Search Publications
Characteristics of Type-II Radio Bursts Associated with Flares and CMEs
Vršnak, Bojan; Umapathy, S.; Vasanth, V. +1 more
We present a statistical study of the characteristics of type-II radio bursts observed in the metric (m) and deca-hectometer (DH) wavelength range during 1997-2008. The collected events are divided into two groups: Group I contains the events of m-type-II bursts with starting frequency ≥ 100 MHz, and group II contains the events with starting freq…
The 5 hr Pulse Period and Broadband Spectrum of the Symbiotic X-Ray Binary 3A 1954+319
Fürst, Felix; Grinberg, Victoria; Pottschmidt, Katja +7 more
We present an analysis of the highly variable accreting X-ray pulsar 3A 1954+319 using 2005-2009 monitoring data obtained with INTEGRAL and Swift. This considerably extends the pulse period history and covers flaring episodes in 2005 and 2008. In 2006 the source was identified as one of only a few known symbiotic X-ray binaries (SyXBs), i.e., syst…
Spitzer Imaging of Herschel-atlas Gravitationally Lensed Submillimeter Sources
Smail, I.; Rodighiero, G.; Valtchanov, I. +49 more
We present physical properties of two submillimeter selected gravitationally lensed sources, identified in the Herschel Astrophysical Terahertz Large Area Survey. These submillimeter galaxies (SMGs) have flux densities >100 mJy at 500 µm, but are not visible in existing optical imaging. We fit light profiles to each component of the lensi…
Evolution of microflares associated with bright points in coronal holes and in quiet regions
Curdt, W.; Innes, D. E.; Teriaca, L. +1 more
Aims: We aim to find similarities and differences between microflares at coronal bright points found in quiet regions and coronal holes, and to study their relationship with large scale flares.
Methods: Coronal bright points in quiet regions and in coronal holes were observed with Hinode/EIS using the same sequence. Microflares associate…
Infrared Narrowband Tomography of the Local Starburst NGC 1569 with the Large Binocular Telescope/LUCIFER
Quirrenbach, A.; Rix, H. -W.; Brandner, W. +24 more
We used the near-IR imager/spectrograph LUCIFER mounted on the Large Binocular Telescope to image, with subarcsecond seeing, the local dwarf starburst NGC 1569 in the JHK bands and He I 1.08 µm, [Fe II] 1.64 µm, and Brγ narrowband filters. We obtained high-quality spatial maps of He I 1.08 µm, [Fe II] 1.64 µm, and Brγ emiss…
Measuring Gravitational Lensing Flexion in A1689 Using an Analytic Image Model
Schechter, Paul L.; Cain, Benjamin; Bautz, M. W.
Measuring dark matter substructure within galaxy cluster halos is a fundamental probe of the ΛCDM model of structure formation. Gravitational lensing is a technique for measuring the total mass distribution which is independent of the nature of the gravitating matter, making it a vital tool for studying these dark-matter-dominated objects. We pres…
Solar Cycle Variations in the Elemental Abundance of Helium and Fractionation of Iron in the Fast Solar Wind: Indicators of an Evolving Energetic Release of Mass from the Lower Solar Atmosphere
McIntosh, Scott W.; Kasper, Justin C.; Stevens, Michael L. +2 more
We present and discuss the strong correspondence between evolution of the emission length scale in the lower transition region and in situ measurements of the fast solar wind composition during the most recent solar minimum. We combine recent analyses demonstrating the variance in the (supergranular) network emission length scale measured by the S…
The X-ray spectral signatures from the complex circumnuclear regions in the Compton thick AGN NGC 424
Bianchi, S.; Piconcelli, E.; Iwasawa, K. +4 more
Aims: Most of our knowledge of the circumnuclear matter in Seyfert galaxies is based on the X-ray spectra of the brightest Compton-thick Seyfert 2 galaxies. The complete obscuration of the nuclear radiation in these sources allows us to study all the components arising from reprocessing of the primary continuum in the circumnuclear matter in …
The near-infrared radius-luminosity relationship for active galactic nuclei
Peterson, Bradley M.; Elvis, Martin; Karovska, Margarita +4 more
Black hole masses for samples of active galactic nuclei (AGNs) are currently estimated from single-epoch optical spectra. In particular, the size of the broad-line emitting region needed to compute the black hole mass is derived from the optical or ultraviolet continuum luminosity. Here we consider the relationship between the broad-line region si…
Radio Observations of the Solar Corona During an Eclipse
Ramesh, R.; Kathiravan, C.; Barve, Indrajit V. +1 more
We carried out radio observations of the solar corona at 170 MHz during the eclipse of 2008 August 1, from the Gauribidanur observatory located about 100 km north of Bangalore in India. The results indicate the presence of a discrete radio source of very small angular dimension (≈15'') in the corona from where the observed radiation originated.