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An XMM-Newton observation of IGR J16320-4751 = AX J1631.9-4752
Tomsick, J. A.; Rodriguez, J.; Walter, R. +4 more
The hard X-ray sensitivity and arcminute position accuracy of the recently launched International Gamma-Ray Laboratory (INTEGRAL) has lead to the (re-)discovery of a class of heavily absorbed hard X-ray sources lying in the Galactic plane. We report on the analysis of an XMM observation of such a source IGR J16320-4751 = AX J1631.9-4752. Our analy…
Twenty-three cycles of changing open solar magnetic flux
Lockwood, M.
This paper presents a comparison of various estimates of the open solar flux, deduced from measurements of the interplanetary magnetic field, from the aa geomagnetic index and from photospheric magnetic field observations. The first two of these estimates are made using the Ulysses discovery that the radial heliospheric field is approximately inde…
The X-Ray-faint Emission of the Supermassive Nuclear Black Hole of IC 1459
Zezas, A.; Elvis, M.; Pellegrini, S. +6 more
Chandra observations of the supermassive black hole in the nucleus of IC 1459 show a weak (LX=8×1040 ergs s-1, 0.3-8 keV), unabsorbed nuclear X-ray source, with a slope Γ=1.88+/-0.09, and no strong Fe K line at 6.4 keV (EW<382 eV). This describes a normal active galactic nucleus (AGN) X-ray spectrum but lies at …
The Multiphase Intergalactic Medium toward PKS 2155-304
Shull, J. Michael; Tumlinson, Jason; Giroux, Mark L.
We study the cluster of H I and O VI absorption systems and the claimed detection of O VIII absorption from the intergalactic medium at z~0.0567, associated with a group of galaxies toward the BL Lac object PKS 2155-304. As measured by spectrographs on the Hubble Space Telescope, Far Ultraviolet Spectroscopic Explorer, and Chandra, this system app…
Relation between the radial speed and theexpansion speed of coronal mass ejections
Schwenn, R.; Gonzalez, W. D.; Dal Lago, A.
We have selected 57 limb coronal mass ejections observed by LASCO during the period of January1997 to April 2001. We used the related EIT activity close to the limb to define these CMEs as "limbs". We measured the radial speed of the leading edge close to the center of these CMEs and the lateral expansion speed of the structures. Comparison of bot…
ISOCAM and molecular observations of the edge of the Horsehead nebula
Perault, M.; Olofsson, G.; Boulanger, F. +20 more
We present ISOCAM observations (5-18 mu m) of the Horsehead nebula, together with observations of the (J=1-0) and (J=2-1) transitions of 12CO, 13CO and C18O taken at the IRAM 30-m telescope. The Horsehead nebula presents a typical photodissociation region illuminated by the O9.5 V system sigma Ori. The ISOCAM emiss…
Spectroscopic and photometric studies of low-metallicity star-forming dwarf galaxies. III. SBS 1415+437
Thuan, T. X.; Izotov, Y. I.; Green, R. F. +4 more
We present a detailed optical spectroscopic and B, V, I, Hα photometric study of the metal-deficient cometary blue compact dwarf (BCD) galaxy SBS 1415+437. We derive an oxygen abundance 12 + log (O/H) = 7.61+/-0.01 and 7.62+/-0.03 (Z = Zsun/20) in the two brightest H II regions, among the lowest in BCDs. The helium mass fractions in the…
A strong decrease in Saturn's equatorial jet at cloud level
Hueso, R.; Sánchez-Lavega, A.; Rojas, J. F. +2 more
The atmospheres of the giant planets Jupiter and Saturn have a puzzling system of zonal (east-west) winds alternating in latitude, with the broad and intense equatorial jets on Saturn having been observed previously to reach a velocity of about 470ms-1 at cloud level. Globally, the location and intensity of Jupiter's jets are stable in …
The Kinematics and Physical Conditions of the Ionized Gas in Markarian 509. I. Chandra High Energy Grating Spectroscopy
Yaqoob, Tahir; Crenshaw, D. Michael; George, Ian M. +4 more
We observed the Seyfert 1 galaxy Mrk 509 for ~59 ks with the Chandra high-energy transmission gratings, simultaneously with HST/STIS and RXTE. Here we present a detailed analysis of the soft X-ray spectrum observed with Chandra. We measure strong absorption lines from He-like Ne and Mg and from H-like N, O, and Ne. Weaker absorption lines may also…
The Fundamental Plane and the evolution of the M/L ratio of early-type field galaxies up to z~ 1
Franx, M.; van Dokkum, P. G.; van de Ven, G.
We analyse the Fundamental Plane (FP) of 26 strong gravitational lens galaxies with redshifts up to z~ 1, using tabulated data from Kochanek et al. and Rusin et al. The lens galaxies effectively form a mass-selected sample of early-type galaxies in environments of relatively low density. We analyse the FP and its evolution in the rest-frame Johnso…