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Evidence of Magnetoacoustic Oscillations above the Brightened and Magnetically Active Quiet-Sun
Srivastava, A. K.; Dwivedi, B. N.
We study the near photospheric Fe I 6302 Å (V-component) and chromospheric Ca II H 3968 Å radiance oscillations in the lower solar atmosphere above the four brightened and magnetically active regions of the quiet-Sun as observed by the solar optical telescope onboard Hinode. At the chosen locations (L1, L3, L4), we obtain the statistically signifi…
Analysis of luminosity distributions of strong lensing galaxies: subtraction of diffuse lensed signal
Magain, P.; Biernaux, J.; Hauret, C.
Context. Strong gravitational lensing gives access to the total mass distribution of galaxies. It can unveil a great deal of information about the lenses' dark matter content when combined with the study of the lenses' light profile. However, gravitational lensing galaxies, by definition, appear surrounded by lensed signal, both point-like and dif…
Music and astronomy. II. Unitedsoundofcosmos
Caballero, J. A.; Arias, A.; Machuca, J. J. +1 more
We have been congratulated on the stage by a Nobel laureate (he was our curtain raiser), shocked audiences in rock concerts, written monthly on Musica Universalis , made the second concert in 3D in Spain after Kraftwerk and broadcasted it live in Radio 3, mixed our music with poetry read aloud by scientists, composed the soundtracks of CARMENES, Q…
Optical, Near-IR, and X-Ray Observations of SN 2015J and Its Host Galaxy
Boutsia, K.; Testa, V.; Nucita, A. A. +7 more
SN 2015J was discovered on 2015 April 27th and is classified as an SN IIn. At first, it appeared to be an orphan SN candidate, I.e., without any clear identification of its host galaxy. Here, we present an analysis of the observations carried out by the VLT 8 m class telescope with the FORS2 camera in the R band and the Magellan telescope (6.5 m) …
Nonlinear effects associated with kinetic Alfvén wave in magnetic islands
Sharma, R. P.; Sharma, Swati; Yadav, Nitin +1 more
Observations show that kinetic Alfvén waves (KAWs) play a very important role in turbulence as well as in magnetic reconnection and have also been a topic of debate in the context of particle heating. In this paper, we aim to investigate the effect of magnetic islands on the dynamics of the nonlinear KAW. The formation of current sheet/coherent st…
High-resolution spectral analysis of unevenly spaced data using a regularization approach
Seghouani, N.
The problem of estimating the power spectrum of unevenly spaced time series is considered. Indeed, this problem is quite common in ground-based astronomy, and the use of classical methods leads to aliased frequency detection. Moreover, the spectral resolution is limited by the observation time (Shannon-Nyquist law). We propose a regularized method…
Method of frequency dependent correlations: investigating the variability of total solar irradiance
Pelt, J.; Käpylä, M. J.; Olspert, N.
Context. This paper contributes to the field of modeling and hindcasting of the total solar irradiance (TSI) based on different proxy data that extend further back in time than the TSI that is measured from satellites.
Aims: We introduce a simple method to analyze persistent frequency-dependent correlations (FDCs) between the time series and …
Luminosity Dependence of the Covering Factor of the Dust Torus in Active Galactic Nuclei Revealed by Akari
Oyabu, Shinki; Ohyama, Youichi; Takita, Satoshi +7 more
Hubble COS Spectroscopy of the Dwarf Nova CW Mon: The White Dwarf in Quiescence?
Szkody, Paula; Sion, Edward M.; Godon, Patrick +4 more
We present a synthetic spectral analysis of the HST COS spectrum of the U Geminorum-type dwarf nova CW Mon, taken during quiescence as part of our COS survey of accreting white dwarfs (WDs) in Cataclysmic Variables. We use a synthetic photosphere and optically thick accretion disk spectra to model the COS spectrum as well as archival IUE spectra o…
XMM-Newton: Status and scientific perspective
Schartel, N.; Jansen, F.; Ward, M. J.
Over the last 50 years, X-ray astronomy has become firmly established as an essential window on the universe. We review some selected scientific highlights based on observations made with XMM-Newton during the most recent few years of its 16-year operation. These range from studies of objects in our solar system to topics in cosmology. Now, as the…