Search Publications
The Variable Near-infrared Counterpart of the Microquasar GRS 1758-258
Luque-Escamilla, Pedro L.; Martí, Josep; Muñoz-Arjonilla, Álvaro J.
We present a new study of the microquasar system GRS 1758-258 in the near-infrared domain based on archival observations with the Hubble Space Telescope and the NICMOS camera. In addition to confirming the near-infrared counterpart pointed out by Muñoz-Arjonilla et al., we show that this object displays significant photometric variability. From it…
Energy-dependent Evolution in IC10 X-1: Hard Evidence for an Extended Corona and Implications
Steiner, J. F.; Stevens, I. R.; Barnard, R. +3 more
We have analyzed a ~130 ks XMM-Newton observation of the dynamically confirmed black hole + Wolf-Rayet (BH+WR) X-ray binary (XB) IC10 X-1, covering ~1 orbital cycle. This system experiences periodic intensity dips every ~35 hr. We find that energy-independent evolution is rejected at a >5σ level. The spectral and timing evolution of IC10 X-1 ar…
Spectral Lag Features of GRB 060814 from Swift BAT and Suzaku Observations
Roychoudhury, Arundhati; Sarkar, Samir K.; Bhadra, Arunava
This work reports a study on the spectral lag of the prompt emission spectrum of a multi-pulse gamma-ray burst (GRB) GRB 060814 (z = 0.84) using the observations of the Swift Burst Alert Telescope and the Suzaku Wide Area Monitor. We found that the spectral lag for GRB 060814 is positive for the first two and the fourth pulses, while the third pul…
Diagnostics of the Solar Corona from Comparison between Faraday Rotation Measurements and Magnetohydrodynamic Simulations
Kasper, J. C.; Cohen, O.; Le Chat, G. +1 more
Polarized natural radio sources passing behind the Sun experience Faraday rotation as a consequence of the electron density and magnetic field strength in coronal plasma. Since Faraday rotation is proportional to the product of the density and the component of the magnetic field along the line of sight of the observer, a model is required to inter…
The Time-dependent Chemistry of Cometary Debris in the Solar Corona
Bryans, P.; Pesnell, W. D.
Recent improvements in solar observations have greatly progressed the study of sungrazing comets. They can now be imaged along the entirety of their perihelion passage through the solar atmosphere, revealing details of their composition and structure not measurable through previous observations in the less volatile region of the orbit further from…
Initiation and Early Evolution of the Coronal Mass Ejection on 2009 May 13 from Extreme-ultraviolet and White-light Observations
Reva, A. A.; Ulyanov, A. S.; Kuzin, S. V. +1 more
We present the results of the observations of a coronal mass ejection (CME) that occurred on 2009 May 13. The most important feature of these observations is that the CME was observed from the very early stage (the solar surface) up to a distance of 15 solar radii (R ⊙). Below 2 R ⊙, we used the data from the TESIS extreme-ul…
Initial Results from NuSTAR Observations of the Norma Arm
Hailey, Charles J.; Mori, Kaya; Bauer, Franz E. +13 more
Results are presented for an initial survey of the Norma Arm gathered with the focusing hard X-Ray Telescope NuSTAR. The survey covers 0.2 deg2 of sky area in the 3-79 keV range with a minimum and maximum raw depth of 15 ks and 135 ks, respectively. Besides a bright black-hole X-ray binary in outburst (4U 1630-47) and a new X-ray transi…
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…
Verification of the Helioseismology Travel-time Measurement Technique and the Inversion Procedure for Sound Speed Using Artificial Data
Kosovichev, A. G.; Parchevsky, K. V.; Zhao, J. +1 more
We performed three-dimensional numerical simulations of the solar surface acoustic wave field for the quiet Sun and for three models with different localized sound-speed perturbations in the interior with deep, shallow, and two-layer structures. We used the simulated data generated by two solar acoustics codes that employ the same standard solar m…
The Dynamic Character of the Polar Solar Wind
Jackson, B. V.; Buffington, A.; Hick, P. P. +1 more
The Solar and Heliospheric Observatory (SOHO) Large Angle and Spectrometric Coronagraph C2 and Solar Terrestrial Relations Observatory (STEREO) COR2A coronagraph images, when analyzed using correlation tracking techniques, show a surprising result in places ordinarily thought of as "quiet" solar wind above the poles in coronal hole regions. Instea…