Wind Zone Research Articles

Diffuse X-ray emissions from dynamic planetary nebulae

We present theoretical results of a piecewise isothermal shock wind model devised for predicting the luminosity and surface brightness profile of diffuse X-ray emissions primarily from the inner shocked downstream wind zone of a planetary nebula (PN) surrounded by self-similar shocked dense shell and outer slow AGB wind envelope involving self-gravity and compare/fit our computational model results with available observations of a few grossly spherical X-ray emitting PNe. Matching shocked piecewise isothermal self-similar void (ISSV) solutions with self-gravity of Lou & Zhai (LZ) for the outer zone and a stationary isothermal fast tenuous wind with a reverse shock for the inner zone across an expanding contact discontinuity, we can consistently construct dynamic evolution models of PNe with diffuse X-ray emissions. On the basis of such a chosen dynamic wind interaction model, both X-ray luminosity and radial X-ray brightness profile are determined by three key parameters, namely the so-called X-ray parameter $X$, two radii $R_{rs}$ and $R_c$ of the reverse shock and the contact discontinuity. We find that morphologies of X-ray emissions would appear in the forms of either a central luminous sphere or a bright ring embedded within optically bright shells. In contrast to previous adiabatic models, the X-ray brightness peaks around the reverse shock, instead of the contact discontinuity surface just inside the outer shocked dense shell. Diffuse X-ray emissions of a few observed PNe appear to support this wind-wind dynamic interaction scenario.

The cannabinoid receptor type 2 is time-dependently expressed during skeletal muscle wound healing in rats

The expression of the cannabinoid receptor type 2 (CB2R) was investigated by immunohistochemistry, Western blotting, and RT-PCR during wound healing of contused skeletal muscle in rats with attempt of its applicability to skeletal muscle wound age estimation. Furthermore, Macrophage Marker (MAC387) was utilized to identify macrophages recruited into injured skeletal muscle tissue. Co-localization of CB2R with Macrophage Marker was detected by confocal laser scanning microscopy. A total of 50 Sprague-Dawley male rats were divided into control and contusion groups (3 h, 6 h, 12 h, 1 day, 3 days, 5 days, 7 days, 10 days, and 14 days post-injury). In the uninjured controls, immunoreactivity of CB2R was detected in the sarcolemma and sarcoplasm of normal myofibers. In the contusion groups, a few polymorphonulcear cells, a large number of macrophages, and spindle-shaped fibroblastic cells showed a positive staining for CB2R in wounded zones. By Western blotting analysis, the average of CB2R to GAPDH ratios in 5-7 days post-injury groups was highest, and all the samples had ratios of >2.60. In the other groups, no samples showed ratios of >2.60 and the CB2R to GAPDH ratios ranged from 1.19 to 2.59. The expression tendency was also confirmed by RT-PCR. From the viewpoint of forensic pathology, these observations suggested that the ratio markedly exceeding 2.60 strongly indicated a wound age of 5-7 days. In conclusion, dynamic distribution and expression of CB2R suggest that CB2R be involved in modulating macrophages in response to inflammatory event in rat skeletal muscle wound healing and CB2R be available as a marker for wound age determination.

Origin and transport of Mediterranean moisture and air

Abstract. Considering the Mediterranean as a region of high evaporation and low precipitation, evaluations of sinks and sources of moisture and precipitation in the Mediterranean basin have been carried out within the frame of the CIRCE (Climate Change and Impact Research: the Mediterranean Environment) project. Besides these evaluations, residence time and stagnation/ventilation analyses have been carried out to investigate transport to and from the Mediterranean basin and in the basin itself. A Lagrangian moisture diagnosis method calculating budgets of evaporation minus precipitation was applied to a 5.5 year (October 1999–April 2005) trajectory data set and evaluated for eight representative Mediterranean Regions Of Interest (ROI). The Mediterranean basin has been identified as a major source of moisture and precipitation to the surrounding land area and to the basin itself. Main regions of stagnation, i.e. the Po basin, have been defined on a seasonal basis through residence time analysis. Evaluation of the transport to and from the basin shows that the Mediterranean is a crossroad of airstreams where air enters mainly from the northwest and continues in two separate streams, one going southwest over North Africa into the trade wind zone and the other one to the northeast through Central Asia.

