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M Orio - One of the best experts on this subject based on the ideXlab platform.
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x ray Grating Spectra of novae in outburst and the cases of two luminous novae in the magellanic clouds
Advances in Space Research, 2020Co-Authors: M OrioAbstract:Abstract High resolution X-ray Spectra of classical and recurrent novae in outburst have opened a new window into the nova phenomenon, allowing to observe both the hydrogen burning white dwarf (WD) with only a very thin atmosphere on top, and violent phenomena occurring in the ejecta. By means of these Spectra, the mass and chemical composition of the WD can be estimated and insight is obtained into the mass ejection process. I present here the cases of two Magellanic Clouds novae, the recurrent LMC 2009a, and SMC 2016a, the most luminous nova observed in the Clouds. The bolometric and X-ray luminosity of LMC 2009a peaked at only about 10% of the Eddington luminosity; our interpretation is that the WD was partially obscured, probably by the accretion disk, or by large clumps in the ejecta. SMC 2016a instead reached super-Eddington luminosity and was observed at or above the Eddington level for about 6 months. The WD was more massive than 1.2 M ⊙ in both novae, but the short recurrence time and the (inferred) much higher accretion rate caused a less energetic outburst in LMC 2009a. While the SMC 2016a spectrum is dominated by the characteristic continuum and features of the WD atmosphere, the LMC 2009a spectrum is much more complex and has an overlap of absorption and emission features. The main contribution to the continuum in both novae originated in the WD atmosphere, but the Spectral features of N LMC 2009a were produced also in different regions, and most likely were due to more than one mechanism.
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what we learn from the x ray Grating Spectra of nova smc 2016
The Astrophysical Journal, 2018Co-Authors: M Orio, J U Ness, A Dobrotka, E Gatuzz, N Ospina, E Aydi, E Behar, David A H BuckleyAbstract:Facilities: Chandra - , XMM-Newton - . Software: XSPEC (v12.6.0 Arnaud 1996), CIAO (v4.9; Fruscione et al. 2006), XMM-SAS v16.1.0
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what we learn from the x ray Grating Spectra of nova smc 2016
arXiv: High Energy Astrophysical Phenomena, 2018Co-Authors: M Orio, J U Ness, A Dobrotka, E Gatuzz, N Ospina, E Aydi, E Behar, David A H BuckleyAbstract:Nova SMC 2016 has been the most luminous nova known in the direction of the Magellanic Clouds. It turned into a very luminous supersoft X-ray source between day 16 and 28 after the optical maximum. We observed it with Chandra, the HRC-S camera and the Low Energy Transmission Grating (LETG) on 2016 November and 2017 January (days 39 and 88 after optical maximum), and with XMM-Newton on 2016 December (day 75). We detected the compact white dwarf (WD) spectrum as a luminous supersoft X-ray continuum with deep absorption features of carbon, nitrogen, magnesium, calcium, probably argon and sulfur on day 39, and oxygen, nitrogen and carbon on days 75 and 88. The Spectral features attributed to the WD atmosphere are all blue-shifted, by about 1800 km/s on day 39 and up to 2100 km/s in the following observations. Spectral lines attributed to low ionization potential transitions in the interstellar medium are also observed. Assuming the distance of the Small Magellanic Cloud, the bolometric luminosity exceeded Eddington level for at least three months. A preliminary analysis with atmospheric models indicates effective temperature around 700,000 K on day 39, peaking at the later dates in the 850,000-900,000 K range, as expected for a 1.25 m(sol) WD. We suggest a possible classification as an oxygen-neon WD, but more precise modeling is needed to accurately determine the abundances. The X-ray light curves show large, aperiodic ux variability, not associated with Spectral variability. We detected red noise, but did not find periodic or quasi-periodic modulations.
