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Stellar Disks and Halos of Edge-on Spiral Galaxies: NGC 891, NGC 4144, and NGC 4244
Tikhonov, N. A.; Galazutdinova, O. A.
Stellar photometry of images from the ACS and WFPC2 cameras on the Hubble Space Telescope (HST) is used to study the star composition and spatial distribution of stars in three edge-on visible spiral galaxies: NGC 891, NGC 4144, and NGC 4244. Measurements of the surface number density of old stars revealed two stellar subsystems in these galaxies:…
A Search for Discrete X-Ray Spectral Features in a Sample of Bright γ-Ray Burst Afterglows
Sako, Masao; Harrison, Fiona A.; Rutledge, Robert E.
We present uniform, detailed spectral analyses of γ-ray burst (GRB) X-ray afterglows observed with ASCA, BeppoSAX, Chandra, and XMM-Newton and critically evaluate the statistical significances of X-ray emission and absorption features in these spectra. The sample consists of 21 X-ray afterglow observations up to and including that of GRB 040106 wi…
Massive elliptical galaxies in X-rays: The role of late gas accretion
Matteucci, F.; Kawata, D.; Gibson, B. K. +1 more
We present a new chemical evolution model meant to be a first step in the self-consistent study of both optical and X-ray properties of elliptical galaxies. Detailed cooling and heating processes in the interstellar medium (ISM) are taken into account using a mono-phase one-zone treatment which allows a more reliable modelling of the galactic wind…
Normal Nearby Galaxies
Tuffs, Richard J.; Popescu, Cristina C.; Sauvage, Marc
Following on from IRAS, ISO has provided a huge advancement in our knowledge of the phenomenology of the infrared (IR) emission of normal galaxies and the underlying physical processes. Highlights include the discovery of an extended cold dust emission component, present in all types of gas-rich galaxies and carrying the bulk of the dust luminosit…
X-rays from α Centauri - The darkening of the solar twin
Schmitt, J. H. M. M.; Robrade, J.; Favata, F.
We present first results from five XMM-Newton observations of the binary system α Centauri, which has been observed in snapshot like exposures of roughly two hours each during the last two years. In all our observations the X-ray emission of the system is dominated by α Cen B, a K1 star. The derived light curves of the individual components reveal…
X-ray synchrotron emission from the oblique shock in the jet of the powerful radio galaxy 3C346
Birkinshaw, M.; Worrall, D. M.
We report the first detection, with Chandra, of X-ray emission from the jet of the powerful narrow-line radio galaxy 3C346. X-rays are detected from the bright radio and optical knot at which the jet apparently bends by approximately 70°. The Chandra observation also reveals a bright galaxy-scale atmosphere within the previously known cluster and …
On the widths and ratios of Mg X 609.79 and 624.94 Å lines in polar off-limb regions
Doyle, J. G.; Banerjee, D.; O'Shea, E.
Using measurements of Mg X 609.78 and 624.94 Å lines from the Coronal Diagnostic Spectrometer (CDS) on board SOHO, we seek to examine the variation of line width and line ratio in regions far off-limb at the Northern pole of the Sun. It is found that above ≈1150´´ the ratio of the two coronal Mg X resonance lines reduces to values that might be ex…
ISO's Contribution to the Study of Clusters of Galaxies
Metcalfe, Leo; Fadda, Dario; Biviano, Andrea
Starting with nearby galaxy clusters like Virgo and Coma, and continuing out to the furthest galaxy clusters for which ISO results have yet been published (z = 0.56), we discuss the development of knowledge of the infrared and associated physical properties of galaxy clusters from early IRAS observations, through the “ISO-era” to the present, in o…
Kinematic Structure of H2 and [Fe II] in the Bipolar Planetary Nebula M2-9
Smith, Nathan; Gehrz, Robert D.; Balick, Bruce
We present new high-dispersion, long-slit, infrared (IR) spectra of the double-shell bipolar planetary nebula M2-9 in the emission lines [Fe II] λ16435 and H2v=1-0 S(1) λ21218. H2 spectra reveal for the first time the kinematic structure of the outer shell in M2-9. Kinematics of the inner shell, traced by [Fe II], resemble th…
UV Continuum Spectroscopy of a 6L* z = 5.5 Starburst Galaxy1,
Rosati, P.; Fazio, G. G.; van der Wel, A. +10 more
We have obtained a high S/N (22.3 hr integration) UV continuum VLT FORS2 spectrum of an extremely bright (z850=24.3) z = 5.515 +/- 0.003 star-forming galaxy (BD38) in the field of the z = 1.24 cluster RDCS 1252.9-2927. From HST Advanced Camera for Surveys imaging, this object was selected as a potential z ~ 6 Lyman break galaxy (LBG) ba…