Herschel Measurements of Molecular Oxygen in Orion

We report observations of three rotational transitions of molecular oxygen (O_2) in emission from the H_2 Peak 1 position of vibrationally excited molecular hydrogen in Orion. We observed the 487 GHz, 774 GHz, and 1121 GHz lines using the Heterodyne Instrument for the Far Infrared on the Herschel Space Observatory, having velocities of 11 km s^(–1) to 12 km s^(–1) and widths of 3 km s^(–1). The beam-averaged column density is N(O_2) = 6.5 × 10^(16) cm^(–2), and assuming that the source has an equal beam-filling factor for all transitions (beam widths 44, 28, and 19"), the relative line intensities imply a kinetic temperature between 65 K and 120 K. The fractional abundance of O_2 relative to H_2 is (0.3-7.3) × 10^(–6). The unusual velocity suggests an association with a ~5" diameter source, denoted Peak A, the Western Clump, or MF4. The mass of this source is ~10 M_⊙ and the dust temperature is ≥150 K. Our preferred explanation of the enhanced O_2 abundance is that dust grains in this region are sufficiently warm (T ≥ 100 K) to desorb water ice and thus keep a significant fraction of elemental oxygen in the gas phase, with a significant fraction as O_2. For this small source, the line ratios require a temperature ≥180 K. The inferred O_2 column density ≃5 × 10^(18) cm^(–2) can be produced in Peak A, having N(H_2) ≃4 × 10^(24) cm^(–2). An alternative mechanism is a low-velocity (10-15 km s^(–1)) C-shock, which can produce N(O_2) up to 10^(17) cm^(–2)

Multi-line detection of O_2 toward ρ Ophiuchi A

Context. Models of pure gas-phase chemistry in well-shielded regions of molecular clouds predict relatively high levels of molecular oxygen, O_2, and water, H_(2)O. These high abundances imply high cooling rates, leading to relatively short timescales for the evolution of gravitationally unstable dense cores, forming stars and planets. Contrary to expectations, the dedicated space missions SWAS and Odin typically found only very small amounts of water vapour and essentially no O_2 in the dense star-forming interstellar medium. Aims. Only toward ρOph   A did Odin detect a very weak line of O_2 at 119 GHz in a beam of size 10 arcmin. The line emission of related molecules changes on angular scales of the order of some tens of arcseconds, requiring a larger telescope aperture such as that of the Herschel Space Observatory to resolve the O2 emission and pinpoint its origin. Methods. We use the Heterodyne Instrument for the Far Infrared (HIFI) aboard Herschel to obtain high resolution O_2 spectra toward selected positions in the ρOph A   core. These data are analysed using standard techniques for O_2 excitation and compared to recent PDR-like chemical cloud models. Results. The N_J = 3_(3) − 1_(2) line at 487.2 GHz is clearly detected toward all three observed positions in the ρOph A  core. In addition, an oversampled map of the 5_(4)−3_(4) transition at 773.8 GHz reveals the detection of the line in only half of the observed area. On the basis of their ratios, the temperature of the O_2 emitting gas appears to vary quite substantially, with warm gas (≳ 50K) being adjacent to a much colder region, of temperatures lower than 30 K. Conclusions. The exploited models predict that the O_2 column densities are sensitive to the prevailing dust temperatures, but rather insensitive to the temperatures of the gas. In agreement with these models, the observationally determined O_2 column densities do not seem to depend strongly on the derived gas temperatures, but fall into the range N(O_2) = 3 to ≳ 6 × 10^(15) cm^(-2). Beam-averaged O2 abundances are about 5 × 10^(-8) relative to H_2. Combining the HIFI data with earlier Odin observations yields a source size at 119 GHz in the range of 4 to 5 arcmin, encompassing the entire ρOph A core. We speculate that one of the reasons for the generally very low detection rate of O2 is the short period of time during which O_2 molecules are reasonably abundant in molecular clouds

Dust emission in the Sagittarius B2 molecular cloud core

A model is presented for the dust emission from the Sagittarius B2 molecular cloud core which reproduces the observed spectrum between 30 and 1300 micron, as well as the distribution of the emission at 1300 micron. The model is based on the assumption that Sgr B2(N) continuum source is located behind the dust cloud associated with Sgr B2(M) continuum source. The fact that Sgr B2(N) is stronger at 1300 micron can be attributed to a local column density maximum at the position of this source. Absence of a 53 micron emission peak at the position of Sgr B2(N) suggests that the luminosity of the north source is lower than that of the middle source

First results on Martian carbon monoxide from Herschel/HIFI observations

We report on the initial analysis of Herschel/HIFI carbon monoxide (CO) observations of the Martian atmosphere performed between 11 and 16 April 2010. We selected the (7–6) rotational transitions of the isotopes ^(13)CO at 771 GHz and C^(18)O and 768 GHz in order to retrieve the mean vertical profile of temperature and the mean volume mixing ratio of carbon monoxide. The derived temperature profile agrees within less than 5 K with general circulation model (GCM) predictions up to an altitude of 45 km, however, show about 12–15 K lower values at 60 km. The CO mixing ratio was determined as 980 ± 150 ppm, in agreement with the 900 ppm derived from Herschel/SPIRE observations in November 2009