Liposomal form of dihydroquercetin contributes to skin regeneration after thermal burns

It was found that dihydroquercetin, a flavonoid of plant origin, localized in lecitin nanoparticles with glycine amino acid, reduced inflammatory reactions in wound zones after thermal burns. The application of the liposomal complex to burn trauma stabilized the endogenous antioxidant system and minimized the area of secondary necrosis in the wound. The intensification of skin regeneration and repair of hair follicles and sebaceous glands were also observed.

A non-hydrodynamical model for acceleration of line-driven winds in active galactic nuclei

We present a study of the acceleration phase of line-driven winds in AGNs, in order to examine the physical conditions for the existence of such winds for a wide variety of initial conditions. We built a simple and fast non-hydrodynamic model, QWIND, where we assume that a wind is launched from the accretion disc at supersonic velocities of the order of a few 10^2 km/s and we concentrate on the subsequent supersonic phase. We show that this model can produce a wind with terminal velocities of the order of 10^4 km/s. There are three zones in the wind, only the middle one of which can launch a wind: in the inner zone the wind is too ionized and so experiences only the Compton radiation force which is not effective in accelerating gas. This inner failed wind however plays an important role in shielding the next zone, lowering the ionization parameter there. In the middle zone the lower ionization of the gas leads to a much larger radiation force and the gas achieves escape velocity This middle zone is quite thin (about 100 gravitational radii). The outer, third, zone is shielded from the UV radiation by the central wind zone and so does not achieve a high enough acceleration to reach escape velocity. We also describe a simple analytic approximation of our model, based on neglecting the effects of gravity during the acceleration phase. This analytic approach is in agreement with the results of the numerical code, and is a powerful way to check whether a radiation driven wind can be accelerated with a given set of initial parameters. Our analytical analysis and the fast QWIND model are in agreement with more complex hydrodynamical models, and allow an exploration of the dependence of the wind properties for a wide set of initial parameters: black hole mass, Eddington ratio, initial density profile, X-ray to UV ratio.

Circumstellar molecular composition of the oxygen-rich AGB star IK Tauri

<i>Context. <i/>The interstellar medium is enriched primarily by matter ejected from evolved low and intermediate mass stars. The outflow from these stars creates a circumstellar envelope in which a rich gas-phase chemistry takes place. Complex shock-induced non-equilibrium chemistry takes place in the inner wind envelope, dust-gas reactions and ion-molecule reactions alter the abundances in the intermediate wind zone, and the penetration of cosmic rays and ultraviolet photons dissociates the molecules in the outer wind region.<i>Aims. <i/>Little observational information exists on the circumstellar molecular abundance stratifications of many molecules. Furthermore, our knowledge of oxygen-rich envelopes is not as profound as for the carbon-rich counterparts. The aim of this paper is therefore to study the circumstellar chemical abundance pattern of 11 molecules and isotopologs (<sup>12<sup/>CO, <sup>13<sup/>CO, SiS, <sup>28<sup/>SiO, <sup>29<sup/>SiO, <sup>30<sup/>SiO, HCN, CN, CS, SO, SO<sub>2<sub/>) in the oxygen-rich evolved star IK Tau.<i>Methods. <i/>We have performed an in-depth analysis of a large number of molecular emission lines excited in the circumstellar envelope around IK Tau. The analysis is done based on a non-local thermodynamic equilibrium (non-LTE) radiative transfer analysis, which calculates the temperature and velocity structure in a self-consistent way. The chemical abundance pattern is coupled to theoretical outer wind model predictions including photodestruction and cosmic ray ionization. Not only the integrated line intensities, but also the line shapes are used as diagnostic tool to study the envelope structure.<i>Results. <i/>The deduced wind acceleration is much slower than predicted from classical theories. SiO and SiS are depleted in the envelope, possibly due to the adsorption onto dust grains. For HCN and CS a clear difference with respect to inner wind non-equilibrium predictions is found, either indicating uncertainties in the inner wind theoretical modeling or the possibility that HCN and CS (or the radical CN) participate in the dust formation. The low signal-to-noise profiles of SO and CN prohibit an accurate abundance determination; the modeling of high-excitation SO<sub>2<sub/> lines is cumbersome, possibly related to line misidentifications or problems with the collisional rates. The SiO isotopic ratios (<sup>29<sup/>SiO/<sup>28<sup/>SiO and <sup>30<sup/>SiO/<sup>28<sup/>SiO) point toward an enhancement in <sup>28<sup/>SiO compared to results of classical stellar evolution codes. Predictions for H<sub>2<sub/>O emission lines in the spectral range of the Herschel/HIFI mission are performed.