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thomson scattering and collisional ionization in the x ray Grating Spectra of the recurrent nova u scorpii
Monthly Notices of the Royal Astronomical Society, 2013Co-Authors: M Orio, Ehud Behar, J S Gallagher, A Bianchini, E Chiosi, G J M Luna, T Nelson, T Rauch, Bradley E SchaeferAbstract:Fil: Orio, M.. INAF Osservatorio di Padova; Italia. University of Wisconsin; Estados Unidos
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x ray Grating Spectra of rs ophiuchi in outburst
THE MULTICOLORED LANDSCAPE OF COMPACT OBJECTS AND THEIR EXPLOSIVE ORIGINS, 2007Co-Authors: M Orio, Thomas Nelson, E M Leibowitz, R Gonzalezriestra, P MucciarelliAbstract:The recurrent nova RS Ophiuchi was observed five times with Chandra and XMM‐Newton, on four different dates after the 2006 outburst. In the first month we detected an emission spectrum with prominent lines of H and He‐like ions of metals including O, N, Si, Fe, Ne and Mg, showing a large range of plasma temperatures. At this stage the emission was originated in the red giant wind material shocked by the nova ejecta. Later Spectra show a large increase in emission at longer wavelengths, peaking two months after the outburst. We attribute this to the emergence of the underlying white dwarf. Preliminary fits with NLTE white dwarf atmospheric models yield log g = 9, and T ∼800,000K, appropriate a white dwarf mass of >1.2 M⊙. The constant bolometric luminosity phase was very short, less than three months, as expected for a white dwarf mass ≈ 1.35 M⊙. We detected an oscillation with a period ∼35 s in March and April light curves, which may be due to the spin of the white dwarf and may represents further evidenc...
F Nicastro - One of the best experts on this subject based on the ideXlab platform.
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the two phase two velocity ionized absorber in the seyfert 1 galaxy ngc 5548
The Astrophysical Journal, 2010Co-Authors: Mercedes Andradevelazquez, Y Krongold, Martin Elvis, F Nicastro, Nancy S Brickhouse, L Binette, Smita Mathur, E JimenezbailonAbstract:We present an analysis of X-ray high-quality Grating Spectra of the Seyfert 1 galaxy NGC 5548 using archival Chandra-High Energy Transmission Grating Spectrometer and Low Energy Transmission Grating Spectrometer observations for a total exposure time of 800 ks. The continuum emission (between 0.2 keV and 8 keV) is well represented by a power law (GAMMA = 1.6) plus a blackbody component (kT = 0.1 keV). We find that the well-known X-ray warm absorber (WA) in this source consists of two different outflow velocity systems. One absorbing system has a velocity of -1110 +- 150 km s{sup -1} and the other of -490 +- 150 km s{sup -1}. Recognizing the presence of these kinematically distinct components allows each system to be fitted independently, each with two absorption components with different ionization levels. The high-velocity system consists of two components, one with a temperature of 2.7 +- 0.6 x 10{sup 6} K, log U = 1.23, and another with a temperature of 5.8 +- 1.0 x 10{sup 5} K, log U = 0.67. The high-velocity, high-ionization component produces absorption by charge states Fe XXI-XXIV, while the high-velocity, low-ionization component produces absorption by Ne IX-X, Fe XVII-XX, and O VII-VIII. The low-velocity systemmore » also required two absorbing components, one with a temperature of 5.8 +- 0.8 x 10{sup 5} K, log U = 0.67, producing absorption by Ne IX-X, Fe XVII-XX, and O VII-VIII, and the other with a lower temperature of 3.5 +- 0.35 x 10{sup 4} K and a lower ionization of log U = -0.49, producing absorption by O VI-VII and the Fe VII-XII M-shell Unresolved Transitions Array. Once these components are considered, the data do not require any further absorbers. In particular, a model consisting of a continuous radial range of ionization structures (as suggested by a previous analysis) is not required. The two absorbing components in each velocity system are in pressure equilibrium with each other. This suggests that each velocity system consists of a multi-phase medium. This is the first time that different outflow velocity systems have been modeled independently in the X-ray band for this source. The kinematic components and column densities found from the X-rays are in agreement with the main kinematic components found in the UV absorber. This supports the idea that the UV and X-ray absorbing gas is part of the same phenomenon. NGC 5548 can now be seen to fit in a pattern established for other WAs: two or three discrete phases in pressure equilibrium. There are no remaining cases of a well-studied WA in which a model consisting of a multi-phase medium is not viable.« less