Submillimeter Imaging of NGC 891 with SHARC

The advent of submillimeter wavelength array cameras operating on large ground-based telescopes is revolutionizing imaging at these wavelengths, enabling high-resolution submillimeter surveys of dust emission in star-forming regions and galaxies. Here we present a recent 350 micron image of the edge-on galaxy NGC 891, which was obtained with the Submillimeter High Angular Resolution Camera (SHARC) at the Caltech Submillimeter Observatory (CSO). We find that high resolution submillimeter data is a vital complement to shorter wavelength satellite data, which enables a reliable separation of the cold dust component seen at millimeter wavelengths from the warmer component which dominates the far-infrared (FIR) luminosity.Comment: 4 pages LaTeX, 2 EPS figures, with PASPconf.sty; to appear in "Astrophysics with Infrared Surveys: A Prelude to SIRTF

Istraživanje segregacije bora kod niskougljičnih čelika

Traces of born in the range 0,002-0,009 % are usually added to many grades of steel. The effect of boron on phase transformations and hardenability of low carbon low alloy steels depends on the form of its behavior in solid solution either in segregations or in precipitations. Temperature and cooling rate determine the existence of boron segregations on grain boundaries. In present paper simulations of boron concentrations were calculated with computer programme DICTRA for low carbon 0,08 %C steel with 0,006 % boron. Investigations were carried out for temperature 1300 – 700°C and cooling rates from 1°C/s to 100°C/s. The changes of boron concentrations in austenite and ferrite after commencement of γ→α phase transformation were established.Tragovi bora u rasponu 0,002-0,009 % se obično dodaju mnogim tipovima čelika. Utjecaj bora na fazne transformacije i zakaljivost niskougljičnih niskolegiranih čelika ovisi o obliku njegovog ponašanja u čvrstoj otpini ili u segregacijama ili u precipitatima. Temperatura i brzina hlađenja određuju postojanje segregacija bora na granicama zrna. U ovom radu simulacije koncentracija bora su proračunate pomoću kompjutorskog programa DICTRA za niskougljični čelik s 0,08 % C i 0,006 % bora. Istraživanja su provedena ta temperature 1 300–700°C i brzine hlađenja od 1°C/s do 100°C/s. Utvrđene su promjene koncentracije bora u austenitu i feritu nakon početka γ→α fazne transformacije

Istraživanje segregacije bora kod niskougljičnih čelika

Traces of born in the range 0,002-0,009 % are usually added to many grades of steel. The effect of boron on phase transformations and hardenability of low carbon low alloy steels depends on the form of its behavior in solid solution either in segregations or in precipitations. Temperature and cooling rate determine the existence of boron segregations on grain boundaries. In present paper simulations of boron concentrations were calculated with computer programme DICTRA for low carbon 0,08 %C steel with 0,006 % boron. Investigations were carried out for temperature 1300 – 700°C and cooling rates from 1°C/s to 100°C/s. The changes of boron concentrations in austenite and ferrite after commencement of γ→α phase transformation were established.Tragovi bora u rasponu 0,002-0,009 % se obično dodaju mnogim tipovima čelika. Utjecaj bora na fazne transformacije i zakaljivost niskougljičnih niskolegiranih čelika ovisi o obliku njegovog ponašanja u čvrstoj otpini ili u segregacijama ili u precipitatima. Temperatura i brzina hlađenja određuju postojanje segregacija bora na granicama zrna. U ovom radu simulacije koncentracija bora su proračunate pomoću kompjutorskog programa DICTRA za niskougljični čelik s 0,08 % C i 0,006 % bora. Istraživanja su provedena ta temperature 1 300–700°C i brzine hlađenja od 1°C/s do 100°C/s. Utvrđene su promjene koncentracije bora u austenitu i feritu nakon početka γ→α fazne transformacije

HIFI observations of water in the atmosphere of comet C/2008 Q3 (Garradd)

High-resolution far-infrared and sub-millimetre spectroscopy of water lines is an important tool to understand the physical and chemical properties of cometary atmospheres.We present observations of several rotational ortho- and para-water transitions in comet C/2008 Q3 (Garradd) performed with HIFI on Herschel. These observations have provided the first detection of the 2_(12)−1_(01) (1669 GHz) ortho and 1_(11)−0_(00) (1113 GHz) para transitions of water in a cometary spectrum. In addition, the ground-state transition 1_(10)−1_(01) at 557 GHz is detected and mapped. By detecting several water lines quasi-simultaneously and mapping their emission we can constrain the excitation parameters in the coma. Synthetic line profiles are computed using excitation models which include excitation by collisions, solar infrared radiation, and radiation trapping. We obtain the gas kinetic temperature, constrain the electron density profile, and estimate the coma expansion velocity by analyzing the map and line shapes. We derive water production rates of 1.7−2.8 × 10^(28) s^(−1) over the range r_h = 1.83−1.85 AU