Deep Chandra observations of TeV binaries - I. LS I +61°303

We report on a 95ks Chandra observation of the TeV emitting High Mass X-ray Binary LSI +61 303, using the ACIS-S camera in Continuos Clocking mode to search for a possible X-ray pulsar in this system. The observation was performed while the compact object was passing from phase 0.94 to 0.98 in its orbit around the Be companion star (hence close to the apastron passage). We did not find any periodic or quasi-periodic signal (at this orbital phase) in a frequency range of 0.005-175 Hz. We derived an average pulsed fraction 3 sigma upper limit for the presence of a periodic signal of ~10% (although this limit is strongly dependent on the frequency and the energy band), the deepest limit ever reached for this object. Furthermore, the source appears highly variable in flux and spectrum even in this very small orbital phase range, in particular we detect two flares, lasting thousands of seconds, with a very hard X-ray spectrum with respect to the average source spectral distribution. The X-ray pulsed fraction limits we derived are lower than the pulsed fraction of any isolated rotational-powered pulsar, in particular having a TeV counterpart. In this scenario most of the X-ray emission of LSI +61 303 should necessarily come from the interwind or inner-pulsar wind zone shock rather than from the magnetosphere of the putative pulsar. Furthermore, we did not find evidence for the previously suggested extended X-ray emission (abridged).

Implication of adenylyl cyclase 8 in pathological smooth muscle cell migration occurring in rat and human vascular remodelling

Recently, we discovered on primary cell cultures that adenylyl cyclase type 8 (AC8) was involved in the transition of rat vascular smooth muscle cells (VSMCs) to an inflammatory phenotype. Here we demonstrate, in human vessels displaying early or advanced atherosclerotic lesions, that: (a) only intimal VSMCs strongly express AC8; and (b) very few AC8-positive VSMCs were detected in the medial layer, either in atherosclerotic or healthy arteries. Furthermore, over-expressing AC8 in primary rat VSMC cultures triggered the recolonization of a wounded zone and similar results were obtained in the presence of mitomycin, a potent inhibitor of proliferation. This phenomenon was prevented by silencing AC8. Indeed, in IL-1 beta-treated cells, AC8 silencing halted migration and decreased the matrix-metalloproteinases 2/9 secretion, known to be involved in VSMC migration. In vivo, we showed: (a) a pronounced up-regulation of AC8 expression in highly migrating VSMCs of the injured rat carotid artery; (b) an undetectable AC8 labelling in re-endothelized vessels where neo-intimal thickening had stopped. From our data, we conclude that AC8 expression appears closely linked to the properties developed by VSMCs in atherosclerosis and post-angioplasty neo-intima formation leading to restenosis. In addition, it reinforces the idea that VSMC responses to their cell environment greatly depend on the AC isoforms expressed and attributes a new role for AC8 in these pathological vascular processes.

