Search Publications
Carrington cycle 24: the solar chromospheric emission in a historical and stellar perspective
Schmitt, J. H. M. M.; Schröder, K. -P.; Mittag, M. +3 more
We present the solar S-index record of cycle 24, obtained by the Telescopio Internacional de Guanajuato, Robotico Espectroscopico robotic telescope facility and its high-resolution spectrograph HEROS (R ≈ 20 000), which measures the solar chromospheric Ca II H&K line emission by using moonlight. Our calibration process uses the same set of sta…
CCD astrometric observations of Amalthea and Thebe in the Gaia era
Colas, F.; Saquet, E.; Robert, V. +1 more
In the framework of the 2014-2015 campaign of mutual events, we observed Jupiter's inner satellites Amalthea (JV) and Thebe (JXIV). We focused on estimating whether the positioning accuracy determined from direct astrometry could compete with that derived from photometric observations of eclipses, for dynamical purposes. We present the analysis of…
Comparison of Gaia and asteroseismic distances
Roth, M.; Örtel, S.; Yıldız, M. +1 more
Asteroseismology provides fundamental properties (mass, radius and effective temperature) of solar-like oscillating stars using so-called scaling relations. These properties allow the computation of the asteroseismic distance of stars. We compare the asteroseismic distances with the recently released Gaia distances for 74 stars studied in Yıldız e…
The mass distribution of the unusual merging cluster Abell 2146 from strong lensing
Baum, Stefi A.; O'Dea, Christopher P.; McNamara, Brian R. +11 more
Abell 2146 consists of two galaxy clusters that have recently collided close to the plane of the sky, and it is unique in showing two large shocks on Chandra X-ray Observatory images. With an early stage merger, shortly after first core passage, one would expect the cluster galaxies and the dark matter to be leading the X-ray emitting plasma. In t…
XMM-Newton observations of the peculiar cataclysmic variable Lanning 386: X-ray evidence for a magnetic primary
Garnavich, P. M.; Kennedy, M. R.; Fausnaugh, M. +2 more
We present the first X-ray observations of the eclipsing cataclysmic variables Lanning 386 and MASTER OTJ192328.22+612413.5, possible SW Sextantis systems. The X-ray light curve of Lanning 386 shows deep eclipses, similar to the eclipses seen in the optical light curve, confirming the high inclination of the system. There is evidence of a periodic…
Three-dimensional Monte Carlo dust radiative transfer study of the H-poor planetary nebula IRAS 18333-2357 located in M22
Muthumariappan, C.
We analyse the characteristics of dust and its distribution in the planetary nebula IRAS 18333-2357 located in M22 using a three-dimensional radiative transfer code Hochunk3D. The spectral energy distribution was constructed using ultraviolet, optical and infrared archival data. We also have used Spitzer 8-µm and Wide-field Infrared Survey E…
Modelling the effect of absorption from the interstellar medium on transient black hole X-ray binaries
Vaughan, S.; Wynn, G. A.; Eckersall, A. J.
All observations of Galactic X-ray binaries are affected by absorption from gas and dust in the interstellar medium (ISM) which imprints narrow (line) and broad (photoelectric edges) features on the continuum emission spectrum of the binary. Any spectral model used to fit data from a Galactic X-ray binary must therefore take account of these featu…
Hot DA white dwarf model atmosphere calculations: including improved Ni PI cross-sections
Barstow, M. A.; Holberg, J. B.; Hubeny, I. +2 more
To calculate realistic models of objects with Ni in their atmospheres, accurate atomic data for the relevant ionization stages need to be included in model atmosphere calculations. In the context of white dwarf stars, we investigate the effect of changing the Ni IV-VI bound-bound and bound-free atomic data on model atmosphere calculations. Models …
Multiwavelength monitoring of a very active dwarf nova AX J1549.8-5416 with an unusually high duty cycle
Gelfand, Joseph D.; Bernardini, Federico; Lewis, Fraser +5 more
We present the results of our analysis of new optical, ultraviolet (UV) and X-ray observations of a highly variable source - AX J1549.8-5416. Both the detection of several fast rise, exponential decay outbursts in the optical light curve and the lack of He II emission lines in the optical spectra suggest AX J1549.8-5416 is a cataclysmic variable o…
Cross-calibration of the Rosetta Navigation Camera based on images of the 67P comet nucleus
Statella, Thiago; Geiger, Bernhard
The Rosetta spacecraft carried a Navigation Camera (NavCam) for optical navigation in the vicinity of the comet. In order to facilitate the use of the data for quantitative scientific work, we performed a cross-calibration study based on images taken with the OSIRIS near-angle camera. For this purpose, we selected sets of images acquired roughly s…