Total Fe Mass Research Articles

HST Detection of Extended Neutral Hydrogen in a Massive Elliptical at z = 0.4

Abstract We report the first detection of extended neutral hydrogen (H i) gas in the interstellar medium (ISM) of a massive elliptical galaxy beyond . The observations utilize the doubly lensed images of QSO HE 0047−1756 at as absorption-line probes of the ISM in the massive ( ) elliptical lens at z = 0.408, detecting gas at projected distances of d = 3.3 and 4.6 kpc on opposite sides of the lens. Using the Space Telescope Imaging Spectrograph, we obtain UV absorption spectra of the lensed QSO and identify a prominent flux discontinuity and associated absorption features matching the Lyman series transitions at z = 0.408 in both sightlines. The H i column density is log at both locations across the lens, comparable to what is seen in 21 cm images of nearby ellipticals. The H i gas kinematics are well-matched with the kinematics of the Fe ii absorption complex revealed in ground-based echelle data, displaying a large velocity shear of ≈360 across the galaxy. We estimate an ISM Fe abundance of 0.3–0.4 solar at both locations. Including likely dust depletions increases the estimated Fe abundances to solar or supersolar, similar to those of the hot ISM and stars of nearby ellipticals. Assuming 100% covering fraction of this Fe-enriched gas, we infer a total Fe mass of in the cool ISM of the massive elliptical lens, which is no more than 5% of the total Fe mass observed in the hot ISM.

Fractional iron solubility of atmospheric iron inputs to the Southern Ocean

Deposition of iron (Fe) bearing aerosols to Fe deficient waters of the Southern Ocean may drive rapid changes in primary productivity, trophic structure and the biological uptake of carbon dioxide. The fractional solubility (i.e., the ratio of water leachable Fe to total Fe) of aerosol Fe is an important variable determining its availability for biological uptake, and is a function of both particle type and the experimental conditions used to leach the particles. There have been few studies of fractional Fe solubility over the Southern Ocean where the aerosol loading is the lowest in the world. To investigate Southern Ocean aerosol Fe solubility, the fractional solubility of Fe was determined in cryogenically archived Southern Ocean aerosols. Samples were collected at the Cape Grim Baseline Air Pollution Station (CGBAPS), Tasmania, Australia from February 1999 to April 2000. Fractions determined included water soluble Fe (<0.45μm), labile Fe (>0.45μm; acetic acid and hydroxylamine hydrochloride leachable Fe) and refractory Fe (>0.45μm; total digestion using nitric and hydrofluoric acids). Extremely low Fe mass concentrations were observed for baseline Southern Ocean air during the study period. An inverse hyperbolic relationship was observed between fractional Fe solubility (0.5 to 56%) and total Fe mass concentration (0.04 to 5.8ngm3; excluding an anomalously high sample). A peak of 4.6ngm3 of labile Fe occurred during May/June 1999 and was linked to atmospheric transport from South Western Australia over the Southern Ocean. Bioavailable Fe was estimated by summing the water soluble and labile Fe fractions, and this likely represents the upper bound of long range transport aerosol over the Southern Ocean. The results confirm previous reports of a range of fractional Fe solubility within all atmospheric particles measured and also suggest that a large fraction of the Fe from Australian mineral aerosols is labile and potentially bioavailable.

The bioavailability of manganese in welders in relation to its solubility in welding fumes

Blood and urine samples for determination of manganese (Mn) and iron (Fe) concentrations were collected in a cross-sectional study of 137 currently exposed welders, 137 referents and 34 former welders. Aerosol samples for measurements of personal air exposure to Mn and Fe were also collected. The aerosol samples were assessed for their solubility using a simulated lung lining fluid (Hatch solution). On average 13.8% of the total Mn mass (range 1-49%; N = 237) was soluble (Hatch sol), while only 1.4% (<0.1-10.0%; N = 237) of the total Fe mass was Hatch sol. The welders had statistically significantly higher geometric mean concentrations of Mn in whole blood (B-Mn 12.8 vs. 8.0 μg L (-1)), serum (S-Mn 1.04 vs. 0.77 μg L(-1)) and urine (U-Mn 0.36 vs. 0.07 μg g (-1) cr.) than the referents. Statistically significant univariate correlations were observed between exposure to Hatch sol Mn in the welding aerosol and B-Mn, S-Mn and U-Mn respectively. Pearson's correlation coefficient between mean Hatch sol Mn of two days preceding the collection of biological samples and U-Mn was 0.46 (p < 0.001). The duration of employment as a welder in years was also associated with B-Mn and S-Mn, but not with U-Mn. Statistically significantly higher U-Mn and B-Mn were observed in welders currently exposed to even less than 12 and 6 μg m (-3) Hatchsol Mn, respectively. When using the 95(th) percentile concentration among the referents as a cut-point, 70.0 and 64.5% of the most highly exposed welders exceeded this level with respect to B-Mn and U-Mn. The concentrations of B-Mn, S-Mn and U-Mn were all highly correlated in the welders, but not in the referents.