THE OPTICAL STRUCTURE OF THE STARBURST GALAXY M82. II. NEBULAR PROPERTIES OF THE DISK AND INNER WIND

(Abridged) In this second paper of the series, we present the results from optical Gemini-North GMOS-IFU and WIYN DensePak IFU spectroscopic observations of the starburst and inner wind zones of M82, with a focus on the state of the T~10^4 K ionized interstellar medium. Our electron density maps show peaks of a few 1000 cm-3, local small spatial-scale variations, and a fall-off in the minor axis direction. We discuss the implications of these results with regards to the conditions/locations that may favour the escape of individual cluster winds. Our findings imply that the starburst environment is highly fragmented into a range of clouds from small/dense clumps with low filling factors (<1pc, n_e>10^4 cm-3) to larger filling factor, less dense gas. The near-constant state of the ionization state of the ~10^4 K gas throughout the starburst can be explained as a consequence of the small cloud sizes, which allow the gas conditions to respond quickly to any changes. We have examined in more detail both the broad (FWHM 150-350 km/s) line component found in Paper I that we associated with emission from turbulent mixing layers on the gas clouds, and the discrete outflow channel identified within the inner wind. The channel appears as a coherent, expanding cylindrical structure of length >120 pc and and width 35-50 pc and the walls maintain an approximately constant (but subsonic) expansion velocity of ~60 km/s. We use the channel to examine further the relationship between the narrow and broad component emitting gas within the inner wind. Within the starburst energy injection zone, we find that turbulent motions (as traced by the broad component) appear to play an increasing role with height.

Protective effect of erchonia laser in ischemic zone of burn wound

Protective effect of erchonia laser in ischemic zone of burn wound

Comparison between radarsat-1 SAR different data modes for oil spill detection by a fractal box counting algorithm

This work presents a modified formula for the fractal box counting dimension. The method is based on the utilisation of the probability distribution formula in the fractal box count. The purpose of this method is to use it for the discrimination of oil spill areas from the surrounding features, e.g. sea surface and look-alikes, using RADARSAT-1 SAR Wide beam mode (W1), Standard beam mode (S2) and Standard beam mode (S1) data acquisition under different wind speeds. The results show that the new formula is able to discriminate between oil spills and look-alike areas. The results also illustrate that the new fractal formula identifies well the deficiency of oil spills in pairs of S2 data. Further, there are no significant differences between fractal values of look-alikes, low wind zone, and current shear features in different beam modes for acquisition of RADARSAT-1 SAR data. The W1 mode data, however, show an error standard deviation of 0.002, thus performing a better discrimination of oil spills than the S1 and S2 mode data.

γ-RAY EMISSION FROM LS I +61 303: THE IMPACT OF BASIC SYSTEM UNCERTAINTIES

LS I +61 303 has been recently detected as a periodic γ-ray source by the Major Atmospheric Imaging Cerenkov (MAGIC) telescope. A distinctive orbital correlation of the γ-ray emission was found. This work shows that the range of uncertainties yet at hand in the orbital elements of the binary system LS I +61 303 as well as in the possible assumptions on the stellar wind of the optical companion play a non-negligible role in the computation of opacities to high-energy processes leading to γ-ray predictions. The geometry influence on the propagation and escape of γ-ray photons is explored. With this study at hand, we analyze the results of a pulsar wind zone model for the production of γ-rays and compare it with recent MAGIC observations.

Multi-waveband photons and high energy neutrinos from the Crab nebula

We study multi-waveband photon emission properties and possible high-energy neutrino emission from the Crab nebula produced by pulsar’s accelerated heavy nuclei. Heavy nuclei are accelerated in the outer magnetosphere of the Crab pulsar, and then suffer partial photo-disintegration in the non-thermal radiation fields of the pulsar’s outer magnetosphere. The products (protons and neutrons) of the photo-disintegration and surviving heavier nuclei are injected into the expanding supernova remnant in which the surviving heavier nuclei are further accelerated in the pulsar wind zone. In such a case, relativistic hadrons and leptons are produced; the hadrons consist of direct protons and the protons produced through neutron decay in nuclei disintegration process, the leptons consist of positrons accelerated in a realistic magneto-sonic lepton-heavy iron plasma shock, electrons from the neutron decay, direct electrons, and secondary electron/positron pairs in a proton-proton interaction. We calculate the photo-disintegration rate for a nucleus of atomic number A releasing i nucleons and the hadronic and leptonic spectra in the Crab nebula. We then calculate the multi-waveband nonthermal photon spectrum and possible high-energy neutrino spectrum of the Crab nebula. Our results indicate that the photon spectrum up to ∼10 TeV has a leptonic origin, but it is difficult to distinguish leptonic and hadronic origins of the spectrum with energy greater than 10 TeV.

