Crowded field 3D spectroscopy of LBV candidates in M33

We present integral field spectroscopy of the LBV candidate stars B416 and v532 in the local group galaxy M33. B416 is surrounded by an elongated ring-like nebula, which has a projected radius of 20x30 pc. From the datacube we create ionization and radial velocity maps of the nebula. The excitation of the gas decreases towards the outer part of the ring, while the inner part of the nebula is filled with a more excited gas. In the EW direction the ring is seen to expand with a maximum projected velocity amplitude of about 40 km/s. The eastern part approaches the observer. We estimate the nebula dynamical lifetime 8*10E5 years. It could be a residual MS bubble, which indicates a main-sequence or pre-LBV status of the star. We classify B416 as an "iron star" or B[e]-supergiant. In v532 an elongated nebula has been marginally detected. The total projected size of the nebula along the main axis is 30 pc, and the total radial velocity gradient is 44+/-11 km/s. v532 exhibits both strong photometric and spectral variability. At the time of our observations it was in an intermediate brightness state with a rich nitrogen spectrum. We classify v532 as an LBV, showing LBV Ofpe/WN transitions. We stress the importance of integral field spectroscopy as the optimal technique for studying nebulae and the evolution of LBV-like stars in nearby galaxies.Comment: 12 pages, 10 Postscript figures, A&A accepte

XMM-Newton observations of a superbubble in N 158 in the LMC

Aims: We study the diffuse X-ray emission observed in the field of view of the pulsar B 0540-69 in the Large Magellanic Cloud (LMC) by XMM-Newton. We want to understand the nature of this soft diffuse emission, which coincides with the superbubble in the HII region N 158, and improve our understanding of the evolution of superbubbles. Methods: We analyse the XMM-Newton spectra of the diffuse emission. Using the parameters obtained from the spectral fit, we perform calculations of the evolution of the superbubble. The mass loss and energy input rates are based on the initial mass function (IMF) of the observed OB association inside the superbubble. Results: The analysis of the spectra shows that the soft X-ray emission arises from hot shocked gas surrounded by a thin shell of cooler, ionised gas. We show that the stellar winds alone cannot account for the energy inside the superbubble, but the energy release of 2 - 3 supernova explosions in the past ~1 Myr provides a possible explanation. Conclusions: The combination of high sensitivity X-ray data, allowing spectral analysis, and analytical models for superbubbles bears the potential to reveal the evolutionary state of interstellar bubbles, if the stellar content is known.Comment: 7 pages. Accepted for publication in A&

Numerical Modeling of Eta Carinae Bipolar Outflows

In this paper, we present two-dimensional gas dynamic simulations of the formation and evolution of the eta-Car bipolar outflows. Adopting the interacting nonspherical winds model, we have carried out high-resolution numerical simulations, which include explicitly computed time-dependent radiative cooling, for different possible scenarios of the colliding winds. In our simulations, we consider different degrees of non-spherical symmetry for the pre-outburst wind and the great eruption of the 1840s presented by the eta-Car wind. From these models, we obtain important differences in the shape and kinematical properties of the Homunculus structure. In particular, we find an appropriate combination of the wind parameters (that control the degree of non-spherical symmetry) and obtain numerical experiments that best match both the observed morphology and the expansion velocity of the eta-Car bipolar shell. In addition, our numerical simulations show the formation of a bipolar nebula embedded within the Homunculus (the little Homunculus) developed from a secondary eruptive event suffered by the star in the 1890s, and also the development of tenuous, high velocity ejections in the equatorial region that result from the impact of the eruptive wind of the 1840s with the pre-outburst wind and that could explain some of the high speed features observed in the equatorial ejecta. The models were, however, unable to produce equatorial ejections associated to the second eruptive event.Comment: 33 pages, 9 figures, accepted by the Astrophysical Journa

One Hundred Years of Observations of the Be Star HDE 245770 (the X-ray Binary A0535+26/V725 Tau): The End of an Active Phase

UBV observations of the X-ray binary system A0535+26/V725 Tau at the Crimean Station of the Sternberg Astronomical Institute in 1980-1998 are presented. Based on our and published data, we analyze the photometric history of the star from 1898.Comment: Translated from Pis'ma Astronomicheskii Zhurnal, Vol. 26, No. 1, 2000, pp. 13-2

The constant-velocity highly collimated outflows of the planetary nebula He 2-90

We present high-dispersion echelle spectroscopic observations and a narrow-band [N II] image of the remarkable jet-like features of He 2-90. They are detected in the echelle spectra in the H-alpha and [N II] lines but not in other nebular lines. The [N II]/H-alpha ratio is uniformly high, ~1. The observed kinematics reveals bipolar collimated outflows in the jet-like features and shows that the southeast (northwest) component expands towards (away from) the observer at a remarkably constant line-of-sight velocity, 26.0+-0.5 km/s. The observed expansion velocity and the opening angle of the jet-like features are used to estimate an inclination angle of ~5 degrees with respect to the sky plane and a space expansion velocity of ~290 km/s. The spectrum of the bright central nebula reveals a profusion of Fe lines and extended wings of the H-alpha line, similar to those seen in symbiotic stars and some young planetary nebulae that are presumed to host a mass-exchanging binary system. If this is the case for He 2-90, the constant velocity and direction of the jets require a very stable dynamic system against precession and warping.Comment: 8 pages (emulate ApJ), 5 figure, 1 tabl