Suzaku View of the Supernova Remnant RCW 86: X-Ray Studies of Newly-Discovered Fe-Rich Ejecta

Abstract We report on results of imaging and spectral analysis of the supernova remnant (SNR) RCW 86 observed with Suzaku. The SNR is known to exhibit K-shell emission of low ionized Fe, possibly originating from supernova ejecta. We revealed the global distribution of the Fe-rich plasma in the entire remnant, for the first time; the Fe-K emission was clearly detected from the west, north, and south regions, in addition to the X-ray brighter shells of southwest and northeast, where the presence of the Fe-rich ejecta has already been reported. The spectrum of each region is well represented by a three-component model consisting of low- and high-temperature thermal plasmas and non-thermal emission. The lower-temperature component, with elemental abundances of near the solar values, likely originates from the forward shocked interstellar medium, while the Fe-rich ejecta is described by the hotter plasma. From the morphologies of the forward and reverse shocks in the west region, the total ejecta mass is estimated to be 1–2 $\ M_{\odot}$ for the typical explosion energy of $\sim\ $ 1 $\times$ 10 $^{51}\ $ erg. The integrated flux of the Fe-K emission from the entire SNR roughly corresponds to a total Fe mass of about 1 $\ M_{\odot}$ . Both of these estimates suggest a Type Ia supernova origin of this SNR. We also find possible evidence of an Fe-rich clump located beyond the forward-shock front in the north rim, which is reminiscent of ejecta knots observed in the Tycho and Vela SNRs.

Distribution and biological cycle of iron in freshwater peatlands of Sanjiang Plain, Northeast China

Iron cycling in wetlands is important because it plays an important role in interactions among wetland soils/sediments, plants and microorganisms. The seasonal variation of iron (Fe) distributed in two freshwater peatland ecosystems dominated by Calamagrostis angustifolia (CA) and Carex lasiocarpa (CL), was observed in Sanjiang Plain of Northeast China. The compartmentalization of the Fe cycle including storage in the atmosphere, litter, soil, and above- and below ground plant material was determined. The results showed that the Fe input from rain was 0.06 g m − 2 a − 1 , and the total Fe mass in the peatland ecosystem was 5.18 × 10 3 for CA and 1.40 × 10 3 g m − 2 for CL. The major Fe pools were soils (98.6% and 97.1% for CA and CL, respectively). The Fe fluxes between each compartment resulted in the increase of the belowground Fe pool and decrease of the litter Fe pool currently both for CA and CL. CL has greater uptake coefficient (0.024) and cycle coefficient (0.034), but smaller use coefficient (0.58) than that of CA (0.02, 0.006, and 0.77, respectively). Peatland conversion for agriculture affected the former natural Fe cycle processes and mass balance to a certain extent in long term, because the Fe assimilated by soybean and rice are less than that of CA and CL, and cannot return to soils from harvesting. Drainage and ditch excavation for agricultural conversion caused considerable Fe loss via aqueous movement, so that Fe was likely lost and transported downstream by these ditch networks.

Metal transport by gas sloshing in M87

We present the results of an XMM-Newton mosaic covering the central ~200 kpc of the nearby Virgo cluster. We focus on a strong surface brightness discontinuity in the outskirts of the brightest cluster galaxy, M87. Using both XMM-Newton and Suzaku, we derive accurate temperature and metallicity profiles across this feature and show that it is a cold front probably due to sloshing of the Virgo ICM. It is also associated with a discontinuity in the chemical composition. The gas in the inner, bright region of the front is ~40% more abundant in Fe than the gas outside the front, suggesting the important role of sloshing in transporting metals through the ICM. For the first time, we provide a quantitative estimate of the mass of Fe transported by a cold front. This amounts to ~6% of the total Fe mass within the radial range affected by sloshing, significantly more than the amount of metals transported by the AGN in the same cluster core. The very low Fe abundance of only ~0.2 solar immediately outside the cold front at a radius of 90 kpc suggests we are witnessing first-hand the transport of higher metallicity gas into a pristine region, whose abundance is typical of the cluster outskirts. The Mg/Fe and O/Fe abundance ratios remain approximately constant over the entire radial range between the centre of M87 and the faint side of the cold front, which requires the presence of a centrally peaked distribution not only for Fe but also for core-collapse type supernova products. This peak may stem from the star formation triggered as the BCG assembled during the protocluster phase.

A Candidate Neutron Star within the Radio Shell of Sgr A East

We present imaging and spectral analyses of Sgr A East from deep Chandra observations. A nearby hard point-like source CXOGC J174545.5-285829 (dubbed the cannonball) appears to be a high-velocity neutron star. The estimated total Fe mass of Sgr A East supports a core-collapse origin from a massive star. Based on these results and the proximity between the features, we propose that the cannonball is a candidate neutron star created by the supernova that also produced the remnant Sgr A East.

Coupling and feedback between iron and sulphur in air-sea exchange

Iron in surface seawater has been demonstrated to be the limiting nutrient factor for primary productivity in certain oceanic regions. In 1992 we reported inNature at first Fe(II) existence in marine aerosols over the remote Pacific and Atlantic and proposed the hypothesis of coupling and feedback between iron and sulfur in air-sea exchange. We recently detected a considerable amount of Fe(II) in the aerosols collected during dust storm in Beijing. The concentration of Fe(II) in the dust storm was as high as 1.8–4.3 g · m−3 that accounted for 1.4% –2.6% of the total Fe mass concentration in aerosols, while Fe(II) in the aerosols collected from non-dust storm days was 0.7% of the total Fe. Fe and S concentrations in the dust storm aerosol samples represent a very positive correlationship. The size distribution of Fe, Fe(II), and S in either dust storm particles or the normal aerosols showed the same peak at 1–3 μm. The oxidation of S(IV) under natural light and UV in addition of Fe(III) was 6.5 and 14 times faster respectively compared with that of non-addition. The photoreduction of Fe(□) to Fe(II), through the formation of an OH radical, associated with the oxidation of S(IV) to S(VI) could account for ∼3%–20% of the formation of non-sea salt sulfate aerosols at Midway, central Pacific. These results further support the Fe-S coupling hypothesis. From consideration of both the marine biological production of dimethylsulphide (DMS) and the subsequent oxidation of reduced forms of sulfur in the atmosphere, the iron and sulphur cycles in both the atmosphere and the ocean may be closely coupled.