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the two phase two velocity ionized absorber in the seyfert 1 galaxy ngc 5548
arXiv: Cosmology and Nongalactic Astrophysics, 2010Co-Authors: Mercedes Andradevelazquez, Y Krongold, Martin Elvis, F Nicastro, Nancy S Brickhouse, L Binette, Smita Mathur, E JimenezbailonAbstract:We present an analysis of X-ray high quality Grating Spectra of the Seyfert 1 galaxy NGC 5548 using archival Chandra HETGS and LETGS observations for a total exposure time of 800ks. The continuum emission is well represented by a powerlaw plus a black-body component. We find that the well known X-ray warm absorber in this source consists of two different outflow velocity systems. Recognizing the presence of these kinematically distinct components allows each system to be fitted independently, each with two absorption components with different ionization levels. The high velocity system consists of a component with temperature of 2.7X10^6K and another component with temperature of 5.8X10^5K. The low-velocity system required also two absorbing components, one with temperature of 5.8X10^5K; the other with lower temperature (3.5X10^4K). Once these components are considered, the data do not require any further absorbers. In particular, a model consisting of a continuous radial range of ionization structures is not required. The two absorbing components in each velocity system are in pressure equilibrium with each other. This suggests that each velocity system consists of a multi-phase medium. This is the first time that different outflow velocity systems have been modelled independently in the X-ray band for this source. The kinematic components and column densities found from the X-rays are in agreement with the main kinematic components found in the UV absorber. This supports the idea that the UV and X-ray absorbing gas is part of the same phenomenon. NGC 5548 can now be seen to fit in a pattern established for other warm absorbers: 2 or 3 discrete phases in pressure equilibrium. There are no remaining cases of a well studied warm absorber in which a model consisting of a multi-phase medium is not viable.
E Gatuzz - One of the best experts on this subject based on the ideXlab platform.
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what we learn from the x ray Grating Spectra of nova smc 2016
The Astrophysical Journal, 2018Co-Authors: M Orio, J U Ness, A Dobrotka, E Gatuzz, N Ospina, E Aydi, E Behar, David A H BuckleyAbstract:Facilities: Chandra - , XMM-Newton - . Software: XSPEC (v12.6.0 Arnaud 1996), CIAO (v4.9; Fruscione et al. 2006), XMM-SAS v16.1.0
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what we learn from the x ray Grating Spectra of nova smc 2016
arXiv: High Energy Astrophysical Phenomena, 2018Co-Authors: M Orio, J U Ness, A Dobrotka, E Gatuzz, N Ospina, E Aydi, E Behar, David A H BuckleyAbstract:Nova SMC 2016 has been the most luminous nova known in the direction of the Magellanic Clouds. It turned into a very luminous supersoft X-ray source between day 16 and 28 after the optical maximum. We observed it with Chandra, the HRC-S camera and the Low Energy Transmission Grating (LETG) on 2016 November and 2017 January (days 39 and 88 after optical maximum), and with XMM-Newton on 2016 December (day 75). We detected the compact white dwarf (WD) spectrum as a luminous supersoft X-ray continuum with deep absorption features of carbon, nitrogen, magnesium, calcium, probably argon and sulfur on day 39, and oxygen, nitrogen and carbon on days 75 and 88. The Spectral features attributed to the WD atmosphere are all blue-shifted, by about 1800 km/s on day 39 and up to 2100 km/s in the following observations. Spectral lines attributed to low ionization potential transitions in the interstellar medium are also observed. Assuming the distance of the Small Magellanic Cloud, the bolometric luminosity exceeded Eddington level for at least three months. A preliminary analysis with atmospheric models indicates effective temperature around 700,000 K on day 39, peaking at the later dates in the 850,000-900,000 K range, as expected for a 1.25 m(sol) WD. We suggest a possible classification as an oxygen-neon WD, but more precise modeling is needed to accurately determine the abundances. The X-ray light curves show large, aperiodic ux variability, not associated with Spectral variability. We detected red noise, but did not find periodic or quasi-periodic modulations.