Pulsar wind zone processes in LS 5039

Several γ-ray binaries have been recently detected by the high-energy stereoscopy array (HESS) and the major atmospheric imaging cerenkov (MAGIC) telescope. In at least two cases, their nature is unknown. In this paper we aim to provide the details of a theoretical model of close γ-ray binaries containing a young energetic pulsar as compact object, earlier presented in recent letters. This model includes a detailed account of the system geometry, the angular dependence of processes such as Klein–Nishina inverse Compton and γγ absorption in the anisotropic radiation field of the massive star, and a Monte Carlo simulation of leptonic cascading. We present and derive the used formulae and give all details about their numerical implementation, particularly, on the computation of cascades. In this model, emphasis is put in the processes occurring in the pulsar wind zone of the binary, since, as we show, opacities in this region can be already important for close systems. We provide a detailed study on all relevant opacities and geometrical dependencies along the orbit of binaries, exemplifying with the case of LS 5039. This is used to understand the formation of the very high-energy lightcurve and phase dependent spectrum. For the particular case of LS 5039, we uncover an interesting behavior of the magnitude representing the shock position in the direction to the observer along the orbit, and analyze its impact in the predictions. We show that in the case of LS 5039, the HESS phenomenology is matched by the presented model, and explore the reasons why this happens while discussing future ways of testing the model.

Perturbations of the ozone layer induced by intense atmospheric vortices

Based on the complex analysis of ozone fields in regions of tropical cyclogenesis, diagnostic and prognostic signatures of tropical cyclone (TC) evolution are revealed, manifesting themselves in the features of ozone field perturbations. We show that a typical increase in total ozone (TO) observed at the periphery of the developing tropical depression 2–4 days before its transformation into a tropical storm can be considered as a very early prognostic sign of a TC. Proposed and substantiated are the basic mechanisms determining the ozone variations observed at all the stages of TC development. A conceptual model of TC impact on the ozone layer was developed. Based on the analysis of Total Ozone Mapping Spectrometer (TOMS) data, a connection between TO field perturbation characteristics in the TC zones and the parameters controlling the TC energy was revealed. The characteristics of the ozone negative anomaly in the zone of TC action (effective size of the ozone anomaly and its extreme depth) were found to be determined by the effective dimensions of the storm and hurricane wind zones.

Superdiscs in radio galaxies: jet–wind interactions

Taking a clue from their sharp-edged (strip-like) morphology observed in several cases, a new mechanism is proposed for the formation of the emission gaps seen between the radio lobes of many powerful extragalactic double radio sources. Canonical understanding of the radio gaps invokes either blocking of the back-flowing lobe plasma by the denser interstellar medium (ISM) of the host galaxy, or "squeezing" of the radio bridge in the middle through buoyancy force exerted by either the ISM or the surrounding intra-cluster medium (ICM). These pictures encounter difficulties in explaining situations where the sharp-edged radio gaps associated with non-cluster radio galaxies have widths running into several tens (even hundreds) of kiloparsecs. More particularly, the required dense high-pressure ISM/ICM is likely to be lacking at least in the case of high-redshift radio galaxies. We propose here that radio emission gaps in at least such cases could arise from a dynamical interaction between the powerful thermal wind outflowing from the active galactic nucleus and the back-flowing synchrotron plasma in the two radio lobes, which occurs once the rapidly advancing jets have crossed out of the wind zone into the intergalactic medium. A simple analytical scheme is presented to explore the plausibility of the side-ways confinement of the thermal wind by the radio lobe pair, which would "freeze" pancake shaped conduits in the space, along which the hot, metal enriched wind from the AGN can escape (roughly orthogonal to the radio axis). Some other possible consequences of this scenario are pointed out.

