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Photometric properties of facular features over the activity cycle
Ermolli, I.; Giorgi, F.; Criscuoli, S. +2 more
Aims:We have analyzed the contrast of facular features identified in a large dataset of PSPT full-disk photometric images and SoHO/MDI magnetograms, obtained from 1998 to 2005. The aim of this work is to contribute to the improvement of semi-empirical atmospheric models and of irradiance studies and to understand the reasons for the controversial …
XMM-Newton broad-band observations of NGC 7582: N{H} variations and fading out of the active nucleus
Fiore, F.; Bianchi, S.; Guainazzi, M. +2 more
We present results from two XMM-Newton observations of the bright classical Seyfert 2 galaxy NGC 7582 taken four years apart (2001 May and 2005 April). We present the analysis of the high-resolution (0.3-1 keV) RGS and low-resolution (0.3-10 keV) EPIC spectroscopic data. A comparison with a 1998 BeppoSAX observation suggests that XMM-Newton caught…
Global Properties of the Globular Cluster Systems of Four Spiral Galaxies
Kundu, Arunav; Zepf, Stephen E.; Rhode, Katherine L. +1 more
We present results from a wide-field imaging study of the globular cluster (GC) systems of a sample of edge-on, Sb-Sc spiral galaxies ~7-20 Mpc away. This study is part of a larger survey of the ensemble properties of the GC populations of giant galaxies. We imaged the galaxies in BVR filters with large-format CCD detectors on the WIYN 3.5 m teles…
X-Ray Emission from PSR J1809-1917 and Its Pulsar Wind Nebula, Possibly Associated with the TeV Gamma-Ray Source HESS J1809-193
Pavlov, G. G.; Kargaltsev, O.
We detected the 50 kyr old pulsar J1809-1917, and resolved its pulsar wind nebula (PWN) with the Chandra X-Ray Observatory. The pulsar spectrum fits a power-law+blackbody (PL+BB) model, with a photon index Γpsr=1.2+/-0.6 and T~2 MK for nH=0.7×1022 cm-2. At a distance of 3.5 kpc, the luminosities of the P…
Draco, a flawless dwarf galaxy*
Chapman, S.; Martin, N. F.; Irwin, M. J. +2 more
The Draco dwarf spheroidal galaxy (dSph), with its apparent immense mass-to-light ratio and compact size, holds many clues to the nature of the enigmatic dark matter. Here we present deep photometric studies of this dwarf galaxy, undertaken with the MegaCam Camera at the Canada-France-Hawaii Telescope, the Wide Field Camera at the Isaac Newton Tel…
Three-dimensional Numerical Simulations of the Acoustic Wave Field in the Upper Convection Zone of the Sun
Kosovichev, A. G.; Parchevsky, K. V.
Results of numerical three-dimensional (3D) simulations of propagation of acoustic waves inside the Sun are presented. A linear 3D code which utilizes the realistic OPAL equation of state was developed. A modified convectively stable standard solar model with a smoothly joined chromosphere was used as a background model. A high-order dispersion re…
On the Remote Galactic Globular Cluster NGC 2419
Marconi, Marcella; Dall'Ora, Massimo; Ripepi, Vincenzo +8 more
We present a new, deep (V~26) study of the Galactic globular cluster NGC 2419 based on B, V, I time-series CCD photometry over about 10 years and extending beyond the cluster published tidal radius. We have identified 101 variable stars, of which 60 are new discoveries, doubling the known RR Lyrae stars and including 12 SX Phoenicis stars. The ave…
A Spectroscopic Study of Mass Outflows in the Interacting Binary RY Scuti
Gies, Douglas R.; Smith, Nathan; Gehrz, Robert D. +5 more
The massive interacting binary RY Scuti is an important representative of an active mass-transferring system that is changing before our eyes and which may be an example of the formation of a Wolf-Rayet star through tidal stripping. Utilizing new and previously published spectra, we present examples of how a number of illustrative absorption and e…
The Globular Cluster NGC 1978 in the Large Magellanic Cloud
Mucciarelli, Alessio; Ferraro, Francesco R.; Origlia, Livia +1 more
We have used deep, high-resolution Hubble Space Telescope ACS observations to image the cluster NGC 1978 in the Large Magellanic Cloud. This high-quality photometric data set allowed us to confirm the high ellipticity (ɛ~0.30+/-0.02) of this stellar system. The derived color-magnitude diagram allowed a detailed study of the main evolutionary seque…
Precision Fe Kα and Fe Kβ Line Spectroscopy of the Seyfert 1.9 Galaxy NGC 2992 with Suzaku
Haba, Yoshito; Okajima, Takashi; Serlemitsos, Peter J. +13 more
We present detailed time-averaged X-ray spectroscopy in the 0.5-10keV band of the Seyfert 1.9 galaxy NGC 2992 with the Suzaku X-ray Imaging Spectrometer (XIS). There is an Fe K line emission complex that we model with broad and narrow lines and we show that the intensities of the two components are decoupled at a confidence level >3σ The broad …