keyword(s):  
Hot Gas ◽  
Co Emission

Aperture synthesis observations of CO emission from the W3 molecular cloud core

1984 ◽  
Vol 285 ◽  
pp. L79 ◽  
Author(s):  
M. J. Claussen ◽  
G. L. Berge ◽  
G. M. Heiligman ◽  
R. B. Leighton ◽  
K. Y. Lo ◽  
...  
Keyword(s):  
Molecular Cloud ◽  
Aperture Synthesis ◽  
Co Emission ◽  
Cloud Core

Chlorophyll and phytoplankton spatial distribution in the Arabian/Persian Gulf and the Sea of Oman

2020 ◽  
Author(s):  
Igor Polikarpov ◽  
Maria Saburova ◽  
Faiza Al-Yamani
Keyword(s):  
Spatial Distribution ◽  
Indian Ocean ◽  
Persian Gulf ◽  
Western Indian Ocean ◽  
Water Masses ◽  
Northwestern Part ◽  
Phytoplankton Abundance ◽  
Data Set ◽  
Sea Of Oman

<p>Spatial distribution of the chlorophyll-<em>a</em> and phytoplankton community composition related to different water masses were studied during regional cruise in February-March 2006 across the Arabian/Persian Gulf and the Sea of Oman, the marginal seas of the Western Indian Ocean.</p><p>Chlorophyll-<em>a</em> concentrations were measured using <em>in vitro</em> method with fluorescence detection and also were assessed as <em>in vivo</em> fluorescence measured by submersible fluorometer. Nearly four hundred species of phytoplankton were enumerated and identified using microscopy in the samples collected at the same stations.</p><p>High phytoplankton abundance was associated with diatom-dominated phytoplankton blooms in the central and northwestern part of the Gulf, in the Strait of Hormuz and in the Sea of Oman. The average concentration of <em>in vitro</em> measured surface chlorophyll-<em>a</em> in the studied area was 2.5 mg/m<sup>3</sup>, with the maximum over 9 mg/m<sup>3</sup>. The relationships between the concentrations of satellite remotely sensed chlorophyll and <em>in vitro</em> measured chlorophyll-<em>a</em> were found to be mostly in good agreement. The highest concentrations of the surface chlorophyll (> 4 mg/m<sup>3</sup>) were observed in the areas where diatom-dominated blooms were identified. It was revealed a significant relationship between the phytoplankton composition and water masses indexed by salinity.</p><p>The main significance of this study is in the first data set of <em>in vitro</em> measured precise chlorophyll-<em>a</em> concentrations that were obtained along with phytoplankton abundance and taxonomic diversity from the entire region of the Arabian/Persian Gulf and the Sea of Oman. This data set can be used for remote sensing measurements validation and as a baseline for future studies of the biological productivity changes in the Western Indian Ocean.</p>

scholarly journals CHIMPS2: survey description and 12CO emission in the Galactic Centre

2020 ◽  
Vol 498 (4) ◽  
pp. 5936-5951 ◽  
Author(s):  
D J Eden ◽  
T J T Moore ◽  
M J Currie ◽  
A J Rigby ◽  
E Rosolowsky ◽  
...  
Keyword(s):  
High Resolution ◽  
Milky Way ◽  
Angular Resolution ◽  
Galactic Plane ◽  
Galactic Centre ◽  
Data Set ◽  
Valuable Data ◽  
Future Studies ◽  
James Clerk Maxwell ◽  
Array Receiver

