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GRBs and the 511 keV emission of the Galactic bulge
Paul, J.; Cassé, M.; Parizot, E. +1 more
We consider the phenomenology of the 511 keV emission in the Galactic bulge, as recently observed by INTEGRAL, and propose a model in which the positrons are produced by gamma-ray bursts (GRB) associated with mini-starbursts in the central molecular zone (CMZ). We show that the positrons can easily diffuse across the bulge on timescales of ∼ 10
Links between magnetic fields and plasma flows in a coronal hole
Marsch, E.; Xia, L. D.; Wiegelmann, T.
We compare the small-scale features visible in the Ne viii Doppler-shift map of an equatorial coronal hole (CH) as observed by SUMER with the small-scale structures of the magnetic field as constructed from a simultaneous photospheric magnetogram by a potential magnetic-field extrapolation. The combined data set is analysed with respect to the sma…
Observations of the Transient X-ray Pulsar KS 1947+300 by the INTEGRAL and RXTE Observatories
Tsygankov, S. S.; Lutovinov, A. A.
We analyze the observations of the X-ray pulsar KS 1947+300 performed by the INTEGRAL and RXTE observatories over a wide (3 100 keV) X-ray energy range. The shape of the pulse profile was found to depend on the luminosity of the source. Based on the model of a magnetized neutron star, we study the characteristics of the pulsar using the change in …
Magnetic Free Energies of Breakout Coronal Mass Ejections
Antiochos, Spiro K.; DeVore, C. Richard
A critical issue in understanding and eventually predicting coronal mass ejections (CMEs) is determining the magnetic free energy that can drive the explosive eruption. We present calculations of this free energy for the breakout CME model, which postulates that the preeruption magnetic topology is a multipolar field with a null point in the coron…
The Ages of Globular Clusters in NGC 4365 Revisited with Deep HST Observations
Vesperini, Enrico; Kundu, Arunav; Zepf, Stephen E. +6 more
We present new Hubble Space Telescope (HST) NIC3, near-infrared H-band photometry of globular clusters (GCs) around NGC 4365 and NGC 1399 in combination with archival HST WFPC2 and ACS optical data. We find that NGC 4365 has a number of globular clusters with bluer optical colors than expected for their red optical-to-near-infrared colors and an o…
The Absorption Spectrum of High-Density Stellar Ejecta in the Line of Sight to η Carinae
Gull, T. R.; Nielsen, K. E.; Bruhweiler, F. +3 more
Using the high-dispersion near-UV (NUV) mode of the Space Telescope Imaging Spectrograph (STIS) aboard the Hubble Space Telescope (HST) to observe η Carinae, we have resolved and identified over 500 sharp circumstellar absorption lines of iron-group singly ionized and neutral elements with ~20 velocity components ranging from -146 to -585 km s
Calibration of the Planetary Fourier Spectrometer long wavelength channel
Piccioni, G.; Grassi, D.; Khatuntsev, I. +17 more
The Planetary Fourier Spectrometer (PFS) experiment on board the Mars Express mission has two channels covering the 1.2-5 µm (SWC) and the 5-50 µm (LWC). The Long Wavelength Channel (LWC) measures the thermal emission spectrum of Mars between 200 and 2000 cm -1 with a spectral resolution of 1.4 cm -1, in absence o…
A study of bright Southern long period variables
Lebzelter, T.; Hinkle, K. H.; Wood, P. R. +2 more
In this paper we present radial velocity curves of AGB variables that exhibit various kinds of anomalies: semiregular variables (SRVs) with typical mira periods, SRVs exceeding the mira 2.5 mag amplitude limit, miras with secondary maxima in their light curves, and a SRV with a long secondary period. The stars with reliable Hipparcos parallaxes fr…
HST/WFPC2 morphologies and bar structures of field galaxies at 0.4 < z < 1
Flores, H.; Hammer, F.; Assémat, F. +2 more
To address how the galaxy Hubble sequence is established and what physical processes are involved, we studied morphological properties and internal structures of field galaxies in the past (0.4<z<1). In addition to structural parameters derived from bulge+disk decomposition, Zheng et al. (2004, A&A, 421, 847) introduced color maps in rec…
Star-forming accretion flows and the low-luminosity nuclei of giant elliptical galaxies
Tan, Jonathan C.; Blackman, Eric G.
The luminosities of the centres of nearby elliptical galaxies are very low compared to models of thin disc accretion on to their black holes at the Bondi rate, typically a few hundredths to a few tenths of a solar mass per year. This has motivated models of inefficiently radiated accretion that invoke weak electron-ion thermal coupling, and/or inh…