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erratum photoionization modeling of oxygen k absorption in the interstellar medium the chandra Grating Spectra of xte j1817 330 2013 apj 768 60
The Astrophysical Journal, 2013Co-Authors: E Gatuzz, Javier A Garcia, C Mendoza, T R Kallman, M Witthoeft, Anne M Lohfink, M A Bautista, P PalmeriAbstract:In the published version of this paper, there are some minor inaccuracies in the absorption-line wavelengths listed in Table 4 as a result of a faulty reduction procedure of the Obs6615 spectrum. The shifts have been detected in a comparison with the wavelengths listed for this spectrum in the Chandra Transmission Grating Catalog and Archive (TGCat8). They are due to incorrect centroid positions of the zero-order image in both reductions as determined by the tgdetect utility which, when disentangled, yield the improved line positions of the amended Table 4 given below. It must also be pointed out that other quantitative findings of the original paper: 1. Table 5, p. 9: the column density (NH), ionization parameter, oxygen abundance of the warmabs model and the normalization and photon index of the power-law model; 2. Table 6, p. 9: the hydrogen column density of the warmabs fit; 3. Table 7, p. 9: the present oxygen equivalent widths of XTE J1817-330; and 4. Table 8, p. 10: the present oxygen column densities of XTE J1817-330 derived from both the curve of growth and warmabs model fit have been revised in the new light and are, within the estimated uncertainty ranges, in good accord with the new rendering.
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photoionization modeling of oxygen k absorption in the interstellar medium the chandra Grating Spectra of xte j1817 330
The Astrophysical Journal, 2013Co-Authors: E Gatuzz, Javier A Garcia, C Mendoza, T R Kallman, M Witthoeft, Anne M Lohfink, M A Bautista, P PalmeriAbstract:We present detailed analyses of oxygen K absorption in the interstellar medium (ISM) using four high-resolution Chandra Spectra toward the X-ray low-mass binary XTE J1817-330. The 11-25 A broadband is described with a simple absorption model that takes into account the pile-up effect and results in an estimate of the hydrogen column density. The oxygen K-edge region (21-25 A) is fitted with the physical warmabs model, which is based on a photoionization model grid generated with the XSTAR code with the most up-to-date atomic database. This approach allows a benchmark of the atomic data which involves wavelength shifts of both the K lines and photoionization cross sections in order to fit the observed Spectra accurately. As a result we obtain a column density of N H = 1.38 ± 0.01 × 1021 cm–2; an ionization parameter of log ξ = –2.70 ± 0.023; an oxygen abundance of ; and ionization fractions of O I/O = 0.911, O II/O = 0.077, and O III/O = 0.012 that are in good agreement with results from previous studies. Since the oxygen abundance in warmabs is given relative to the solar standard of Grevesse & Sauval, a rescaling with the revision by Asplund et al. yields , a value close to solar that reinforces the new standard. We identify several atomic absorption lines—Kα, Kβ, and Kγ in O I and O II and Kα in O III, O VI, and O VII—the last two probably residing in the neighborhood of the source rather than in the ISM. This is the first firm detection of oxygen K resonances with principal quantum numbers n > 2 associated with ISM cold absorption.