ABSTRACT The latest generation of Galactic Plane surveys is enhancing our ability to study the effects of galactic environment upon the process of star formation. We present the first data from CO Heterodyne Inner Milky Way Plane Survey 2 (CHIMPS2). CHIMPS2 is a survey that will observe the Inner Galaxy, the Central Molecular Zone (CMZ), and a section of the Outer Galaxy in 12CO, 13CO, and C18O $(J = 3\rightarrow 2)$ emission with the Heterodyne Array Receiver Program on the James Clerk Maxwell Telescope (JCMT). The first CHIMPS2 data presented here are a first look towards the CMZ in 12CO J = 3 → 2 and cover ${-}3^{\circ }\, \le \, \ell \, \le \, 5^{\circ }$ and $\mid {b} \mid \, \le \, 0{_{.}^{\circ}} 5$ with angular resolution of 15 arcsec, velocity resolution of 1 km s−1, and rms $\Delta \, T_A ^\ast =$ 0.58 K at these resolutions. Such high-resolution observations of the CMZ will be a valuable data set for future studies, whilst complementing the existing Galactic Plane surveys, such as SEDIGISM, the ${Herschel}$ infrared Galactic Plane Survey, and ATLASGAL. In this paper, we discuss the survey plan, the current observations and data, as well as presenting position–position maps of the region. The position–velocity maps detect foreground spiral arms in both absorption and emission.

scholarly journals Discovery of a Highly Collimated Flow from the High-mass Protostar ISOSS J23053+5953 SMM2

2021 ◽  
Vol 922 (1) ◽  
pp. 66
Author(s):  
Tatiana M. Rodríguez ◽  
Peter Hofner ◽  
Esteban D. Araya ◽  
Qizhou Zhang ◽  
Hendrik Linz ◽  
...  
Keyword(s):  
Dust Emission ◽  
High Mass ◽  
Continuum Emission ◽  
Large Array ◽  
Lower Velocity ◽  
Very Large Array ◽  
Molecular Outflow ◽  
Systemic Velocity ◽  
Massive Outflow ◽  
Co Emission

Abstract We present Very Large Array C-, X-, and Q-band continuum observations, as well as 1.3 mm continuum and CO(2-1) observations with the Submillimeter Array toward the high-mass protostellar candidate ISOSS J23053+5953 SMM2. Compact centimeter continuum emission was detected near the center of the SMM2 core with a spectral index of 0.24(± 0.15) between 6 and 3.6 cm, and a radio luminosity of 1.3(±0.4) mJy kpc2. The 1.3 mm thermal dust emission indicates a mass of the SMM2 core of 45.8 (±13.4) M ⊙, and a density of 7.1 (±1.2)× 106 cm−3. The CO(2-1) observations reveal a large, massive molecular outflow centered on the SMM2 core. This fast outflow (>50 km s−1 from the cloud systemic velocity) is highly collimated, with a broader, lower-velocity component. The large values for outflow mass (45.2 ± 12.6 M ⊙) and momentum rate (6 ± 2 × 10−3 M ⊙ km s−1yr−1) derived from the CO emission are consistent with those of flows driven by high-mass YSOs. The dynamical timescale of the flow is between 1.5 and 7.2 × 104 yr. We also found from the C18O to thermal dust emission ratio that CO is depleted by a factor of about 20, possibly due to freeze-out of CO molecules on dust grains. Our data are consistent with previous findings that ISOSS J23053 + 5953 SMM2 is an emerging high-mass protostar in an early phase of evolution, with an ionized jet and a fast, highly collimated, and massive outflow.

scholarly journals The Hot Gas in the Galactic Bulge

1996 ◽  
Vol 169 ◽  
pp. 287-295
Author(s):  
K. Koyama ◽  
Y. Maeda
Keyword(s):  
Galactic Center ◽  
Remarkable Feature ◽  
Strong Emission ◽  
X Ray ◽  
Hot Gas ◽  
Bright Spots ◽  
X Ray Imaging ◽  
Soft Spectrum ◽  
Sgr A ◽  
Extended Emission

X-ray imaging spectroscopic observations near the Galactic center region were carried out with the ASCA satellite. We found two bright spots very close to the Galactic center (Sgr A∗); one is extended and has a soft spectrum associated with strong emission lines from highly ionized irons, while the other is a point-like object with a harder spectrum and a larger absorption. We also found extended emission with K-shell transition lines from highly ionized Si, S, Ar, Ca and Fe. Remarkable feature found with ASCA is an extended emission of 6.4 keV lines of low ionization irons. The 6.4 keV line fluxes are found to be well correlated to the region of cool clouds. We interpret that the 6.4 keV line is due to florescence from the cool clouds irradiated by strong (and obscured from our line of sight) X-ray beams.