Changing women's roles, changing environmental knowledges: evidence from Upper Egypt

The aim of this paper is to investigate the ways in which changing gender roles in a Bedouin community in Upper Egypt, brought about by settlement over the last 20 years on the shores of Lake Nasser, have impacted on the accumulation and development of indigenous environmental knowledges by Bedouin women. The research was carried out among four groups of Ababda Bedouin in the Eastern Desert of Egypt and involved in-depth monthly conversations carried out over a period of 12 months. The main conclusions of the study are that the women of the study area have had to develop new knowledges which, in some cases, are now different from those held by men because of the different economic circumstances in which many find themselves; that these knowledges are fluid, dynamic and ever-changing with their own internal dynamism; and that socially constructed notions of gender are vital in the development process, notions that are sensitive to both men's and women's interests and their interrelationships

Abundances and Physical Conditions in the Warm Neutral Medium Towards mu Columbae

We present ultraviolet interstellar absorption line measurements for the sightline towards the O9.5 V star mu Columbae obtained with the Goddard High Resolution Spectrograph (GHRS) on board the Hubble Space Telescope. These archival data represent the most complete GHRS interstellar absorption line measurements for any line of sight towards an early-type star. The 3.5 km/s resolution of the instrument allow us to accurately derive the gas-phase column densities of many important ionic species in the diffuse warm neutral medium using a combination of apparent column density and component fitting techniques, and we study in detail the contamination from ionized gas along this sightline. The low-velocity material shows gas-phase abundance patterns similar to the warm cloud (cloud A) towards the disk star zeta Oph, while the component at v = +20.1 km/s shows gas-phase abundances similar to those found in warm halo clouds. We find the velocity-integrated gas-phase abundances of Zn, P, and S relative to H along this sightline are indistinguishable from solar system abundances. We discuss the implications of our gas-phase abundance measurements for the composition of interstellar dust. The relative ionic column density ratios of the intermediate velocity components show the imprint both of elemental incorporation into grains and (photo)ionization. The components at v = -30 and -48 km/s along this sightline likely trace shocked gas with very low hydrogen column densities. Appendices include a new derivation of the GHRS instrumental line spread function, and a new very accurate determination of the total H I column along this sightline. (Abridged)Comment: Accepted for publication in the Astrophysical Journal. 80 pages including 19 embedded figures and 12 embedded tables. Version with higher resolution figures can be downloaded from http://fuse.pha.jhu.edu/~howk/Papers/papers.htm

Description of the Scenario Machine

We present here an updated description of the "Scenario Machine" code. This tool is used to carry out a population synthesis of binary stars. Previous version of the description can be found at http://xray.sai.msu.ru/~mystery//articles/review/contents.htmlComment: 32 pages, 3 figures. Corrected typo

Spectral Energy Distributions of Be and Other Massive Stars

We present spectrophotometric data from 0.4 to 4.2 microns for bright, northern sky, Be stars and several other types of massive stars. Our goal is to use these data with ongoing, high angular resolution, interferometric observations to model the density structure and sky orientation of the gas surrounding these stars. We also present a montage of the H-alpha and near-infrared emission lines that form in Be star disks. We find that a simplified measurement of the IR excess flux appears to be correlated with the strength of emission lines from high level transitions of hydrogen. This suggests that the near-IR continuum and upper level line fluxes both form in the inner part of the disk, close to the star.Comment: 2010, PASP, 122, 37

Wind Accretion and State Transitions in Cygnus X-1

We present the results of a spectroscopic monitoring program (from 1998 to 2002) of the H-alpha emission strength in HDE 226868, the optical counterpart of the black hole binary, Cyg X-1. The H-alpha profiles consist of (1) a P Cygni component associated with the wind of the supergiant, (2) emission components that attain high velocity at the conjunctions and that probably form in enhanced outflows both towards and away from the black hole, and (3) an emission component that moves in anti-phase with the supergiant's motion. We argue that the third component forms in accreted gas near the black hole, and the radial velocity curve of the emission is consistent with a mass ratio of M_X / M_opt = 0.36 +/- 0.05. We find that there is a general anti-correlation between the H-alpha emission strength and X-ray flux in the sense that when the H-alpha emission is strong (W_\lambda < -0.5 Angstroms) the X-ray flux is weaker and the spectrum harder. On the other hand, there is no correlation between H-alpha emission strength and X-ray flux when H-alpha is weak. During the low/hard X-ray state, the strong wind is fast and the accretion rate is relatively low, while in the high/soft state the weaker, highly ionized wind attains only a moderate velocity and the accretion rate increases. We argue that the X-ray transitions from the normal low/hard to the rare high/soft state are triggered by episodes of decreased mass loss rate in the supergiant donor star.Comment: 45 pages, 16 figures, ApJ, in pres