GRB blastwaves through wind-shaped circumburst media

Context:A significant fraction of progenitors for long gamma-ray bursts (GRBs) are believed to be massive stars. The investigation of long GRBs therefore requires modeling the propagation of ultra-relativistic blastwaves through the circumburst medium surrounding massive stars. We simulate the expansion of an isotropic, adiabatic relativistic fireball into the wind-shaped medium around a massive GRB progenitor. The circumburst medium is composed of a realistically stratified stellar wind zone up to its termination shock, followed by a region of shocked wind characterized by a constant density. Aims: We followed the evolution of the blastwave through all its stages, including the extremely rapid acceleration up to a Lorentz factor 75 flow, its deceleration by interaction with stellar wind, its passage of the wind termination shock, until its propagation through shocked wind. Methods: We used the adaptive mesh refinement versatile advection code to follow the evolution of the fireball. Results: We show that the acceleration from purely thermal to ultra-relativistic kinetic regimes is abrupt and produces an internally structured blastwave. We resolved the structure of this ultra-relativistic shell in all stages, thanks to the adaptive mesh. We comment on the dynamical roles played by forward and reverse shock pairs in the phase of interaction with the free stellar wind and clearly identify the complex shock-dominated structure created when the shell crosses the terminal shock. Conclusion: We show that in our model where the terminal shock is taken relatively close to the massive star, the phase of self-similar deceleration of Blandford-McKee type can only be produced in the constant density, shocked wind zone.

Detection of extended very-high-energy γ-ray emission towards the young stellar cluster Westerlund 2

Results from gamma-ray observations by the H.E.S.S. telescope array in the direction of the young stellar cluster Westerlund 2 are presented. Stereoscopic imaging of Cherenkov light emission of gamma-ray induced showers in the atmosphere is used to study the celestial region around the massive Wolf-Rayet (WR) binary WR 20a. Spectral and positional analysis is performed using standard event reconstruction techniques and parameter cuts. The detection of a new gamma-ray source is reported from H.E.S.S. observations in 2006. HESS J1023-575 is found to be coincident with the young stellar cluster Westerlund 2 in the well-known HII complex RCW 49. The source is detected with a statistical significance of more than 9 sigma, and shows extension beyond a point-like object within the H.E.S.S. point-spread function. The differential gamma-ray spectrum of the emission region is measured over approximately two orders of magnitude in flux. The spatial coincidence between HESS J1023-575 and the young open cluster Westerlund 2, hosting e.g. the massive WR binary WR 20a, requires a look into a variety of potential models to account for the observed very-high-energy (VHE) gamma-ray emission. Considered emission scenarios include emission from the colliding wind zone of WR 20a, collective stellar winds from the extraordinary ensemble of hot and massive stars in the stellar cluster Westerlund 2, diffusive shock acceleration in the wind-blown bubble itself, and supersonic winds breaking out into the interstellar medium (ISM). The observed source extension argues against a single star origin of the observed VHE emission.