scholarly journals Estimation of activity the methane seepage from the Black Sea floor using MODIS images and geosciences data

2018 ◽  
Vol 26 (1) ◽  
pp. 135-142
Author(s):  
T. A. Melnichenko
Keyword(s):  
Black Sea ◽  
Satellite Images ◽  
Weather Data ◽  
The Black Sea ◽  
Northwestern Part ◽  
Data Set ◽  
Methane Gas ◽  
Methane Seepage ◽  
Cloudy Weather ◽  
Gas Seepage

The publication presents the results of a certain stage of the study: the features of methane gas seepage characteristics in the transition zone of shelf-continental slope in the region of the Dnieper Paleodelts in the northwestern part of the Black Sea are identified, taking into account the data set: information of satellite images and of geological-geophysical (acoustic) data. About 2000 of the MODIS satellite images (product MOD021KM) are acquired in stages over one year period. The image processing was carried out in the GIS environment. It was established that the volume of methane gas seepage on the investigated site is fixed on satellite images and is most pronounced during increased seismotectonic activity (activation of earthquakes in the Black Sea region) - this is due to the tectonic structure of the study area, which is in the regional plan on the edge of the Eastern European platform, and in the local area, is the Dnepr paleo-delta in the zone of decomposition, which is an additional factor for gas outlets here. On satellite images small clouds are observed in cloudy weather or absence of clouds on the background of continuous clouds. This is due to the physical properties of methane, which is (according to geochemical studies) about 99% of the released gas. Methane rising from the bottom of the sea to the surface, and then to the troposphere is much colder than the surface water and warmer than the atmosphere layer, which provokes the formation of condensate over the site with methane gas seepage, and when the weather conditions change, forming a rainy cloud with a sharp drop in temperature, the volume of methane gas of seepage up are much warmer than clouds, forming a cloudy area on a background of continuous clouds. This phenomenon is recorded in various spectral (thermal and infrared) bands in satellite images (NASA – MODIS, NOAA, etc.), methane rising to the lower layers of the atmosphere intensively absorbs thermal radiation of the Earth in the infrared spectral region at a wavelength of 7.66 µm. It enables to determine the methane gas seepage in satellite images for future studies of gas outlets from the bottom of the sea, taking into account the geological information and additional hydrological  and weather data. The conducted monitoring of the satellite images showed that during the period of increased seismic activity in this region (in particular under the influence of the zone Vranch), it directly affects the tectonic situation in the northwestern part of the Black Sea and increases the emissions of methane gases from the bottom of the sea, which are then recorded on the MODIS sensor. 

scholarly journals Infrared and sub-mm observations of outbursting young stars with Herschel and Spitzer

2019 ◽  
Vol 631 ◽  
pp. A30
Author(s):  
A. Postel ◽  
M. Audard ◽  
E. Vorobyov ◽  
O. Dionatos ◽  
C. Rab ◽  
...  
Keyword(s):  
Far Infrared ◽  
Young Stars ◽  
Spectral Energy ◽  
Strong Increase ◽  
Gas Emission ◽  
Strong Emission ◽  
Circumstellar Material ◽  
Long Time ◽  
Molecular Lines ◽  
Co Emission

Context. Episodic accretion plays an important role in the evolution of young stars. Although it has been under investigation for a long time, the origin of such episodic accretion events is not yet understood. Aims. We investigate the dust and gas emission of a sample of young outbursting sources in the infrared to get a better understanding of their properties and circumstellar material, and we use the results in a further work to model the objects. Methods. We used Herschel data, from our PI program of 12 objects and complemented with archival observations to obtain the spectral energy distributions (SEDs) and spectra of our targets. We report here the main characteristics of our sample, focussing on the SED properties and on the gas emission lines detected in the PACS and SPIRE spectra. Results. The SEDs of our sample show the diversity of the outbursting sources, with several targets showing strong emission in the far-infrared from the embedded objects. Most of our targets reside in a complex environment, which we discuss in detail. We detected several atomic and molecular lines, in particular rotational CO emission from several transitions from J = 38−37 to J = 4−3. We constructed rotational diagrams for the CO lines, and derived in three domains of assumed local thermodynamic equilibrium (LTE) temperatures and column densities, ranging mainly between 0−100 K and 400−500 K. We confirm correlation in our sample between intense CO J = 16−15 emission and the column density of the warm domain of CO, N(warm). We notice a strong increase in luminosity of HH 381 IRS and a weaker increase for PP 13 S, which shows the beginning of an outburst.

