Search Publications
Testing the Anomalous Growth of the Black Hole Radius from AGN
Addazi, Andrea; Marciano, Antonino; Qian, Chenyang
We analyze constraints on the anomalous growth of the black hole radius or the black hole spin from the X-rays spectrum data of Active Galactic Nuclei (AGN) in NGC 5506. The anomalous growth of the mass or of the spin of a black hole may be unveiled within the framework of models of alternative gravity, including f(R)-gravity. Our phenomenological…
3D Electric Waveforms of Solar Wind Turbulence
Goetz, K.; Kellogg, P. J.; Monson, S. J.
Electric fields provide the major coupling between the turbulence of the solar wind and particles. A large part of the turbulent spectrum of fluctuations in the solar wind is thought to be kinetic Alfvén waves; however, whistlers have recently been found to be important. In this article, we attempt to determine the mode identification of individua…
Velocity shear Kelvin-Helmholtz instability with inhomogeneous DC electric field in the magnetosphere of Saturn
Kandpal, Praveen; Kaur, Rajbir; Pandey, R. S.
In this paper parallel flow velocity shear Kelvin-Helmholtz instability has been studied in two different extended regions of the inner magnetosphere of Saturn. The method of the characteristic solution and kinetic approach has been used in the mathematical calculation of dispersion relation and growth rate of K-H waves. Effect of magnetic field (…
Disentangling Blended K2 Photometry: Determining the Planetary Host Star
Kane, Stephen R.; Ciardi, David R.; Carter, Brad +1 more
The presence of companion stars, whether bound or unbound, make correct identification of the planetary hosting star difficult when a planet has been detected through a photometrically blended transiting event. We present an approach that uses a combination of light curve analysis and stellar modeling to disentangle eight K2 photometrically blende…
Discovery of the first Earth-sized planets orbiting a star other than our Sun in the Kepler-20 system
Torres, Guillermo; Fressin, François
Discovering other worlds the size of our own has been a long-held dream of astronomers. The transiting planets Kepler-20 e and Kepler-20 f, which belong to a multi-planet system, hold a very special place among the many groundbreaking discoveries of the Kepler mission because they finally realized that dream. The radius of Kepler-20 f is essential…
Raman-scattered laser guide-star photons to monitor the scatter of astronomical telescope mirrors
Mieske, Steffen; Milli, Julien; Kuntschner, Harald +26 more
The first observations of laser guide-star photons that are Raman-scattered by air molecules above the Very Large Telescope (VLT) were reported in June 2017. The initial detection came from the Multi-Unit Spectroscopic Explorer (MUSE) optical integral field spectrograph, following the installation of the 4 Laser Guide Star Facility (4LGSF) on Unit…
An XMM-Newton observation of the symbiotic star AG Peg: the X-ray emission after the end of its 2015 outburst
Zhekov, Svetozar A.; Tomov, Toma V.
We present an analysis of the XMM-Newton observation of the symbiotic star AG Peg, obtained after the end of its 2015 outburst. The X-ray emission of AG Peg is soft and of thermal origin. AG Peg is an X-ray source of class β of the X-ray sources among the symbiotic stars, whose X-ray spectrum is well matched by a two-temperature optically thin pla…
The Rosetta science operations and planning implementation
Almeida, Miguel; Pérez-Ayúcar, Miguel; Merritt, Donald +8 more
The international Rosetta mission was launched on 2nd March 2004 for a ten year journey to its target destination, comet 67P/Churyumov-Gerasimenko. Following the January 2014 exit from a 31 month hibernation period, Rosetta approached and rendezvoused with the comet in August 2014. On 12th November 2014, the Philae lander was deployed from Rosetta…
Exploring the Spectral Variability of the Ultraluminous X-Ray Source M81 X-6 with Suzaku and XMM-Newton
Jithesh, V.; Misra, Ranjeev
We present X-ray spectral variability studies of the ultraluminous X-ray source (ULX) M81 X-6 using Suzaku and XMM-Newton observations performed during 2001-2015. The spectra were first fitted by a standard multitemperature disk and a thermal Comptonization component that revealed spectral variability where the primary distinction is the change in…
Reply to comment "On the hydrogen escape: Comment to variability of the hydrogen in the Martian upper atmosphere as simulated by a 3D atmosphere-exosphere coupling by J.-Y. Chaufray et al." by V. Krasnopolsky, Icarus, 281, 262
Forget, F.; Chaufray, J. -Y.; Leblanc, F. +4 more
Krasnopolsky (2017) makes a careful review of our recent results about the Martian hydrogen content of the Martian upper atmosphere (Chaufray et al., 2015). We comment here on his two major points. First, he suggests that the non-thermal escape of H2, and particularly collisions with hot oxygen, not taken into account in our general cir…