Pulsar Magnetohydrodynamic Winds

The acceleration and collimation/decollimation of relativistic magnetocentrifugal winds are discussed concerning a cold plasma from a strongly magnetized, rapidly rotating neutron star in a steady axisymmetric state based on ideal magnetohydrodynamics. There exist unipolar inductors associated with the field line angular frequency, $\alpha$, at the magnetospheric base surface, $S_{\mathrm{B}}$, with a huge potential difference between the poles and the equator, which drive electric current through the pulsar magnetosphere. Any “current line” must emanate from one terminal of the unipolar inductor and return to the other, converting the Poynting flux to the kinetic flux of the wind at finite distances. In a plausible field structure satisfying the transfield force-balance equation, the fast surface, $S_{\mathrm{F}}$, must exist somewhere between the subasymptotic and asymptotic domains, i.e., at the innermost point along each field line of the asymptotic domain of $\varpi_{\mathrm{A}}^2 / \varpi^2 \ll 1$, where $\varpi_{\mathrm{A}}$ is the Alfvénic axial distance. The criticality condition at $S_{\mathrm{F}}$ yields the Lorentz factor, $\gamma_{\mathrm{F}} = \mu_{\varepsilon}^{1/3}$, and the angular momentum flux, $\beta$, as the eigenvalues in terms of the field line angular velocity, $\alpha$, the mass flux per unit flux tube, $\eta$, and one of the Bernoulli integrals, $\mu_{\delta}$, which are assumed to be specifiable as the boundary conditions at $S_{\mathrm{B}}$. The other Bernoulli integral, $\mu_{\varepsilon}$, is related to $\mu_{\delta}$ as $\mu_{\varepsilon} = \mu_{\delta} [1-(\alpha^2 \varpi_{\mathrm{A}}^2 / c^2)]^{-1}$, and both $\mu_{\varepsilon}$ and $\varpi_{\mathrm{A}}^2$ are eigenvalues to be determined by the criticality condition at $S_{\mathrm{F}}$. Ongoing MHD acceleration is possible in the superfast domain. This fact may be helpful in resolving a discrepancy between the wind theory and the Crab-nebula model. It is argued that the “anti-collimation theorem” holds for relativistic winds, based on the curvature of field streamlines determined by the transfield force balance. The “theorem” combines with the “current-closure condition” as a global condition in the wind zone to produce a two-component “quasi-conical” field structure as one of the basic properties of MHD outflows of centrifugal origin in the pulsar magnetosphere.

Near-infrared interferometry of η Carinae with spectral resolutions of 1 500 and 12 000 using AMBER/VLTI

Aims. We present the first NIR spectro-interferometry of the LBV ? Carinae. The observations were performed with the AMBER instrument of the ESO Very Large Telescope Interferometer (VLTI) using baselines from 42 to 89 m. The aim of this work is to study the wavelength dependence of ? Car's optically thick wind region with a high spatial resolution of 5 mas (11 AU) and high spectral resolution. Methods: The observations were carried out with three 8.2 m Unit Telescopes in the K-band. The raw data are spectrally dispersed interferograms obtained with spectral resolutions of 1500 (MR-K mode) and 12 000 (HR-K mode). The MR-K observations were performed in the wavelength range around both the He I 2.059 ?m and the Br? 2.166 ?m emission lines, the HR-K observations only in the Br? line region. Results: The spectrally dispersed AMBER interferograms allow the investigation of the wavelength dependence of the visibility, differential phase, and closure phase of ? Car. In the K-band continuum, a diameter of 4.0±0.2 mas (Gaussian FWHM, fit range 28-89 m baseline length) was measured for ? Car's optically thick wind region. If we fit Hillier et al. (2001, ApJ, 553, 837) model visibilities to the observed AMBER visibilities, we obtain 50% encircled-energy diameters of 4.2, 6.5 and 9.6 mas in the 2.17 ?m continuum, the He I, and the Br? emission lines, respectively. In the continuum near the Br? line, an elongation along a position angle of 120°±15° was found, consistent with previous VINCI/VLTI measurements by van Boekel et al. (2003, A&A, 410, L37). We compare the measured visibilities with predictions of the radiative transfer model of Hillier et al. (2001), finding good agreement. Furthermore, we discuss the detectability of the hypothetical hot binary companion. For the interpretation of the non-zero differential and closure phases measured within the Br? line, we present a simple geometric model of an inclined, latitude-dependent wind zone. Our observations support theoretical models of anisotropic winds from fast-rotating, luminous hot stars with enhanced high-velocity mass loss near the polar regions. Based on observations collected at the European Southern Observatory, Paranal, Chile, within the AMBER guaranteed time programme 074.A-9025 and the VLTI science demonstration programme 074.A-9024.