Search Publications
Dynamo regime transition among Sun-like stars in M 34. A time evolution model of X-ray activity on the main sequence
Gondoin, P.
Context. The X-ray emission from late-type stars in open clusters exhibits two kinds of dependences on stellar rotation. While fast rotators have a relatively constant X-ray emission level, slower rotators show a decline of their X-ray emission with decreasing rotation rate. The physical significance of the transition between these two X-ray emiss…
Nonlinear Force-free Modeling of a Three-dimensional Sigmoid Observed on the Sun
Choe, G. S.; Inoue, S.; Magara, T. +1 more
In this work, we analyze the characteristics of the three-dimensional magnetic structure of a sigmoid observed over an active region (AR 10930) and followed by X-class flares. This is accomplished by combining a nonlinear force-free field (NLFFF) model of a coronal magnetic field and the high-resolution vector-field measurement of a photospheric m…
Analysis of GRB 080319B and GRB 050904 within the Fireshell Model: Evidence for a Broader Spectral Energy Distribution
Izzo, L.; Bernardini, M. G.; Patricelli, B. +5 more
The observation of GRB 080319B, with an isotropic energy E iso = 1.32 × 1054 erg, and GRB 050904, with E iso = 1.04 × 1054 erg, offers the possibility of studying the spectral properties of the prompt radiation of two of the most energetic gamma-ray bursts (GRBs). This allows us to probe the validity of …
Acoustic spectrum fitting for a large set of solar-like pulsators
Baudin, F.; Chaplin, W. J.; Elsworth, Y. +2 more
Asteroseismology provides the means both to constrain the global properties and to probe the internal structures of stars. Asteroseismic data are now available on large numbers of solar-type stars, thanks in particular to the CoRoT and Kepler space missions, and automated data-analysis pipelines are needed to provide efficient and timely results. …
Dielectric constant estimation of the uppermost Basal Unit layer in the martian Boreales Scopuli region
Orosei, Roberto; Pettinelli, Elena; Mattei, Elisabetta +3 more
An electromagnetic inversion model has been applied to echoes from the subsurface sounding Shallow Radar (SHARAD) to retrieve the dielectric properties of the uppermost Basal Unit (BU) beneath the North Polar Layered Deposits of Mars. SHARAD data have been carefully selected to satisfy the assumption of the inversion model which requires a stratig…
A Hubble Space Telescope Treasury Study of Star-forming Regions in the Local Group. II. Young Stellar Populations in M31
Bianchi, Luciana; Hodge, Paul; Kang, Yongbeom +1 more
We studied the young stellar populations of 22 star-forming regions in the Andromeda galaxy (M31), with Hubble Space Telescope (HST) multi-band imaging from far-UV to I. The regions were selected from Galaxy Evolution Explorer (GALEX) wide-field far-UV imaging; they sample different environments and galactocentric distances from 6 to 22 kpc. They …
A time-variable, phase-dependent emission line in the X-ray spectrum of the isolated neutron star RX J0822-4300
Caraveo, P. A.; Bignami, G. F.; Tiengo, A. +9 more
RX J0822-4300 is the central compact object associated with the Puppis A supernova remnant. Previous X-ray observations suggested RX J0822-4300 to be a young neutron star with a weak dipole field and a peculiar surface temperature distribution dominated by two antipodal spots with different temperatures and sizes. An emission line at 0.8 keV was a…
12 Years of X-Ray Variability in M31 Globular Clusters, Including 8 Black Hole Candidates, as Seen by Chandra
Murray, S. S.; Barnard, R.; Garcia, M.
We examined 134 Chandra observations of the population of X-ray sources associated with globular clusters (GCs) in the central region of M31. These are expected to be X-ray binary systems (XBs), consisting of a neutron star or black hole accreting material from a close companion. We created long-term light curves for these sources, correcting for …
Suzaku X-Ray Follow-up Observations of Seven Unassociated Fermi-LAT Gamma-Ray Sources at High Galactic Latitudes
Cheung, C. C.; Guillemot, L.; Kataoka, J. +8 more
We report on our second-year campaign of X-ray follow-up observations of unidentified Fermi Large Area Telescope (LAT) γ-ray sources at high Galactic latitudes (|b| > 10°) using the X-ray Imaging Spectrometer on board the Suzaku X-ray Observatory. In this second year of the project, seven new targets were selected from the First Fermi-LAT Catal…
A statistical study of energy release and transport midway between the magnetic reconnection and initial dipolarization regions in the near-Earth magnetotail associated with substorm expansion onsets
Paterson, W. R.; Miyashita, Y.; Saito, Y. +3 more
Our previous study showed that the energy release associated with substorm expansion onsets is the most significant midway between the magnetic reconnection and initial dipolarization regions (-12 > X > -18 RE in the premidnight sector) in the magnetotail. In the present paper, we have statistically studied the substorm-associated…