Search Publications
On Thermal-Pulse-Driven Plasma Flows in Coronal Funnels as Observed by the Hinode/ EUV Imaging Spectrometer (EIS)
Srivastava, A. K.; Konkol, P.; Murawski, K. +2 more
Using one-arcsecond-slit-scan observations from the Hinode/EUVImagingSpectrometer (EIS) on 5 February 2007, we find the plasma outflows in the open and expanding coronal funnels at the eastern boundary of AR 10940. The Doppler-velocity map of Fe XII 195.120 Å shows the diffuse closed-loop system to be mostly red-shifted. The open arches (funnels) …
A Herschel and BIMA study of the sequential star formation near the W 48A H II region
Hill, T.; White, G. J.; André, Ph. +22 more
We present the results of Herschel HOBYS (Herschel imaging survey of OB Young Stellar objects) photometric mapping combined with Berkeley Illinois Maryland Association (BIMA) observations and additional archival data, and perform an in-depth study of the evolutionary phases of the star-forming clumps in W 48A and their surroundings. Age estimates …
The XMM-Newton Bright Survey sample of absorbed quasars: X-ray and accretion properties
Vignali, C.; Ballo, L.; Carrera, F. J. +5 more
Although absorbed quasars are extremely important for our understanding of the energetics of the Universe, the main physical parameters of their central engines are still poorly known. In this work, we present and study a complete sample of 14 quasars (QSOs) that are absorbed in the X-rays (column density NH > 4 × 1021 cm<…
Quantitative Method for the Optimal Subtraction of Continuum Emission from Narrow-band Images: Skewness Transition Analysis
Dickinson, Mark; Calzetti, Daniela; Hong, Sungryong
We present an objective method to remove the stellar continuum emission from narrow-band images to derive emission-line images. The method is based on the skewness of the pixel histogram of the residual images. Specifically, we exploit a transition in the skewness of the signal in the continuum-subtracted image, which appears when the image change…
The Emerging Planetary Nebula CRL 618 and its Unsettled Central Star(s)
Velázquez, P. F.; Balick, B.; Kwitter, K. B. +2 more
We report deep long-slit emission-line spectra, the line flux ratios, and Doppler profile shapes of various bright optical lines. The low-ionization lines (primarily [N I], [O I], [S II], and [N II]) originate in shocked knots, as reported by many previous observers. Dust-scattered lines of higher ionization are seen throughout the lobes but do no…
The effective temperatures of O-type stars from UV spectroscopy
Bianchi, Luciana; Garcia, Miriam
We present an analysis of high resolution spectra in the far-UV - UV range (∼905-2000 Å) with non-LTE, spherical, hydrodynamical, line-blanketed models, of three O-type Galactic stars, and derive their photospheric and wind parameters. These data extend previously analyzed samples and fill a gap in spectral type coverage. The combined sample confi…
Timing studies of X Persei and the discovery of its transient quasi-periodic oscillation feature
Serim, M. M.; Şahiner, Ş.; Baykal, A. +3 more
We present a timing analysis of X Persei (X Per) using observations made between 1998 and 2010 with the Proportional Counter Array (PCA) onboard the Rossi X-ray Timing Explorer (RXTE) and with the INTEGRAL Soft Gamma-Ray Imager (ISGRI). All pulse arrival times obtained from the RXTE-PCA observations are phase-connected and a timing solution is obt…
Rummaging inside the Eskimo's parka: variable asymmetric planetary nebula fast wind and a binary nucleus?
Prinja, R. K.; Urbaneja, M. A.
We report on high-resolution optical time series spectroscopy of the central star of the `Eskimo' planetary nebula NGC 2392. Data sets were secured with the European Southern Observatory (ESO) 2.3 m in 2006 March and Canada-France-Hawaii Telescope (CFHT) 3.6 m in 2010 March to diagnose the fast wind and photospheric properties of the central star.…
Hard X-ray continuum from lunar surface: Results from High Energy X-ray spectrometer (HEX) onboard Chandrayaan-1
Banerjee, D.; Sreekumar, P.; Sudhakar, M. +10 more
The High Energy X-ray spectrometer (HEX) on Chandrayaan-1 was designed to study the photon emission in the range of 30-270 keV from naturally occurring radioactive decay of 238U and 232Th series nuclides from the lunar surface. The primary objective of HEX was to study the transport of volatiles on the lunar surface using rad…
The main pillar: Assessment of space weather observational asset performance supporting nowcasting, forecasting, and research to operations
St. Cyr, O. C.; Hesse, M.; Posner, A.
Space weather forecasting critically depends upon availability of timely and reliable observational data. It is therefore particularly important to understand how existing and newly planned observational assets perform during periods of severe space weather. Extreme space weather creates challenging conditions under which instrumentation and space…