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photoionization modeling of oxygen k absorption in the interstellar medium the chandra Grating Spectra of xte j1817 330
arXiv: High Energy Astrophysical Phenomena, 2013Co-Authors: E Gatuzz, Javier A Garcia, C Mendoza, T R Kallman, M Witthoeft, Anne M Lohfink, M A Bautista, P PalmeriAbstract:We present detailed analyses of oxygen K absorption in the interstellar medium (ISM) using four high-resolution Chandra Spectra towards the X-ray low-mass binary XTE J1817-330. The 11-25 A broadband is described with a simple absorption model that takes into account the pileup effect and results in an estimate of the hydrogen column density. The oxygen K-edge region (21-25 A) is fitted with the physical warmabs model, which is based on a photoionization model grid generated with the xstar code with the most up-to-date atomic database. This approach allows a benchmark of the atomic data which involves wavelength shifts of both the K lines and photoionization cross sections in order to fit the observed Spectra accurately. As a result we obtain: a column density of N(H)=1.38+/-0.01\times 10^21 cm^-2; ionization parameter of log(xi)=-2.70+/-0.023; oxygen abundance of A(O)= 0.689^{+0.015}_{-0.010}; and ionization fractions of OI/O = 0.911, OII/O = 0.077, and OIII/O = 0.012 that are in good agreement with previous studies. Since the oxygen abundance in warmabs is given relative to the solar standard of Grevesse et al. (1998), a rescaling with the revision by Asplund et al. (2009) yields A(O)=0.952^{+0.020}_{-0.013}, a value close to solar that reinforces the new standard. We identify several atomic absorption lines Kalpha, Kbeta, and Kgamma in OI and OII; and Kalpha in OIII, OVI, and OVII - last two probably residing in the neighborhood of the source rather than in the ISM. This is the first firm detection of oxygen K resonances with principal quantum numbers n>2 associated to ISM cold absorption.
Kwang Yong Song - One of the best experts on this subject based on the ideXlab platform.
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characterization of nonlinear temperature dependence of brillouin dynamic Grating Spectra in polarization maintaining fibers
Journal of Lightwave Technology, 2015Co-Authors: Yong Hyun Kim, Kwang Yong SongAbstract:Temperature dependencies of the Brillouin dynamic Grating (BDG) Spectra in polarization-maintaining fibers (PMF's) are rigorously investigated. PANDA fiber, Bow-tie fiber, and PM photonic crystal fiber (PM-PCF) with different parameters are tested in the temperature range of −30 to +150 °C, where the linear and nonlinear temperature dependencies are quantified for each fiber. It is observed that bare PANDA and Bow-tie fibers show similar shape and magnitude of the nonlinear temperature dependence, while the contribution of the acrylate coating appears differently for each fiber. Suppression of the temperature dependence is observed in the PM-PCF, where notable effects of the acrylate coating on the birefringence are observed only below the room temperature. We also present the result of comparative measurement of the polarization beat length using the BDG analysis and the periodic lateral force method, which confirms the validity of the BDG-based birefringence measurement.
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optical time domain measurement of brillouin dynamic Grating spectrum in a polarization maintaining fiber
Optics Letters, 2009Co-Authors: Kwang Yong Song, Zuyuan He, Kazuo HotateAbstract:We demonstrate the distributed measurement of Brillouin dynamic Grating Spectra in a polarization-maintaining fiber based on time-domain analysis. Local reflection Spectra of the Brillouin dynamic Grating are acquired by synchronized propagation of the pump and the probe pulses based on the map of the Brillouin frequency distribution. Large temperature sensitivity as high as −50.9 MHz/°C is observed with 2 m spatial resolution in 100 m range.
P Palmeri - One of the best experts on this subject based on the ideXlab platform.
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erratum photoionization modeling of oxygen k absorption in the interstellar medium the chandra Grating Spectra of xte j1817 330 2013 apj 768 60
The Astrophysical Journal, 2013Co-Authors: E Gatuzz, Javier A Garcia, C Mendoza, T R Kallman, M Witthoeft, Anne M Lohfink, M A Bautista, P PalmeriAbstract:In the published version of this paper, there are some minor inaccuracies in the absorption-line wavelengths listed in Table 4 as a result of a faulty reduction procedure of the Obs6615 spectrum. The shifts have been detected in a comparison with the wavelengths listed for this spectrum in the Chandra Transmission Grating Catalog and Archive (TGCat8). They are due to incorrect centroid positions of the zero-order image in both reductions as determined by the tgdetect utility which, when disentangled, yield the improved line positions of the amended Table 4 given below. It must also be pointed out that other quantitative findings of the original paper: 1. Table 5, p. 9: the column density (NH), ionization parameter, oxygen abundance of the warmabs model and the normalization and photon index of the power-law model; 2. Table 6, p. 9: the hydrogen column density of the warmabs fit; 3. Table 7, p. 9: the present oxygen equivalent widths of XTE J1817-330; and 4. Table 8, p. 10: the present oxygen column densities of XTE J1817-330 derived from both the curve of growth and warmabs model fit have been revised in the new light and are, within the estimated uncertainty ranges, in good accord with the new rendering.