Numerical Analysis of Effusion Plates for Combustor Liners Cooling With Varying Density Ratio

2013 ◽  
Author(s):  
L. Andrei ◽  
A. Andreini ◽  
C. Bianchini ◽  
B. Facchini ◽  
L. Mazzei
Keyword(s):  
Gas Flow ◽  
Density Ratio ◽  
Reference Conditions ◽  
Numerical Procedure ◽  
Acoustic Properties ◽  
Computational Grids ◽  
Wall Region ◽  
Adiabatic Wall ◽  
Data Set ◽  
Hot Gas

Effusion cooling technology has been assessed in past years as one of the most efficient methods to maintain allowable working temperature of combustor liners. Despite many efforts reported in literature to characterize the cooling performances of those devices, detailed analysis of the mixing process between coolant and hot gas are difficult to perform especially in case superposition and density ratio effects become important. Furthermore, recent investigations on the acoustic properties of these perforations pointed out the challenge to maintain optimal cooling performance also with orthogonal holes which showed higher sound absorption. This paper performs a CFD analysis of the flow and thermal field associated with adiabatic wall conditions to compute the cooling effectiveness. The geometry consists of an effusion cooling plate drilled with 18 holes and fed separately with a cold and hot gas flow. Two types of perforations equivalent in porosity and pitches are investigated to assess the influence of the drilling angle between 30 and 90 deg. The reference conditions considered in this work comprehend an effective blowing ratio ranging between 1 and 3 at isothermal conditions (reaching a maximum hole Reynolds number of 10000) and high inlet turbulence intensity (17%). This set of conditions was exploited to perform a validation of the numerical procedure against detailed experimental data presented in another paper. Inlet turbulence effects highlighted by measurements for the slanted perforation were also investigated simulating a low turbulence condition corresponding to 1.6% of intensity. Furthermore the nominal DR = 1.0 was increased up to 1.7 to expand the available data set towards typical working conditions for aero-engines. Steady state RANS calculations were performed with the commercial code ANSYS® CFX, modeling turbulence by means of the k — ω SST. In order to include anisotropic diffusion effects due to turbulence damping in the near wall region, the turbulence model is corrected considering a tensorial definition of the eddy viscosity with an algebraic correction to dope its stream-span components. Computational grids were finely clustered close to the main plate and inside the holes to obtain y+ < 1, to maximize solver accuracy according to previous similar analysis.

Vacuum ultraviolet emission by active nitrogen. II. The excitation of singlet and triplet states of carbon monoxide by active nitrogen

1972 ◽  
Vol 330 (1580) ◽  
pp. 97-108 ◽  
Keyword(s):  
Carbon Monoxide ◽  
Vacuum Ultraviolet ◽  
Triplet States ◽  
Efficient Energy Transfer ◽  
Ultraviolet Emission ◽  
Active Nitrogen ◽  
Excited Triplet ◽  
Strong Emission ◽  
Singlet And Triplet States ◽  
Co Emission

The addition of small amounts of carbon monoxide to active nitrogen induces strong emission of the CO fourth positive bands, (A 1 Π—X 1 ∑ + ), which extends up to v ' = 8. The kinetic behaviour of the emission is closely similar to that of the Lyman-Birge-Hopfield emission of N 2 , comprising terms proportional to [N] 2 /([M] + γ) and [N] 3 /[M], the latter being enhanced in argon carriers. It is shown that CO(A 1 Π) is excited by efficient energy transfer from N 2 (a 1 Π g ) and is removed predominantly by radiation. Excited triplet states of N 2 excite triplet states of CO but they do not contribute significantly to singlet CO emission.

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