Search Publications
Effects of Solar Surface Magnetic Fields on the Time-Distance Analysis of Solar Subsurface Meridional Flows
Liang, Zhi-Chao; Chou, Dean-Yi
The solar meridional flow in the deep convection zone can be measured with time-distance analysis. The difference between northward and southward acoustic wave travel times relates to the speed of meridional flow in the solar convection zone. We study the effects of surface magnetic field on the measured travel time difference in time-distance ana…
Cold ion escape from the Martian ionosphere
Fedorov, A.; Barabash, S.; Fränz, M. +3 more
We here report on new measurements of the escape flux of oxygen ions from Mars by combining the observations of the ASPERA-3 and MARSIS experiments on board the European Mars Express spacecraft. We show that in previous estimates of the total heavy ion escape flow the contribution of the cold ionospheric outflow with energies below 10 eV has been …
NGC 2276: a remarkable galaxy with a large number of ultraluminous X-ray sources
Wolter, Anna; Esposito, Paolo; Mapelli, Michela +2 more
The starbusting, nearby (D = 32.9 Mpc) spiral (Sc) galaxy NGC 2276 belongs to the sparse group dominated by the elliptical galaxy NGC 2300. NGC 2276 is a remarkable galaxy, as it displays a disturbed morphology at many wavelengths. This is possibly due to gravitational interaction with the central elliptical galaxy of the group. Previous ROSAT and…
Diagnostics of a Coronal Hole and the Adjacent Quiet Sun by The Hinode/EUV Imaging Spectrometer (EIS)
Srivastava, A. K.; Banerjee, D.; Kayshap, P.
A comparison between a coronal hole (CH) and the adjacent quiet Sun (QS) has been performed using the spectroscopic diagnostics of the Hinode/EUV Imaging Spectrometer (EIS). Based on spectral signatures, we identify the coronal funnels that play an important role in the formation and propagation of the nascent fast solar wind. From the observed li…
The initial mass function and star formation law in the outer disc of NGC 2915
Elson, E. C.; Blakeslee, John P.; Ford, H. +4 more
Using Hubble Space Telescope (HST) Advanced Camera for Surveys/Wide Field Camera data we present the photometry and spatial distribution of resolved stellar populations in the outskirts of NGC 2915, a blue compact dwarf with an extended H I disc. These observations reveal an elliptical distribution of red giant branch stars, and a clumpy distribut…
The environmental dependence of the structure of galactic discs in STAGES S0 galaxies: implications for S0 formation
Wolf, Christian; Aragón-Salamanca, Alfonso; Jogee, Shardha +4 more
We present an analysis of V-band radial surface brightness µ(r) profiles for S0 galaxies in different environments using Hubble Space Telescope/Advanced Camera for Surveys imaging and data from the Space Telescope A901/2 Galaxy Evolution Survey. Using a large sample of ∼280 field and cluster S0s, we find that in both environments, ∼25 per ce…
Spatially Resolved Energetic Electron Properties for the 21 May 2004 Flare from Radio Observations and 3D Simulations
Kontar, E. P.; Kuznetsov, A. A.
We investigated in detail the 21 May 2004 flare using simultaneous observations of the Nobeyama Radioheliograph, the Nobeyama Radiopolarimeters, the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI), and the Solar and Heliospheric Observatory (SOHO). The flare images in different spectral ranges reveal a well-defined single flaring loo…
Sh2-138: physical environment around a small cluster of massive stars
Bhatt, B. C.; Dewangan, L. K.; Ojha, D. K. +4 more
We present a multiwavelength study of the Sh2-138, a Galactic compact H II region. The data comprise of optical and near-infrared (NIR) photometric and spectroscopic observations from the 2-m Himalayan Chandra Telescope, radio observations from the Giant Metrewave Radio Telescope (GMRT), and archival data covering radio through NIR wavelengths. A …
The Role of the Ionosphere in Providing Plasma to the Terrestrial Magnetosphere—An Historical Overview
Chappell, Charles R.
Through the more than half century of space exploration, the perception and recognition of the fundamental role of the ionospheric plasma in populating the Earth's magnetosphere has evolved dramatically. A brief history of this evolution in thinking is presented. Both theory and measurements have unveiled a surprising new understanding of this imp…
NuSTAR and Multifrequency Study of the Two High-redshift Blazars S5 0836+710 and PKS 2149-306
Covino, S.; Tagliaferri, G.; Ghisellini, G. +15 more
Powerful blazars are flat-spectrum radio quasars whose emission is dominated by a Compton component peaking between a few hundred keV and a few hundred MeV. We observed two bright blazars, PKS 2149-306 at redshift z = 2.345 and S5 0836+710 at z = 2.172, in the hard X-ray band with the Nuclear Spectroscopic Telescope Array satellite. Simultaneous s…