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photoionization modeling of oxygen k absorption in the interstellar medium the chandra Grating Spectra of xte j1817 330
The Astrophysical Journal, 2013Co-Authors: E Gatuzz, Javier A Garcia, C Mendoza, T R Kallman, M Witthoeft, Anne M Lohfink, M A Bautista, P PalmeriAbstract:We present detailed analyses of oxygen K absorption in the interstellar medium (ISM) using four high-resolution Chandra Spectra toward the X-ray low-mass binary XTE J1817-330. The 11-25 A broadband is described with a simple absorption model that takes into account the pile-up effect and results in an estimate of the hydrogen column density. The oxygen K-edge region (21-25 A) is fitted with the physical warmabs model, which is based on a photoionization model grid generated with the XSTAR code with the most up-to-date atomic database. This approach allows a benchmark of the atomic data which involves wavelength shifts of both the K lines and photoionization cross sections in order to fit the observed Spectra accurately. As a result we obtain a column density of N H = 1.38 ± 0.01 × 1021 cm–2; an ionization parameter of log ξ = –2.70 ± 0.023; an oxygen abundance of ; and ionization fractions of O I/O = 0.911, O II/O = 0.077, and O III/O = 0.012 that are in good agreement with results from previous studies. Since the oxygen abundance in warmabs is given relative to the solar standard of Grevesse & Sauval, a rescaling with the revision by Asplund et al. yields , a value close to solar that reinforces the new standard. We identify several atomic absorption lines—Kα, Kβ, and Kγ in O I and O II and Kα in O III, O VI, and O VII—the last two probably residing in the neighborhood of the source rather than in the ISM. This is the first firm detection of oxygen K resonances with principal quantum numbers n > 2 associated with ISM cold absorption.
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photoionization modeling of oxygen k absorption in the interstellar medium the chandra Grating Spectra of xte j1817 330
arXiv: High Energy Astrophysical Phenomena, 2013Co-Authors: E Gatuzz, Javier A Garcia, C Mendoza, T R Kallman, M Witthoeft, Anne M Lohfink, M A Bautista, P PalmeriAbstract:We present detailed analyses of oxygen K absorption in the interstellar medium (ISM) using four high-resolution Chandra Spectra towards the X-ray low-mass binary XTE J1817-330. The 11-25 A broadband is described with a simple absorption model that takes into account the pileup effect and results in an estimate of the hydrogen column density. The oxygen K-edge region (21-25 A) is fitted with the physical warmabs model, which is based on a photoionization model grid generated with the xstar code with the most up-to-date atomic database. This approach allows a benchmark of the atomic data which involves wavelength shifts of both the K lines and photoionization cross sections in order to fit the observed Spectra accurately. As a result we obtain: a column density of N(H)=1.38+/-0.01\times 10^21 cm^-2; ionization parameter of log(xi)=-2.70+/-0.023; oxygen abundance of A(O)= 0.689^{+0.015}_{-0.010}; and ionization fractions of OI/O = 0.911, OII/O = 0.077, and OIII/O = 0.012 that are in good agreement with previous studies. Since the oxygen abundance in warmabs is given relative to the solar standard of Grevesse et al. (1998), a rescaling with the revision by Asplund et al. (2009) yields A(O)=0.952^{+0.020}_{-0.013}, a value close to solar that reinforces the new standard. We identify several atomic absorption lines Kalpha, Kbeta, and Kgamma in OI and OII; and Kalpha in OIII, OVI, and OVII - last two probably residing in the neighborhood of the source rather than in the ISM. This is the first firm detection of oxygen K resonances with principal quantum numbers n>2 associated to ISM cold absorption.
